.. This work is licensed under a Creative Commons Attribution 4.0 International License. .. SPDX-License-Identifier: CC-BY-4.0 .. CAUTION: this document is generated from source in doc/src/rtd. .. To make changes edit the source and recompile the document. .. Do NOT make changes directly to .rst or .md files. RMR User's Guide ============================================================================================ The RIC Message Router (RMR) is a library which applications use to send and receive messages where the message routing, endpoint selection, is based on the message type rather than on traditional DNS names or IP addresses. Because the user documentation for RMR is a collection of UNIX manpages (included in the development package, and available via the man command when installed), there is no separate "User's Guide." To provide something for the document scrapers to find, this is a collection of the RMR manual pages formatted directly from their source which might be a bit ragged when combined into a single markup document. Read the manual pages :) NAME -------------------------------------------------------------------------------------------- rmr_alloc_msg SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_alloc_msg( void* ctx, int size ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_alloc_msg function is used to allocate a buffer which the user programme can write into and then send through the RMR library. The buffer is allocated such that sending it requires no additional copying out of the buffer. If the value passed in size is 0, then the default size supplied on the *rmr_init* call will be used. The *ctx* parameter is the void context pointer that was returned by the *rmr_init* function. The pointer to the message buffer returned is a structure which has some user application visible fields; the structure is described in rmr.h, and is illustrated below. :: typedef struct { int state; int mtype; int len; unsigned char* payload; unsigned char* xaction; uint sub_id; uint tp_state; } rmr_mbuf_t; state Is the current buffer state. Following a call to rmr_send_msg the state indicates whether the buffer was successfully sent which determines exactly what the payload points to. If the send failed, the payload referenced by the buffer is the message that failed to send (allowing the application to attempt a retransmission). When the state is RMR_OK the buffer represents an empty buffer that the application may fill in in preparation to send. mtype When sending a message, the application is expected to set this field to the appropriate message type value (as determined by the user programme). Upon send this value determines how the RMR library will route the message. For a buffer which has been received, this field will contain the message type that was set by the sending application. len The application using a buffer to send a message is expected to set the length value to the actual number of bytes that it placed into the message. This is likely less than the total number of bytes that the message can carry. For a message buffer that is passed to the application as the result of a receive call, this will be the value that the sending application supplied and should indicate the number of bytes in the payload which are valid. payload The payload is a pointer to the actual received data. The user programme may read and write from/to the memory referenced by the payload up until the point in time that the buffer is used on a rmr_send, rmr_call or rmr_reply function call. Once the buffer has been passed back to a RMR library function the user programme should **NOT** make use of the payload pointer. xaction The *xaction* field is a pointer to a fixed sized area in the message into which the user may write a transaction ID. The ID is optional with the exception of when the user application uses the rmr_call function to send a message and wait for the reply; the underlying RMR processing expects that the matching reply message will also contain the same data in the *xaction* field. sub_id This value is the subscription ID. It, in combination with the message type is used by rmr to determine the target endpoint when sending a message. If the application to application protocol does not warrant the use of a subscription ID, the RMR constant RMR_VOID_SUBID should be placed in this field. When an application is forwarding or returning a buffer to the sender, it is the application's responsibility to set/reset this value. tp_state For C applications making use of RMR, the state of a transport based failure will often be available via errno. However, some wrapper environments may not have direct access to the C-lib errno value. RMR send and receive operations will place the current value of errno into this field which should make it available to wrapper functions. User applications are strongly cautioned against relying on the value of errno as some transport mechanisms may not set this value on all calls. This value should also be ignored any time the message status is RMR_OK. RETURN VALUE -------------------------------------------------------------------------------------------- The function returns a pointer to a rmr_mbuf structure, or NULL on error. ERRORS -------------------------------------------------------------------------------------------- ENOMEM Unable to allocate memory. SEE ALSO -------------------------------------------------------------------------------------------- rmr_tralloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_init_trace(3), rmr_get_trace(3), rmr_get_trlen(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_set_trace(3) NAME -------------------------------------------------------------------------------------------- rmr_bytes2meid SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_bytes2meid( rmr_mbuf_t* mbuf, unsigned char* src, int len ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_bytes2meid function will copy up to *len* butes from *src* to the managed entity ID (meid) field in the message. The field is a fixed length, gated by the constant RMR_MAX_MEID and if len is larger than this value, only RMR_MAX_MEID bytes will actually be copied. RETURN VALUE -------------------------------------------------------------------------------------------- On success, the actual number of bytes copied is returned, or -1 to indicate a hard error. If the length is less than 0, or not the same as length passed in, errno is set to one of the errors described in the *Errors* section. ERRORS -------------------------------------------------------------------------------------------- If the returned length does not match the length passed in, errno will be set to one of the following constants with the meaning listed below. EINVAL The message, or an internal portion of the message, was corrupted or the pointer was invalid. EOVERFLOW The length passed in was larger than the maximum length of the field; only a portion of the source bytes were copied. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_bytes2xact(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_meid(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_bytes2payload SYNOPSIS -------------------------------------------------------------------------------------------- :: #include void rmr_bytes2payload( rmr_mbuf_t* mbuf, unsigned char* src, int len ) DESCRIPTION -------------------------------------------------------------------------------------------- This is a convenience function as some wrapper languages might not have the ability to directly copy into the payload buffer. The bytes from *src* for the length given are copied to the payload. It is the caller's responsibility to ensure that the payload is large enough. Upon successfully copy, the len field in the message buffer is updated to reflect the number of bytes copied. There is little error checking, and no error reporting. RETURN VALUE -------------------------------------------------------------------------------------------- None. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_bytes2xact(3), rmr_bytes2payload(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_meid(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_bytes2xact SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_bytes2xact( rmr_mbuf_t* mbuf, unsigned char* src, int len ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_bytes2xact function will copy up to *len* butes from *src* to the transaction ID (xaction) field in the message. The field is a fixed length, gated by the constant RMR_MAX_XID and if len is larger than this value, only RMR_MAX_XID bytes will actually be copied. RETURN VALUE -------------------------------------------------------------------------------------------- On success, the actual number of bytes copied is returned, or -1 to indicate a hard error. If the length is less than 0, or not the same as length passed in, errno is set to one of the errors described in the *Errors* section. ERRORS -------------------------------------------------------------------------------------------- If the returned length does not match the length passed in, errno will be set to one of the following constants with the meaning listed below. EINVAL The message, or an internal portion of the message, was corrupted or the pointer was invalid. EOVERFLOW The length passed in was larger than the maximum length of the field; only a portion of the source bytes were copied. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_bytes2meid(3), rmr_call(3), rmr_free_msg(3), rmr_get_meid(3), rmr_get_rcvfd(3), rmr_get_xact(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_call SYNOPSIS -------------------------------------------------------------------------------------------- :: #include extern rmr_mbuf_t* rmr_call( void* vctx, rmr_mbuf_t* msg ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_call function sends the user application message to a remote endpoint, and waits for a corresponding response message before returning control to the user application. The user application supplies a completed message buffer, as it would for a rmr_send call, but unlike with the send, the buffer returned will have the response from the application that received the message. Messages which are received while waiting for the response are queued internally by RMR, and are returned to the user application when rmr_rcv_msg is invoked. These messages are returned in th order received, one per call to rmr_rcv_msg. Call Timeout ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The rmr_call function implements a timeout failsafe to prevent, in most cases, the function from blocking forever. The timeout period is **not** based on time (calls to clock are deemed too expensive for a low latency system level library, but instead the period is based on the number of received messages which are not the response. Using a non-time mechanism for *timeout* prevents the async queue from filling (which would lead to message drops) in an environment where there is heavy message traffic. When the threshold number of messages have been queued without receiving a response message, control is returned to the user application and a NULL pointer is returned to indicate that no message was received to process. Currently the threshold is fixed at 20 messages, though in future versions of the library this might be extended to be a parameter which the user application may set. Retries ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The send operations in RMr will retry *soft* send failures until one of three conditions occurs: 1. The message is sent without error 2. The underlying transport reports a * hard * failure 3. The maximum number of retry loops has been attempted A retry loop consists of approximately 1000 send attemps ** without** any intervening calls to * sleep() * or * usleep(). * The number of retry loops defaults to 1, thus a maximum of 1000 send attempts is performed before returning to the user application. This value can be set at any point after RMr initialisation using the * rmr_set_stimeout() * function allowing the user application to completely disable retires (set to 0), or to increase the number of retry loops. Transport Level Blocking ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The underlying transport mechanism used to send messages is configured in *non-blocking* mode. This means that if a message cannot be sent immediately the transport mechanism will **not** pause with the assumption that the inability to send will clear quickly (within a few milliseconds). This means that when the retry loop is completely disabled (set to 0), that the failure to accept a message for sending by the underlying mechanisms (software or hardware) will be reported immediately to the user application. It should be noted that depending on the underlying transport mechanism being used, it is extremly possible that during normal operations that retry conditions are very likely to happen. These are completely out of RMr's control, and there is nothing that RMr can do to avoid or midigate these other than by allowing RMr to retry the send operation, and even then it is possible (e.g. during connection reattempts), that a single retry loop is not enough to guarentee a successful send. RETURN VALUE -------------------------------------------------------------------------------------------- The rmr_call function returns a pointer to a message buffer with the state set to reflect the overall state of call processing (see Errors below). In some cases a NULL pointer will be returned; when this is the case only *errno* will be available to describe the reason for failure. ERRORS -------------------------------------------------------------------------------------------- These values are reflected in the state field of the returned message. RMR_OK The call was successful and the message buffer references the response message. RMR_ERR_CALLFAILED The call failed and the value of *errno,* as described below, should be checked for the specific reason. The global "variable" *errno* will be set to one of the following values if the overall call processing was not successful. ETIMEDOUT Too many messages were queued before receiving the expected response ENOBUFS The queued message ring is full, messages were dropped EINVAL A parameter was not valid EAGAIN The underlying message system wsa interrupted or the device was busy; the message was **not** sent, and user application should call this function with the message again. EXAMPLE -------------------------------------------------------------------------------------------- The following code bit shows one way of using the rmr_call function, and illustrates how the transaction ID must be set. :: int retries_left = 5; // max retries on dev not available int retry_delay = 50000; // retry delay (usec) static rmr_mbuf_t* mbuf = NULL; // response msg msg_t* pm; // private message (payload) m// get a send buffer and reference the payload mbuf = rmr_alloc_msg( mr, RMR_MAX_RCV_BYTES ); pm = (msg_t*) mbuf->payload; p// generate an xaction ID and fill in payload with data and msg type snprintf( mbuf->xaction, RMR_MAX_XID, "%s", gen_xaction() ); snprintf( pm->req, sizeof( pm->req ), "{ \\"req\\": \\"num users\\"}" ); mbuf->mtype = MT_REQ; msg = rmr_call( mr, msg ); if( ! msg ) { // probably a timeout and no msg received return NULL; // let errno trickle up } if( mbuf->state != RMR_OK ) { while( retries_left-- > 0 && // loop as long as eagain errno == EAGAIN && (msg = rmr_call( mr, msg )) != NULL && mbuf->state != RMR_OK ) { usleep( retry_delay ); } if( mbuf == NULL || mbuf->state != RMR_OK ) { rmr_free_msg( mbuf ); // safe if nil return NULL; } } // do something with mbuf SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_free_msg(3), rmr_init(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_set_stimeout(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_wh_open SYNOPSIS -------------------------------------------------------------------------------------------- :: #include void rmr_close( void* vctx ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_close function closes the listen socket effectively cutting the application off. The route table listener is also stopped. Calls to rmr_rcv_msg() will fail with unpredictable error codes, and calls to rmr_send_msg(), rmr_call(), and rmr_rts_msg() will have unknown results. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_free_msg SYNOPSIS -------------------------------------------------------------------------------------------- :: #include void rmr_free_msg( rmr_mbuf_t* mbuf ); DESCRIPTION -------------------------------------------------------------------------------------------- The message buffer is returned to the pool, or the associated memory is released depending on the needs of the underlying messaging system. This allows the user application to release a buffer that is not going to be used. It is safe to pass a nil pointer to this function, and doing so does not result in a change to the value of errrno. After calling, the user application should **not** use any of the pointers (transaction ID, or payload) which were available. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_init(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_get_meid SYNOPSIS -------------------------------------------------------------------------------------------- :: #include char* rmr_get_meid( rmr_mbuf_t* mbuf, unsigned char* dest ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_get_meid function will copy the managed entity ID (meid) field from the message into the *dest* buffer provided by the user. The buffer referenced by *dest* is assumed to be at least RMR_MAX_MEID bytes in length. If *dest* is NULL, then a buffer is allocated (the calling application is expected to free when the buffer is no longer needed). RETURN VALUE -------------------------------------------------------------------------------------------- On success, a pointer to the extracted string is returned. If *dest* was supplied, then this is just a pointer to the caller's buffer. If *dest* was NULL, this is a pointer to the allocated buffer. If an error occurs, a nil pointer is returned and errno is set as described below. ERRORS -------------------------------------------------------------------------------------------- If an error occurs, the value of the global variable errno will be set to one of the following with the indicated meaning. EINVAL The message, or an internal portion of the message, was corrupted or the pointer was invalid. ENOMEM A nil pointer was passed for *dest,* however it was not possible to allocate a buffer using malloc(). SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_bytes2xact(3), rmr_bytes2meid(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_xact(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_get_rcvfd SYNOPSIS -------------------------------------------------------------------------------------------- :: #include void* rmr_get_rcvfd( void* ctx ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_get_rcvfd function returns a file descriptor which may be given to epoll_wait() by an application that wishes to use event poll in a single thread rather than block on the arrival of a message via calls to rmr_rcv_msg(). When epoll_wait() indicates that this file descriptor is ready, a call to rmr_rcv_msg() will not block as at least one message has been received. The context (ctx) pointer passed in is the pointer returned by the call to rmr_init(). **NOTE:** There is no support for epoll in Nanomsg, thus his function is only supported when linking with the NNG version of RMr and the file descriptor returned when using the Nanomsg verfsion will always return an error. RETURN VALUE -------------------------------------------------------------------------------------------- The rmr_get_rcvfd function returns a file descriptor greater or equal to 0 on success and -1 on error. If this function is called from a user application linked against the Nanomsg RMr library, calls will always return -1 with errno set to EINVAL. ERRORS -------------------------------------------------------------------------------------------- The following error values are specifically set by this RMR function. In some cases the error message of a system call is propagated up, and thus this list might be incomplete. EINVAL The use of this function is invalid in this environment. EXAMPLE -------------------------------------------------------------------------------------------- The following short code bit illustrates the use of this function. Error checking has been omitted for clarity. :: #include #include #include #include int main() { int rcv_fd; // pollable fd void* mrc; //msg router context struct epoll_event events[10]; // support 10 events to poll struct epoll_event epe; // event definition for event to listen to int ep_fd = -1; rmr_mbuf_t* msg = NULL; int nready; int i; mrc = rmr_init( "43086", RMR_MAX_RCV_BYTES, RMRFL_NONE ); rcv_fd = rmr_get_rcvfd( mrc ); rep_fd = epoll_create1( 0 ); _ B ,// initialise epoll environment epe.events = EPOLLIN; epe.data.fd = rcv_fd; epoll_ctl( ep_fd, EPOLL_CTL_ADD, rcv_fd, &epe ); // add our info to the mix while( 1 ) { nready = epoll_wait( ep_fd, events, 10, -1 ); // -1 == block forever (no timeout) for( i = 0; i < nready && i < 10; i++ ) { // loop through to find what is ready if( events[i].data.fd == rcv_fd ) { // RMr has something msg = rmr_rcv_msg( mrc, msg ); if( msg ) { // do something with msg } } // check for other ready fds.... } } } SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_get_src SYNOPSIS -------------------------------------------------------------------------------------------- :: #include unsigned char* rmr_get_src( rmr_mbuf_t* mbuf, unsigned char* dest ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_get_src function will copy the *source* information from the message to a buffer (dest) supplied by the user. In an RMr message, the source is the sender's information that is used for return to sender function calls, and is generally the hostname and port in the form *name*. The source might be an IP address port combination; the data is populated by the sending process and the only requirement is that it be capable of being used to start a TCP session with the sender. The maximum size allowed by RMr is 64 bytes (including the nil string terminator), so the user must ensure that the destination buffer given is at least 64 bytes. RETURN VALUE -------------------------------------------------------------------------------------------- On success, a pointer to the destination buffer is given as a convenience to the user programme. On failure, a nil pointer is returned and the value of errno is set. ERRORS -------------------------------------------------------------------------------------------- If an error occurs, the value of the global variable errno will be set to one of the following with the indicated meaning. EINVAL The message, or an internal portion of the message, was corrupted or the pointer was invalid. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_bytes2xact(3), rmr_bytes2meid(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_srcip(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_get_srcip SYNOPSIS -------------------------------------------------------------------------------------------- :: #include unsigned char* rmr_get_srcip( rmr_mbuf_t* mbuf, unsigned char* dest ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_get_srcip function will copy the *source IP address* from the message to a buffer (dest) supplied by the user. In an RMr message, the source IP address is the sender's information that is used for return to sender function calls; this function makes it available to the user application. The address is maintained as IP:port where *IP* could be either an IPv6 or IPv4 address depending on what was provided by the sending application. The maximum size allowed by RMr is 64 bytes (including the nil string terminator), so the user must ensure that the destination buffer given is at least 64 bytes. The user application should use the RMr constant RMR_MAX_SRC to ensure that the buffer supplied is large enough, and to protect against future RMr enhancements which might increase the address buffer size requirement. RETURN VALUE -------------------------------------------------------------------------------------------- On success, a pointer to the destination buffer is given as a convenience to the user programme. On failure, a nil pointer is returned and the value of errno is set. ERRORS -------------------------------------------------------------------------------------------- If an error occurs, the value of the global variable errno will be set to one of the following with the indicated meaning. EINVAL The message, or an internal portion of the message, was corrupted or the pointer was invalid. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_bytes2xact(3), rmr_bytes2meid(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_src(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_get_trace SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_get_trace( rmr_mbuf_t* mbuf, unsigned char* dest, int size ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_get_trace function will copy the trace information from the message into the user's allocated memory referenced by dest. The size parameter is assumed to be the maximum number of bytes which can be copied (size of the destination buffer). RETURN VALUE -------------------------------------------------------------------------------------------- On success, the number of bytes actually copied is returned. If the return value is 0, no bytes copied, then the reason could be that the message pointer was nil, or the size parameter was <= 0. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_tralloc_msg(3), rmr_bytes2xact(3), rmr_bytes2meid(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_trlen(3), rmr_init(3), rmr_init_trace(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3), rmr_set_trace(3), rmr_trace_ref(3) NAME -------------------------------------------------------------------------------------------- rmr_get_trlen SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_get_trlen( rmr_mbuf_t* msg ); DESCRIPTION -------------------------------------------------------------------------------------------- Given a message buffer, this function returns the amount of space (bytes) that have been allocated for trace data. If no trace data has been allocated, then 0 is returned. RETURN VALUE -------------------------------------------------------------------------------------------- The number of bytes allocated for trace information in the given message. ERRORS -------------------------------------------------------------------------------------------- INVAL Parameter(s) passed to the function were not valid. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_trace(3), rmr_init(3), rmr_init_trace(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_set_trace(3), rmr_tralloc_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_get_xact SYNOPSIS -------------------------------------------------------------------------------------------- :: #include char* rmr_get_xact( rmr_mbuf_t* mbuf, unsigned char* dest ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_get_xact function will copy the transaction field from the message into the *dest* buffer provided by the user. The buffer referenced by *dest* is assumed to be at least RMR_MAX_XID bytes in length. If *dest* is NULL, then a buffer is allocated (the calling application is expected to free when the buffer is no longer needed). RETURN VALUE -------------------------------------------------------------------------------------------- On success, a pointer to the extracted string is returned. If *dest* was supplied, then this is just a pointer to the caller's buffer. If *dest* was NULL, this is a pointer to the allocated buffer. If an error occurs, a nil pointer is returned and errno is set as described below. ERRORS -------------------------------------------------------------------------------------------- If an error occurs, the value of the global variable errno will be set to one of the following with the indicated meaning. EINVAL The message, or an internal portion of the message, was corrupted or the pointer was invalid. ENOMEM A nil pointer was passed for *dest,* however it was not possible to allocate a buffer using malloc(). SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_bytes2xact(3), rmr_bytes2meid(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_meid(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_init SYNOPSIS -------------------------------------------------------------------------------------------- :: #include void* rmr_init( char* proto_port, int max_msg_size, int flags ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_init function prepares the environment for sending and receiving messages. It does so by establishing a worker thread (pthread) which subscribes to a route table generator which provides the necessary routing information for the RMR library to send messages. *Port* is used to listen for connection requests from other RMR based applications. The *max_msg_size* parameter is used to allocate receive buffers and is the maximum message size which the application expects to receive. This value is the sum of **both** the maximum payload size **and** the maximum trace data size. This value is also used as the default message size when allocating message buffers. Messages arriving which are longer than the given maximum will be dropped without notification to the application. A warning is written to standard error for the first message which is too large on each connection. *Flags* allows for selection of some RMr options at the time of initialisation. These are set by ORing RMRFL constants from the RMr header file. Currently the following flags are supported: RMRFL_NONE No flags are set. RMRFL_NOTHREAD The route table collector thread is not to be started. This should only be used by the route table generator application if it is based on RMr. RMRFL_MTCALL Enable multi-threaded call support. &ditem Some underlying transport providers (e.g. SI95) enable locking to be turned off if the user application is single threaded, or otherwise can guarantee that RMR functions will not be invoked concurrently from different threads. Turning off locking can help make message receipt more efficient. If this flag is set when the underlying transport does not support disabling locks, it will be ignored. Multi-threaded Calling ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The support for an application to issue a *blocking call* by the rmr_call() function was limited such that only user applications which were operating in a single thread could safely use the function. Further, timeouts were message count based and not time unit based. Multi-threaded call support adds the ability for a user application with multiple threads to invoke a blocking call function with the guarantee that the correct response message is delivered to the thread. The additional support is implemented with the *rmr_mt_call()* and *rmr_mt_rcv()* function calls. Multi-threaded call support requires the user application to specifically enable it when RMr is initialised. This is necessary because a second, dedicated, receiver thread must be started, and requires all messages to be examined and queued by this thread. The additional overhead is minimal, queuing information is all in the RMr message header, but as an additional process is necessary the user application must "opt in" to this approach. ENVIRONMENT -------------------------------------------------------------------------------------------- As a part of the initialisation process rmr_init will look into the available environment variables to influence it's setup. The following variables will be used when found. RMR_SEED_RT Assumes this is the filename of the seed route table file to use. In normal situations, the library will wait for an update from the route table generator (expected within a few seconds of initialisation) before being able to send messages. However, in some situations where a bootstrap table is necessary, this is the means to supply it to the library. RMR_RTG_SVC The route table generator assumes that RMr is listening on a well known port (4561) by default, but this environment variable can be used to change the listening port if needed. The value of the variable is expected to be just the port. RETURN VALUE -------------------------------------------------------------------------------------------- The rmr_init function returns a void pointer (a contex if you will) that is passed as the first parameter to nearly all other RMR functions. If rmr_init is unable to properly initialise the environment, NULL is returned and errno is set to an appropriate value. ERRORS -------------------------------------------------------------------------------------------- The following error values are specifically set by this RMR function. In some cases the error message of a system call is propagated up, and thus this list might be incomplete. ENOMEM Unable to allocate memory. EXAMPLE -------------------------------------------------------------------------------------------- :: void* uh; rmr_mbuf* buf = NULL; uh = rmr_init( "43086", 4096, 0 ); buf = rmr_rcv_msg( uh, buf ); SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_mt_call(3), rmr_mt_rcv(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_init_trace SYNOPSIS -------------------------------------------------------------------------------------------- :: #include void* rmr_init_trace( void* ctx ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_init_trace function establishes the default trace space placed in each message buffer allocated with rmr_alloc_msg(). If this function is never called, then no trace space is allocated by default into any message buffer. Trace space allows the user application to pass some trace token, or other data with the message, but outside of the payload. Trace data may be added to any message with rmr_set_trace(), and may be extracted from a message with rmr_get_trace(). The number of bytes that a message contains for/with trace data can be determined by invoking rmr_get_trlen(). This function may be safely called at any time during the life of the user programme to (re)set the default trace space reserved. If the user programme needs to allocate a message with trace space of a different size than is allocated by default, without fear of extra overhead of reallocating a message later, the rmr_tralloc_msg() function can be used. RETURN VALUE -------------------------------------------------------------------------------------------- A value of 1 is returned on success, and 0 on failure. A failure indicates that the RMr context (a void pointer passed to this function was not valid. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_tr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_trace(3), rmr_get_trlen(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_set_trace(3) NAME -------------------------------------------------------------------------------------------- rmr_mt_call SYNOPSIS -------------------------------------------------------------------------------------------- :: #include extern rmr_mbuf_t* rmr_mt_call( void* vctx, rmr_mbuf_t* msg, int id, int timeout ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_mt_call function sends the user application message to a remote endpoint, and waits for a corresponding response message before returning control to the user application. The user application supplies a completed message buffer, as it would for a rmr_send_msg call, but unlike with a send, the buffer returned will have the response from the application that received the message. The thread invoking the *rmr_mt_call()* will block until a message arrives or until *timeout* milliseconds has passed; which ever comes first. Using a timeout value of zero (0) will cause the thread to block without a timeout. The *id* supplied as the third parameter is an integer in the range of 2 through 255 inclusive. This is a caller defined "thread number" and is used to match the response message with the correct user application thread. If the ID value is not in the proper range, the attempt to make the call will fail. Messages which are received while waiting for the response are queued on a *normal* receive queue and will be delivered to the user application with the next invocation of *rmr_mt_rcv()* or *rmr_rvv_msg().* by RMR, and are returned to the user application when rmr_rcv_msg is invoked. These messages are returned in th order received, one per call to rmr_rcv_msg. NOTE: Currently the multi-threaded functions are supported only when the NNG transport mechanism is being used. It will not be possible to link a programme using the Nanomsg version of the library when references to this function are present. The Transaction ID ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The user application is responsible for setting the value of the transaction ID field before invoking *rmr_mt_call.* The transaction ID is a RMR_MAX_XID byte field that is used to match the response message when it arrives. RMr will compare **all** of the bytes in the field, so the caller must ensure that they are set correctly to avoid missing the response message. (The application which returns the response message is also expected to ensure that the return buffer has the matching transaction ID. This can be done transparently if the application uses the *rmr_rts_msg()* function and does not adjust the transaction ID. Retries ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The send operations in RMr will retry *soft* send failures until one of three conditions occurs: 1. The message is sent without error 2. The underlying transport reports a * hard * failure 3. The maximum number of retry loops has been attempted A retry loop consists of approximately 1000 send attemps ** without** any intervening calls to * sleep() * or * usleep(). * The number of retry loops defaults to 1, thus a maximum of 1000 send attempts is performed before returning to the user application. This value can be set at any point after RMr initialisation using the * rmr_set_stimeout() * function allowing the user application to completely disable retires (set to 0), or to increase the number of retry loops. Transport Level Blocking ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The underlying transport mechanism used to send messages is configured in *non-blocking* mode. This means that if a message cannot be sent immediately the transport mechanism will **not** pause with the assumption that the inability to send will clear quickly (within a few milliseconds). This means that when the retry loop is completely disabled (set to 0), that the failure to accept a message for sending by the underlying mechanisms (software or hardware) will be reported immediately to the user application. It should be noted that depending on the underlying transport mechanism being used, it is extremly possible that during normal operations that retry conditions are very likely to happen. These are completely out of RMr's control, and there is nothing that RMr can do to avoid or midigate these other than by allowing RMr to retry the send operation, and even then it is possible (e.g. during connection reattempts), that a single retry loop is not enough to guarentee a successful send. RETURN VALUE -------------------------------------------------------------------------------------------- The rmr_mt_call function returns a pointer to a message buffer with the state set to reflect the overall state of call processing. If the state is RMR_OK then the buffer contains the response message; otherwise the state indicates the error encountered while attempting to send the message. If no response message is received when the timeout period has expired, a nil pointer will be returned (NULL). ERRORS -------------------------------------------------------------------------------------------- These values are reflected in the state field of the returned message. RMR_OK The call was successful and the message buffer references the response message. RMR_ERR_BADARG An argument passed to the function was invalid. RMR_ERR_CALLFAILED The call failed and the value of *errno,* as described below, should be checked for the specific reason. RMR_ERR_NOENDPT An endpoint associated with the message type could not be found in the route table. RMR_ERR_RETRY The underlying transport mechanism was unable to accept the message for sending. The user application can retry the call operation if appropriate to do so. The global "variable" *errno* will be set to one of the following values if the overall call processing was not successful. ETIMEDOUT Too many messages were queued before receiving the expected response ENOBUFS The queued message ring is full, messages were dropped EINVAL A parameter was not valid EAGAIN The underlying message system wsa interrupted or the device was busy; the message was **not** sent, and user application should call this function with the message again. EXAMPLE -------------------------------------------------------------------------------------------- The following code bit shows one way of using the rmr_mt_call function, and illustrates how the transaction ID must be set. :: int retries_left = 5; // max retries on dev not available static rmr_mbuf_t* mbuf = NULL; // response msg msg_t* pm; // private message (payload) m// get a send buffer and reference the payload mbuf = rmr_alloc_msg( mr, RMR_MAX_RCV_BYTES ); pm = (msg_t*) mbuf->payload; p// generate an xaction ID and fill in payload with data and msg type rmr_bytes2xact( mbuf, xid, RMR_MAX_XID ); snprintf( pm->req, sizeof( pm->req ), "{ \\"req\\": \\"num users\\"}" ); mbuf->mtype = MT_USR_RESP; msg = rmr_mt_call( mr, msg, my_id, 100 ); e :// wait up to 100ms if( ! msg ) { // probably a timeout and no msg received return NULL; // let errno trickle up } if( mbuf->state != RMR_OK ) { while( retries_left-- > 0 && // loop as long as eagain mbuf->state == RMR_ERR_RETRY && (msg = rmr_mt_call( mr, msg )) != NULL && mbuf->state != RMR_OK ) { usleep( retry_delay ); } if( mbuf == NULL || mbuf->state != RMR_OK ) { rmr_free_msg( mbuf ); // safe if nil return NULL; } } // do something with mbuf SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_free_msg(3), rmr_init(3), rmr_mt_rcv(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_set_stimeout(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_mt_rcv SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_mt_rcv( void* vctx, rmr_mbuf_t* old_msg, int timeout ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_mt_rcv function blocks until a message is received, or the timeout period (milliseconds) has passed. The result is an RMr message buffer which references a received message. In the case of a timeout the state will be reflected in an "empty buffer" (if old_msg was not nil, or simply with the return of a nil pointer. If a timeout value of zero (0) is given, then the function will block until the next message received. The *vctx* pointer is the pointer returned by the rmr_init function. *Old_msg* is a pointer to a previously used message buffer or NULL. The ability to reuse message buffers helps to avoid alloc/free cycles in the user application. When no buffer is available to supply, the receive function will allocate one. The *old_msg* parameter allows the user to pass a previously generated RMr message back to RMr for reuse. Optionally, the user application may pass a nil pointer if no reusable message is available. When a timeout occurs, and old_msg was not nil, the state will be returned by returning a pointer to the old message with the state set. It is possible to use the *rmr_rcv_msg()* function instead of this function. Doing so might be advantagous if the user programme does not always start the multi-threaded mode and the use of *rmr_rcv_msg()* would make the flow of the code more simple. The advantags of using this function are the ability to set a timeout without using epoll, and a small performance gain (if multi-threaded mode is enabled, and the *rmr_rcv_msg()* function is used, it simply invokes this function without a timeout value, thus there is the small cost of a second call that results). Similarly, the *rmr_torcv_msg()* call can be used when in multi-threaded mode with the same "pass through" overhead to using this function directly. NOTE: Currently the multi-threaded functions are supported only when the NNG transport mechanism is being used. It will not be possible to link a programme using the nanomsg version of the library when references to this function are present. RETURN VALUE -------------------------------------------------------------------------------------------- When a message is received before the timeout period expires, a pointer to the RMr message buffer which describes the message is returned. This will, with a high probability, be a different message buffer than *old_msg;* the user application should not continue to use *old_msg* after it is passed to this function. In the event of a timeout the return value will be the old msg with the state set, or a nil pointer if no old message was provided. ERRORS -------------------------------------------------------------------------------------------- The *state* field in the message buffer will be set to one of the following values: RMR_OK The message was received without error. RMR_ERR_BADARG A parameter passed to the function was not valid (e.g. a nil pointer). indicate either RMR_OK or RMR_ERR_EMPTY if an empty message was received. RMR_ERR_EMPTY The message received had no associated data. The length of the message will be 0. RMR_ERR_NOTSUPP The multi-threaded option was not enabled when RMr was initialised. See the man page for *rmr_init()* for details. RMR_ERR_RCVFAILED A hard error occurred preventing the receive from completing. When a nil pointer is returned, or any other state value was set in the message buffer, errno will be set to one of the following: INVAL Parameter(s) passed to the function were not valid. EBADF The underlying message transport is unable to process the request. ENOTSUP The underlying message transport is unable to process the request. EFSM The underlying message transport is unable to process the request. EAGAIN The underlying message transport is unable to process the request. EINTR The underlying message transport is unable to process the request. ETIMEDOUT The underlying message transport is unable to process the request. ETERM The underlying message transport is unable to process the request. EXAMPLE -------------------------------------------------------------------------------------------- :: rmr_mbuf_t* mbuf = NULL; // received msg msg = rmr_mt_recv( mr, mbuf, 100 ); // wait up to 100ms if( msg != NULL ) { switch( msg->state ) { case RMR_OK: printf( "got a good message\\n" ); break; case RMR_ERR_EMPTY: printf( "received timed out\\n" ); break; default: printf( "receive error: %d\\n", mbuf->state ); break; } } else { printf( "receive timeout (nil)\\n" ); } SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_init(3), rmr_mk_ring(3), rmr_mt_call(3), rmr_payload_size(3), rmr_send_msg(3), rmr_torcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_ring_free(3), rmr_torcv_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_payload_size SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_payload_size( rmr_mbuf_t* msg ); DESCRIPTION -------------------------------------------------------------------------------------------- Given a message buffer, this function returns the amount of space (bytes) available for the user application to consume in the message payload. This is different than the message length available as a field in the message buffer. RETURN VALUE -------------------------------------------------------------------------------------------- The number of bytes available in the payload. ERRORS -------------------------------------------------------------------------------------------- INVAL Parameter(s) passed to the function were not valid. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_rcv_msg SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_rcv_msg( void* vctx, rmr_mbuf_t* old_msg ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_rcv_msg function blocks until a message is received, returning the message to the caller via a pointer to a rmr_mbuf_t structure type. If messages were queued while waiting for the response to a previous invocation of rmr_call, the oldest message is removed from the queue and returned without delay. The *vctx* pointer is the pointer returned by the rmr_init function. *Old_msg* is a pointer to a previously used message buffer or NULL. The ability to reuse message buffers helps to avoid alloc/free cycles in the user application. When no buffer is available to supply, the receive function will allocate one. RETURN VALUE -------------------------------------------------------------------------------------------- The function returns a pointer to the rmr_mbuf_t structure which references the message information (state, length, payload), or a NULL pointer in the case of an extreme error. ERRORS -------------------------------------------------------------------------------------------- The *state* field in the message buffer will indicate either RMR_OK or RMR_ERR_EMPTY if an empty message was received. If a nil pointer is returned, or any other state value was set in the message buffer, errno will be set to one of the following: INVAL Parameter(s) passed to the function were not valid. EBADF The underlying message transport is unable to process the request. ENOTSUP The underlying message transport is unable to process the request. EFSM The underlying message transport is unable to process the request. EAGAIN The underlying message transport is unable to process the request. EINTR The underlying message transport is unable to process the request. ETIMEDOUT The underlying message transport is unable to process the request. ETERM The underlying message transport is unable to process the request. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_init(3), rmr_mk_ring(3), rmr_payload_size(3), rmr_send_msg(3), rmr_torcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_ring_free(3), rmr_torcv_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_ready SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_ready( void* vctx ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_ready function checks to see if a routing table has been successfully received and installed. The return value indicates the state of readiness. RETURN VALUE -------------------------------------------------------------------------------------------- A return value of 1 (true) indicates that the routing table is in place and attempts to send messages can be made. When 0 is returned (false) the routing table has not been received and thus attempts to send messages will fail with *no endpoint* errors. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_realloc_payload SYNOPSIS -------------------------------------------------------------------------------------------- :: #include extern rmr_mbuf_t* rmr_realloc_payload( rmr_mbuf_t* msg, int new_len, int copy, int clone ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_realloc_payload function will return a pointer to an RMR message buffer struct (rmr_mbuf_t) which has a payload large enough to accomodate *new_len* bytes. If necessary, the underlying payload is reallocated, and the bytes from the original payload are copied if the *copy* parameter is true (1). If the message passed in has a payload large enough, there is no additional memory allocation and copying. Cloning The Message Buffer ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This function can also be used to generate a separate copy of the original message, with the desired payload size, without destroying the original message buffer or the original payload. A standalone copy is made only when the *clone* parameter is true (1). When cloning, the payload is copied to the cloned message **only** if the *copy* parameter is true. Message Buffer Metadata ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The metadata in the original message buffer (message type, subscription ID, and payload length) will be preserved if the *copy* parameter is true. When this parameter is not true (0), then these values are set to the uninitialised value (-1) for type and ID, and the length is set to 0. RETURN VALUE -------------------------------------------------------------------------------------------- The rmr_realloc_payload function returns a pointer to the message buffer with the payload which is large enough to hold *new_len* bytes. If the *clone* option is true, this will be a pointer to the newly cloned message buffer; the original message buffer pointer may still be used to referenced that message. It is the calling application's responsibility to free the memory associateed with both messages using the rmr_free_msg() function. When the *clone* option is not used, it is still good practice by the calling application to capture and use this reference as it is possible that the message buffer, and not just the payload buffer, was reallocated. In the event of an error, a nil pointer will be returned and the value of *errno* will be set to reflect the problem. ERRORS -------------------------------------------------------------------------------------------- These value of *errno* will reflect the error condition if a nil pointer is returned: ENOMEM Memory allocation of the new payload failed. EINVAL The pointer passed in was nil, or refrenced an invalid message, or the required length was not valid. EXAMPLE -------------------------------------------------------------------------------------------- The following code bit illustrates how this function can be used to reallocate a buffer for a return to sender acknowledgement message which is larger than the message received. :: if( rmr_payload_size( msg ) < ack_sz ) { // received message too small for ack msg = rmr_realloc_payload( msg, ack_sz, 0, 0 ); // reallocate the message with a payload big enough if( msg == NULL ) { fprintf( stderr, "[ERR] realloc returned a nil pointer: %s\\n", strerror( errno ) ); } else { } e// populate and send ack message }} } SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_free_msg(3), rmr_init(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_set_stimeout(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_rts_msg SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_rts_msg( void* vctx, rmr_mbuf_t* msg ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_rts_msg function sends a message returning it to the endpoint which sent the message rather than selecting an endpoint based on the message type and routing table. Other than this small difference, the behaviour is exactly the same as rmr_send_msg. Retries ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The send operations in RMr will retry *soft* send failures until one of three conditions occurs: 1. The message is sent without error 2. The underlying transport reports a * hard * failure 3. The maximum number of retry loops has been attempted A retry loop consists of approximately 1000 send attemps ** without** any intervening calls to * sleep() * or * usleep(). * The number of retry loops defaults to 1, thus a maximum of 1000 send attempts is performed before returning to the user application. This value can be set at any point after RMr initialisation using the * rmr_set_stimeout() * function allowing the user application to completely disable retires (set to 0), or to increase the number of retry loops. Transport Level Blocking ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The underlying transport mechanism used to send messages is configured in *non-blocking* mode. This means that if a message cannot be sent immediately the transport mechanism will **not** pause with the assumption that the inability to send will clear quickly (within a few milliseconds). This means that when the retry loop is completely disabled (set to 0), that the failure to accept a message for sending by the underlying mechanisms (software or hardware) will be reported immediately to the user application. It should be noted that depending on the underlying transport mechanism being used, it is extremly possible that during normal operations that retry conditions are very likely to happen. These are completely out of RMr's control, and there is nothing that RMr can do to avoid or midigate these other than by allowing RMr to retry the send operation, and even then it is possible (e.g. during connection reattempts), that a single retry loop is not enough to guarentee a successful send. PAYLOAD SIZE -------------------------------------------------------------------------------------------- When crafting a response based on a received message, the user application must take care not to write more bytes to the message payload than the allocated message has. In the case of a received message, it is possible that the response needs to be larger than the payload associated with the inbound message. In order to use the return to sender function, the source infomration in the orignal message must be present in the response; information which cannot be added to a message buffer allocated through the standard RMR allocation function. To allocate a buffer with a larger payload, and which retains the necessary sender data needed by this function, the *rmr_realloc_payload()* function must be used to extend the payload to a size suitable for the response. RETURN VALUE -------------------------------------------------------------------------------------------- On success, a new message buffer, with an empty payload, is returned for the application to use for the next send. The state in this buffer will reflect the overall send operation state and should be RMR_OK. If the state in the returned buffer is anything other than UT_OK, the user application may need to attempt a retransmission of the message, or take other action depending on the setting of errno as described below. In the event of extreme failure, a NULL pointer is returned. In this case the value of errno might be of some use, for documentation, but there will be little that the user application can do other than to move on. ERRORS -------------------------------------------------------------------------------------------- The following values may be passed back in the *state* field of the returned message buffer. RMR_ERR_BADARG The message buffer pointer did not refer to a valid message. RMR_ERR_NOHDR The header in the message buffer was not valid or corrupted. RMR_ERR_NOENDPT The message type in the message buffer did not map to a known endpoint. RMR_ERR_SENDFAILED The send failed; errno has the possible reason. The following values may be assigned to errno on failure. INVAL Parameter(s) passed to the function were not valid, or the underlying message processing environment was unable to interpret the message. ENOKEY The header information in the message buffer was invalid. ENXIO No known endpoint for the message could be found. EMSGSIZE The underlying transport refused to accept the message because of a size value issue (message was not attempted to be sent). EFAULT The message referenced by the message buffer is corrupt (NULL pointer or bad internal length). EBADF Internal RMR error; information provided to the message transport environment was not valid. ENOTSUP Sending was not supported by the underlying message transport. EFSM The device is not in a state that can accept the message. EAGAIN The device is not able to accept a message for sending. The user application should attempt to resend. EINTR The operation was interrupted by delivery of a signal before the message was sent. ETIMEDOUT The underlying message environment timed out during the send process. ETERM The underlying message environment is in a shutdown state. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_set_stimeout(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_send_msg SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_send_msg( void* vctx, rmr_mbuf_t* msg ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_send_msg function accepts a message buffer from the user application and attempts to send it. The destination of the message is selected based on the message type specified in the message buffer, and the matching information in the routing tables which are currently in use by the RMR library. This may actually result in the sending of the message to multiple destinations which could degrade expected overall performance of the user application. (Limiting excessive sending of messages is the responsibility of the application(s) responsible for building the routing table used by the RMR library, and not the responsibility of the library.) Retries ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The send operations in RMr will retry *soft* send failures until one of three conditions occurs: 1. The message is sent without error 2. The underlying transport reports a * hard * failure 3. The maximum number of retry loops has been attempted A retry loop consists of approximately 1000 send attemps ** without** any intervening calls to * sleep() * or * usleep(). * The number of retry loops defaults to 1, thus a maximum of 1000 send attempts is performed before returning to the user application. This value can be set at any point after RMr initialisation using the * rmr_set_stimeout() * function allowing the user application to completely disable retires (set to 0), or to increase the number of retry loops. Transport Level Blocking ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The underlying transport mechanism used to send messages is configured in *non-blocking* mode. This means that if a message cannot be sent immediately the transport mechanism will **not** pause with the assumption that the inability to send will clear quickly (within a few milliseconds). This means that when the retry loop is completely disabled (set to 0), that the failure to accept a message for sending by the underlying mechanisms (software or hardware) will be reported immediately to the user application. It should be noted that depending on the underlying transport mechanism being used, it is extremly possible that during normal operations that retry conditions are very likely to happen. These are completely out of RMr's control, and there is nothing that RMr can do to avoid or midigate these other than by allowing RMr to retry the send operation, and even then it is possible (e.g. during connection reattempts), that a single retry loop is not enough to guarentee a successful send. RETURN VALUE -------------------------------------------------------------------------------------------- On success, a new message buffer, with an empty payload, is returned for the application to use for the next send. The state in this buffer will reflect the overall send operation state and will be RMR_OK when the send was successful. When the message cannot be successfully sent this function will return the unsent (original) message buffer with the state set to indicate the reason for failure. The value of *errno* may also be set to reflect a more detailed failure reason if it is known. In the event of extreme failure, a NULL pointer is returned. In this case the value of errno might be of some use, for documentation, but there will be little that the user application can do other than to move on. **CAUTION:** In some cases it is extremely likely that the message returned by the send function does **not** reference the same memory structure. Thus is important for the user programme to capture the new pointer for future use or to be passed to rmr_free(). If you are experiencing either double free errors or segment faults in either rmr_free() or rmr_send_msg(), ensure that the return value from this function is being captured and used. ERRORS -------------------------------------------------------------------------------------------- The following values may be passed back in the *state* field of the returned message buffer. RMR_RETRY The message could not be sent, but the underlying transport mechanism indicates that the failure is temporary. If the send operation is tried again it might be successful. RMR_SEND_FAILED The send operation was not successful and the underlying transport mechanism indicates a permanent (hard) failure; retrying the send is not possible. RMR_ERR_BADARG The message buffer pointer did not refer to a valid message. RMR_ERR_NOHDR The header in the message buffer was not valid or corrupted. RMR_ERR_NOENDPT The message type in the message buffer did not map to a known endpoint. The following values may be assigned to errno on failure. INVAL Parameter(s) passed to the function were not valid, or the underlying message processing environment was unable to interpret the message. ENOKEY The header information in the message buffer was invalid. ENXIO No known endpoint for the message could be found. EMSGSIZE The underlying transport refused to accept the message because of a size value issue (message was not attempted to be sent). EFAULT The message referenced by the message buffer is corrupt (NULL pointer or bad internal length). EBADF Internal RMR error; information provided to the message transport environment was not valid. ENOTSUP Sending was not supported by the underlying message transport. EFSM The device is not in a state that can accept the message. EAGAIN The device is not able to accept a message for sending. The user application should attempt to resend. EINTR The operation was interrupted by delivery of a signal before the message was sent. ETIMEDOUT The underlying message environment timed out during the send process. ETERM The underlying message environment is in a shutdown state. EXAMPLE -------------------------------------------------------------------------------------------- The following is a simple example of how the rmr_send_msg function is called. In this example, the send message buffer is saved between calls and reused eliminating alloc/free cycles. :: static rmr_mbuf_t* send_msg = NULL; // message to send; reused on each call msg_t* send_pm; // payload for send msg_t* pm; // our message format in the received payload mif( send_msg == NULL ) { send_msg = rmr_alloc_msg( mr, MAX_SIZE ); r// new buffer to send } // reference payload and fill in message type pm = (msg_t*) send_msg->payload; send_msg->mtype = MT_ANSWER; msg->len = generate_data( pm ); // something that fills the payload in msg = rmr_send_msg( mr, send_msg ); // ensure new pointer used after send mif( ! msg ) { m !return ERROR; m} else { m sif( msg->state != RMR_OK ) { m s m// check for RMR_ERR_RETRY, and resend if needed m s m// else return error m s} m} mreturn OK; SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_payload_size(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_torcv_rcv(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_set_stimeout SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_set_stimeout( void* vctx, int rloops ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_set_stimeout function sets the configuration for how RMr will retry message send operations which complete with either a *timeout* or *again* completion value. (Send operations include all of the possible message send functions: *rmr_send_msg(), rmr_call(), rmr_rts_msg()* and *rmr_wh_send_msg().* The *rloops* parameter sets the maximum number of retry loops that will be attempted before giving up and returning the unsuccessful state to the user application. Each retry loop is approximately 1000 attempts, and RMr does **not** invoke any sleep function between retries in the loop; a small, 1 mu-sec, sleep is executed between loop sets if the *rloops* value is greater than 1. Disabling Retries ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ By default, the send operations will execute with an *rloop* setting of 1; each send operation will attempt to resend the message approximately 1000 times before giving up. If the user application does not want to have send operations retry when the underlying transport mechanism indicates *timeout* or *again,* the application should invoke this function and pass a value of 0 (zero) for *rloops.* With this setting, all RMr send operations will attempt a send operation only **once,** returning immediately to the caller with the state of that single attempt. RETURN VALUE -------------------------------------------------------------------------------------------- This function returns a -1 to indicate that the *rloops* value could not be set, and the value *RMR_OK* to indicate success. ERRORS -------------------------------------------------------------------------------------------- Currently errno is **not** set by this function; the only cause of a failure is an invalid context (*vctx*) pointer. EXAMPLE -------------------------------------------------------------------------------------------- The following is a simple example of how the rmr_set_stimeout function is called. :: #define NO_FLAGS 0 char* Oport = "43086"; // port for message router listen int rmax_size = 4096; // max message size for default allocations void* mr_context; // message router context mr_context = rmr_init( port, max_size, NO_FLAGS ); if( mr_context != NULL ) { rmr_set_stimeout( mr_context, 0 ); // turn off retries } SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_payload_size(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_send_msg(3), rmr_torcv_rcv(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_set_trace SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_bytes2payload( rmr_mbuf_t* mbuf, unsigned char* data, int len ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_set_trace function will copy len bytes from data into the trace portion of mbuf. If the trace area of mbuf is not the correct size, the message buffer will be reallocated to ensure that enough space is available for the trace data. RETURN VALUE -------------------------------------------------------------------------------------------- The rmr_set_trace function returns the number of bytes successfully copied to the message. If 0 is returned either the message pointer was nil, or the size in the parameters was <= 0. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_tralloc_msg(3), rmr_bytes2xact(3), rmr_bytes2payload(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_meid(3), rmr_get_trace(3), rmr_get_trlen(3), rmr_init(3), rmr_init_trace(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_str2meid SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_str2meid( rmr_mbuf_t* mbuf, unsigned char* src, int len ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_str2meid function will copy the string pointed to by src to the managed entity ID (meid) field in the given message. The field is a fixed length, gated by the constant RMR_MAX_MEID and if string length is larger than this value, then **nothing** will be copied. (Note, this differs slightly from the behaviour of the lrmr_bytes2meid() function.) RETURN VALUE -------------------------------------------------------------------------------------------- On success, the value RMR_OK is returned. If the string cannot be copied to the message, the return value will be one of the errors listed below. ERRORS -------------------------------------------------------------------------------------------- If the return value is not RMR_OK, then it will be set to one of the values below. RMR_ERR_BADARG The message, or an internal portion of the message, was corrupted or the pointer was invalid. RMR_ERR_OVERFLOW The length passed in was larger than the maximum length of the field; only a portion of the source bytes were copied. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_meid(3), rmr_get_rcvfd(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_bytes2meid(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_str2xact SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_str2xact( rmr_mbuf_t* mbuf, unsigned char* src, int len ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_str2xact function will copy the string pointed to by src to the transaction ID (xaction) field in the given message. The field is a fixed length, gated by the constant RMR_MAX_XID and if string length is larger than this value, then **nothing** will be copied. (Note, this differs slightly from the behaviour of the lrmr_bytes2xact() function.) RETURN VALUE -------------------------------------------------------------------------------------------- On success, the value RMR_OK is returned. If the string cannot be copied to the message, the return value will be one of the errors listed below. ERRORS -------------------------------------------------------------------------------------------- If the return value is not RMR_OK, then it will be set to one of the values below. RMR_ERR_BADARG The message, or an internal portion of the message, was corrupted or the pointer was invalid. RMR_ERR_OVERFLOW The length passed in was larger than the maximum length of the field; only a portion of the source bytes were copied. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_bytes2meid(3), rmr_bytes2xact(3), rmr_call(3), rmr_free_msg(3), rmr_get_meid(3), rmr_get_rcvfd(3), rmr_get_xact(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- RMR support functions SYNOPSIS -------------------------------------------------------------------------------------------- :: #include #include char* rmr_fib( char* fname ); int rmr_has_str( char const* buf, char const* str, char sep, int max ); int rmr_tokenise( char* buf, char** tokens, int max, char sep ); void* rmr_mk_ring( int size ); void rmr_ring_free( void* vr ); static inline void* rmr_ring_extract( void* vr ) static inline int rmr_ring_insert( void* vr, void* new_data ) DESCRIPTION -------------------------------------------------------------------------------------------- These functions support the RMR library, and are made available to user applications as some (e.g. route table generators) might need and/or want to make use of them. The rmr_fib function accepts a file name and reads the entire file into a single buffer. The intent is to provide an easy way to load a static route table without a lot of buffered I/O hoops. The rmr_has_str function accepts a *buffer* containing a set of delimited tokens (e.g. foo,bar,goo) and returns true if the target string, *str,* matches one of the tokens. The *sep* parameter provides the separation character in the buffer (e.g a comma) and *max* indicates the maximum number of tokens to split the buffer into before checking. The rmr_tokenise function is a simple tokeniser which splits *buf* into tokens at each occurrence of *sep*. Multiple occurrences of the separator character (e.g. a,,b) result in a nil token. Pointers to the tokens are placed into the *tokens* array provided by the caller which is assumed to have at least enough space for *max* entries. The rmr_mk_ring function creates a buffer ring with *size* entries. The rmr_ring_free function accepts a pointer to a ring context and frees the associated memory. The rmr_ring_insert and rmr_ring_extract functions are provided as static inline functions via the *rmr/ring_inline.h* header file. These functions both accept the ring *context* returned by mk_ring, and either insert a pointer at the next available slot (tail) or extract the data at the head. RETURN VALUES -------------------------------------------------------------------------------------------- The following are the return values for each of these functions. The rmr_fib function returns a pointer to the buffer containing the contents of the file. The buffer is terminated with a single nil character (0) making it a legitimate C string. If the file was empty or nonexistent, a buffer with an immediate nil character. If it is important to the calling programme to know if the file was empty or did not exist, the caller should use the system stat function call to make that determination. The rmr_has_str function returns 1 if *buf* contains the token referenced by &ita and false (0) if it does not. On error, a -1 value is returned and errno is set accordingly. The rmr_tokenise function returns the actual number of token pointers placed into *tokens* The rmr_mk_ring function returns a void pointer which is the *context* for the ring. The rmr_ring_insert function returns 1 if the data was successfully inserted into the ring, and 0 if the ring is full and the pointer could not be deposited. The rmr_ring_extract will return the data which is at the head of the ring, or NULL if the ring is empty. ERRORS -------------------------------------------------------------------------------------------- Not many of these functions set the value in errno, however the value may be one of the following: INVAL Parameter(s) passed to the function were not valid. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), NAME -------------------------------------------------------------------------------------------- rmr_torcv_msg SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_torcv_msg( void* vctx, rmr_mbuf_t* old_msg, int ms_to ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_torcv_msg function will pause for *ms_to* milliseconds waiting for a message to arrive. If a message arrives before the timeout expires the message buffer returned will have a status of RMR_OK and the payload will contain the data received. If the timeout expires before the message is received, the status will have the value RMR_ERR_TIMEOUT. When a received message is returned the message buffer will also contain the message type and length set by the sender. If messages were queued while waiting for the response to a previous invocation of rmr_call, the oldest message is removed from the queue and returned without delay. The *vctx* pointer is the pointer returned by the rmr_init function. *Old_msg* is a pointer to a previously used message buffer or NULL. The ability to reuse message buffers helps to avoid alloc/free cycles in the user application. When no buffer is available to supply, the receive function will allocate one. RETURN VALUE -------------------------------------------------------------------------------------------- The function returns a pointer to the rmr_mbuf_t structure which references the message information (state, length, payload), or a NULL pointer in the case of an extreme error. ERRORS -------------------------------------------------------------------------------------------- The *state* field in the message buffer will be one of the following: RMR_OK The message buffer (payload) references the received data. RMR_ERR_INITFAILED The first call to this function must initialise an underlying system notification mechanism. On failure, this error is returned and errno will have the system error status set. If this function fails to intialise, the poll mechansim, it is likely that message receives will never be successful. RMR_ERR_TIMEOUT The timeout expired before a complete message was received. All other fields in the message buffer are not valid. RMR_ERR_EMPTY A message was received, but it had no payload. All other fields in the message buffer are not valid. INVAL Parameter(s) passed to the function were not valid. EBADF The underlying message transport is unable to process the request. ENOTSUP The underlying message transport is unable to process the request. EFSM The underlying message transport is unable to process the request. EAGAIN The underlying message transport is unable to process the request. EINTR The underlying message transport is unable to process the request. ETIMEDOUT The underlying message transport is unable to process the request. ETERM The underlying message transport is unable to process the request. EXAMPLE -------------------------------------------------------------------------------------------- SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_init(3), rmr_payload_size(3), rmr_rcv_msg(3), rmr_send_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3) NAME -------------------------------------------------------------------------------------------- rmr_trace_ref SYNOPSIS -------------------------------------------------------------------------------------------- :: #include int rmr_trace_ref( rmr_mbuf_t* mbuf, int* sizeptr ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_trace_ref function return a pointer to the trace area in the message, and optionally populate the user programme supplied size integer with the trace area size, if *sizeptr* is not nil. RETURN VALUE -------------------------------------------------------------------------------------------- On success, a void pointer to the trace area of the message is returned. A nil pointer is returned if the message has no trace data area allocated, or if the message itself is invalid. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_tralloc_msg(3), rmr_bytes2xact(3), rmr_bytes2meid(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_get_trlen(3), rmr_init(3), rmr_init_trace(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_str2meid(3), rmr_str2xact(3), rmr_wh_open(3), rmr_wh_send_msg(3), rmr_set_trace(3) NAME -------------------------------------------------------------------------------------------- rmr_tralloc_msg SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_tralloc_msg( void* vctx, int size, int trace_size, unsigned const char *tr_data ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_alloc_msg function is used to allocate a buffer which the user programme can write into and then send through the a library. The buffer is allocated such that sending it requires no additional copying from the buffer as it passes through the underlying transport mechanism. The *size* parameter is used to set the payload length in the message and If it is 0, then the default size supplied on the *rmr_init* call will be used. In addition to allocating the payload, a space in the buffer is reserved for *trace* data (tr_size bytes), and the bytes pointed to by *tr_data* are copied into that portion of the message. The *vctx* parameter is the void context pointer that was returned by the *rmr_init* function. The pointer to the message buffer returned is a structure which has some user application visible fields; the structure is described in rmr.h, and is illustrated below. :: typedef struct { int state; int mtype; int len; unsigned char* payload; unsigned char* xaction; } rmr_mbuf_t; state Is the current buffer state. Following a call to rmr_send_msg the state indicates whether the buffer was successfully sent which determines exactly what the payload points to. If the send failed, the payload referenced by the buffer is the message that failed to send (allowing the application to attempt a retransmission). When the state is a_OK the buffer represents an empty buffer that the application may fill in in preparation to send. mtype When sending a message, the application is expected to set this field to the appropriate message type value (as determined by the user programme). Upon send this value determines how the a library will route the message. For a buffer which has been received, this field will contain the message type that was set by the sending application. len The application using a buffer to send a message is expected to set the length value to the actual number of bytes that it placed into the message. This is likely less than the total number of bytes that the message can carry. For a message buffer that is passed to the application as the result of a receive call, this will be the value that the sending application supplied and should indicate the number of bytes in the payload which are valid. payload The payload is a pointer to the actual received data. The user programme may read and write from/to the memory referenced by the payload up until the point in time that the buffer is used on a rmr_send, rmr_call or rmr_reply function call. Once the buffer has been passed back to a a library function the user programme should **NOT** make use of the payload pointer. xaction The *xaction* field is a pointer to a fixed sized area in the message into which the user may write a transaction ID. The ID is optional with the exception of when the user application uses the rmr_call function to send a message and wait for the reply; the underlying a processing expects that the matching reply message will also contain the same data in the *xaction* field. RETURN VALUE -------------------------------------------------------------------------------------------- The function returns a pointer to a rmr_mbuf structure, or NULL on error. ERRORS -------------------------------------------------------------------------------------------- ENOMEM Unable to allocate memory. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_mbuf(3) rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_init_trace(3), rmr_get_trace(3), rmr_get_trlen(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_set_trace(3) NAME -------------------------------------------------------------------------------------------- rmr_wh_open SYNOPSIS -------------------------------------------------------------------------------------------- :: #include void rmr_close( void* vctx, rmr_whid_t whid ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_wh_close function closes the wormhole associated with the wormhole id passed in. Future calls to rmr_wh_send_msg with this ID will fail. The underlying TCP connection to the remote endpoint is **not** closed as this session may be reqruired for regularlly routed messages (messages routed based on message type). There is no way to force a TCP session to be closed at this point in time. SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_wh_open(3), rmr_wh_send_msg(3) NAME -------------------------------------------------------------------------------------------- rmr_wh_open SYNOPSIS -------------------------------------------------------------------------------------------- :: #include void* rmr_wh_open( void* vctx, char* target ) DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_wh_open function creates a direct link for sending, a wormhole, to another RMr based process. Sending messages through a wormhole requires that the connection be established overtly by the user application (via this function), and that the ID returned by rmr_wh_open be passed to the rmr_wh_send_msg function. *Target* is the *name* or *IP-address* combination of the processess that the wormhole should be connected to. *Vctx* is the RMr void context pointer that was returned by the rmr_init function. When invoked, this function immediatly attempts to connect to the target process. If the connection cannot be established, an error is returned to the caller, and no direct messages can be sent to the target. Once a wormhole is connected, the underlying transport mechanism (e.g. NNG) will provide reconnects should the connection be lost, however the handling of messages sent when a connection is broken is undetermined as each underlying transport mechanism may handle buffering and retries differently. RETURN VALUE -------------------------------------------------------------------------------------------- The rmr_wh_open function returns a type rmr_whid_t which must be passed to the rmr_wh_send_msg function when sending a message. The id may also be tested to determine success or failure of the connection by using the RMR_WH_CONNECTED macro and passing the ID as the parameter; a result of 1 indicates that the connection was esablished and that the ID is valid. ERRORS -------------------------------------------------------------------------------------------- The following error values are specifically set by this RMR function. In some cases the error message of a system call is propagated up, and thus this list might be incomplete. EINVAL A parameter passed was not valid. EACCESS The user applicarion does not have the ability to establish a wormhole to the indicated target (or maybe any target). ECONNREFUSED The connection was refused. EXAMPLE -------------------------------------------------------------------------------------------- :: void* rmc; rmr_whid_t wh; rmc = rmr_init( "43086", 4096, 0 ); // init context wh = rmr_wh_open( rmc, "localhost:6123" ); if( !RMR_WH_CONNECTED( wh ) ) { f fprintf( stderr, "unable to connect wormhole: %s\\n", strerror( errno ) ); } SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_get_rcvfd(3), rmr_payload_size(3), rmr_send_msg(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_wh_send_msg(3), rmr_wh_close(3) NAME -------------------------------------------------------------------------------------------- rmr_wh_send_msg SYNOPSIS -------------------------------------------------------------------------------------------- :: #include rmr_mbuf_t* rmr_wh_send_msg( void* vctx, rmr_whid_t id, rmr_mbuf_t* msg ); DESCRIPTION -------------------------------------------------------------------------------------------- The rmr_wh_send_msg function accepts a message buffer from the user application and attempts to send it using the wormhole ID provided (id). Unlike *rmr_send_msg,* this function attempts to send the message directly to a process at the other end of a wormhole which was created with *rmr_wh-open().* When sending message via wormholes, the normal RMr routing based on message type is ignored, and the caller may leave the message type unspecified in the message buffer (unless it is needed by the receiving process). The message buffer (msg) used to send is the same format as used for regular RMr send and reply to sender operations, thus any buffer allocated by these means, or calls to *rmr_rcv_msg()* can be passed to this function. Retries ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The send operations in RMr will retry *soft* send failures until one of three conditions occurs: 1. The message is sent without error 2. The underlying transport reports a * hard * failure 3. The maximum number of retry loops has been attempted A retry loop consists of approximately 1000 send attemps ** without** any intervening calls to * sleep() * or * usleep(). * The number of retry loops defaults to 1, thus a maximum of 1000 send attempts is performed before returning to the user application. This value can be set at any point after RMr initialisation using the * rmr_set_stimeout() * function allowing the user application to completely disable retires (set to 0), or to increase the number of retry loops. Transport Level Blocking ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ The underlying transport mechanism used to send messages is configured in *non-blocking* mode. This means that if a message cannot be sent immediately the transport mechanism will **not** pause with the assumption that the inability to send will clear quickly (within a few milliseconds). This means that when the retry loop is completely disabled (set to 0), that the failure to accept a message for sending by the underlying mechanisms (software or hardware) will be reported immediately to the user application. It should be noted that depending on the underlying transport mechanism being used, it is extremly possible that during normal operations that retry conditions are very likely to happen. These are completely out of RMr's control, and there is nothing that RMr can do to avoid or midigate these other than by allowing RMr to retry the send operation, and even then it is possible (e.g. during connection reattempts), that a single retry loop is not enough to guarentee a successful send. RETURN VALUE -------------------------------------------------------------------------------------------- On success, a new message buffer, with an empty payload, is returned for the application to use for the next send. The state in this buffer will reflect the overall send operation state and should be RMR_OK. If the state in the returned buffer is anything other than RMR_OK, the user application may need to attempt a retransmission of the message, or take other action depending on the setting of errno as described below. In the event of extreme failure, a NULL pointer is returned. In this case the value of errno might be of some use, for documentation, but there will be little that the user application can do other than to move on. ERRORS -------------------------------------------------------------------------------------------- The following values may be passed back in the *state* field of the returned message buffer. RMR_ERR_WHID The wormhole ID passed in was not associated with an open wormhole, or was out of range for a valid ID. RMR_ERR_NOWHOPEN No wormholes exist, further attempt to validate the ID are skipped. RMR_ERR_BADARG The message buffer pointer did not refer to a valid message. RMR_ERR_NOHDR The header in the message buffer was not valid or corrupted. The following values may be assigned to errno on failure. INVAL Parameter(s) passed to the function were not valid, or the underlying message processing environment was unable to interpret the message. ENOKEY The header information in the message buffer was invalid. ENXIO No known endpoint for the message could be found. EMSGSIZE The underlying transport refused to accept the message because of a size value issue (message was not attempted to be sent). EFAULT The message referenced by the message buffer is corrupt (NULL pointer or bad internal length). EBADF Internal RMR error; information provided to the message transport environment was not valid. ENOTSUP Sending was not supported by the underlying message transport. EFSM The device is not in a state that can accept the message. EAGAIN The device is not able to accept a message for sending. The user application should attempt to resend. EINTR The operation was interrupted by delivery of a signal before the message was sent. ETIMEDOUT The underlying message environment timed out during the send process. ETERM The underlying message environment is in a shutdown state. EXAMPLE -------------------------------------------------------------------------------------------- The following is a simple example of how the a wormhole is created (rmr_wh_open) and then how rmr_wh_send_msg function is used to send messages. Some error checking is omitted for clarity. :: #include .// system headers omitted for clarity int main() { rmr_whid_t whid = -1; // wormhole id for sending void* mrc; //msg router context int i; rmr_mbuf_t* sbuf; // send buffer int count = 0; mrc = rmr_init( "43086", RMR_MAX_RCV_BYTES, RMRFL_NONE ); if( mrc == NULL ) { fprintf( stderr, "[FAIL] unable to initialise RMr environment\\n" ); exit( 1 ); } while( ! rmr_ready( mrc ) ) { e i// wait for routing table info sleep( 1 ); } sbuf = rmr_alloc_msg( mrc, 2048 ); while( 1 ) { if( whid < 0 ) { whid = rmr_wh_open( mrc, "localhost:6123" ); // open fails if endpoint refuses conn w if( RMR_WH_CONNECTED( wh ) ) { snprintf( sbuf->payload, 1024, "periodic update from sender: %d", count++ ); sbuf->len = strlen( sbuf->payload ); sbuf = rmr_wh_send_msg( mrc, whid, sbuf ); } } sleep( 5 ); } } SEE ALSO -------------------------------------------------------------------------------------------- rmr_alloc_msg(3), rmr_call(3), rmr_free_msg(3), rmr_init(3), rmr_payload_size(3), rmr_rcv_msg(3), rmr_rcv_specific(3), rmr_rts_msg(3), rmr_ready(3), rmr_fib(3), rmr_has_str(3), rmr_tokenise(3), rmr_mk_ring(3), rmr_ring_free(3), rmr_set_stimeout(3), rmr_wh_open(3), rmr_wh_close(3)