X-Git-Url: https://gerrit.o-ran-sc.org/r/gitweb?a=blobdiff_plain;f=docs%2Frmr_send_msg.3.rst;h=9d214fefc89c3bade9a588c83de8552c657ec7f5;hb=refs%2Ftags%2F4.7.4;hp=06487bedb985b73028159ec957746cf4eba47616;hpb=a3a121ca4a0426ec964fa684fb27c397f2ee9e24;p=ric-plt%2Flib%2Frmr.git diff --git a/docs/rmr_send_msg.3.rst b/docs/rmr_send_msg.3.rst index 06487be..9d214fe 100644 --- a/docs/rmr_send_msg.3.rst +++ b/docs/rmr_send_msg.3.rst @@ -1,14 +1,14 @@ -.. 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. - -============================================================================================ -Man Page: rmr_send_msg -============================================================================================ - - +.. 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. + +============================================================================================ +Man Page: rmr_send_msg +============================================================================================ + + RMR LIBRARY FUNCTIONS @@ -19,263 +19,263 @@ RMR LIBRARY FUNCTIONS NAME ---- -rmr_send_msg +rmr_send_msg SYNOPSIS -------- - -:: - - #include - - rmr_mbuf_t* rmr_send_msg( void* vctx, rmr_mbuf_t* msg ); - + +:: + + #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.) +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: - - - &item The message is sent without error - - &item The underlying transport reports a *hard* failure - - &item The maximum number of retry loops has been attempted - - -A retry loop consists of approximately 1000 send attempts -**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. +The send operations in RMR will retry *soft* send failures +until one of three conditions occurs: + + +* The message is sent without error + +* The underlying transport reports a *hard* failure + +* The maximum number of retry loops has been attempted + + +A retry loop consists of approximately 1000 send attempts +**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 extremely likely that retry -conditions will happen during normal operations. These are -completely out of RMR's control, and there is nothing that -RMR can do to avoid or mitigate 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 guarantee a successful send. +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 extremely likely that retry +conditions will happen during normal operations. These are +completely out of RMR's control, and there is nothing that +RMR can do to avoid or mitigate 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 guarantee 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 nil 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. +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 nil 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. - - - .. list-table:: - :widths: auto - :header-rows: 0 - :class: borderless - - * - **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. - - .. list-table:: - :widths: auto - :header-rows: 0 - :class: borderless - - * - **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 (nil - 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. - - +The following values may be passed back in the *state* field +of the returned message buffer. + + + .. list-table:: + :widths: auto + :header-rows: 0 + :class: borderless + + * - **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. + + .. list-table:: + :widths: auto + :header-rows: 0 + :class: borderless + + * - **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 (nil + 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 - - if( send_msg == NULL ) { - send_msg = rmr_alloc_msg( mr, MAX_SIZE ); // 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 - if( ! msg ) { - return ERROR; - } else { - if( msg->state != RMR_OK ) { - // check for RMR_ERR_RETRY, and resend if needed - // else return error - } - } - return OK; - - +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 + + if( send_msg == NULL ) { + send_msg = rmr_alloc_msg( mr, MAX_SIZE ); // 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 + if( ! msg ) { + return ERROR; + } else { + if( msg->state != RMR_OK ) { + // check for RMR_ERR_RETRY, and resend if needed + // else return error + } + } + return 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) +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)