.if false
==================================================================================
- Copyright (c) 2019 Nokia
- Copyright (c) 2018-2019 AT&T Intellectual Property.
+ Copyright (c) 2019 Nokia
+ Copyright (c) 2018-2019 AT&T Intellectual Property.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
==================================================================================
.fi
.if false
- Mnemonic rmr_alloc_msg.xfm
- Abstract The manual page for the rmr_alloc_msg function.
- Author E. Scott Daniels
- Date 28 January 2019
+ Mnemonic rmr_alloc_msg.xfm
+ Abstract The manual page for the rmr_alloc_msg function.
+ Author E. Scott Daniels
+ Date 28 January 2019
.fi
.gv e LIB lib
&line_len(6i)
&h1(RMR Library Functions)
&h2(NAME)
- rmr_alloc_msg
+ rmr_alloc_msg
&h2(SYNOPSIS )
&indent
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 &cw(size) is 0, then the default size supplied on the
-&ital(rmr_init) call will be used.
+If the value passed in &cw(size) is less than or equal to 0, then the
+&ital(normal maximum size) supplied on the &ital(rmr_init) call will be used.
+When &ital(size) is greater than zero, the message allocated will have at least
+the indicated number of bytes in the payload.
+There is no maximum size imposed by RMR, however the underlying system memory
+managerment (e.g. malloc) functions may impose a limit.
+
+&space
The &ital(ctx) parameter is the void context pointer that was returned by
the &ital(rmr_init) function.
int len;
unsigned char* payload;
unsigned char* xaction;
- int sub_id;
- int tp_state;
+ int sub_id;
+ int tp_state;
} rmr_mbuf_t;
&ex_end
&space
&beg_dlist(.75i : ^&bold_font )
-&ditem(state) Is the current buffer state. Following a call to &cw(rmr_send_msg)
+&diitem(state) Is the current buffer state. Following a call to &cw(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
may fill in in preparation to send.
&half_space
-&ditem(mtype) When sending a message, the application is expected to set this field
+&diitem(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.
&half_space
-&ditem(len) The application using a buffer to send a message is expected to set the
+&diitem(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
indicate the number of bytes in the payload which are valid.
&half_space
-&ditem(payload) The payload is a pointer to the actual received data. The
+&diitem(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 &cw(rmr_send, rmr_call)
or &cw(rmr_reply) function call.
&half_space
-&ditem(xaction) The &ital(xaction) field is a pointer to a fixed sized area in
+&diitem(xaction) The &ital(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 &cw(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
&ital(xaction) field.
-&end_dlist
&half_space
-&ditem(sub_id)
+&diitem(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
application's responsibility to set/reset this value.
&half_space
-&ditem(tp_state)
+&diitem(tp_state)
For C applications making use of RMR, the state of a transport based failure will
often be available via &cw(errno.)
However, some wrapper environments may not have direct access to the C-lib &cw(errno)
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 &cw(RMR_OK.)
+&end_dlist
&h2(RETURN VALUE)
The function returns a pointer to a &cw(rmr_mbuf) structure, or NULL on error.
rmr_ring_free(3),
rmr_set_trace(3)
-.qu
-