2 ==================================================================================
3 Copyright (c) 2019 Nokia
4 Copyright (c) 2018-2019 AT&T Intellectual Property.
6 Licensed under the Apache License, Version 2.0 (the "License");
7 you may not use this file except in compliance with the License.
8 You may obtain a copy of the License at
10 http://www.apache.org/licenses/LICENSE-2.0
12 Unless required by applicable law or agreed to in writing, software
13 distributed under the License is distributed on an "AS IS" BASIS,
14 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15 See the License for the specific language governing permissions and
16 limitations under the License.
17 ==================================================================================
20 Mnemonic rmr_rcv_msg_man.xfm
21 Abstract The manual page for the rmr_rcv_msg function.
22 Author E. Scott Daniels
27 .im &{lib}/man/setup.im
31 &h1(RMR Library Functions)
40 rmr_mbuf_t* rmr_rcv_msg( void* vctx, rmr_mbuf_t* old_msg );
45 The &cw(rmr_rcv_msg) function blocks until a message is received, returning
46 the message to the caller via a pointer to a &cw(rmr_mbuf_t) structure type.
47 If messages were queued while waiting for the response to a previous invocation
48 of &cw(rmr_call,) the oldest message is removed from the queue and returned
52 The &ital(vctx) pointer is the pointer returned by the &cw(rmr_init) function.
53 &ital(Old_msg) is a pointer to a previously used message buffer or NULL.
54 The ability to reuse message buffers helps to avoid alloc/free cycles in the
56 When no buffer is available to supply, the receive function will allocate one.
59 The function returns a pointer to the &cw(rmr_mbuf_t) structure which references
60 the message information (state, length, payload), or a NULL pointer in the case
64 The &ital(state) field in the message buffer will indicate either &cw(RMR_OK)
65 when the message receive process was successful and the message can be used
67 Depending on the underlying transport mechanism, one of the following RMR
68 error stats may be returned:
71 &beg_dlist(.75i : ^&bold_font )
72 &di(RMR_ERR_EMPTY) The message received had no payload, or was completely empty.
75 &di(RMR_ERR_TIMEOUT) For some transport mechanisms, or if reading the receive
76 queue from multiple threads, it is possible for one thread to find no data
77 waiting when it queries the queue. When this state is reported, the
78 message buffer does not contain message data and the user application should
79 reinvoke the receive function.
85 When an RMR error state is reported, the underlying &cw(errno) value might
86 provide more information. The following is a list of possible values that
87 might accompany the states listed above:
90 &cw(RMR_ERR_EMPTY) if an empty message was received.
91 If a nil pointer is returned, or any other state value was set in the message
92 buffer, &cw(errno) will be set to one of the following:
95 &beg_dlist(.75i : ^&bold_font )
96 &di(INVAL) Parameter(s) passed to the function were not valid.
99 &di(EBADF) The underlying message transport is unable to process the request.
102 &di(ENOTSUP) The underlying message transport is unable to process the request.
105 &di(EFSM) The underlying message transport is unable to process the request.
108 &di(EAGAIN) The underlying message transport is unable to process the request.
111 &di(EINTR) The underlying message transport is unable to process the request.
114 &di(ETIMEDOUT) The underlying message transport is unable to process the request.
117 &di(ETERM) The underlying message transport is unable to process the request.