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86 lines
3.0 KiB
86 lines
3.0 KiB
/*
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Copyright (c) 2012-2013 Martin Sustrik All rights reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"),
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to deal in the Software without restriction, including without limitation
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the rights to use, copy, modify, merge, publish, distribute, sublicense,
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and/or sell copies of the Software, and to permit persons to whom
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the Software is furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included
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in all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
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IN THE SOFTWARE.
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*/
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#ifndef NN_MSGQUEUE_INCLUDED
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#define NN_MSGQUEUE_INCLUDED
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#include "../../utils/msg.h"
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#include <stddef.h>
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/* This class is a simple uni-directional message queue. */
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/* It's not 128 so that chunk including its footer fits into a memory page. */
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#define NN_MSGQUEUE_GRANULARITY 126
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struct nn_msgqueue_chunk {
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struct nn_msg msgs [NN_MSGQUEUE_GRANULARITY];
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struct nn_msgqueue_chunk *next;
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};
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struct nn_msgqueue {
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/* Pointer to the position where next message should be written into
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the message queue. */
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struct {
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struct nn_msgqueue_chunk *chunk;
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int pos;
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} out;
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/* Pointer to the first unread message in the message queue. */
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struct {
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struct nn_msgqueue_chunk *chunk;
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int pos;
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} in;
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/* Number of messages in the queue. */
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size_t count;
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/* Amount of memory used by messages in the queue. */
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size_t mem;
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/* Maximal queue size (in bytes). */
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size_t maxmem;
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/* One empty chunk is always cached so that in case of steady stream
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of messages through the pipe there are no memory allocations. */
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struct nn_msgqueue_chunk *cache;
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};
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/* Initialise the message pipe. maxmem is the maximal queue size in bytes. */
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void nn_msgqueue_init (struct nn_msgqueue *self, size_t maxmem);
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/* Terminate the message pipe. */
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void nn_msgqueue_term (struct nn_msgqueue *self);
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/* Returns 1 if there are no messages in the queue, 0 otherwise. */
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int nn_msgqueue_empty (struct nn_msgqueue *self);
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/* Writes a message to the pipe. -EAGAIN is returned if the message cannot
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be sent because the queue is full. */
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int nn_msgqueue_send (struct nn_msgqueue *self, struct nn_msg *msg);
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/* Reads a message from the pipe. -EAGAIN is returned if there's no message
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to receive. */
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int nn_msgqueue_recv (struct nn_msgqueue *self, struct nn_msg *msg);
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#endif
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