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