203 lines
5.7 KiB
C
203 lines
5.7 KiB
C
/*
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* Copyright (C) 2009-2012 Thomas Preud'homme <thomas.preud-homme@lip6.fr>
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*
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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"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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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 THE
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* 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 FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#define _BATCH_QUEUE_C_ 1
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#include <stdio.h>
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#include <stdlib.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <stdint.h>
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#include <limits.h>
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/* Non standard include */
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#include <commtech.h>
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#include <specific_comm.h>
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#define BASE_SHM_NAME "/channel"
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#define ROUNDUP(size) ((size + page_size) & ~(page_size - 1))
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static uintptr_t buf_mask;
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static uintptr_t page_mask;
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static int nb_buf_entries;
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static unsigned int page_size;
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void *create_comm_channel(void)
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{
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int ret, shm_fd;
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static int chan_idx = 0;
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char shm_name[NAME_MAX];
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struct channel *channel1, *channel2;
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channel1 = NULL;
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channel2 = NULL;
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ret = sysconf(_SC_PAGESIZE);
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if (ret == -1)
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{
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perror("BatchQueue init sysconf");
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return NULL;
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}
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page_size = ret;
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page_mask = ~((uintptr_t) (page_size - 1));
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ret = snprintf(shm_name, NAME_MAX, BASE_SHM_NAME"%d\n", chan_idx);
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if (ret < 0)
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{
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fprintf(stderr, "BatchQueue init snprintf failed\n");
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return NULL;
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} else if (ret >= NAME_MAX)
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{
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fprintf(stderr, "Too many channels created: impossible to ");
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fprintf(stderr, "create a channel named "BASE_SHM_NAME);
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fprintf(stderr, "%d\n", chan_idx);
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return NULL;
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}
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shm_fd = shm_open(shm_name, O_RDWR | O_CREAT, S_IRUSR | S_IWUSR);
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if (shm_fd == -1)
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{
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perror("BatchQueue init shm_open failed");
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return NULL;
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}
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ret = ftruncate(shm_fd, sizeof(*channel1));
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if (ret == -1)
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{
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perror("BatchQueue init ftruncate failed");
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goto close_file;
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}
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channel1 = mmap(NULL, ROUNDUP(sizeof(*channel1)),
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PROT_READ | PROT_WRITE, MAP_PRIVATE, shm_fd, 0);
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channel2 = mmap(NULL, ROUNDUP(sizeof(*channel1)),
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PROT_READ | PROT_WRITE, MAP_PRIVATE, shm_fd, 0);
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if ((channel1 == MAP_FAILED) || (channel2 == MAP_FAILED))
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{
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perror("Batchqueue init mmap failed");
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channel1 = NULL;
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goto close_file;
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}
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channel1->mapping1 = channel1;
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channel1->mapping2 = channel2;
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channel1->state = 0;
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channel1->sender_ptr = channel1->buf[0];
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channel1->receiver_ptr = channel1->buf[0];
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channel1->buf_end1 = channel1->buf[0] +
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(sizeof channel1->buf[0] / sizeof channel1->buf[0][0]);
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channel1->buf_end2 = channel1->mapping2->buf[1] +
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(sizeof channel1->buf[1] / sizeof channel1->buf[1][0]);
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channel1->sender_ptr_end = channel1->buf_end1;
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buf_mask = sizeof channel1->buf[0] - 1;
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nb_buf_entries = sizeof channel1->buf[0] / sizeof channel1->buf[0][0];
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close_file:
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shm_unlink(shm_name);
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return channel1;
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}
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int end_producer(void *unused __attribute__ ((unused)))
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{
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return 0;
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}
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int destroy_comm_channel(void *channel)
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{
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size_t mapping_size;
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struct channel *mapping1, *mapping2, *channel_ptr;
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channel_ptr = (struct channel *) channel;
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mapping1 = channel_ptr->mapping1;
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mapping2 = channel_ptr->mapping2;
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mapping_size = ROUNDUP(sizeof(*mapping1));
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if (munmap(mapping1, mapping_size) || munmap(mapping2, mapping_size))
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return -1;
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else
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return 0;
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}
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/*
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* Copy at max count received data into buf
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* @param buf The buffer in which received data must be copied into
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* @return Number of data received and copied into buf
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*
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* @warning recv_one_data should not be used in conjonction of
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* recv_some_data
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*/
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void *recv_one_data(struct channel *channel)
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{
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void *result;
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if (unlikely(!((uintptr_t) channel->receiver_ptr & buf_mask)))
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while (!channel->state);
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result = *channel->receiver_ptr++;
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if (unlikely(!((uintptr_t) channel->receiver_ptr & buf_mask)))
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{
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uintptr_t rcvr_ptr_high;
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rcvr_ptr_high = (uintptr_t) channel->receiver_ptr & page_mask;
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channel->state = 0;
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if ((void *) rcvr_ptr_high == channel->mapping1)
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channel->receiver_ptr = channel->mapping2->buf[1];
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else
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channel->receiver_ptr = channel->mapping1->buf[0];
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}
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return result;
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}
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/*
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* Copy at max count received data into buf
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* @param buf The buffer in which received data must be copied into
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* @return Number of data received and copied into buf
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*
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* @warning recv_some_data should not be used in conjonction of
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* recv_one_data
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* @warning count must be a multiple of BUF_SIZE
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*/
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ssize_t recv_some_data(struct channel *channel, void **buf, size_t count)
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{
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size_t nb_read;
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nb_read = 0;
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while (channel->state && nb_read < count)
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{
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void * volatile *chanbuf_ptr;
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uintptr_t rcvr_ptr_high;
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chanbuf_ptr = channel->receiver_ptr;
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channel->receiver_ptr += nb_buf_entries;
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rcvr_ptr_high = (uintptr_t) channel->receiver_ptr & page_mask;
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for(; chanbuf_ptr != channel->receiver_ptr; chanbuf_ptr++)
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*buf++ = *chanbuf_ptr;
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nb_read += nb_buf_entries;
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channel->state = 0;
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if ((void *) rcvr_ptr_high == channel->mapping1)
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channel->receiver_ptr = channel->mapping2->buf[1];
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else
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channel->receiver_ptr = channel->mapping1->buf[0];
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}
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return nb_read;
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}
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