| 1 | /* |
| 2 | * CFLAGS=-lpthread make pthread_msgqueue |
| 3 | */ |
| 4 | |
| 5 | #include <pthread.h> |
| 6 | #include <time.h> |
| 7 | #include <string.h> |
| 8 | #include <stdio.h> |
| 9 | #include <stdbool.h> |
| 10 | #include <stdlib.h> |
| 11 | #include <assert.h> |
| 12 | |
| 13 | typedef struct pthread_mq_t { |
| 14 | pthread_mutex_t lock; |
| 15 | pthread_cond_t cond_readable; |
| 16 | pthread_cond_t cond_writable; |
| 17 | void * data; |
| 18 | size_t msg_size; |
| 19 | size_t msg_count; |
| 20 | size_t msg_count_max; |
| 21 | size_t head_idx; |
| 22 | char * name; |
| 23 | } pthread_mq_t; |
| 24 | |
| 25 | bool pthread_mq_readable(pthread_mq_t *mq) { return (mq->msg_count > 0); } |
| 26 | bool pthread_mq_writable(pthread_mq_t *mq) { return (mq->msg_count < mq->msg_count_max); } |
| 27 | |
| 28 | bool pthread_mq_init(pthread_mq_t *mq, size_t msg_size, size_t msg_count_max) { |
| 29 | pthread_mutex_init(&mq->lock, NULL); |
| 30 | pthread_cond_init(&mq->cond_readable, NULL); |
| 31 | pthread_cond_init(&mq->cond_writable, NULL); |
| 32 | mq->data = malloc(msg_size*msg_count_max); |
| 33 | mq->msg_size = msg_size; |
| 34 | mq->msg_count_max = msg_count_max; |
| 35 | mq->msg_count = 0; |
| 36 | mq->head_idx = 0; |
| 37 | mq->name = NULL; |
| 38 | |
| 39 | if(((msg_size*msg_count_max) > 0) && mq->data == NULL) return false; |
| 40 | return true; |
| 41 | } |
| 42 | |
| 43 | void pthread_mq_free(pthread_mq_t *mq) { |
| 44 | free(mq->data); |
| 45 | } |
| 46 | |
| 47 | void pthread_mq_cond(pthread_mq_t *mq) { |
| 48 | if(pthread_mq_readable(mq)) pthread_cond_broadcast(&mq->cond_readable); |
| 49 | if(pthread_mq_writable(mq)) pthread_cond_broadcast(&mq->cond_writable); |
| 50 | } |
| 51 | |
| 52 | bool pthread_mq_reset(pthread_mq_t *mq) { |
| 53 | if(pthread_mutex_lock(&mq->lock)) return false; |
| 54 | mq->msg_count = 0; |
| 55 | mq->head_idx = 0; |
| 56 | pthread_mq_cond(mq); |
| 57 | pthread_mutex_unlock(&mq->lock); |
| 58 | return true; |
| 59 | } |
| 60 | |
| 61 | bool pthread_mq_send_generic(pthread_mq_t *mq, void * data, bool to_front, bool block, const struct timespec *restrict abs_timeout) { |
| 62 | int ret; |
| 63 | |
| 64 | //Lock queue |
| 65 | if(pthread_mutex_timedlock(&mq->lock, abs_timeout)) return false; |
| 66 | |
| 67 | //Wait for queue to be in writable condition |
| 68 | while(!pthread_mq_writable(mq)) { |
| 69 | if(abs_timeout == NULL) { |
| 70 | ret = pthread_cond_wait(&mq->cond_writable, &mq->lock); |
| 71 | } else { |
| 72 | ret = pthread_cond_timedwait(&mq->cond_writable, &mq->lock, abs_timeout); |
| 73 | } |
| 74 | if(ret) { |
| 75 | pthread_mutex_unlock(&mq->lock); |
| 76 | return false; |
| 77 | } |
| 78 | } |
| 79 | printf("Writable\n"); |
| 80 | |
| 81 | //Write data to queue |
| 82 | size_t idx = ( ( mq->msg_count_max + mq->head_idx + (to_front?-1:mq->msg_count) ) % mq->msg_count_max ); |
| 83 | void *ptr = mq->data + (idx * mq->msg_size); |
| 84 | mq->msg_count++; |
| 85 | if(to_front) mq->head_idx = (mq->msg_count_max + mq->head_idx - 1) % mq->msg_count_max; |
| 86 | memcpy(ptr, data, mq->msg_size); |
| 87 | |
| 88 | //Signal conditions and unlock |
| 89 | pthread_mq_cond(mq); |
| 90 | pthread_mutex_unlock(&mq->lock); |
| 91 | return true; |
| 92 | } |
| 93 | |
| 94 | int main() { |
| 95 | pthread_mq_t myq; |
| 96 | pthread_mq_init(&myq, 6, 5); |
| 97 | pthread_mq_send_generic(&myq, "AHOJ1", false, true, NULL); |
| 98 | pthread_mq_send_generic(&myq, "AHOJ2", false, true, NULL); |
| 99 | pthread_mq_send_generic(&myq, "AHOJ3", true, true, NULL); |
| 100 | pthread_mq_send_generic(&myq, "AHOJ4", true, true, NULL); |
| 101 | pthread_mq_send_generic(&myq, "AHOJ5", false, true, NULL); |
| 102 | //pthread_mq_send_generic(&myq, "AHOJ6", false, true, NULL); |
| 103 | |
| 104 | for(int i = 0; i<5; i++) { |
| 105 | printf("%.6s\n", (char *)(myq.data+i*6)); |
| 106 | } |
| 107 | } |