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concurrence bugfix

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This commit is contained in:
Cloud Wu
2014-05-22 11:24:36 +08:00
parent 1fbee1ac0b
commit 90cd967333
1 changed files with 9 additions and 20 deletions
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29
skynet-src/skynet_mq.c
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@@ -34,7 +34,6 @@ struct global_queue {
struct message_queue ** queue;
// We use a separated flag array to ensure the mq is pushed.
// See the comments below.
bool * flag;
struct message_queue *list;
};
@@ -49,7 +48,10 @@ static void
skynet_globalmq_push(struct message_queue * queue) {
struct global_queue *q= Q;
if (q->flag[GP(q->tail)]) {
uint32_t tail = GP(__sync_fetch_and_add(&q->tail,1));
// only one thread can set the slot (change q->queue[tail] from NULL to queue)
if (!__sync_bool_compare_and_swap(&q->queue[tail], NULL, queue)) {
// The queue may full seldom, save queue in list
assert(queue->next == NULL);
struct message_queue * last;
@@ -60,14 +62,6 @@ skynet_globalmq_push(struct message_queue * queue) {
return;
}
uint32_t tail = GP(__sync_fetch_and_add(&q->tail,1));
// The thread would suspend here, and the q->queue[tail] is last version ,
// but the queue tail is increased.
// So we set q->flag[tail] after changing q->queue[tail].
q->queue[tail] = queue;
__sync_synchronize();
q->flag[tail] = true;
}
struct message_queue *
@@ -93,18 +87,14 @@ skynet_globalmq_pop() {
}
}
// Check the flag first, if the flag is false, the pushing may not complete.
if(!q->flag[head_ptr]) {
return NULL;
}
__sync_synchronize();
struct message_queue * mq = q->queue[head_ptr];
if (!__sync_bool_compare_and_swap(&q->head, head, head+1)) {
return NULL;
}
q->flag[head_ptr] = false;
// only one thread can get the slot (change q->queue[head_ptr] to NULL)
if (!__sync_bool_compare_and_swap(&q->queue[head_ptr], mq, NULL)) {
return NULL;
}
return mq;
}
@@ -220,8 +210,7 @@ skynet_mq_init() {
struct global_queue *q = skynet_malloc(sizeof(*q));
memset(q,0,sizeof(*q));
q->queue = skynet_malloc(MAX_GLOBAL_MQ * sizeof(struct message_queue *));
q->flag = skynet_malloc(MAX_GLOBAL_MQ * sizeof(bool));
memset(q->flag, 0, sizeof(bool) * MAX_GLOBAL_MQ);
memset(q->queue, 0, sizeof(struct message_queue *) * MAX_GLOBAL_MQ);
Q=q;
}