diff options
Diffstat (limited to 'mysys/wqueue.c')
| -rw-r--r-- | mysys/wqueue.c | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/mysys/wqueue.c b/mysys/wqueue.c new file mode 100644 index 00000000000..bfe9cba1235 --- /dev/null +++ b/mysys/wqueue.c @@ -0,0 +1,169 @@ + +#include <wqueue.h> + +#define STRUCT_PTR(TYPE, MEMBER, a) \ + (TYPE *) ((char *) (a) - offsetof(TYPE, MEMBER)) +/* + Link a thread into double-linked queue of waiting threads. + + SYNOPSIS + wqueue_link_into_queue() + wqueue pointer to the queue structure + thread pointer to the thread to be added to the queue + + RETURN VALUE + none + + NOTES. + Queue is represented by a circular list of the thread structures + The list is double-linked of the type (**prev,*next), accessed by + a pointer to the last element. +*/ + +void wqueue_link_into_queue(WQUEUE *wqueue, struct st_my_thread_var *thread) +{ + struct st_my_thread_var *last; + if (!(last= wqueue->last_thread)) + { + /* Queue is empty */ + thread->next= thread; + thread->prev= &thread->next; + } + else + { + thread->prev= last->next->prev; + last->next->prev= &thread->next; + thread->next= last->next; + last->next= thread; + } + wqueue->last_thread= thread; +} + + +/* + Add a thread to single-linked queue of waiting threads + + SYNOPSIS + wqueue_add_to_queue() + wqueue pointer to the queue structure + thread pointer to the thread to be added to the queue + + RETURN VALUE + none + + NOTES. + Queue is represented by a circular list of the thread structures + The list is single-linked of the type (*next), accessed by a pointer + to the last element. +*/ + +void wqueue_add_to_queue(WQUEUE *wqueue, struct st_my_thread_var *thread) +{ + struct st_my_thread_var *last; + if (!(last= wqueue->last_thread)) + thread->next= thread; + else + { + thread->next= last->next; + last->next= thread; + } + wqueue->last_thread= thread; +} + +/* + Unlink a thread from double-linked queue of waiting threads + + SYNOPSIS + wqueue_unlink_from_queue() + wqueue pointer to the queue structure + thread pointer to the thread to be removed from the queue + + RETURN VALUE + none + + NOTES. + See NOTES for link_into_queue +*/ + +void wqueue_unlink_from_queue(WQUEUE *wqueue, struct st_my_thread_var *thread) +{ + if (thread->next == thread) + /* The queue contains only one member */ + wqueue->last_thread= NULL; + else + { + thread->next->prev= thread->prev; + *thread->prev= thread->next; + if (wqueue->last_thread == thread) + wqueue->last_thread= STRUCT_PTR(struct st_my_thread_var, next, + thread->prev); + } + thread->next= NULL; +} + + +/* + Remove all threads from queue signaling them to proceed + + SYNOPSIS + wqueue_realease_queue() + wqueue pointer to the queue structure + thread pointer to the thread to be added to the queue + + RETURN VALUE + none + + NOTES. + See notes for add_to_queue + When removed from the queue each thread is signaled via condition + variable thread->suspend. +*/ + +void wqueue_release_queue(WQUEUE *wqueue) +{ + struct st_my_thread_var *last= wqueue->last_thread; + struct st_my_thread_var *next= last->next; + struct st_my_thread_var *thread; + do + { + thread= next; + pthread_cond_signal(&thread->suspend); + next= thread->next; + thread->next= NULL; + } + while (thread != last); + wqueue->last_thread= NULL; +} + + +/* + Add thread and wait + + SYNOPSYS + wqueue_add_and_wait() + wqueue queue to add to + thread thread which is waiting + lock mutex need for the operation +*/ + +void wqueue_add_and_wait(WQUEUE *wqueue, + struct st_my_thread_var *thread, + pthread_mutex_t *lock) +{ + DBUG_ENTER("wqueue_add_and_wait"); + DBUG_PRINT("enter", + ("thread: 0x%lx cond: 0x%lx mutex: 0x%lx", + (ulong) thread, (ulong) &thread->suspend, (ulong) lock)); + wqueue_add_to_queue(wqueue, thread); + do + { + DBUG_PRINT("info", ("wait... cond: 0x%lx mutex: 0x%lx", + (ulong) &thread->suspend, (ulong) lock)); + pthread_cond_wait(&thread->suspend, lock); + DBUG_PRINT("info", ("wait done cond: 0x%lx mutex: 0x%lx next: 0x%lx", + (ulong) &thread->suspend, (ulong) lock, + (ulong) thread->next)); + } + while (thread->next); + DBUG_VOID_RETURN; +} |