medfall

commit f9b0431908aed740a5cd35988aba5424111060bf
parent c756c6337b10d8042e0c4c239cc311f2857d18b0
Author: Michael Savage <mikejsavage@gmail.com>
Date:   Sat Sep 10 18:11:19 -0700

Properly check if a WorkQueue is full

Diffstat:
work_queue.cc
 | 
13
+++----------
work_queue.h
 | 
3
---
2 files changed, 3 insertions(+), 13 deletions(-)
diff --git a/work_queue.cc b/work_queue.cc
@@ -22,8 +22,6 @@ static bool workqueue_step( u32 thread_id, WorkQueue * queue ) {
 		if( compare_exchange_seqcst( &queue->head, &current_head, new_head ) ) {
 			const Job & job = queue->jobs[ current_head % array_count( queue->jobs ) ];
 			job.callback( job.data, &queue->arenas[ thread_id ] );
-
-			fetch_add_seqcst( &queue->jobs_completed, 1 );
 		}
 
 		return true;
@@ -83,23 +81,18 @@ void workqueue_init( WorkQueue * queue, MemoryArena * arena, u32 num_threads ) {
 }
 
 void workqueue_enqueue( WorkQueue * queue, WorkQueueCallback * callback, void * data ) {
-	assert( queue->jobs_queued < array_count( queue->jobs ) );
+	u32 tail = fetch_add_release( &queue->tail, 1 );
+	assert( tail - load_acquire( &queue->head ) < array_count( queue->jobs ) - 1 );
 
 	Job job = { callback, data };
 
-	u32 tail = fetch_add_seqcst( &queue->tail, 1 );
-
 	queue->jobs[ tail % array_count( queue->jobs ) ] = job;
-	queue->jobs_queued++;
 
 	semaphore_signal( &queue->sem );
 }
 
 void workqueue_exhaust( WorkQueue * queue ) {
-	while( load_seqcst( &queue->jobs_completed ) < queue->jobs_queued ) {
+	while( load_relaxed( &queue->head ) != load_acquire( &queue->tail ) ) {
 		workqueue_step( queue->num_threads, queue );
 	}
-
-	queue->jobs_queued = 0;
-	store_seqcst( &queue->jobs_completed, 0 );
 }
diff --git a/work_queue.h b/work_queue.h
@@ -23,9 +23,6 @@ struct WorkQueue {
 	atomic_u32 head;
 	atomic_u32 tail;
 
-	u32 jobs_queued;
-	atomic_u32 jobs_completed;
-
 	u32 num_threads;
 	MemoryArena * arenas;
 };