[Mesa-dev] [RFC] gallium/u_queue: add barrier function

[Rob Clark]

Helper to block until all previous jobs are complete.
---
So I think this might end up being useful to me in some cases.. but
the implementation only works for a single threaded queue (which is
all I need).  I could also just put a helper in my driver code.

Opinions?

 src/gallium/auxiliary/util/u_queue.c | 12 ++++++++++++
 src/gallium/auxiliary/util/u_queue.h |  2 ++
 2 files changed, 14 insertions(+)

diff --git a/src/gallium/auxiliary/util/u_queue.c b/src/gallium/auxiliary/util/u_queue.c
index 838464f..861faca 100644
--- a/src/gallium/auxiliary/util/u_queue.c
+++ b/src/gallium/auxiliary/util/u_queue.c
@@ -242,3 +242,15 @@ util_queue_add_job(struct util_queue *queue,
    pipe_condvar_signal(queue->has_queued_cond);
    pipe_mutex_unlock(queue->lock);
 }
+
+static void dummy_execute(void *job, int thread_index) {}
+
+/* blocks until all previously queued jobs complete: */
+void util_queue_barrier(struct util_queue *queue)
+{
+   struct util_queue_fence fence;
+   util_queue_fence_init(&fence);
+   util_queue_add_job(queue, &fence /*dummy*/, &fence, dummy_execute, NULL);
+   util_queue_job_wait(&fence);
+   util_queue_fence_destroy(&fence);
+}
diff --git a/src/gallium/auxiliary/util/u_queue.h b/src/gallium/auxiliary/util/u_queue.h
index 59646cc..8a22ee0 100644
--- a/src/gallium/auxiliary/util/u_queue.h
+++ b/src/gallium/auxiliary/util/u_queue.h
@@ -85,6 +85,8 @@ void util_queue_add_job(struct util_queue *queue,
 
 void util_queue_job_wait(struct util_queue_fence *fence);
 
+void util_queue_barrier(struct util_queue *queue);
+
 /* util_queue needs to be cleared to zeroes for this to work */
 static inline bool
 util_queue_is_initialized(struct util_queue *queue)
-- 
2.7.4