util: move pipe_barrier into src/util and rename to util_barrier

The #if guard is probably not 100% equivalent to the previous PIPE_OS
check, but if anything it should be an over-approximation (are there
pthread implementations without barriers?), so people will get either
a good implementation or compile errors that are easy to fix.

Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/auxiliary/os/os_thread.h

@@ -60,82 +60,6 @@ __pipe_mutex_assert_locked(mtx_t *mutex)
 }
 
 
-/*
- * pipe_barrier
- */
-
-#if (defined(PIPE_OS_LINUX) || defined(PIPE_OS_BSD) || defined(PIPE_OS_SOLARIS) || defined(PIPE_OS_HURD)) && (!defined(PIPE_OS_ANDROID) || ANDROID_API_LEVEL >= 24)
-
-typedef pthread_barrier_t pipe_barrier;
-
-static inline void pipe_barrier_init(pipe_barrier *barrier, unsigned count)
-{
-   pthread_barrier_init(barrier, NULL, count);
-}
-
-static inline void pipe_barrier_destroy(pipe_barrier *barrier)
-{
-   pthread_barrier_destroy(barrier);
-}
-
-static inline void pipe_barrier_wait(pipe_barrier *barrier)
-{
-   pthread_barrier_wait(barrier);
-}
-
-
-#else /* If the OS doesn't have its own, implement barriers using a mutex and a condvar */
-
-typedef struct {
-   unsigned count;
-   unsigned waiters;
-   uint64_t sequence;
-   mtx_t mutex;
-   cnd_t condvar;
-} pipe_barrier;
-
-static inline void pipe_barrier_init(pipe_barrier *barrier, unsigned count)
-{
-   barrier->count = count;
-   barrier->waiters = 0;
-   barrier->sequence = 0;
-   (void) mtx_init(&barrier->mutex, mtx_plain);
-   cnd_init(&barrier->condvar);
-}
-
-static inline void pipe_barrier_destroy(pipe_barrier *barrier)
-{
-   assert(barrier->waiters == 0);
-   mtx_destroy(&barrier->mutex);
-   cnd_destroy(&barrier->condvar);
-}
-
-static inline void pipe_barrier_wait(pipe_barrier *barrier)
-{
-   mtx_lock(&barrier->mutex);
-
-   assert(barrier->waiters < barrier->count);
-   barrier->waiters++;
-
-   if (barrier->waiters < barrier->count) {
-      uint64_t sequence = barrier->sequence;
-
-      do {
-         cnd_wait(&barrier->condvar, &barrier->mutex);
-      } while (sequence == barrier->sequence);
-   } else {
-      barrier->waiters = 0;
-      barrier->sequence++;
-      cnd_broadcast(&barrier->condvar);
-   }
-
-   mtx_unlock(&barrier->mutex);
-}
-
-
-#endif
-
-
 /*
  * Semaphores
  */

src/gallium/drivers/llvmpipe/lp_rast.c

@@ -32,6 +32,7 @@
 #include "util/u_surface.h"
 #include "util/u_pack_color.h"
 #include "util/u_string.h"
+#include "util/u_thread.h"
 
 #include "os/os_time.h"
 
@@ -822,7 +823,7 @@ thread_function(void *init_data)
       /* Wait for all threads to get here so that threads[1+] don't
        * get a null rast->curr_scene pointer.
        */
-      pipe_barrier_wait( &rast->barrier );
+      util_barrier_wait( &rast->barrier );
 
       /* do work */
       if (debug)
@@ -832,7 +833,7 @@ thread_function(void *init_data)
                       rast->curr_scene);
       
       /* wait for all threads to finish with this scene */
-      pipe_barrier_wait( &rast->barrier );
+      util_barrier_wait( &rast->barrier );
 
       /* XXX: shouldn't be necessary:
        */
@@ -914,7 +915,7 @@ lp_rast_create( unsigned num_threads )
 
    /* for synchronizing rasterization threads */
    if (rast->num_threads > 0) {
-      pipe_barrier_init( &rast->barrier, rast->num_threads );
+      util_barrier_init( &rast->barrier, rast->num_threads );
    }
 
    memset(lp_dummy_tile, 0, sizeof lp_dummy_tile);
@@ -973,7 +974,7 @@ void lp_rast_destroy( struct lp_rasterizer *rast )
 
    /* for synchronizing rasterization threads */
    if (rast->num_threads > 0) {
-      pipe_barrier_destroy( &rast->barrier );
+      util_barrier_destroy( &rast->barrier );
    }
 
    lp_scene_queue_destroy(rast->full_scenes);

src/gallium/drivers/llvmpipe/lp_rast_priv.h

@@ -28,8 +28,8 @@
 #ifndef LP_RAST_PRIV_H
 #define LP_RAST_PRIV_H
 
-#include "os/os_thread.h"
 #include "util/u_format.h"
+#include "util/u_thread.h"
 #include "gallivm/lp_bld_debug.h"
 #include "lp_memory.h"
 #include "lp_rast.h"
@@ -130,7 +130,7 @@ struct lp_rasterizer
    thrd_t threads[LP_MAX_THREADS];
 
    /** For synchronizing the rasterization threads */
-   pipe_barrier barrier;
+   util_barrier barrier;
 };
 
 

src/gallium/tests/unit/pipe_barrier_test.c

@@ -27,7 +27,7 @@
 
 
 /*
- *  Test case for pipe_barrier.
+ *  Test case for util_barrier.
  *
  *  The test succeeds if no thread exits before all the other threads reach
  *  the barrier.
@@ -37,9 +37,9 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "os/os_thread.h"
 #include "os/os_time.h"
 #include "util/u_atomic.h"
+#include "util/u_thread.h"
 
 
 #define NUM_THREADS 10
@@ -47,7 +47,7 @@
 static int verbosity = 0;
 
 static thrd_t threads[NUM_THREADS];
-static pipe_barrier barrier;
+static util_barrier barrier;
 static int thread_ids[NUM_THREADS];
 
 static volatile int waiting = 0;
@@ -78,7 +78,7 @@ thread_function(void *thread_data)
    CHECK(p_atomic_read(&proceeded) == 0);
    p_atomic_inc(&waiting);
 
-   pipe_barrier_wait(&barrier);
+   util_barrier_wait(&barrier);
 
    CHECK(p_atomic_read(&waiting) == NUM_THREADS);
 
@@ -109,7 +109,7 @@ int main(int argc, char *argv[])
 
    LOG("pipe_barrier_test starting\n");
 
-   pipe_barrier_init(&barrier, NUM_THREADS);
+   util_barrier_init(&barrier, NUM_THREADS);
 
    for (i = 0; i < NUM_THREADS; i++) {
       thread_ids[i] = i;
@@ -122,7 +122,7 @@ int main(int argc, char *argv[])
 
    CHECK(p_atomic_read(&proceeded) == NUM_THREADS);
 
-   pipe_barrier_destroy(&barrier);
+   util_barrier_destroy(&barrier);
 
    LOG("pipe_barrier_test exiting\n");
 

src/util/u_thread.h

@@ -100,4 +100,78 @@ static inline bool u_thread_is_self(thrd_t thread)
    return false;
 }
 
+/*
+ * util_barrier
+ */
+
+#if defined(HAVE_PTHREAD)
+
+typedef pthread_barrier_t util_barrier;
+
+static inline void util_barrier_init(util_barrier *barrier, unsigned count)
+{
+   pthread_barrier_init(barrier, NULL, count);
+}
+
+static inline void util_barrier_destroy(util_barrier *barrier)
+{
+   pthread_barrier_destroy(barrier);
+}
+
+static inline void util_barrier_wait(util_barrier *barrier)
+{
+   pthread_barrier_wait(barrier);
+}
+
+
+#else /* If the OS doesn't have its own, implement barriers using a mutex and a condvar */
+
+typedef struct {
+   unsigned count;
+   unsigned waiters;
+   uint64_t sequence;
+   mtx_t mutex;
+   cnd_t condvar;
+} util_barrier;
+
+static inline void util_barrier_init(util_barrier *barrier, unsigned count)
+{
+   barrier->count = count;
+   barrier->waiters = 0;
+   barrier->sequence = 0;
+   (void) mtx_init(&barrier->mutex, mtx_plain);
+   cnd_init(&barrier->condvar);
+}
+
+static inline void util_barrier_destroy(util_barrier *barrier)
+{
+   assert(barrier->waiters == 0);
+   mtx_destroy(&barrier->mutex);
+   cnd_destroy(&barrier->condvar);
+}
+
+static inline void util_barrier_wait(util_barrier *barrier)
+{
+   mtx_lock(&barrier->mutex);
+
+   assert(barrier->waiters < barrier->count);
+   barrier->waiters++;
+
+   if (barrier->waiters < barrier->count) {
+      uint64_t sequence = barrier->sequence;
+
+      do {
+         cnd_wait(&barrier->condvar, &barrier->mutex);
+      } while (sequence == barrier->sequence);
+   } else {
+      barrier->waiters = 0;
+      barrier->sequence++;
+      cnd_broadcast(&barrier->condvar);
+   }
+
+   mtx_unlock(&barrier->mutex);
+}
+
+#endif
+
 #endif /* U_THREAD_H_ */