[Mesa-dev] [PATCH 1/2] vulkan/wsi: Add a thread-safe queue implementation

[Jason Ekstrand]

From: Kevin Strasser <kevin.strasser at intel.com>

In order to support FIFO mode without blocking the application on calls
to vkQueuePresentKHR it is necessary to enqueue the request and defer
calling the server until the next vblank period. The xcb present api
doesn't offer a way to register a callback, so we will have to spawn a
worker thread that will wait for a request to be added to the queue, call
to the server, and then make the image available for reuse.  This commit
introduces the queue data structure needed to implement this.

Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
---
 src/vulkan/wsi/Makefile.sources   |   3 +-
 src/vulkan/wsi/wsi_common_queue.h | 156 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 158 insertions(+), 1 deletion(-)
 create mode 100644 src/vulkan/wsi/wsi_common_queue.h

diff --git a/src/vulkan/wsi/Makefile.sources b/src/vulkan/wsi/Makefile.sources
index 3139e6d..50660f9 100644
--- a/src/vulkan/wsi/Makefile.sources
+++ b/src/vulkan/wsi/Makefile.sources
@@ -1,6 +1,7 @@
 
 VULKAN_WSI_FILES := \
-	wsi_common.h
+	wsi_common.h \
+	wsi_common_queue.h
 
 VULKAN_WSI_WAYLAND_FILES := \
 	wsi_common_wayland.c \
diff --git a/src/vulkan/wsi/wsi_common_queue.h b/src/vulkan/wsi/wsi_common_queue.h
new file mode 100644
index 0000000..ec2a925
--- /dev/null
+++ b/src/vulkan/wsi/wsi_common_queue.h
@@ -0,0 +1,156 @@
+/*
+ * Copyright © 2016 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#ifndef VULKAN_WSI_COMMON_QUEUE_H
+#define VULKAN_WSI_COMMON_QUEUE_H
+
+#include <time.h>
+#include <pthread.h>
+#include "util/u_vector.h"
+
+struct wsi_queue {
+   struct u_vector vector;
+   pthread_mutex_t mutex;
+   pthread_cond_t cond;
+};
+
+static inline int
+wsi_queue_init(struct wsi_queue *queue, int length)
+{
+   int ret;
+
+   uint32_t length_pow2 = 4;
+   while (length_pow2 < length)
+      length_pow2 *= 2;
+
+   ret = u_vector_init(&queue->vector, sizeof(uint32_t),
+                       sizeof(uint32_t) * length_pow2);
+   if (!ret)
+      return -ENOMEM;
+
+   pthread_condattr_t condattr;
+   ret = pthread_condattr_init(&condattr);
+   if (ret)
+      goto fail_vector;
+
+   ret = pthread_condattr_setclock(&condattr, CLOCK_MONOTONIC);
+   if (ret)
+      goto fail_condattr;
+
+   ret = pthread_cond_init(&queue->cond, &condattr);
+   if (ret)
+      goto fail_condattr;
+
+   ret = pthread_mutex_init(&queue->mutex, NULL);
+   if (ret) {
+      pthread_cond_destroy(&queue->cond);
+      goto fail_cond;
+   }
+
+   return 0;
+
+fail_cond:
+   pthread_cond_destroy(&queue->cond);
+fail_condattr:
+   pthread_condattr_destroy(&condattr);
+fail_vector:
+   u_vector_finish(&queue->vector);
+
+   return ret;
+}
+
+static inline void
+wsi_queue_destroy(struct wsi_queue *queue)
+{
+   u_vector_finish(&queue->vector);
+   pthread_mutex_destroy(&queue->mutex);
+   pthread_cond_destroy(&queue->cond);
+}
+
+static inline void
+wsi_queue_push(struct wsi_queue *queue, uint32_t index)
+{
+   uint32_t *elem;
+
+   pthread_mutex_lock(&queue->mutex);
+
+   if (u_vector_length(&queue->vector) == 0)
+      pthread_cond_signal(&queue->cond);
+
+   elem = u_vector_add(&queue->vector);
+   *elem = index;
+
+   pthread_mutex_unlock(&queue->mutex);
+}
+
+#define NSEC_PER_SEC 1000000000
+#define INT_TYPE_MAX(type) ((1ull << (sizeof(type) * 8 - 1)) - 1)
+
+static inline VkResult
+wsi_queue_pull(struct wsi_queue *queue, uint32_t *index, uint64_t timeout)
+{
+   VkResult result;
+   int32_t ret;
+
+   pthread_mutex_lock(&queue->mutex);
+
+   struct timespec now;
+   clock_gettime(CLOCK_MONOTONIC, &now);
+
+   uint32_t abs_nsec = now.tv_nsec + timeout % NSEC_PER_SEC;
+   uint64_t abs_sec = now.tv_sec + (abs_nsec / NSEC_PER_SEC) +
+                      (timeout / NSEC_PER_SEC);
+   abs_nsec %= NSEC_PER_SEC;
+
+   /* Avoid roll-over in tv_sec on 32-bit systems if the user provided timeout
+    * is UINT64_MAX
+    */
+   struct timespec abstime;
+   abstime.tv_nsec = abs_nsec;
+   abstime.tv_sec = MIN2(abs_sec, INT_TYPE_MAX(abstime.tv_sec));
+
+   while (u_vector_length(&queue->vector) == 0) {
+      ret = pthread_cond_timedwait(&queue->cond, &queue->mutex, &abstime);
+      if (ret == 0) {
+         continue;
+      } else if (ret == ETIMEDOUT) {
+         result = VK_TIMEOUT;
+         goto end;
+      } else {
+         /* Something went badly wrong */
+         result = VK_ERROR_OUT_OF_DATE_KHR;
+         goto end;
+      }
+   }
+
+   uint32_t *elem = u_vector_remove(&queue->vector);
+   *index = *elem;
+   result = VK_SUCCESS;
+
+end:
+   pthread_mutex_unlock(&queue->mutex);
+
+   return result;
+}
+
+#endif /* VULKAN_WSI_COMMON_QUEUE_H */
-- 
2.5.0.400.gff86faf