1/**************************************************************************
2 *
3 * Copyright 2009 VMware, Inc.
4 * All Rights Reserved.
5 *
6 * Permission is hereby granted, free of charge, to any person obtaining a
7 * copy of this software and associated documentation files (the
8 * "Software"), to deal in the Software without restriction, including
9 * without limitation the rights to use, copy, modify, merge, publish,
10 * distribute, sub license, and/or sell copies of the Software, and to
11 * permit persons to whom the Software is furnished to do so, subject to
12 * the following conditions:
13 *
14 * The above copyright notice and this permission notice (including the
15 * next paragraph) shall be included in all copies or substantial portions
16 * of the Software.
17 *
18 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
19 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
20 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
21 * IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
22 * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
23 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
24 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
25 *
26 **************************************************************************/
27
28
29/**
30 * Scene queue.  We'll use two queues.  One contains "full" scenes which
31 * are produced by the "setup" code.  The other contains "empty" scenes
32 * which are produced by the "rast" code when it finishes rendering a scene.
33 */
34
35#include "os/os_thread.h"
36#include "util/u_memory.h"
37#include "lp_scene_queue.h"
38#include "util/u_math.h"
39#include "lp_setup_context.h"
40
41
42#define SCENE_QUEUE_SIZE MAX_SCENES
43
44
45
46/**
47 * A queue of scenes
48 */
49struct lp_scene_queue
50{
51   struct lp_scene *scenes[SCENE_QUEUE_SIZE];
52
53   mtx_t mutex;
54   cnd_t change;
55
56   /* These values wrap around, so that head == tail means empty.  When used
57    * to index the array, we use them modulo the queue size.  This scheme
58    * works because the queue size is a power of two.
59    */
60   unsigned head;
61   unsigned tail;
62};
63
64
65
66/** Allocate a new scene queue */
67struct lp_scene_queue *
68lp_scene_queue_create(void)
69{
70   /* Circular queue behavior depends on size being a power of two. */
71   STATIC_ASSERT(SCENE_QUEUE_SIZE > 0);
72   STATIC_ASSERT((SCENE_QUEUE_SIZE & (SCENE_QUEUE_SIZE - 1)) == 0);
73
74   struct lp_scene_queue *queue = CALLOC_STRUCT(lp_scene_queue);
75
76   if (!queue)
77      return NULL;
78
79   (void) mtx_init(&queue->mutex, mtx_plain);
80   cnd_init(&queue->change);
81
82   return queue;
83}
84
85
86/** Delete a scene queue */
87void
88lp_scene_queue_destroy(struct lp_scene_queue *queue)
89{
90   cnd_destroy(&queue->change);
91   mtx_destroy(&queue->mutex);
92   FREE(queue);
93}
94
95
96/** Remove first lp_scene from head of queue */
97struct lp_scene *
98lp_scene_dequeue(struct lp_scene_queue *queue, boolean wait)
99{
100   mtx_lock(&queue->mutex);
101
102   if (wait) {
103      /* Wait for queue to be not empty. */
104      while (queue->head == queue->tail)
105         cnd_wait(&queue->change, &queue->mutex);
106   } else {
107      if (queue->head == queue->tail) {
108         mtx_unlock(&queue->mutex);
109         return NULL;
110      }
111   }
112
113   struct lp_scene *scene = queue->scenes[queue->head++ % SCENE_QUEUE_SIZE];
114
115   cnd_signal(&queue->change);
116   mtx_unlock(&queue->mutex);
117
118   return scene;
119}
120
121
122/** Add an lp_scene to tail of queue */
123void
124lp_scene_enqueue(struct lp_scene_queue *queue, struct lp_scene *scene)
125{
126   mtx_lock(&queue->mutex);
127
128   /* Wait for free space. */
129   while (queue->tail - queue->head >= SCENE_QUEUE_SIZE)
130      cnd_wait(&queue->change, &queue->mutex);
131
132   queue->scenes[queue->tail++ % SCENE_QUEUE_SIZE] = scene;
133
134   cnd_signal(&queue->change);
135   mtx_unlock(&queue->mutex);
136}
137