cc: Reduce command buffer flushes related to creating texture ids.

cc/resources/resource_provider.cc

Index: cc/resources/resource_provider.cc
diff --git a/cc/resources/resource_provider.cc b/cc/resources/resource_provider.cc
index 874fe3f641907df4c4e2b198316ce662d639b2a2..36c6f9e62727549997d32875d1fd6e7182a754e9 100644
--- a/cc/resources/resource_provider.cc
+++ b/cc/resources/resource_provider.cc
@@ -216,12 +216,14 @@ scoped_ptr<ResourceProvider> ResourceProvider::Create(
     OutputSurface* output_surface,
     SharedBitmapManager* shared_bitmap_manager,
     int highp_threshold_min,
-    bool use_rgba_4444_texture_format) {
+    bool use_rgba_4444_texture_format,
+    size_t texture_id_allocation_chunk_size) {
   scoped_ptr<ResourceProvider> resource_provider(
       new ResourceProvider(output_surface,
                            shared_bitmap_manager,
                            highp_threshold_min,
-                           use_rgba_4444_texture_format));
+                           use_rgba_4444_texture_format,
+                           texture_id_allocation_chunk_size));
 
   bool success = false;
   if (resource_provider->Context3d()) {
@@ -647,7 +649,7 @@ const ResourceProvider::Resource* ResourceProvider::LockForRead(ResourceId id) {
             context3d->waitSyncPoint(resource->mailbox.sync_point()));
         resource->mailbox.ResetSyncPoint();
       }
-      resource->gl_id = context3d->createTexture();
+      resource->gl_id = NextTextureId();
       GLC(context3d, context3d->bindTexture(resource->target, resource->gl_id));
       GLC(context3d,
           context3d->consumeTextureCHROMIUM(resource->target,
@@ -791,7 +793,8 @@ ResourceProvider::ScopedWriteLockSoftware::~ScopedWriteLockSoftware() {
 ResourceProvider::ResourceProvider(OutputSurface* output_surface,
                                    SharedBitmapManager* shared_bitmap_manager,
                                    int highp_threshold_min,
-                                   bool use_rgba_4444_texture_format)
+                                   bool use_rgba_4444_texture_format,
+                                   size_t texture_id_allocation_chunk_size)
     : output_surface_(output_surface),
       shared_bitmap_manager_(shared_bitmap_manager),
       lost_output_surface_(false),
@@ -804,8 +807,10 @@ ResourceProvider::ResourceProvider(OutputSurface* output_surface,
       use_shallow_flush_(false),
       max_texture_size_(0),
       best_texture_format_(RGBA_8888),
-      use_rgba_4444_texture_format_(use_rgba_4444_texture_format) {
+      use_rgba_4444_texture_format_(use_rgba_4444_texture_format),
+      texture_id_allocation_chunk_size_(texture_id_allocation_chunk_size) {
   DCHECK(output_surface_->HasClient());
+  DCHECK(texture_id_allocation_chunk_size_);
 }
 
 void ResourceProvider::InitializeSoftware() {
@@ -863,6 +868,14 @@ void ResourceProvider::CleanUpGLIfNeeded() {
   DCHECK(context3d);
   context3d->makeContextCurrent();
   texture_uploader_.reset();
+  if (!unused_texture_ids_.empty()) {
+    size_t size = unused_texture_ids_.size();
+    scoped_ptr<WebKit::WebGLId[]> ids(new WebKit::WebGLId[size]);
+    for (size_t i = 0; i < size; ++i)
+      ids[i] = unused_texture_ids_[i];
+    GLC(context3d, context3d->deleteTextures(size, ids.get()));
+    unused_texture_ids_.clear();
+  }
   Finish();
 }
 
@@ -988,7 +1001,7 @@ void ResourceProvider::ReceiveFromChild(
       // (and is simpler) to wait.
       if (it->sync_point)
         GLC(context3d, context3d->waitSyncPoint(it->sync_point));
-      GLC(context3d, texture_id = context3d->createTexture());
+      texture_id = NextTextureId();
       GLC(context3d, context3d->bindTexture(it->target, texture_id));
       GLC(context3d,
           context3d->consumeTextureCHROMIUM(it->target, it->mailbox.name));
@@ -1546,11 +1559,12 @@ void ResourceProvider::LazyCreate(Resource* resource) {
   if (resource->texture_pool == 0)
     return;
 
+  resource->gl_id = NextTextureId();
+
   WebGraphicsContext3D* context3d = Context3d();
   DCHECK(context3d);
 
   // Create and set texture properties. Allocation is delayed until needed.
-  GLC(context3d, resource->gl_id = context3d->createTexture());
   GLC(context3d, context3d->bindTexture(resource->target, resource->gl_id));
   GLC(context3d,
       context3d->texParameteri(
@@ -1729,4 +1743,20 @@ WebKit::WebGraphicsContext3D* ResourceProvider::Context3d() const {
   return context_provider ? context_provider->Context3d() : NULL;
 }
 
+unsigned ResourceProvider::NextTextureId() {
+  if (unused_texture_ids_.empty()) {
+    size_t size = texture_id_allocation_chunk_size_;
+    scoped_ptr<WebKit::WebGLId[]> ids(new WebKit::WebGLId[size]);
+    WebGraphicsContext3D* context3d = Context3d();
+    DCHECK(context3d);
+    GLC(context3d, context3d->genTextures(size, ids.get()));
+    unused_texture_ids_.assign(ids.get(), ids.get() + size);
+  }
+
+  unsigned gl_id = unused_texture_ids_.front();
+  unused_texture_ids_.pop_front();

[piman, 2013/10/31 01:32:58]

nit: why a deque rather than a vector? You can take from the end and still not
incur reallocs/copies. deque is slightly bigger.

[reveman, 2013/10/31 13:38:31]

I think we should give out ids in the order they are generated as that might be
useful for debugging purposes and we might even have some unit test code that
rely on it. ie. if you create one resource it's given ids[0] not ids[63]. We can
of course accomplish that while using std::vector but we have to replace the use
of .assign(ids..) above with a loop. I prefer using a deque for that reason but
don't feel that strongly about it.

+
+  return gl_id;
+}
+
 }  // namespace cc