cc::ResourcePool - Re-use larger resources for smaller requests

cc/resources/resource_pool.cc

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/resources/resource_pool.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <algorithm>
 #include <utility>
 
 #include "base/format_macros.h"
 #include "base/memory/memory_coordinator_client_registry.h"
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/trace_event/memory_dump_manager.h"
 #include "cc/base/container_util.h"
 #include "cc/resources/resource_provider.h"
 #include "cc/resources/resource_util.h"
 #include "cc/resources/scoped_resource.h"
 
 using base::trace_event::MemoryAllocatorDump;
 using base::trace_event::MemoryDumpLevelOfDetail;
 
 namespace cc {
+namespace {
+bool ResourceMeetsSizeRequirements(const gfx::Size& requested_size,
+                                   const gfx::Size& actual_size,
+                                   bool disallow_non_exact_reuse) {
+  const float kReuseThreshold = 2.0f;
+
+  if (disallow_non_exact_reuse)
+    return requested_size == actual_size;
+
+  // Allocating new resources is expensive, and we'd like to re-use our
+  // existing ones within reason. Allow a larger resource to be used for a
+  // smaller request.
+  if (actual_size.width() < requested_size.width() ||
+      actual_size.height() < requested_size.height())
+    return false;
+
+  // GetArea will crash on overflow, however all sizes in use are tile sizes.
+  // These are capped at ResourceProvider::max_texture_size(), and will not
+  // overflow.
+  float actual_area = actual_size.GetArea();
+  float requested_area = requested_size.GetArea();
+  // Don't use a resource that is more than |kReuseThreshold| times the
+  // requested pixel area, as we want to free unnecessarily large resources.
+  if (actual_area / requested_area > kReuseThreshold)
+    return false;
+
+  return true;
+}
+
+}  // namespace
+
 base::TimeDelta ResourcePool::kDefaultExpirationDelay =
-    base::TimeDelta::FromSeconds(1);
+    base::TimeDelta::FromSeconds(5);
 
 void ResourcePool::PoolResource::OnMemoryDump(
     base::trace_event::ProcessMemoryDump* pmd,
     const ResourceProvider* resource_provider,
     bool is_free) const {
   // Resource IDs are not process-unique, so log with the ResourceProvider's
   // unique id.
   std::string parent_node =
       base::StringPrintf("cc/resource_memory/provider_%d/resource_%d",
                          resource_provider->tracing_id(), id());
@@ skipping 10 matching lines @@
                   MemoryAllocatorDump::kUnitsBytes, total_bytes);
 
   if (is_free) {
     dump->AddScalar("free_size", MemoryAllocatorDump::kUnitsBytes, total_bytes);
   }
 }
 
 ResourcePool::ResourcePool(ResourceProvider* resource_provider,
                            base::SingleThreadTaskRunner* task_runner,
                            gfx::BufferUsage usage,
-                           const base::TimeDelta& expiration_delay)
+                           const base::TimeDelta& expiration_delay,
+                           bool disallow_non_exact_reuse)
     : resource_provider_(resource_provider),
       use_gpu_memory_buffers_(true),
       usage_(usage),
       task_runner_(task_runner),
       resource_expiration_delay_(expiration_delay),
+      disallow_non_exact_reuse_(disallow_non_exact_reuse),
       weak_ptr_factory_(this) {
   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
       this, "cc::ResourcePool", task_runner_.get());
 
   // Register this component with base::MemoryCoordinatorClientRegistry.
   base::MemoryCoordinatorClientRegistry::GetInstance()->Register(this);
 }
 
 ResourcePool::ResourcePool(ResourceProvider* resource_provider,
                            base::SingleThreadTaskRunner* task_runner,
                            ResourceProvider::TextureHint hint,
-                           const base::TimeDelta& expiration_delay)
+                           const base::TimeDelta& expiration_delay,
+                           bool disallow_non_exact_reuse)
     : resource_provider_(resource_provider),
       use_gpu_memory_buffers_(false),
       hint_(hint),
       task_runner_(task_runner),
       resource_expiration_delay_(expiration_delay),
+      disallow_non_exact_reuse_(disallow_non_exact_reuse),
       weak_ptr_factory_(this) {
   base::trace_event::MemoryDumpManager::GetInstance()->RegisterDumpProvider(
       this, "cc::ResourcePool", task_runner_.get());
 
   // Register this component with base::MemoryCoordinatorClientRegistry.
   base::MemoryCoordinatorClientRegistry::GetInstance()->Register(this);
 }
 
 ResourcePool::~ResourcePool() {
   base::trace_event::MemoryDumpManager::GetInstance()->UnregisterDumpProvider(
@@ skipping 20 matching lines @@
   // Finding resources in |unused_resources_| from MRU to LRU direction, touches
   // LRU resources only if needed, which increases possibility of expiring more
   // LRU resources within kResourceExpirationDelayMs.
   for (ResourceDeque::iterator it = unused_resources_.begin();
        it != unused_resources_.end(); ++it) {
     ScopedResource* resource = it->get();
     DCHECK(resource_provider_->CanLockForWrite(resource->id()));
 
     if (resource->format() != format)
       continue;
-    if (resource->size() != size)
+    if (!ResourceMeetsSizeRequirements(size, resource->size(),
+                                       disallow_non_exact_reuse_))
       continue;
     if (resource->color_space() != color_space)
       continue;
 
     // Transfer resource to |in_use_resources_|.
     in_use_resources_[resource->id()] = std::move(*it);
     unused_resources_.erase(it);
     in_use_memory_usage_bytes_ += ResourceUtil::UncheckedSizeInBytes<size_t>(
         resource->size(), resource->format());
     return resource;
@@ skipping 347 matching lines @@
   }
   return true;
 }
 
 void ResourcePool::OnPurgeMemory() {
   // Release all resources, regardless of how recently they were used.
   EvictResourcesNotUsedSince(base::TimeTicks() + base::TimeDelta::Max());
 }
 
 }  // namespace cc