Caching AudioOutputDevice instances in mixer manager

content/renderer/media/audio_renderer_sink_cache_impl.cc

+// Copyright 2016 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 <algorithm>
+
+#include "base/bind.h"
+#include "base/location.h"
+#include "base/memory/ptr_util.h"
+#include "base/synchronization/lock.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "content/renderer/media/audio_device_factory.h"
+#include "content/renderer/media/audio_renderer_sink_cache_impl.h"
+#include "media/audio/audio_device_description.h"
+#include "media/base/audio_renderer_sink.h"
+#include "url/origin.h"
+
+namespace content {
+
+constexpr int kDeleteTimeoutMs = 5000;
+
+// Cached sink data.
+struct AudioRendererSinkCacheImpl::CacheEntry {
+  int source_render_frame_id;
+  std::string device_id;
+  url::Origin security_origin;
+  scoped_refptr<media::AudioRendererSink> sink;  // Sink instance
+  bool used;                                     // True if in use by a client.
+};
+
+// static
+std::unique_ptr<AudioRendererSinkCache> AudioRendererSinkCache::Create() {
+  return base::WrapUnique(new AudioRendererSinkCacheImpl(
+      base::ThreadTaskRunnerHandle::Get(),
+      base::Bind(AudioDeviceFactory::NewAudioRendererMixerSink),

[DaleCurtis, 2016/05/26 19:18:09]

Hmm, should this have a & ? I'm surprised it compiles without it.

[o1ka, 2016/05/27 13:48:52]

It's a static method, so & is optional (just like with regular functions). But I
had no intention to omit it - it's a misprint. Thanks for catching!

+      base::TimeDelta::FromMilliseconds(kDeleteTimeoutMs)));
+}
+
+AudioRendererSinkCacheImpl::AudioRendererSinkCacheImpl(
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner,
+    const CreateSinkCallback& create_sink_cb,
+    base::TimeDelta delete_timeout)
+    : task_runner_(std::move(task_runner)),
+      create_sink_cb_(create_sink_cb),
+      delete_timeout_(delete_timeout),
+      weak_ptr_factory_(this) {
+  weak_this_ = weak_ptr_factory_.GetWeakPtr();
+}
+
+AudioRendererSinkCacheImpl::~AudioRendererSinkCacheImpl() {
+  // We just release all the cached sinks here.
+}
+
+media::OutputDeviceInfo AudioRendererSinkCacheImpl::GetSinkInfo(
+    int source_render_frame_id,
+    int session_id,
+    const std::string& device_id,
+    const url::Origin& security_origin) {
+  CacheEntry cache_entry = {source_render_frame_id,
+                            std::string() /* device_id */, security_origin,
+                            nullptr /* sink */, false /* not used */};
+
+  if (media::AudioDeviceDescription::UseSessionIdToSelectDevice(session_id,
+                                                                device_id)) {
+    // We are provided with session id instead of device id. Session id is
+    // unique, so we can't find any matching sink. Creating a new one.
+    cache_entry.sink = create_sink_cb_.Run(source_render_frame_id, session_id,
+                                           device_id, security_origin);
+    cache_entry.device_id = cache_entry.sink->GetOutputDeviceInfo().device_id();
+
+    DVLOG(1) << "GetSinkInfo: address: " << cache_entry.sink.get()
+             << " - used session to create new sink.";
+
+    // Cache a newly-created sink.
+    base::AutoLock auto_lock(cache_lock_);
+    cache_.push_back(cache_entry);
+
+  } else {
+    // Ignore session id.
+    base::AutoLock auto_lock(cache_lock_);
+
+    auto cache_iter =
+        FindCacheEntry_Locked(source_render_frame_id, device_id,
+                              security_origin, false /* unused_only */);
+
+    if (cache_iter != cache_.end()) {
+      // A matching cached sink is found.
+      DVLOG(1) << "GetSinkInfo: address: " << cache_iter->sink.get()
+               << " - reused a cached sink.";
+
+      return cache_iter->sink->GetOutputDeviceInfo();
+    }
+
+    // No matching sink found, create a new one.
+    cache_entry.device_id = device_id;
+    cache_entry.sink = create_sink_cb_.Run(
+        source_render_frame_id, 0 /* session_id */, device_id, security_origin);
+
+    DVLOG(1) << "GetSinkInfo: address: " << cache_entry.sink.get()
+             << " - no matching cached sink found, created a new one.";
+
+    // Cache a newly-created sink.
+    cache_.push_back(cache_entry);
+  }
+
+  // Schedule it for deletion.
+  DeleteLaterIfUnused(cache_entry.sink.get());
+
+  DVLOG(1) << "GetSinkInfo: address: " << cache_entry.sink.get()
+           << " created. source_render_frame_id: " << source_render_frame_id
+           << " session_id: " << session_id << " device_id: " << device_id
+           << " security_origin: " << security_origin;
+
+  return cache_entry.sink->GetOutputDeviceInfo();
+}
+
+scoped_refptr<media::AudioRendererSink> AudioRendererSinkCacheImpl::GetSink(
+    int source_render_frame_id,
+    const std::string& device_id,
+    const url::Origin& security_origin) {
+  base::AutoLock auto_lock(cache_lock_);
+
+  auto cache_iter =
+      FindCacheEntry_Locked(source_render_frame_id, device_id, security_origin,
+                            true /* unused_only */);
+
+  if (cache_iter != cache_.end()) {
+    // Found unused sink; mark it as used and return.
+    DVLOG(1) << "GetSink: address: " << cache_iter->sink.get()
+             << " - found unused cached sink, reusing it.";
+
+    cache_iter->used = true;
+    return cache_iter->sink;
+  }
+
+  // No unused sink is found, create one, mark it used, cache it and return.
+  CacheEntry cache_entry = {
+      source_render_frame_id, device_id, security_origin,
+      create_sink_cb_.Run(source_render_frame_id, 0 /* session_id */, device_id,
+                          security_origin),
+      true /* used */};
+
+  cache_.push_back(cache_entry);
+
+  DVLOG(1) << "GetSink: address: " << cache_entry.sink.get()
+           << " - no unused cached sink found, created a new one."
+           << " source_render_frame_id: " << source_render_frame_id
+           << " device_id: " << device_id
+           << " security_origin: " << security_origin;
+  return cache_entry.sink;
+}
+
+void AudioRendererSinkCacheImpl::ReleaseSink(
+    const media::AudioRendererSink* sink_ptr) {
+  // We don't know the sink state, so won't reuse it. Delete it immediately.
+  DeleteSink(sink_ptr, true);
+}
+
+void AudioRendererSinkCacheImpl::DeleteLaterIfUnused(
+    const media::AudioRendererSink* sink_ptr) {
+  task_runner_->PostDelayedTask(
+      FROM_HERE, base::Bind(&AudioRendererSinkCacheImpl::DeleteSink, weak_this_,
+                            sink_ptr, false /*do not delete if used*/),
+      delete_timeout_);
+}
+
+void AudioRendererSinkCacheImpl::DeleteSink(
+    const media::AudioRendererSink* sink_ptr,
+    bool force_delete_used) {
+  DCHECK(sink_ptr);
+
+  scoped_refptr<media::AudioRendererSink> sink_to_stop;
+
+  {
+    base::AutoLock auto_lock(cache_lock_);
+
+    // Looking up the sink by its pointer.
+    auto cache_iter = std::find_if(cache_.begin(), cache_.end(),
+                                   [sink_ptr](const CacheEntry& val) {
+                                     return val.sink.get() == sink_ptr;
+                                   });
+
+    if (cache_iter == cache_.end()) {
+      // If |force_delete_used| is not set it means the sink scheduled for
+      // deletion got aquired and released before scheduled deletion - it's ok.
+      DCHECK(!force_delete_used)
+          << "DeleteSink: address: " << sink_ptr
+          << " could not find a sink which is supposed to be in use";
+
+      DVLOG(1) << "DeleteSink: address: " << sink_ptr
+               << " force_delete_used = false - already deleted.";
+      return;
+    }
+
+    // When |force_delete_used| is set, it's expected that we are deleting a
+    // used sink.
+    DCHECK((!force_delete_used) || (force_delete_used && cache_iter->used))
+        << "Attempt to delete a non-aquired sink.";
+
+    if (!force_delete_used && cache_iter->used) {
+      DVLOG(1) << "DeleteSink: address: " << sink_ptr
+               << " sink in use, skipping deletion.";
+      return;
+    }
+
+    // To stop the sink before deletion if it's not used, we need to hold
+    // a ref to it.
+    if (!cache_iter->used)
+      sink_to_stop = cache_iter->sink;
+
+    cache_.erase(cache_iter);
+    DVLOG(1) << "DeleteSink: address: " << sink_ptr;
+  }  // Lock scope;
+
+  // Stop the sink out of the lock scope.
+  if (sink_to_stop.get()) {
+    DCHECK_EQ(sink_ptr, sink_to_stop.get());
+    sink_to_stop->Stop();
+    DVLOG(1) << "DeleteSink: address: " << sink_ptr << " stopped.";
+  }
+}
+
+AudioRendererSinkCacheImpl::CacheContainer::iterator
+AudioRendererSinkCacheImpl::FindCacheEntry_Locked(
+    int source_render_frame_id,
+    const std::string& device_id,
+    const url::Origin& security_origin,
+    bool unused_only) {
+  return std::find_if(
+      cache_.begin(), cache_.end(),
+      [source_render_frame_id, &device_id, &security_origin,
+       unused_only](const CacheEntry& val) {
+        if (val.used && unused_only)
+          return false;
+        if (val.source_render_frame_id != source_render_frame_id)
+          return false;
+        if (media::AudioDeviceDescription::IsDefaultDevice(device_id) &&
+            media::AudioDeviceDescription::IsDefaultDevice(val.device_id)) {
+          // Both device IDs represent the same default device => do not compare
+          // them; the default device is always authorized => ignore security
+          // origin.
+          return true;
+        }
+        return val.device_id == device_id &&
+               val.security_origin == security_origin;
+      });
+};
+
+int AudioRendererSinkCacheImpl::GetCacheSizeForTesting() {

[DaleCurtis, 2016/05/26 19:18:09]

This can be an inline get_cache_size_for_testing() instead if you like.

[o1ka, 2016/05/27 13:48:52]

Unfortunately not, I need to publish CacheEntry struct in the header to do that
(and then I would not need a method, because test fixture is a friend). I added
a comment.

+  return cache_.size();
+}
+
+}  // namespace content