DO NOT COMMIT - DialogSurface initial implementation.

media/base/android/dialog_surface_callback.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 "media/base/android/dialog_surface_callback.h"
+
+#include <algorithm>
+#include <limits>
+#include <map>
+#include <memory>
+#include <utility>
+
+#include "base/android/build_info.h"
+#include "base/android/jni_android.h"
+#include "base/android/jni_array.h"
+#include "base/android/jni_string.h"
+#include "base/bind.h"
+#include "base/lazy_instance.h"
+#include "base/location.h"
+#include "base/logging.h"
+#include "base/numerics/safe_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/synchronization/lock.h"
+#include "base/synchronization/waitable_event.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "jni/DialogSurfaceCallback_jni.h"
+
+using base::android::AttachCurrentThread;
+
+namespace media {
+
+static long next_id_ = 1;
+
+// Map of ids to DialogSurfaceCallbacks.  This is called from multiple threads.
+class DialogCallbackMap {
+ public:
+  // Associate |thiz| with |id|.
+  void Insert(long id, DialogSurfaceCallback* thiz) {
+    base::AutoLock _l(lock_);
+    map_[id] = thiz;
+  }
+
+  // Forget about |id|.
+  void Erase(long id) {
+    base::AutoLock _l(lock_);
+    map_.erase(id);
+  }
+
+  // Return the associated callback for |id|, or null.
+  DialogSurfaceCallback* Lookup(long id) {
+    base::AutoLock _l(lock_);
+    return LookupLocked(id);
+  }
+
+  // Map |id| to the correct task runner for callbacks, or null.
+  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner(long id) {
+    scoped_refptr<base::SingleThreadTaskRunner> task_runner;
+    base::AutoLock _l(lock_);
+    DialogSurfaceCallback* thiz = LookupLocked(id);
+    // While under lock, |thiz| cannot be removed from the map.
+    if (thiz)
+      task_runner = thiz->GetTaskRunner();
+
+    return task_runner;
+  }
+
+ private:
+  // Lookup |id|.  The caller must hold |lock_|.
+  DialogSurfaceCallback* LookupLocked(long id) {
+    DialogSurfaceCallback* thiz = nullptr;
+    Map::const_iterator it = map_.find(id);
+    if (it != map_.end())
+      thiz = it->second;
+
+    return thiz;
+  }
+
+  // Alternatively, we could put in a callback that is bound to the correct
+  // thread, and use a weak ref.  However, since we still need a default
+  // action when the weak ref is cleared to unblock the callback, it ends up
+  // not being any simpler.
+  using Map = std::map<long, DialogSurfaceCallback*>;
+  Map map_;
+
+  base::Lock lock_;
+};
+
+static base::LazyInstance<DialogCallbackMap>::Leaky g_map =
+    LAZY_INSTANCE_INITIALIZER;
+
+DialogSurfaceCallback::DialogSurfaceCallback(
+    const DialogSurface::Callback& callback)
+    : task_runner_(base::ThreadTaskRunnerHandle::Get()),
+      id_(next_id_++),
+      callback_(callback) {
+  JNIEnv* env = AttachCurrentThread();
+  CHECK(env);
+  j_surface_callback_.Reset(Java_DialogSurfaceCallback_create(env, id_));
+  g_map.Pointer()->Insert(id_, this);
+}
+
+DialogSurfaceCallback::~DialogSurfaceCallback() {
+  DCHECK(thread_checker_.CalledOnValidThread());
+  g_map.Pointer()->Erase(id_);
+}
+
+bool DialogSurfaceCallback::RegisterDialogSurfaceCallback(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+scoped_refptr<base::SingleThreadTaskRunner>
+DialogSurfaceCallback::GetTaskRunner() const {
+  // May be called on any thread.
+  return task_runner_;
+}
+
+bool DialogSurfaceCallback::CalledOnValidThread() const {
+  return thread_checker_.CalledOnValidThread();
+}
+
+void DialogSurfaceCallback::OnCallbackProperThread(
+    long id,
+    DialogSurface::CallbackOp what,
+    base::WaitableEvent* event) {
+  // A callback has happened on some other thread.  We're run on the correct
+  // thread in response to it.
+  DialogSurfaceCallback* thiz = g_map.Pointer()->Lookup(id);
+  // |thiz| cannot be deleted here, since we're on the main thread.  However,
+  // it might have been deleted earlier, so it can be null.
+
+  if (thiz) {
+    DCHECK(thiz->CalledOnValidThread());
+    thiz->callback_.Run(what);
+  }
+
+  // If this is a synchronous callback, then signal that we've completed.
+  if (event)
+    event->Signal();
+}
+
+void OnDialogSurfaceCallbackCallback(JNIEnv* env,
+                                     const JavaParamRef<jclass>& jcaller,
+                                     jlong id,
+                                     jint what) {
+  // Post back to the main thread.  We get a strong ref here to the task
+  // runner, so that it's okay if the controller is deleted.  Holding the
+  // lock during the callback is not safe; the caller might require it to
+  // complete the callback.
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner =
+      g_map.Pointer()->GetTaskRunner(id);
+
+  if (task_runner) {
+    // TODO(liberato): check the thread, and just call if needed.  That way,
+    // we'll work regardless of how the java classes handle threading.
+    base::WaitableEvent event(base::WaitableEvent::ResetPolicy::AUTOMATIC,
+                              base::WaitableEvent::InitialState::NOT_SIGNALED);
+    base::Closure cb =
+        base::Bind(&DialogSurfaceCallback::OnCallbackProperThread, id,
+                   static_cast<DialogSurface::CallbackOp>(what), &event);
+    task_runner->PostTask(FROM_HERE, cb);
+    event.Wait();
+  }
+}
+
+}  // namespace media