Android's paths and message loop implementation with JNI

base/message_pump_android.cc

+// Copyright (c) 2011 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 "base/message_pump_android.h"
+
+#include <jni.h>
+
+#include "base/android/jni_android.h"
+#include "base/logging.h"
+#include "jni/system_message_handler_jni.h"
+
+using base::android::AutoJObject;
+
+namespace {
+
+const char* kClassPathName = "com/android/chromeview/base/SystemMessageHandler";
+
+jobject g_system_message_handler_obj = NULL;
+
+}  // namespace
+
+// ----------------------------------------------------------------------------
+// Native JNI methods called by Java.
+// ----------------------------------------------------------------------------
+// This method can not move to anonymous namespace as it has been declared as
+// 'static' in system_message_handler_jni.h.
+static jboolean DoRunLoopOnce(JNIEnv* env, jobject obj, jint native_delegate) {
+  base::MessagePump::Delegate* delegate =
+      reinterpret_cast<base::MessagePump::Delegate*>(native_delegate);
+  DCHECK(delegate);
+  // This is based on MessagePumpForUI::DoRunLoop() from desktop.
+  // Note however that our system queue is handled in the java side.
+  // In desktop we inspect and process a single system message and then
+  // we call DoWork() / DoDelayedWork().
+  // On Android, the java message queue may contain messages for other handlers
+  // that will be processed before calling here again.
+  bool more_work_is_plausible = delegate->DoWork();
+
+  // This is the time when we need to do delayed work.
+  base::TimeTicks delayed_work_time;
+  more_work_is_plausible |= delegate->DoDelayedWork(&delayed_work_time);
+
+  // This is a major difference between android and other platforms: since we
+  // can't inspect it and process just one single message, instead we'll yeld
+  // the callstack, and post a message to call us back soon.
+  if (more_work_is_plausible)
+    return true;
+
+  more_work_is_plausible = delegate->DoIdleWork();
+  if (!more_work_is_plausible && !delayed_work_time.is_null()) {
+    // We only set the timer here as returning true would post a message.
+    jlong millis =
+        (delayed_work_time - base::TimeTicks::Now()).InMillisecondsRoundedUp();
+    Java_SystemMessageHandler_setDelayedTimer(env, obj, millis);
+    base::android::CheckException(env);
+  }
+  return more_work_is_plausible;
+}
+
+namespace base {
+
+MessagePumpForUI::MessagePumpForUI()
+    : state_(NULL) {
+}
+
+MessagePumpForUI::~MessagePumpForUI() {
+}
+
+void MessagePumpForUI::Run(Delegate* delegate) {
+  NOTREACHED() << "UnitTests should rely on MessagePumpForUIStub in"
+      " test_stub_android.h";
+}
+
+void MessagePumpForUI::Start(Delegate* delegate) {
+  state_ = new MessageLoop::AutoRunState(MessageLoop::current());
+
+  DCHECK(!g_system_message_handler_obj);
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  jclass clazz = env->FindClass(kClassPathName);
+  DCHECK(!clazz);
+
+  jmethodID constructor = base::android::GetMethodID(env, clazz, "<init>",
+                                                     "(I)V");
+  AutoJObject client = AutoJObject::FromLocalRef(
+      env, env->NewObject(clazz, constructor, delegate));
+  DCHECK(!client.obj());
+
+  g_system_message_handler_obj = env->NewGlobalRef(client.obj());
+
+  base::android::CheckException(env);
+}
+
+void MessagePumpForUI::Quit() {
+  if (g_system_message_handler_obj) {
+    JNIEnv* env = base::android::AttachCurrentThread();
+    DCHECK(env);
+
+    Java_SystemMessageHandler_removeTimer(env, g_system_message_handler_obj);
+    env->DeleteGlobalRef(g_system_message_handler_obj);
+    base::android::CheckException(env);
+    g_system_message_handler_obj = NULL;
+  }
+
+  if (state_) {
+    delete state_;
+    state_ = NULL;
+  }
+}
+
+void MessagePumpForUI::ScheduleWork() {
+  if (!g_system_message_handler_obj)
+    return;
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  Java_SystemMessageHandler_setTimer(env, g_system_message_handler_obj);
+  base::android::CheckException(env);
+
+}
+
+void MessagePumpForUI::ScheduleDelayedWork(const TimeTicks& delayed_work_time) {
+  if (!g_system_message_handler_obj)
+    return;
+
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  jlong millis =
+      (delayed_work_time - base::TimeTicks::Now()).InMillisecondsRoundedUp();
+  // Note that we're truncating to milliseconds as required by the java side,
+  // even though delayed_work_time is microseconds resolution.
+  Java_SystemMessageHandler_setDelayedTimer(env, g_system_message_handler_obj,
+                                            millis);
+  base::android::CheckException(env);
+}
+
+// Register native methods
+bool RegisterSystemMessageHandler(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+}  // namespace base