Making a way to create thread with a Java Looper for Android

base/android/java_thread.cc

Index: base/android/java_thread.cc
diff --git a/base/android/java_thread.cc b/base/android/java_thread.cc
new file mode 100644
index 0000000000000000000000000000000000000000..523b5a99beb326501547a986ed2ae941094f4583
--- /dev/null
+++ b/base/android/java_thread.cc
@@ -0,0 +1,59 @@
+// Copyright (c) 2013 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/android/java_thread.h"
+
+#include <jni.h>
+
+#include "base/android/jni_android.h"
+#include "base/android/jni_string.h"
+#include "base/message_loop.h"
+#include "base/synchronization/waitable_event.h"
+#include "jni/JavaThread_jni.h"
+
+namespace base {
+
+namespace android {
+
+JavaThread::JavaThread(const char* name) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  java_thread_.Reset(Java_JavaThread_create(
+      env, ConvertUTF8ToJavaString(env, name).Release()));
+}
+
+void JavaThread::Start() {
+  JNIEnv* env = base::android::AttachCurrentThread();
+  DCHECK(env);
+
+  waitable_event_ = new base::WaitableEvent(false, false);
+  Java_JavaThread_start(env, java_thread_.obj(), reinterpret_cast<jint>(this));
+  // Wait for thread to be initialized so it is ready to be used when Start
+  // returns
+  waitable_event_->Wait();
+
+  // Delete object only used in initialization
+  delete(waitable_event_);

[benm (inactive), 2013/07/10 16:50:06]

nit: no parens

[Kristian Monsen, 2013/07/10 17:50:19]

Done.

+  waitable_event_ = NULL;

[benm (inactive), 2013/07/10 16:50:06]

maybe leave it non null and dcheck == null at the top?

[Kristian Monsen, 2013/07/10 17:50:19]

I don't like to leave deleted variables around as not null. It would maybe be
better to have it as a scoped ptr and pass it through Java.

I guess that doesn't solve what you want to fix, which is that start is only
called once? If that is what you want I would prefer to use a bool for it.

+}
+
+void JavaThread::Stop() {

[benm (inactive), 2013/07/10 16:50:06]

Do we need a way for java to call this so we can clean up? (i.e. delete this so
we can release java_thread_)

[Kristian Monsen, 2013/07/10 17:50:19]

I think it is more the other way round. Currently this is initated and owned
from native. Stop could be called to terminate the Java Thread cleanly.

+}
+
+void JavaThread::InitializeThread(JNIEnv* env, jobject obj) {
+  // TYPE_UI to get the Android java style message loop
+  message_loop_.reset(new base::MessageLoop(base::MessageLoop::TYPE_UI));
+  MessageLoopForUI::current()->Start();
+  waitable_event_->Signal();
+}
+
+// static
+bool JavaThread::RegisterBindings(JNIEnv* env) {
+  return RegisterNativesImpl(env);
+}
+
+} // namespace android
+
+} // namespace base