Android: lazy initialization for method id.

base/android/jni_android_unittest.cc

 // Copyright (c) 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 "base/android/jni_android.h"
 
 #include "base/at_exit.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
@@ skipping 15 matching lines @@
 
 jmethodID GetMethodIDWrapper(JNIEnv* env, jclass clazz, const char* method,
                              const char* jni_signature) {
   g_last_method = method;
   g_last_jni_signature = jni_signature;
   g_last_method_id = g_previous_functions->GetMethodID(env, clazz, method,
                                                        jni_signature);
   return g_last_method_id;
 }
 
+
+static jmethodID g_MTCall = 0;
+jobject MTCall(JNIEnv* env, jclass clazz, int p) {
+  base::android::LazyMethodID::Get<
+      base::android::LazyMethodID::METHODTYPE_STATIC,
+      base::android::LazyMethodID::EXCEPTIONCHECK_NO>(
+      env, clazz,
+      "valueOf",
+      "(I)Ljava/lang/String;",
+      &g_MTCall);
+
+  return env->CallStaticObjectMethod(clazz, g_MTCall, p);
+}
+
+jobject NonMTCall(JNIEnv* env, jclass clazz, int p) {
+  return env->CallStaticObjectMethod(clazz, g_MTCall, p);
+}
+
 }  // namespace
 
 class JNIAndroidTest : public testing::Test {
  protected:
   virtual void SetUp() {
     JNIEnv* env = AttachCurrentThread();
     g_previous_functions = env->functions;
     hooked_functions = *g_previous_functions;
     env->functions = &hooked_functions;
     hooked_functions.GetMethodID = &GetMethodIDWrapper;
@@ skipping 37 matching lines @@
   EXPECT_EQ(id1, id2);
 
   Reset();
   jmethodID id3 = GetMethodIDFromClassName(env, kJavaLangObject, kToString,
                                            kReturningJavaLangString);
   EXPECT_STREQ(kToString, g_last_method);
   EXPECT_STREQ(kReturningJavaLangString, g_last_jni_signature);
   EXPECT_EQ(g_last_method_id, id3);
 }
 
+TEST(JNIAndroidMicrobenchmark, JNIWithLock) {
+  JNIEnv* env = AttachCurrentThread();
+  ScopedJavaLocalRef<jclass> clazz(GetClass(env, "java/lang/String"));
+  base::Time start_mt = base::Time::Now();
+  for (int i = 0; i < 1024; ++i)
+    ScopedJavaLocalRef<jobject> o(env, MTCall(env, clazz.obj(), i));
+  base::Time end_mt = base::Time::Now();
+
+  base::Time start_non_mt = base::Time::Now();
+  for (int i = 0; i < 1024; ++i)
+    ScopedJavaLocalRef<jobject> o(env, NonMTCall(env, clazz.obj(), i));
+  base::Time end_non_mt = base::Time::Now();
+
+  LOG(ERROR) << "JNI MT" <<
+      base::TimeDelta(start_mt - end_mt).InMicroseconds();
+  LOG(ERROR) << "JNI Non-MT" <<
+      base::TimeDelta(start_non_mt - end_non_mt).InMicroseconds();
+}
+
 }  // namespace android
 }  // namespace base