Android: cleanup jni_android to minimize external dependencies.

Other projects will be using the JNI bindings.
- Move GetMethodIDFromClassName down to content/browser/renderer_host/java,
the only place where it's used.
- Remove a few methods that are no longer in use.
- Trim down dependencies.

BUG=

Review URL: https://codereview.chromium.org/23835020

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225471 0039d316-1c4b-4281-b951-d872f2087c98

5 files changed, 222 insertions, 2 deletions

diff --git a/content/browser/renderer_host/java/java_bound_object.cc b/content/browser/renderer_host/java/java_bound_object.cc
index 4199cca..27b9f42 100644
--- a/content/browser/renderer_host/java/java_bound_object.cc
+++ b/content/browser/renderer_host/java/java_bound_object.cc
@@ -11,6 +11,7 @@
 #include "base/strings/stringprintf.h"
 #include "content/browser/renderer_host/java/java_bridge_dispatcher_host_manager.h"
 #include "content/browser/renderer_host/java/java_type.h"
+#include "content/browser/renderer_host/java/jni_helper.h"
 #include "content/public/browser/browser_thread.h"
 #include "third_party/WebKit/public/web/WebBindings.h"
 
@@ -18,7 +19,6 @@ using base::StringPrintf;
 using base::android::AttachCurrentThread;
 using base::android::ConvertUTF8ToJavaString;
 using base::android::GetClass;
-using base::android::GetMethodIDFromClassName;
 using base::android::JavaRef;
 using base::android::ScopedJavaGlobalRef;
 using base::android::ScopedJavaLocalRef;
diff --git a/content/browser/renderer_host/java/java_method.cc b/content/browser/renderer_host/java/java_method.cc
index 3cc569f..ef2d097 100644
--- a/content/browser/renderer_host/java/java_method.cc
+++ b/content/browser/renderer_host/java/java_method.cc
@@ -9,11 +9,11 @@
 #include "base/lazy_instance.h"
 #include "base/memory/singleton.h"
 #include "base/strings/string_util.h"  // For ReplaceSubstringsAfterOffset
+#include "content/browser/renderer_host/java/jni_helper.h"
 
 using base::android::AttachCurrentThread;
 using base::android::ConvertJavaStringToUTF8;
 using base::android::GetClass;
-using base::android::GetMethodIDFromClassName;
 using base::android::MethodID;
 using base::android::ScopedJavaGlobalRef;
 using base::android::ScopedJavaLocalRef;
diff --git a/content/browser/renderer_host/java/jni_helper.cc b/content/browser/renderer_host/java/jni_helper.cc
new file mode 100644
index 0000000..86874b0
--- /dev/null
+++ b/content/browser/renderer_host/java/jni_helper.cc
@@ -0,0 +1,99 @@
+// Copyright 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 "content/browser/renderer_host/java/jni_helper.h"
+
+#include <map>
+
+#include "base/android/jni_android.h"
+#include "base/lazy_instance.h"
+#include "base/threading/platform_thread.h"
+
+namespace content {
+
+namespace {
+
+struct MethodIdentifier {
+  const char* class_name;
+  const char* method;
+  const char* jni_signature;
+
+  bool operator<(const MethodIdentifier& other) const {
+    int r = strcmp(class_name, other.class_name);
+    if (r < 0) {
+      return true;
+    } else if (r > 0) {
+      return false;
+    }
+
+    r = strcmp(method, other.method);
+    if (r < 0) {
+      return true;
+    } else if (r > 0) {
+      return false;
+    }
+
+    return strcmp(jni_signature, other.jni_signature) < 0;
+  }
+};
+
+typedef std::map<MethodIdentifier, jmethodID> MethodIDMap;
+
+const base::subtle::AtomicWord kUnlocked = 0;
+const base::subtle::AtomicWord kLocked = 1;
+base::subtle::AtomicWord g_method_id_map_lock = kUnlocked;
+
+base::LazyInstance<MethodIDMap> g_method_id_map = LAZY_INSTANCE_INITIALIZER;
+
+}  // namespace
+
+jmethodID GetMethodIDFromClassName(JNIEnv* env,
+                                   const char* class_name,
+                                   const char* method,
+                                   const char* jni_signature) {
+  MethodIdentifier key;
+  key.class_name = class_name;
+  key.method = method;
+  key.jni_signature = jni_signature;
+
+  MethodIDMap* map = g_method_id_map.Pointer();
+  bool found = false;
+
+  while (base::subtle::Acquire_CompareAndSwap(&g_method_id_map_lock,
+                                              kUnlocked,
+                                              kLocked) != kUnlocked) {
+    base::PlatformThread::YieldCurrentThread();
+  }
+  MethodIDMap::const_iterator iter = map->find(key);
+  if (iter != map->end()) {
+    found = true;
+  }
+  base::subtle::Release_Store(&g_method_id_map_lock, kUnlocked);
+
+  // Addition to the map does not invalidate this iterator.
+  if (found) {
+    return iter->second;
+  }
+
+  base::android::ScopedJavaLocalRef<jclass> clazz(
+      env, env->FindClass(class_name));
+  jmethodID id = base::android::MethodID::Get<
+      base::android::MethodID::TYPE_INSTANCE>(
+          env, clazz.obj(), method, jni_signature);
+
+  while (base::subtle::Acquire_CompareAndSwap(&g_method_id_map_lock,
+                                              kUnlocked,
+                                              kLocked) != kUnlocked) {
+    base::PlatformThread::YieldCurrentThread();
+  }
+  // Another thread may have populated the map already.
+  std::pair<MethodIDMap::const_iterator, bool> result =
+      map->insert(std::make_pair(key, id));
+  DCHECK_EQ(id, result.first->second);
+  base::subtle::Release_Store(&g_method_id_map_lock, kUnlocked);
+
+  return id;
+}
+
+}  // namespace content
diff --git a/content/browser/renderer_host/java/jni_helper.h b/content/browser/renderer_host/java/jni_helper.h
new file mode 100644
index 0000000..aaba53b
--- /dev/null
+++ b/content/browser/renderer_host/java/jni_helper.h
@@ -0,0 +1,27 @@
+// Copyright 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.
+
+#ifndef CONTENT_BROWSER_RENDERER_HOST_JAVA_JNI_HELPER_H_
+#define CONTENT_BROWSER_RENDERER_HOST_JAVA_JNI_HELPER_H_
+
+#include <jni.h>
+
+#include "content/common/content_export.h"
+
+namespace content {
+
+// Gets the method ID from the class name. Clears the pending Java exception
+// and returns NULL if the method is not found. Caches results.
+// Strings passed to this function are held in the cache and MUST remain valid
+// beyond the duration of all future calls to this function, across all
+// threads. In practice, this means that the function should only be used with
+// string constants.
+CONTENT_EXPORT jmethodID GetMethodIDFromClassName(JNIEnv* env,
+                                                  const char* class_name,
+                                                  const char* method,
+                                                  const char* jni_signature);
+
+}  // namespace content
+
+#endif  // CONTENT_BROWSER_RENDERER_HOST_JAVA_JNI_HELPER_H_
diff --git a/content/browser/renderer_host/java/jni_helper_unittest.cc b/content/browser/renderer_host/java/jni_helper_unittest.cc
new file mode 100644
index 0000000..34b17c2
--- /dev/null
+++ b/content/browser/renderer_host/java/jni_helper_unittest.cc
@@ -0,0 +1,94 @@
+// Copyright 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 "content/browser/renderer_host/java/jni_helper.h"
+
+#include "base/android/jni_android.h"
+#include "base/at_exit.h"
+#include "base/logging.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+
+namespace {
+
+const char kJavaLangObject[] = "java/lang/Object";
+const char kGetClass[] = "getClass";
+const char kToString[] = "toString";
+const char kReturningJavaLangClass[] = "()Ljava/lang/Class;";
+const char kReturningJavaLangString[] = "()Ljava/lang/String;";
+
+const char* g_last_method;
+const char* g_last_jni_signature;
+jmethodID g_last_method_id;
+
+const JNINativeInterface* g_previous_functions;
+
+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;
+}
+
+}  // namespace
+
+class JNIAndroidTest : public testing::Test {
+ protected:
+  virtual void SetUp() {
+    JNIEnv* env = base::android::AttachCurrentThread();
+    g_previous_functions = env->functions;
+    hooked_functions = *g_previous_functions;
+    env->functions = &hooked_functions;
+    hooked_functions.GetMethodID = &GetMethodIDWrapper;
+  }
+
+  virtual void TearDown() {
+    JNIEnv* env = base::android::AttachCurrentThread();
+    env->functions = g_previous_functions;
+    Reset();
+  }
+
+  void Reset() {
+    g_last_method = 0;
+    g_last_jni_signature = 0;
+    g_last_method_id = NULL;
+  }
+  // Needed to cleanup the cached method map in the implementation between
+  // runs (e.g. if using --gtest_repeat)
+  base::ShadowingAtExitManager exit_manager;
+  // From JellyBean release, the instance of this struct provided in JNIEnv is
+  // read-only, so we deep copy it to allow individual functions to be hooked.
+  JNINativeInterface hooked_functions;
+};
+
+TEST_F(JNIAndroidTest, GetMethodIDFromClassNameCaching) {
+  JNIEnv* env = base::android::AttachCurrentThread();
+
+  Reset();
+  jmethodID id1 = GetMethodIDFromClassName(env, kJavaLangObject, kGetClass,
+                                           kReturningJavaLangClass);
+  EXPECT_STREQ(kGetClass, g_last_method);
+  EXPECT_STREQ(kReturningJavaLangClass, g_last_jni_signature);
+  EXPECT_EQ(g_last_method_id, id1);
+
+  Reset();
+  jmethodID id2 = GetMethodIDFromClassName(env, kJavaLangObject, kGetClass,
+                                           kReturningJavaLangClass);
+  EXPECT_STREQ(0, g_last_method);
+  EXPECT_STREQ(0, g_last_jni_signature);
+  EXPECT_EQ(NULL, g_last_method_id);
+  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);
+}
+
+}  // namespace content