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| 1 // Copyright (c) 2013 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. |
| 4 |
| 5 #include "content/browser/renderer_host/java/jni_helper.h" |
| 6 |
| 7 #include <map> |
| 8 |
| 9 #include "base/android/jni_android.h" |
| 10 #include "base/lazy_instance.h" |
| 11 #include "base/threading/platform_thread.h" |
| 12 |
| 13 namespace content { |
| 14 |
| 15 namespace { |
| 16 |
| 17 struct MethodIdentifier { |
| 18 const char* class_name; |
| 19 const char* method; |
| 20 const char* jni_signature; |
| 21 |
| 22 bool operator<(const MethodIdentifier& other) const { |
| 23 int r = strcmp(class_name, other.class_name); |
| 24 if (r < 0) { |
| 25 return true; |
| 26 } else if (r > 0) { |
| 27 return false; |
| 28 } |
| 29 |
| 30 r = strcmp(method, other.method); |
| 31 if (r < 0) { |
| 32 return true; |
| 33 } else if (r > 0) { |
| 34 return false; |
| 35 } |
| 36 |
| 37 return strcmp(jni_signature, other.jni_signature) < 0; |
| 38 } |
| 39 }; |
| 40 |
| 41 typedef std::map<MethodIdentifier, jmethodID> MethodIDMap; |
| 42 |
| 43 const base::subtle::AtomicWord kUnlocked = 0; |
| 44 const base::subtle::AtomicWord kLocked = 1; |
| 45 base::subtle::AtomicWord g_method_id_map_lock = kUnlocked; |
| 46 |
| 47 base::LazyInstance<MethodIDMap> g_method_id_map = LAZY_INSTANCE_INITIALIZER; |
| 48 |
| 49 } // namespace |
| 50 |
| 51 jmethodID GetMethodIDFromClassName(JNIEnv* env, |
| 52 const char* class_name, |
| 53 const char* method, |
| 54 const char* jni_signature) { |
| 55 MethodIdentifier key; |
| 56 key.class_name = class_name; |
| 57 key.method = method; |
| 58 key.jni_signature = jni_signature; |
| 59 |
| 60 MethodIDMap* map = g_method_id_map.Pointer(); |
| 61 bool found = false; |
| 62 |
| 63 while (base::subtle::Acquire_CompareAndSwap(&g_method_id_map_lock, |
| 64 kUnlocked, |
| 65 kLocked) != kUnlocked) { |
| 66 base::PlatformThread::YieldCurrentThread(); |
| 67 } |
| 68 MethodIDMap::const_iterator iter = map->find(key); |
| 69 if (iter != map->end()) { |
| 70 found = true; |
| 71 } |
| 72 base::subtle::Release_Store(&g_method_id_map_lock, kUnlocked); |
| 73 |
| 74 // Addition to the map does not invalidate this iterator. |
| 75 if (found) { |
| 76 return iter->second; |
| 77 } |
| 78 |
| 79 base::android::ScopedJavaLocalRef<jclass> clazz( |
| 80 env, env->FindClass(class_name)); |
| 81 jmethodID id = base::android::MethodID::Get< |
| 82 base::android::MethodID::TYPE_INSTANCE>( |
| 83 env, clazz.obj(), method, jni_signature); |
| 84 |
| 85 while (base::subtle::Acquire_CompareAndSwap(&g_method_id_map_lock, |
| 86 kUnlocked, |
| 87 kLocked) != kUnlocked) { |
| 88 base::PlatformThread::YieldCurrentThread(); |
| 89 } |
| 90 // Another thread may have populated the map already. |
| 91 std::pair<MethodIDMap::const_iterator, bool> result = |
| 92 map->insert(std::make_pair(key, id)); |
| 93 DCHECK_EQ(id, result.first->second); |
| 94 base::subtle::Release_Store(&g_method_id_map_lock, kUnlocked); |
| 95 |
| 96 return id; |
| 97 } |
| 98 |
| 99 } // namespace content |
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