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1 /*
2  * Copyright (C) 2010 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #define LOG_TAG "MessageQueue-JNI"
18 
19 #include "JNIHelp.h"
20 #include <android_runtime/AndroidRuntime.h>
21 
22 #include <utils/Looper.h>
23 #include <utils/Log.h>
24 #include "android_os_MessageQueue.h"
25 
26 namespace android {
27 
28 static struct {
29     jfieldID mPtr;   // native object attached to the DVM MessageQueue
30 } gMessageQueueClassInfo;
31 
32 
33 class NativeMessageQueue : public MessageQueue {
34 public:
35     NativeMessageQueue();
36     virtual ~NativeMessageQueue();
37 
38     virtual void raiseException(JNIEnv* env, const char* msg, jthrowable exceptionObj);
39 
40     void pollOnce(JNIEnv* env, int timeoutMillis);
41 
42     void wake();
43 
44 private:
45     bool mInCallback;
46     jthrowable mExceptionObj;
47 };
48 
49 
MessageQueue()50 MessageQueue::MessageQueue() {
51 }
52 
~MessageQueue()53 MessageQueue::~MessageQueue() {
54 }
55 
raiseAndClearException(JNIEnv * env,const char * msg)56 bool MessageQueue::raiseAndClearException(JNIEnv* env, const char* msg) {
57     jthrowable exceptionObj = env->ExceptionOccurred();
58     if (exceptionObj) {
59         env->ExceptionClear();
60         raiseException(env, msg, exceptionObj);
61         env->DeleteLocalRef(exceptionObj);
62         return true;
63     }
64     return false;
65 }
66 
NativeMessageQueue()67 NativeMessageQueue::NativeMessageQueue() : mInCallback(false), mExceptionObj(NULL) {
68     mLooper = Looper::getForThread();
69     if (mLooper == NULL) {
70         mLooper = new Looper(false);
71         Looper::setForThread(mLooper);
72     }
73 }
74 
~NativeMessageQueue()75 NativeMessageQueue::~NativeMessageQueue() {
76 }
77 
raiseException(JNIEnv * env,const char * msg,jthrowable exceptionObj)78 void NativeMessageQueue::raiseException(JNIEnv* env, const char* msg, jthrowable exceptionObj) {
79     if (exceptionObj) {
80         if (mInCallback) {
81             if (mExceptionObj) {
82                 env->DeleteLocalRef(mExceptionObj);
83             }
84             mExceptionObj = jthrowable(env->NewLocalRef(exceptionObj));
85             ALOGE("Exception in MessageQueue callback: %s", msg);
86             jniLogException(env, ANDROID_LOG_ERROR, LOG_TAG, exceptionObj);
87         } else {
88             ALOGE("Exception: %s", msg);
89             jniLogException(env, ANDROID_LOG_ERROR, LOG_TAG, exceptionObj);
90             LOG_ALWAYS_FATAL("raiseException() was called when not in a callback, exiting.");
91         }
92     }
93 }
94 
pollOnce(JNIEnv * env,int timeoutMillis)95 void NativeMessageQueue::pollOnce(JNIEnv* env, int timeoutMillis) {
96     mInCallback = true;
97     mLooper->pollOnce(timeoutMillis);
98     mInCallback = false;
99     if (mExceptionObj) {
100         env->Throw(mExceptionObj);
101         env->DeleteLocalRef(mExceptionObj);
102         mExceptionObj = NULL;
103     }
104 }
105 
wake()106 void NativeMessageQueue::wake() {
107     mLooper->wake();
108 }
109 
110 // ----------------------------------------------------------------------------
111 
android_os_MessageQueue_getMessageQueue(JNIEnv * env,jobject messageQueueObj)112 sp<MessageQueue> android_os_MessageQueue_getMessageQueue(JNIEnv* env, jobject messageQueueObj) {
113     jint intPtr = env->GetIntField(messageQueueObj, gMessageQueueClassInfo.mPtr);
114     return reinterpret_cast<NativeMessageQueue*>(intPtr);
115 }
116 
android_os_MessageQueue_nativeInit(JNIEnv * env,jclass clazz)117 static jint android_os_MessageQueue_nativeInit(JNIEnv* env, jclass clazz) {
118     NativeMessageQueue* nativeMessageQueue = new NativeMessageQueue();
119     if (!nativeMessageQueue) {
120         jniThrowRuntimeException(env, "Unable to allocate native queue");
121         return 0;
122     }
123 
124     nativeMessageQueue->incStrong(env);
125     return reinterpret_cast<jint>(nativeMessageQueue);
126 }
127 
android_os_MessageQueue_nativeDestroy(JNIEnv * env,jclass clazz,jint ptr)128 static void android_os_MessageQueue_nativeDestroy(JNIEnv* env, jclass clazz, jint ptr) {
129     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
130     nativeMessageQueue->decStrong(env);
131 }
132 
android_os_MessageQueue_nativePollOnce(JNIEnv * env,jclass clazz,jint ptr,jint timeoutMillis)133 static void android_os_MessageQueue_nativePollOnce(JNIEnv* env, jclass clazz,
134         jint ptr, jint timeoutMillis) {
135     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
136     nativeMessageQueue->pollOnce(env, timeoutMillis);
137 }
138 
android_os_MessageQueue_nativeWake(JNIEnv * env,jclass clazz,jint ptr)139 static void android_os_MessageQueue_nativeWake(JNIEnv* env, jclass clazz, jint ptr) {
140     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
141     return nativeMessageQueue->wake();
142 }
143 
144 // ----------------------------------------------------------------------------
145 
146 static JNINativeMethod gMessageQueueMethods[] = {
147     /* name, signature, funcPtr */
148     { "nativeInit", "()I", (void*)android_os_MessageQueue_nativeInit },
149     { "nativeDestroy", "(I)V", (void*)android_os_MessageQueue_nativeDestroy },
150     { "nativePollOnce", "(II)V", (void*)android_os_MessageQueue_nativePollOnce },
151     { "nativeWake", "(I)V", (void*)android_os_MessageQueue_nativeWake }
152 };
153 
154 #define FIND_CLASS(var, className) \
155         var = env->FindClass(className); \
156         LOG_FATAL_IF(! var, "Unable to find class " className);
157 
158 #define GET_FIELD_ID(var, clazz, fieldName, fieldDescriptor) \
159         var = env->GetFieldID(clazz, fieldName, fieldDescriptor); \
160         LOG_FATAL_IF(! var, "Unable to find field " fieldName);
161 
register_android_os_MessageQueue(JNIEnv * env)162 int register_android_os_MessageQueue(JNIEnv* env) {
163     int res = jniRegisterNativeMethods(env, "android/os/MessageQueue",
164             gMessageQueueMethods, NELEM(gMessageQueueMethods));
165     LOG_FATAL_IF(res < 0, "Unable to register native methods.");
166 
167     jclass clazz;
168     FIND_CLASS(clazz, "android/os/MessageQueue");
169 
170     GET_FIELD_ID(gMessageQueueClassInfo.mPtr, clazz,
171             "mPtr", "I");
172 
173     return 0;
174 }
175 
176 } // namespace android
177