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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 
     50 MessageQueue::MessageQueue() {
     51 }
     52 
     53 MessageQueue::~MessageQueue() {
     54 }
     55 
     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 
     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 
     75 NativeMessageQueue::~NativeMessageQueue() {
     76 }
     77 
     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 
     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 
    106 void NativeMessageQueue::wake() {
    107     mLooper->wake();
    108 }
    109 
    110 // ----------------------------------------------------------------------------
    111 
    112 static NativeMessageQueue* android_os_MessageQueue_getNativeMessageQueue(JNIEnv* env,
    113         jobject messageQueueObj) {
    114     jint intPtr = env->GetIntField(messageQueueObj, gMessageQueueClassInfo.mPtr);
    115     return reinterpret_cast<NativeMessageQueue*>(intPtr);
    116 }
    117 
    118 static void android_os_MessageQueue_setNativeMessageQueue(JNIEnv* env, jobject messageQueueObj,
    119         NativeMessageQueue* nativeMessageQueue) {
    120     env->SetIntField(messageQueueObj, gMessageQueueClassInfo.mPtr,
    121              reinterpret_cast<jint>(nativeMessageQueue));
    122 }
    123 
    124 sp<MessageQueue> android_os_MessageQueue_getMessageQueue(JNIEnv* env, jobject messageQueueObj) {
    125     NativeMessageQueue* nativeMessageQueue =
    126             android_os_MessageQueue_getNativeMessageQueue(env, messageQueueObj);
    127     return nativeMessageQueue;
    128 }
    129 
    130 static void android_os_MessageQueue_nativeInit(JNIEnv* env, jobject obj) {
    131     NativeMessageQueue* nativeMessageQueue = new NativeMessageQueue();
    132     if (!nativeMessageQueue) {
    133         jniThrowRuntimeException(env, "Unable to allocate native queue");
    134         return;
    135     }
    136 
    137     nativeMessageQueue->incStrong(env);
    138     android_os_MessageQueue_setNativeMessageQueue(env, obj, nativeMessageQueue);
    139 }
    140 
    141 static void android_os_MessageQueue_nativeDestroy(JNIEnv* env, jobject obj) {
    142     NativeMessageQueue* nativeMessageQueue =
    143             android_os_MessageQueue_getNativeMessageQueue(env, obj);
    144     if (nativeMessageQueue) {
    145         android_os_MessageQueue_setNativeMessageQueue(env, obj, NULL);
    146         nativeMessageQueue->decStrong(env);
    147     }
    148 }
    149 
    150 static void throwQueueNotInitialized(JNIEnv* env) {
    151     jniThrowException(env, "java/lang/IllegalStateException", "Message queue not initialized");
    152 }
    153 
    154 static void android_os_MessageQueue_nativePollOnce(JNIEnv* env, jobject obj,
    155         jint ptr, jint timeoutMillis) {
    156     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
    157     nativeMessageQueue->pollOnce(env, timeoutMillis);
    158 }
    159 
    160 static void android_os_MessageQueue_nativeWake(JNIEnv* env, jobject obj, jint ptr) {
    161     NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
    162     return nativeMessageQueue->wake();
    163 }
    164 
    165 // ----------------------------------------------------------------------------
    166 
    167 static JNINativeMethod gMessageQueueMethods[] = {
    168     /* name, signature, funcPtr */
    169     { "nativeInit", "()V", (void*)android_os_MessageQueue_nativeInit },
    170     { "nativeDestroy", "()V", (void*)android_os_MessageQueue_nativeDestroy },
    171     { "nativePollOnce", "(II)V", (void*)android_os_MessageQueue_nativePollOnce },
    172     { "nativeWake", "(I)V", (void*)android_os_MessageQueue_nativeWake }
    173 };
    174 
    175 #define FIND_CLASS(var, className) \
    176         var = env->FindClass(className); \
    177         LOG_FATAL_IF(! var, "Unable to find class " className);
    178 
    179 #define GET_FIELD_ID(var, clazz, fieldName, fieldDescriptor) \
    180         var = env->GetFieldID(clazz, fieldName, fieldDescriptor); \
    181         LOG_FATAL_IF(! var, "Unable to find field " fieldName);
    182 
    183 int register_android_os_MessageQueue(JNIEnv* env) {
    184     int res = jniRegisterNativeMethods(env, "android/os/MessageQueue",
    185             gMessageQueueMethods, NELEM(gMessageQueueMethods));
    186     LOG_FATAL_IF(res < 0, "Unable to register native methods.");
    187 
    188     jclass clazz;
    189     FIND_CLASS(clazz, "android/os/MessageQueue");
    190 
    191     GET_FIELD_ID(gMessageQueueClassInfo.mPtr, clazz,
    192             "mPtr", "I");
    193 
    194     return 0;
    195 }
    196 
    197 } // namespace android
    198