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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 #ifndef _ANDROID_OS_MESSAGEQUEUE_H
     18 #define _ANDROID_OS_MESSAGEQUEUE_H
     19 
     20 #include "jni.h"
     21 #include <utils/Looper.h>
     22 
     23 namespace android {
     24 
     25 class MessageQueue : public virtual RefBase {
     26 public:
     27     /* Gets the message queue's looper. */
     28     inline sp<Looper> getLooper() const {
     29         return mLooper;
     30     }
     31 
     32     /* Checks whether the JNI environment has a pending exception.
     33      *
     34      * If an exception occurred, logs it together with the specified message,
     35      * and calls raiseException() to ensure the exception will be raised when
     36      * the callback returns, clears the pending exception from the environment,
     37      * then returns true.
     38      *
     39      * If no exception occurred, returns false.
     40      */
     41     bool raiseAndClearException(JNIEnv* env, const char* msg);
     42 
     43     /* Raises an exception from within a callback function.
     44      * The exception will be rethrown when control returns to the message queue which
     45      * will typically cause the application to crash.
     46      *
     47      * This message can only be called from within a callback function.  If it is called
     48      * at any other time, the process will simply be killed.
     49      *
     50      * Does nothing if exception is NULL.
     51      *
     52      * (This method does not take ownership of the exception object reference.
     53      * The caller is responsible for releasing its reference when it is done.)
     54      */
     55     virtual void raiseException(JNIEnv* env, const char* msg, jthrowable exceptionObj) = 0;
     56 
     57 protected:
     58     MessageQueue();
     59     virtual ~MessageQueue();
     60 
     61 protected:
     62     sp<Looper> mLooper;
     63 };
     64 
     65 /* Gets the native object associated with a MessageQueue. */
     66 extern sp<MessageQueue> android_os_MessageQueue_getMessageQueue(
     67         JNIEnv* env, jobject messageQueueObj);
     68 
     69 } // namespace android
     70 
     71 #endif // _ANDROID_OS_MESSAGEQUEUE_H
     72