android_os_MessageQueue.cpp revision 864693461b6223a995038847591b17abe2de647e
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
26namespace android {
27
28static struct {
29    jfieldID mPtr;   // native object attached to the DVM MessageQueue
30} gMessageQueueClassInfo;
31
32
33class NativeMessageQueue : public MessageQueue {
34public:
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
44private:
45    bool mInCallback;
46    jthrowable mExceptionObj;
47};
48
49
50MessageQueue::MessageQueue() {
51}
52
53MessageQueue::~MessageQueue() {
54}
55
56bool 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
67NativeMessageQueue::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
75NativeMessageQueue::~NativeMessageQueue() {
76}
77
78void 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
95void 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
106void NativeMessageQueue::wake() {
107    mLooper->wake();
108}
109
110// ----------------------------------------------------------------------------
111
112sp<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
117static 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
128static void android_os_MessageQueue_nativeDestroy(JNIEnv* env, jclass clazz, jint ptr) {
129    NativeMessageQueue* nativeMessageQueue = reinterpret_cast<NativeMessageQueue*>(ptr);
130    nativeMessageQueue->decStrong(env);
131}
132
133static 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
139static 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
146static 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
162int 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