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_NDEBUG 0
18#define LOG_TAG "ALooper"
19#include <utils/Log.h>
20
21#include <sys/time.h>
22
23#include "ALooper.h"
24
25#include "AHandler.h"
26#include "ALooperRoster.h"
27#include "AMessage.h"
28
29namespace android {
30
31ALooperRoster gLooperRoster;
32
33struct ALooper::LooperThread : public Thread {
34    LooperThread(ALooper *looper, bool canCallJava)
35        : Thread(canCallJava),
36          mLooper(looper),
37          mThreadId(NULL) {
38    }
39
40    virtual status_t readyToRun() {
41        mThreadId = androidGetThreadId();
42
43        return Thread::readyToRun();
44    }
45
46    virtual bool threadLoop() {
47        return mLooper->loop();
48    }
49
50    bool isCurrentThread() const {
51        return mThreadId == androidGetThreadId();
52    }
53
54protected:
55    virtual ~LooperThread() {}
56
57private:
58    ALooper *mLooper;
59    android_thread_id_t mThreadId;
60
61    DISALLOW_EVIL_CONSTRUCTORS(LooperThread);
62};
63
64// static
65int64_t ALooper::GetNowUs() {
66    return systemTime(SYSTEM_TIME_MONOTONIC) / 1000ll;
67}
68
69ALooper::ALooper()
70    : mRunningLocally(false) {
71}
72
73ALooper::~ALooper() {
74    stop();
75}
76
77void ALooper::setName(const char *name) {
78    mName = name;
79}
80
81ALooper::handler_id ALooper::registerHandler(const sp<AHandler> &handler) {
82    return gLooperRoster.registerHandler(this, handler);
83}
84
85void ALooper::unregisterHandler(handler_id handlerID) {
86    gLooperRoster.unregisterHandler(handlerID);
87}
88
89status_t ALooper::start(
90        bool runOnCallingThread, bool canCallJava, int32_t priority) {
91    if (runOnCallingThread) {
92        {
93            Mutex::Autolock autoLock(mLock);
94
95            if (mThread != NULL || mRunningLocally) {
96                return INVALID_OPERATION;
97            }
98
99            mRunningLocally = true;
100        }
101
102        do {
103        } while (loop());
104
105        return OK;
106    }
107
108    Mutex::Autolock autoLock(mLock);
109
110    if (mThread != NULL || mRunningLocally) {
111        return INVALID_OPERATION;
112    }
113
114    mThread = new LooperThread(this, canCallJava);
115
116    status_t err = mThread->run(
117            mName.empty() ? "ALooper" : mName.c_str(), priority);
118    if (err != OK) {
119        mThread.clear();
120    }
121
122    return err;
123}
124
125status_t ALooper::stop() {
126    sp<LooperThread> thread;
127    bool runningLocally;
128
129    {
130        Mutex::Autolock autoLock(mLock);
131
132        thread = mThread;
133        runningLocally = mRunningLocally;
134        mThread.clear();
135        mRunningLocally = false;
136    }
137
138    if (thread == NULL && !runningLocally) {
139        return INVALID_OPERATION;
140    }
141
142    if (thread != NULL) {
143        thread->requestExit();
144    }
145
146    mQueueChangedCondition.signal();
147
148    if (!runningLocally && !thread->isCurrentThread()) {
149        // If not running locally and this thread _is_ the looper thread,
150        // the loop() function will return and never be called again.
151        thread->requestExitAndWait();
152    }
153
154    return OK;
155}
156
157void ALooper::post(const sp<AMessage> &msg, int64_t delayUs) {
158    Mutex::Autolock autoLock(mLock);
159
160    int64_t whenUs;
161    if (delayUs > 0) {
162        whenUs = GetNowUs() + delayUs;
163    } else {
164        whenUs = GetNowUs();
165    }
166
167    List<Event>::iterator it = mEventQueue.begin();
168    while (it != mEventQueue.end() && (*it).mWhenUs <= whenUs) {
169        ++it;
170    }
171
172    Event event;
173    event.mWhenUs = whenUs;
174    event.mMessage = msg;
175
176    if (it == mEventQueue.begin()) {
177        mQueueChangedCondition.signal();
178    }
179
180    mEventQueue.insert(it, event);
181}
182
183bool ALooper::loop() {
184    Event event;
185
186    {
187        Mutex::Autolock autoLock(mLock);
188        if (mThread == NULL && !mRunningLocally) {
189            return false;
190        }
191        if (mEventQueue.empty()) {
192            mQueueChangedCondition.wait(mLock);
193            return true;
194        }
195        int64_t whenUs = (*mEventQueue.begin()).mWhenUs;
196        int64_t nowUs = GetNowUs();
197
198        if (whenUs > nowUs) {
199            int64_t delayUs = whenUs - nowUs;
200            mQueueChangedCondition.waitRelative(mLock, delayUs * 1000ll);
201
202            return true;
203        }
204
205        event = *mEventQueue.begin();
206        mEventQueue.erase(mEventQueue.begin());
207    }
208
209    gLooperRoster.deliverMessage(event.mMessage);
210
211    // NOTE: It's important to note that at this point our "ALooper" object
212    // may no longer exist (its final reference may have gone away while
213    // delivering the message). We have made sure, however, that loop()
214    // won't be called again.
215
216    return true;
217}
218
219}  // namespace android
220