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/*
* Copyright (C) 2012 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
// #define LOG_NDEBUG 0
#define LOG_TAG "WorkQueue"
#include <utils/Log.h>
#include "WorkQueue.h"
namespace android {
// --- WorkQueue ---
WorkQueue::WorkQueue(size_t maxThreads, bool canCallJava) :
mMaxThreads(maxThreads), mCanCallJava(canCallJava),
mCanceled(false), mFinished(false), mIdleThreads(0) {
}
WorkQueue::~WorkQueue() {
if (!cancel()) {
finish();
}
}
status_t WorkQueue::schedule(WorkUnit* workUnit, size_t backlog) {
AutoMutex _l(mLock);
if (mFinished || mCanceled) {
return INVALID_OPERATION;
}
if (mWorkThreads.size() < mMaxThreads
&& mIdleThreads < mWorkUnits.size() + 1) {
sp<WorkThread> workThread = new WorkThread(this, mCanCallJava);
status_t status = workThread->run("WorkQueue::WorkThread");
if (status) {
return status;
}
mWorkThreads.add(workThread);
mIdleThreads += 1;
} else if (backlog) {
while (mWorkUnits.size() >= mMaxThreads * backlog) {
mWorkDequeuedCondition.wait(mLock);
if (mFinished || mCanceled) {
return INVALID_OPERATION;
}
}
}
mWorkUnits.add(workUnit);
mWorkChangedCondition.broadcast();
return OK;
}
status_t WorkQueue::cancel() {
AutoMutex _l(mLock);
return cancelLocked();
}
status_t WorkQueue::cancelLocked() {
if (mFinished) {
return INVALID_OPERATION;
}
if (!mCanceled) {
mCanceled = true;
size_t count = mWorkUnits.size();
for (size_t i = 0; i < count; i++) {
delete mWorkUnits.itemAt(i);
}
mWorkUnits.clear();
mWorkChangedCondition.broadcast();
mWorkDequeuedCondition.broadcast();
}
return OK;
}
status_t WorkQueue::finish() {
{ // acquire lock
AutoMutex _l(mLock);
if (mFinished) {
return INVALID_OPERATION;
}
mFinished = true;
mWorkChangedCondition.broadcast();
} // release lock
// It is not possible for the list of work threads to change once the mFinished
// flag has been set, so we can access mWorkThreads outside of the lock here.
size_t count = mWorkThreads.size();
for (size_t i = 0; i < count; i++) {
mWorkThreads.itemAt(i)->join();
}
mWorkThreads.clear();
return OK;
}
bool WorkQueue::threadLoop() {
WorkUnit* workUnit;
{ // acquire lock
AutoMutex _l(mLock);
for (;;) {
if (mCanceled) {
return false;
}
if (!mWorkUnits.isEmpty()) {
workUnit = mWorkUnits.itemAt(0);
mWorkUnits.removeAt(0);
mIdleThreads -= 1;
mWorkDequeuedCondition.broadcast();
break;
}
if (mFinished) {
return false;
}
mWorkChangedCondition.wait(mLock);
}
} // release lock
bool shouldContinue = workUnit->run();
delete workUnit;
{ // acquire lock
AutoMutex _l(mLock);
mIdleThreads += 1;
if (!shouldContinue) {
cancelLocked();
return false;
}
} // release lock
return true;
}
// --- WorkQueue::WorkThread ---
WorkQueue::WorkThread::WorkThread(WorkQueue* workQueue, bool canCallJava) :
Thread(canCallJava), mWorkQueue(workQueue) {
}
WorkQueue::WorkThread::~WorkThread() {
}
bool WorkQueue::WorkThread::threadLoop() {
return mWorkQueue->threadLoop();
}
}; // namespace android
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