Add a simple work queue abstraction.
Makes it easy to schedule a bunch of work to happen in parallel.
Change-Id: Id9c0e52fc8b6d78d2b9ed4c2ee47abce0a01775c
diff --git a/libs/utils/Android.mk b/libs/utils/Android.mk
index 87d0fb2..b4fc994 100644
--- a/libs/utils/Android.mk
+++ b/libs/utils/Android.mk
@@ -41,6 +41,7 @@
Tokenizer.cpp \
Unicode.cpp \
VectorImpl.cpp \
+ WorkQueue.cpp \
misc.cpp
host_commonCflags := -DLIBUTILS_NATIVE=1 $(TOOL_CFLAGS)
diff --git a/libs/utils/Threads.cpp b/libs/utils/Threads.cpp
index ab207f5..f9277de 100644
--- a/libs/utils/Threads.cpp
+++ b/libs/utils/Threads.cpp
@@ -323,6 +323,7 @@
#endif
}
+#ifdef HAVE_ANDROID_OS
int androidSetThreadSchedulingGroup(pid_t tid, int grp)
{
if (grp > ANDROID_TGROUP_MAX || grp < 0) {
@@ -425,6 +426,7 @@
return ret;
}
+#endif
namespace android {
diff --git a/libs/utils/WorkQueue.cpp b/libs/utils/WorkQueue.cpp
new file mode 100644
index 0000000..3bb99a1
--- /dev/null
+++ b/libs/utils/WorkQueue.cpp
@@ -0,0 +1,171 @@
+/*
+ * 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 <utils/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