Add TaskManager API

This API can be used to run arbitrary tasks on a pool of worker
threads. The number of threads is calculated based on the number
of CPU cores available.

The API is made of 3 classes:

TaskManager
      Creates and manages the worker threads.

Task
      Describes the work to be done and the type of the output.
      A task contains a future used to wait for the worker thread
      to be done computing the result of the task.

TaskProcessor
      The processor dispatches tasks to the TaskManager and is
      responsible for performing the computation required by
      each task. A processor will only be asked to process tasks
      sent to the manager through the processor.

A typical use case:

class MyTask: Task<MyType>

class MyProcessor: TaskProcessor<MyType>

TaskManager m = new TaskManager();
MyProcessor p = new MyProcessor(m);
MyTask t = new MyTask();
p.add(t);

// Waits until the result is available
MyType result = t->getResult();

Change-Id: I1fe845ba4c49bb0e1b0627ab147f9a861c8e0749

5 files changed, 354 insertions, 1 deletions

diff --git a/libs/hwui/thread/Future.h b/libs/hwui/thread/Future.h
index 340fec7..a3ff3bc 100644
--- a/libs/hwui/thread/Future.h
+++ b/libs/hwui/thread/Future.h
@@ -24,7 +24,7 @@
 namespace android {
 namespace uirenderer {
 
-template<class T>
+template<typename T>
 class Future: public LightRefBase<Future<T> > {
 public:
     Future(Condition::WakeUpType type = Condition::WAKE_UP_ONE): mBarrier(type), mResult() { }
diff --git a/libs/hwui/thread/Task.h b/libs/hwui/thread/Task.h
new file mode 100644
index 0000000..9a211a2
--- /dev/null
+++ b/libs/hwui/thread/Task.h
@@ -0,0 +1,63 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#ifndef ANDROID_HWUI_TASK_H
+#define ANDROID_HWUI_TASK_H
+
+#define ATRACE_TAG ATRACE_TAG_VIEW
+
+#include <utils/RefBase.h>
+#include <utils/Trace.h>
+
+#include "Future.h"
+
+namespace android {
+namespace uirenderer {
+
+class TaskBase: public RefBase {
+public:
+    TaskBase() { }
+    virtual ~TaskBase() { }
+};
+
+template<typename T>
+class Task: public TaskBase {
+public:
+    Task(): mFuture(new Future<T>()) { }
+    virtual ~Task() { }
+
+    T getResult() const {
+        ATRACE_NAME("waitForTask");
+        return mFuture->get();
+    }
+
+    void setResult(T result) {
+        mFuture->produce(result);
+    }
+
+protected:
+    const sp<Future<T> >& future() const {
+        return mFuture;
+    }
+
+private:
+    sp<Future<T> > mFuture;
+};
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_HWUI_TASK_H
diff --git a/libs/hwui/thread/TaskManager.cpp b/libs/hwui/thread/TaskManager.cpp
new file mode 100644
index 0000000..ce6c8c0
--- /dev/null
+++ b/libs/hwui/thread/TaskManager.cpp
@@ -0,0 +1,118 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#include <sys/sysinfo.h>
+
+#include "Task.h"
+#include "TaskProcessor.h"
+#include "TaskManager.h"
+
+namespace android {
+namespace uirenderer {
+
+///////////////////////////////////////////////////////////////////////////////
+// Manager
+///////////////////////////////////////////////////////////////////////////////
+
+TaskManager::TaskManager() {
+    // Get the number of available CPUs. This value does not change over time.
+    int cpuCount = sysconf(_SC_NPROCESSORS_ONLN);
+
+    for (int i = 0; i < cpuCount / 2; i++) {
+        String8 name;
+        name.appendFormat("hwuiTask%d", i + 1);
+        mThreads.add(new WorkerThread(name));
+    }
+}
+
+TaskManager::~TaskManager() {
+    for (size_t i = 0; i < mThreads.size(); i++) {
+        mThreads[i]->exit();
+    }
+}
+
+bool TaskManager::canRunTasks() const {
+    return mThreads.size() > 0;
+}
+
+bool TaskManager::addTaskBase(const sp<TaskBase>& task, const sp<TaskProcessorBase>& processor) {
+    if (mThreads.size() > 0) {
+        TaskWrapper wrapper(task, processor);
+
+        size_t minQueueSize = INT_MAX;
+        sp<WorkerThread> thread;
+
+        for (size_t i = 0; i < mThreads.size(); i++) {
+            if (mThreads[i]->getTaskCount() < minQueueSize) {
+                thread = mThreads[i];
+                minQueueSize = mThreads[i]->getTaskCount();
+            }
+        }
+
+        return thread->addTask(wrapper);
+    }
+    return false;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// Thread
+///////////////////////////////////////////////////////////////////////////////
+
+bool TaskManager::WorkerThread::threadLoop() {
+    mSignal.wait();
+    Vector<TaskWrapper> tasks;
+    {
+        Mutex::Autolock l(mLock);
+        tasks = mTasks;
+        mTasks.clear();
+    }
+
+    for (size_t i = 0; i < tasks.size(); i++) {
+        const TaskWrapper& task = tasks.itemAt(i);
+        task.mProcessor->process(task.mTask);
+    }
+
+    return true;
+}
+
+bool TaskManager::WorkerThread::addTask(TaskWrapper task) {
+    if (!isRunning()) {
+        run(mName.string(), PRIORITY_DEFAULT);
+    }
+
+    Mutex::Autolock l(mLock);
+    ssize_t index = mTasks.add(task);
+    mSignal.signal();
+
+    return index >= 0;
+}
+
+size_t TaskManager::WorkerThread::getTaskCount() const {
+    Mutex::Autolock l(mLock);
+    return mTasks.size();
+}
+
+void TaskManager::WorkerThread::exit() {
+    {
+        Mutex::Autolock l(mLock);
+        mTasks.clear();
+    }
+    requestExit();
+    mSignal.signal();
+}
+
+}; // namespace uirenderer
+}; // namespace android
diff --git a/libs/hwui/thread/TaskManager.h b/libs/hwui/thread/TaskManager.h
new file mode 100644
index 0000000..bc86062
--- /dev/null
+++ b/libs/hwui/thread/TaskManager.h
@@ -0,0 +1,100 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#ifndef ANDROID_HWUI_TASK_MANAGER_H
+#define ANDROID_HWUI_TASK_MANAGER_H
+
+#include <utils/Mutex.h>
+#include <utils/String8.h>
+#include <utils/Thread.h>
+#include <utils/Vector.h>
+
+#include "Signal.h"
+
+namespace android {
+namespace uirenderer {
+
+template <typename T>
+class Task;
+class TaskBase;
+
+template <typename T>
+class TaskProcessor;
+class TaskProcessorBase;
+
+class TaskManager {
+public:
+    TaskManager();
+    ~TaskManager();
+
+    /**
+     * Returns true if this task  manager can run tasks,
+     * false otherwise. This method will typically return
+     * true on a single CPU core device.
+     */
+    bool canRunTasks() const;
+
+private:
+    template <typename T>
+    friend class TaskProcessor;
+
+    template<typename T>
+    bool addTask(const sp<Task<T> >& task, const sp<TaskProcessor<T> >& processor) {
+        return addTaskBase(sp<TaskBase>(task), sp<TaskProcessorBase>(processor));
+    }
+
+    bool addTaskBase(const sp<TaskBase>& task, const sp<TaskProcessorBase>& processor);
+
+    struct TaskWrapper {
+        TaskWrapper(): mTask(), mProcessor() { }
+
+        TaskWrapper(const sp<TaskBase>& task, const sp<TaskProcessorBase>& processor):
+            mTask(task), mProcessor(processor) {
+        }
+
+        sp<TaskBase> mTask;
+        sp<TaskProcessorBase> mProcessor;
+    };
+
+    class WorkerThread: public Thread {
+    public:
+        WorkerThread(const String8 name): mSignal(Condition::WAKE_UP_ONE), mName(name) { }
+
+        bool addTask(TaskWrapper task);
+        size_t getTaskCount() const;
+        void exit();
+
+    private:
+        virtual bool threadLoop();
+
+        // Lock for the list of tasks
+        mutable Mutex mLock;
+        Vector<TaskWrapper> mTasks;
+
+        // Signal used to wake up the thread when a new
+        // task is available in the list
+        mutable Signal mSignal;
+
+        const String8 mName;
+    };
+
+    Vector<sp<WorkerThread> > mThreads;
+};
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_HWUI_TASK_MANAGER_H
diff --git a/libs/hwui/thread/TaskProcessor.h b/libs/hwui/thread/TaskProcessor.h
new file mode 100644
index 0000000..d1269f0
--- /dev/null
+++ b/libs/hwui/thread/TaskProcessor.h
@@ -0,0 +1,72 @@
+/*
+ * Copyright (C) 2013 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.
+ */
+
+#ifndef ANDROID_HWUI_TASK_PROCESSOR_H
+#define ANDROID_HWUI_TASK_PROCESSOR_H
+
+#include <utils/RefBase.h>
+
+#include "Task.h"
+#include "TaskManager.h"
+
+namespace android {
+namespace uirenderer {
+
+class TaskProcessorBase: public RefBase {
+public:
+    TaskProcessorBase() { }
+    virtual ~TaskProcessorBase() { };
+
+private:
+    friend class TaskManager;
+
+    virtual void process(const sp<TaskBase>& task) = 0;
+};
+
+template<typename T>
+class TaskProcessor: public TaskProcessorBase {
+public:
+    TaskProcessor(TaskManager* manager): mManager(manager) { }
+    virtual ~TaskProcessor() { }
+
+    bool add(const sp<Task<T> >& task);
+
+    virtual void onProcess(const sp<Task<T> >& task) = 0;
+
+private:
+    virtual void process(const sp<TaskBase>& task) {
+        sp<Task<T> > realTask = static_cast<Task<T>* >(task.get());
+        // This is the right way to do it but sp<> doesn't play nice
+        // sp<Task<T> > realTask = static_cast<sp<Task<T> > >(task);
+        onProcess(realTask);
+    }
+
+    TaskManager* mManager;
+};
+
+template<typename T>
+bool TaskProcessor<T>::add(const sp<Task<T> >& task) {
+    if (mManager) {
+        sp<TaskProcessor<T> > self(this);
+        return mManager->addTask(task, self);
+    }
+    return false;
+}
+
+}; // namespace uirenderer
+}; // namespace android
+
+#endif // ANDROID_HWUI_TASK_PROCESSOR_H