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

1 files changed, 21 insertions, 18 deletions

diff --git a/libs/hwui/PathCache.h b/libs/hwui/PathCache.h
index 1d28ecb..27031a5 100644
--- a/libs/hwui/PathCache.h
+++ b/libs/hwui/PathCache.h
@@ -23,6 +23,8 @@
 #include "Debug.h"
 #include "ShapeCache.h"
 #include "thread/Signal.h"
+#include "thread/Task.h"
+#include "thread/TaskProcessor.h"
 
 class SkPaint;
 class SkPath;
@@ -100,32 +102,33 @@ public:
     void precache(SkPath* path, SkPaint* paint);
 
 private:
-    class PrecacheThread: public Thread {
+    class PathTask: public Task<SkBitmap*> {
     public:
-        PrecacheThread(): mSignal(Condition::WAKE_UP_ONE) { }
+        PathTask(SkPath* path, SkPaint* paint, PathTexture* texture):
+            path(path), paint(paint), texture(texture) {
+        }
 
-        void addTask(PathTexture* texture, SkPath* path, SkPaint* paint);
-        void exit();
+        ~PathTask() {
+            delete future()->get();
+        }
 
-    private:
-        struct Task {
-            PathTexture* texture;
-            SkPath* path;
-            SkPaint* paint;
-        };
+        SkPath* path;
+        SkPaint* paint;
+        PathTexture* texture;
+    };
 
-        virtual bool threadLoop();
+    class PathProcessor: public TaskProcessor<SkBitmap*> {
+    public:
+        PathProcessor(Caches& caches);
+        ~PathProcessor() { }
 
-        // Lock for the list of tasks
-        Mutex mLock;
-        Vector<Task> mTasks;
+        virtual void onProcess(const sp<Task<SkBitmap*> >& task);
 
-        // Signal used to wake up the thread when a new
-        // task is available in the list
-        mutable Signal mSignal;
+    private:
+        uint32_t mMaxTextureSize;
     };
 
-    sp<PrecacheThread> mThread;
+    sp<PathProcessor> mProcessor;
     Vector<SkPath*> mGarbage;
     mutable Mutex mLock;
 }; // class PathCache