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, 41 insertions, 68 deletions

diff --git a/libs/hwui/PathCache.cpp b/libs/hwui/PathCache.cpp
index 9e6ec8488ebf..afdc2c9cd4ed 100644
--- a/libs/hwui/PathCache.cpp
+++ b/libs/hwui/PathCache.cpp
@@ -31,69 +31,32 @@ namespace uirenderer {
 // Path precaching
 ///////////////////////////////////////////////////////////////////////////////
 
-bool PathCache::PrecacheThread::threadLoop() {
-    mSignal.wait();
-    Vector<Task> tasks;
-    {
-        Mutex::Autolock l(mLock);
-        tasks = mTasks;
-        mTasks.clear();
-    }
-
-    Caches& caches = Caches::getInstance();
-    uint32_t maxSize = caches.maxTextureSize;
-
-    ATRACE_BEGIN("pathPrecache");
-    for (size_t i = 0; i < tasks.size(); i++) {
-        const Task& task = tasks.itemAt(i);
-
-        float left, top, offset;
-        uint32_t width, height;
-        PathCache::computePathBounds(task.path, task.paint, left, top, offset, width, height);
-
-        if (width <= maxSize && height <= maxSize) {
-            SkBitmap* bitmap = new SkBitmap();
-
-            PathTexture* texture = task.texture;
-            texture->left = left;
-            texture->top = top;
-            texture->offset = offset;
-            texture->width = width;
-            texture->height = height;
-
-            PathCache::drawPath(task.path, task.paint, *bitmap, left, top, offset, width, height);
-
-            texture->future()->produce(bitmap);
-        } else {
-            task.texture->future()->produce(NULL);
-        }
-    }
-    ATRACE_END();
-    return true;
+PathCache::PathProcessor::PathProcessor(Caches& caches):
+        TaskProcessor<SkBitmap*>(&caches.tasks), mMaxTextureSize(caches.maxTextureSize) {
 }
 
-void PathCache::PrecacheThread::addTask(PathTexture* texture, SkPath* path, SkPaint* paint) {
-    if (!isRunning()) {
-        run("libhwui:pathPrecache", PRIORITY_DEFAULT);
-    }
-
-    Task task;
-    task.texture = texture;
-    task.path = path;
-    task.paint = paint;
-
-    Mutex::Autolock l(mLock);
-    mTasks.add(task);
-    mSignal.signal();
-}
-
-void PathCache::PrecacheThread::exit() {
-    {
-        Mutex::Autolock l(mLock);
-        mTasks.clear();
+void PathCache::PathProcessor::onProcess(const sp<Task<SkBitmap*> >& task) {
+    sp<PathTask> t = static_cast<PathTask* >(task.get());
+    ATRACE_NAME("pathPrecache");
+
+    float left, top, offset;
+    uint32_t width, height;
+    PathCache::computePathBounds(t->path, t->paint, left, top, offset, width, height);
+
+    PathTexture* texture = t->texture;
+    texture->left = left;
+    texture->top = top;
+    texture->offset = offset;
+    texture->width = width;
+    texture->height = height;
+
+    if (width <= mMaxTextureSize && height <= mMaxTextureSize) {
+        SkBitmap* bitmap = new SkBitmap();
+        PathCache::drawPath(t->path, t->paint, *bitmap, left, top, offset, width, height);
+        t->setResult(bitmap);
+    } else {
+        t->setResult(NULL);
     }
-    requestExit();
-    mSignal.signal();
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -101,11 +64,10 @@ void PathCache::PrecacheThread::exit() {
 ///////////////////////////////////////////////////////////////////////////////
 
 PathCache::PathCache(): ShapeCache<PathCacheEntry>("path",
-        PROPERTY_PATH_CACHE_SIZE, DEFAULT_PATH_CACHE_SIZE), mThread(new PrecacheThread()) {
+        PROPERTY_PATH_CACHE_SIZE, DEFAULT_PATH_CACHE_SIZE) {
 }
 
 PathCache::~PathCache() {
-    mThread->exit();
 }
 
 void PathCache::remove(SkPath* path) {
@@ -165,17 +127,18 @@ PathTexture* PathCache::get(SkPath* path, SkPaint* paint) {
     } else {
         // A bitmap is attached to the texture, this means we need to
         // upload it as a GL texture
-        if (texture->future() != NULL) {
+        const sp<Task<SkBitmap*> >& task = texture->task();
+        if (task != NULL) {
             // But we must first wait for the worker thread to be done
             // producing the bitmap, so let's wait
-            SkBitmap* bitmap = texture->future()->get();
+            SkBitmap* bitmap = task->getResult();
             if (bitmap) {
                 addTexture(entry, bitmap, texture);
-                texture->clearFuture();
+                texture->clearTask();
             } else {
                 ALOGW("Path too large to be rendered into a texture (%dx%d)",
                         texture->width, texture->height);
-                texture->clearFuture();
+                texture->clearTask();
                 texture = NULL;
                 mCache.remove(entry);
             }
@@ -189,6 +152,10 @@ PathTexture* PathCache::get(SkPath* path, SkPaint* paint) {
 }
 
 void PathCache::precache(SkPath* path, SkPaint* paint) {
+    if (!Caches::getInstance().tasks.canRunTasks()) {
+        return;
+    }
+
     path = getSourcePath(path);
 
     PathCacheEntry entry(path, paint);
@@ -205,7 +172,9 @@ void PathCache::precache(SkPath* path, SkPaint* paint) {
     if (generate) {
         // It is important to specify the generation ID so we do not
         // attempt to precache the same path several times
-        texture = createTexture(0.0f, 0.0f, 0.0f, 0, 0, path->getGenerationID(), true);
+        texture = createTexture(0.0f, 0.0f, 0.0f, 0, 0, path->getGenerationID());
+        sp<PathTask> task = new PathTask(path, paint, texture);
+        texture->setTask(task);
 
         // During the precaching phase we insert path texture objects into
         // the cache that do not point to any GL texture. They are instead
@@ -215,7 +184,11 @@ void PathCache::precache(SkPath* path, SkPaint* paint) {
         // asks for a path texture. This is also when the cache limit will
         // be enforced.
         mCache.put(entry, texture);
-        mThread->addTask(texture, path, paint);
+
+        if (mProcessor == NULL) {
+            mProcessor = new PathProcessor(Caches::getInstance());
+        }
+        mProcessor->add(task);
     }
 }