expose hwui frame stats through FrameStatsObserver

Change-Id: I88884bafc8e2f6d7f67a36d3609490e83cf8afd5
diff --git a/libs/hwui/FrameStatsReporter.h b/libs/hwui/FrameStatsReporter.h
new file mode 100644
index 0000000..b8a9432
--- /dev/null
+++ b/libs/hwui/FrameStatsReporter.h
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C) 2016 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.
+ */
+
+#pragma once
+
+#include <utils/RefBase.h>
+#include <utils/Log.h>
+
+#include "BufferPool.h"
+#include "FrameInfo.h"
+#include "FrameStatsObserver.h"
+
+#include <string.h>
+#include <vector>
+
+namespace android {
+namespace uirenderer {
+
+class FrameStatsReporter {
+public:
+    FrameStatsReporter() {
+        mBufferPool = new BufferPool(kBufferSize, kBufferCount);
+        LOG_ALWAYS_FATAL_IF(mBufferPool.get() == nullptr, "OOM: unable to allocate buffer pool");
+    }
+
+    void addObserver(FrameStatsObserver* observer) {
+        mObservers.push_back(observer);
+    }
+
+    bool removeObserver(FrameStatsObserver* observer) {
+        for (size_t i = 0; i < mObservers.size(); i++) {
+            if (mObservers[i].get() == observer) {
+                mObservers.erase(mObservers.begin() + i);
+                return true;
+            }
+        }
+        return false;
+    }
+
+    bool hasObservers() {
+        return mObservers.size() > 0;
+    }
+
+    void reportFrameStats(const int64_t* stats) {
+        BufferPool::Buffer* statsBuffer = mBufferPool->acquire();
+
+        if (statsBuffer != nullptr) {
+            // copy in frame stats
+            memcpy(statsBuffer->getBuffer(), stats, kBufferSize * sizeof(*stats));
+
+            // notify on requested threads
+            for (size_t i = 0; i < mObservers.size(); i++) {
+                mObservers[i]->notify(statsBuffer);
+            }
+
+            // drop our reference
+            statsBuffer->release();
+        } else {
+            mDroppedReports++;
+        }
+    }
+
+    int getDroppedReports() { return mDroppedReports; }
+
+private:
+    static const size_t kBufferCount = 3;
+    static const size_t kBufferSize = static_cast<size_t>(FrameInfoIndex::NumIndexes);
+
+    std::vector< sp<FrameStatsObserver> > mObservers;
+
+    sp<BufferPool> mBufferPool;
+
+    int mDroppedReports = 0;
+};
+
+}; // namespace uirenderer
+}; // namespace android
+