Merge "Add micro-benchmark for media metrics"

services/mediametrics/benchmarks/Android.bp

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+cc_test {
+    name: "mediametrics_benchmarks",
+    srcs: ["mediametrics_benchmarks.cpp"],
+    shared_libs: ["libbinder", "libmediametrics",],
+    static_libs: ["libgoogle-benchmark"],
+}

services/mediametrics/benchmarks/README.md

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+This benchmark may fail occasionally, probably due to the binder queue being full.
+If that happens, just re-run it and it will usually work eventually.
+
+adb shell /data/nativetest64/media\_metrics/media\_metrics

services/mediametrics/benchmarks/mediametrics_benchmarks.cpp

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+/*
+ * Copyright (C) 2020 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 <media/MediaMetricsItem.h>
+#include <benchmark/benchmark.h>
+
+class MyItem : public android::mediametrics::BaseItem {
+public:
+    static bool mySubmitBuffer() {
+        // Deliberately lame so that we're measuring just the cost to deliver things to the service.
+        return submitBuffer("", 0);
+    }
+};
+
+static void BM_SubmitBuffer(benchmark::State& state)
+{
+    while (state.KeepRunning()) {
+        MyItem myItem;
+        bool ok = myItem.mySubmitBuffer();
+        if (ok == false) {
+            // submitBuffer() currently uses one-way binder IPC, which provides unreliable delivery
+            // with at-most-one guarantee.
+            // It is expected that the call may occasionally fail if the one-way queue is full.
+            // The Iterations magic number below was tuned to reduce, but not eliminate, failures.
+            state.SkipWithError("failed");
+            return;
+        }
+        benchmark::ClobberMemory();
+    }
+}
+
+BENCHMARK(BM_SubmitBuffer)->Iterations(4000);   // Adjust magic number until test runs
+
+BENCHMARK_MAIN();