Add statsd microbenchmark and fix a crash in LogEvent

+ We should benchmark the core functions in the critical path.
     1. LogEvent parsing
     2. Log matching
     3. Event processing in various metrics
     ....

+ Using microbenchmark, we can quantify the optimization we do in the future.

    ---------------------------------------------------------
    Benchmark                  Time           CPU Iterations
    ---------------------------------------------------------
    BM_LogEventCreation       4772 ns       4705 ns     145738

Test: make -j64 statsd_benchmark

Bug: 72242322

Change-Id: I43aa704ffdc7cd21e02ef9038eff66ca7022dbfb
diff --git a/cmds/statsd/benchmark/hello_world_benchmark.cpp b/cmds/statsd/benchmark/hello_world_benchmark.cpp
new file mode 100644
index 0000000..c732d39
--- /dev/null
+++ b/cmds/statsd/benchmark/hello_world_benchmark.cpp
@@ -0,0 +1,29 @@
+/*
+ * Copyright (C) 2018 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 "benchmark/benchmark.h"
+
+static void BM_StringCreation(benchmark::State& state) {
+    while (state.KeepRunning()) std::string empty_string;
+}
+// Register the function as a benchmark
+BENCHMARK(BM_StringCreation);
+
+// Define another benchmark
+static void BM_StringCopy(benchmark::State& state) {
+    std::string x = "hello";
+    while (state.KeepRunning()) std::string copy(x);
+}
+BENCHMARK(BM_StringCopy);
diff --git a/cmds/statsd/benchmark/log_event_benchmark.cpp b/cmds/statsd/benchmark/log_event_benchmark.cpp
new file mode 100644
index 0000000..43addc2
--- /dev/null
+++ b/cmds/statsd/benchmark/log_event_benchmark.cpp
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2018 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 <vector>
+#include "benchmark/benchmark.h"
+#include "logd/LogEvent.h"
+
+namespace android {
+namespace os {
+namespace statsd {
+
+using std::vector;
+
+/* Special markers for android_log_list_element type */
+static const char EVENT_TYPE_LIST_STOP = '\n'; /* declare end of list  */
+static const char EVENT_TYPE_UNKNOWN = '?';    /* protocol error       */
+
+static const char EVENT_TYPE_INT = 0;
+static const char EVENT_TYPE_LONG = 1;
+static const char EVENT_TYPE_STRING = 2;
+static const char EVENT_TYPE_LIST = 3;
+static const char EVENT_TYPE_FLOAT = 4;
+
+static const int kLogMsgHeaderSize = 28;
+
+static void write4Bytes(int val, vector<char>* buffer) {
+    buffer->push_back(static_cast<char>(val));
+    buffer->push_back(static_cast<char>((val >> 8) & 0xFF));
+    buffer->push_back(static_cast<char>((val >> 16) & 0xFF));
+    buffer->push_back(static_cast<char>((val >> 24) & 0xFF));
+}
+
+static void getSimpleLogMsgData(log_msg* msg) {
+    vector<char> buffer;
+    // stats_log tag id
+    write4Bytes(1937006964, &buffer);
+    buffer.push_back(EVENT_TYPE_LIST);
+    buffer.push_back(2);  // field counts;
+    buffer.push_back(EVENT_TYPE_INT);
+    write4Bytes(10 /* atom id */, &buffer);
+    buffer.push_back(EVENT_TYPE_INT);
+    write4Bytes(99 /* a value to log*/, &buffer);
+    buffer.push_back(EVENT_TYPE_LIST_STOP);
+
+    msg->entry_v1.len = buffer.size();
+    msg->entry.hdr_size = kLogMsgHeaderSize;
+    msg->entry_v1.sec = time(nullptr);
+    std::copy(buffer.begin(), buffer.end(), msg->buf + kLogMsgHeaderSize);
+}
+
+static void BM_LogEventCreation(benchmark::State& state) {
+    log_msg msg;
+    getSimpleLogMsgData(&msg);
+    while (state.KeepRunning()) {
+        benchmark::DoNotOptimize(LogEvent(msg));
+    }
+}
+BENCHMARK(BM_LogEventCreation);
+
+}  //  namespace statsd
+}  //  namespace os
+}  //  namespace android
diff --git a/cmds/statsd/benchmark/main.cpp b/cmds/statsd/benchmark/main.cpp
new file mode 100644
index 0000000..08921f3
--- /dev/null
+++ b/cmds/statsd/benchmark/main.cpp
@@ -0,0 +1,19 @@
+/*
+ * Copyright (C) 2018 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 <benchmark/benchmark.h>
+
+BENCHMARK_MAIN();