NotificationQueue benchmark

Summary: NotificationQueue benchmark

Reviewed By: yfeldblum, djwatson

Differential Revision: D7163944

fbshipit-source-id: f7fe2124b8c61ff3ab39be94d9c50c82a6f8816b

folly/io/async/test/NotificationQueueBenchmark.cpp

+/*
+ * Copyright 2018-present Facebook, Inc.
+ *
+ * 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 <folly/Benchmark.h>
+#include <folly/io/async/EventBase.h>
+#include <folly/synchronization/Baton.h>
+#include <condition_variable>
+#include <mutex>
+#include <thread>
+
+using namespace folly;
+
+static size_t constexpr kMaxRead = 20;
+
+void runTest(int iters, int numThreads) {
+  BenchmarkSuspender susp;
+  EventBase evb;
+  evb.setMaxReadAtOnce(kMaxRead);
+
+  std::mutex m;
+  std::condition_variable cv;
+  int numRunning = 0;
+  int numProcessed = 0;
+  int numTotal = iters * numThreads;
+
+  std::vector<std::thread> threads;
+  for (int i = 0; i < numThreads; i++) {
+    threads.push_back(std::thread([&]() mutable {
+      // wait for all the threads to start up
+      bool notifyAll = false;
+      {
+        std::lock_guard<std::mutex> lk(m);
+        if (++numRunning == numThreads) {
+          notifyAll = true;
+          susp.dismiss();
+        }
+      }
+
+      if (notifyAll) {
+        cv.notify_all();
+      } else {
+        std::unique_lock<std::mutex> lk(m);
+        cv.wait(lk, [&]() { return numRunning == numThreads; });
+      }
+
+      for (auto j = 0; j < iters; j++) {
+        evb.runInEventBaseThread([&]() mutable {
+          if (++numProcessed == numTotal) {
+            evb.terminateLoopSoon();
+            ;
+          }
+        });
+      }
+    }));
+  }
+
+  evb.loopForever();
+  susp.rehire();
+
+  for (auto& t : threads) {
+    t.join();
+  }
+}
+
+BENCHMARK_PARAM(runTest, 1);
+BENCHMARK_PARAM(runTest, 2);
+BENCHMARK_PARAM(runTest, 4);
+BENCHMARK_PARAM(runTest, 8);
+BENCHMARK_PARAM(runTest, 16);
+BENCHMARK_PARAM(runTest, 32);
+
+int main(int argc, char* argv[]) {
+  gflags::ParseCommandLineFlags(&argc, &argv, true);
+  folly::runBenchmarks();
+
+  return 0;
+}