Add first benchmark

Summary: Implement some very basic benchmarking infra. We need benchmarks in css-layout and I want to add something now so that others have the option to follow an example when implementing a benchmark.

Reviewed By: lucasr

Differential Revision: D3648889

fbshipit-source-id: 60b93c6e5ed027a37195a9a5d86e681e3e79a5b9

BUCK

@@ -33,6 +33,18 @@ cxx_library(
   visibility = ['PUBLIC'],
 )
 
+cxx_binary(
+  name = 'benchmark',
+  srcs = glob(['benchmarks/*.c']),
+  headers = subdir_glob([('', 'benchmarks/*.h')]),
+  header_namespace = '',
+  compiler_flags = COMPILER_FLAGS,
+  deps = [
+    ':CSSLayout',
+  ],
+  visibility = ['PUBLIC'],
+)
+
 cxx_library(
   name = 'CSSLayoutTestUtils',
   srcs = glob(['tests/CSSLayoutTestUtils/*.c']),

benchmarks/CSSBenchmark.c

@@ -0,0 +1,31 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#include "CSSBenchmark.h"
+
+#include <CSSLayout/CSSLayout.h>
+
+CSS_BENCHMARKS({
+
+  CSS_BENCHMARK("Stack with flex", {
+    CSSNodeRef root = CSSNodeNew();
+    CSSNodeStyleSetWidth(root, 100);
+    CSSNodeStyleSetHeight(root, 100);
+
+    for (int i = 0; i < 3; i++) {
+      CSSNodeRef child = CSSNodeNew();
+      CSSNodeStyleSetHeight(child, 20);
+      CSSNodeStyleSetFlex(child, 1);
+      CSSNodeInsertChild(root, child, 0);
+    }
+
+    CSSNodeCalculateLayout(root, 100, 100, CSSDirectionLTR);
+  });
+
+});

benchmarks/CSSBenchmark.h

@@ -0,0 +1,43 @@
+/**
+ * Copyright (c) 2014-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+
+#ifndef __CSS_BENCHMARK_H
+#define __CSS_BENCHMARK_H
+
+#include <time.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define NUM_REPETITIONS 100000
+
+#define CSS_BENCHMARKS(BLOCK) \
+int main(int argc, char const *argv[]) { \
+  clock_t __start; \
+  clock_t __end; \
+  { \
+    BLOCK \
+  } \
+  return 0; \
+}
+
+#define CSS_BENCHMARK(NAME, BLOCK) \
+__start = clock(); \
+for (int __i = 0; __i < NUM_REPETITIONS; __i++) { BLOCK } \
+__end = clock(); \
+__printBenchmarkResult(NAME, __start, __end);
+
+void __printBenchmarkResult(char *name, clock_t start, clock_t end) {
+  float total = (end - start) / (double) CLOCKS_PER_SEC * 1000;
+  float mean = total / NUM_REPETITIONS;
+  printf("%s: ", name);
+  printf("%lf ms", mean);
+  printf("\n");
+}
+
+#endif