Bazel client: add a simple profiler

Add a simple profiler that can measure function
call counts and durations, and report statistics
by printing to stderr.

Motivation:
I recently needed a profiler for PR #5445 and
PR #5448, so I'm adding the polished code now.

Usage:
1.  depend on //src/main/cpp/util:profiler
2.  use StopWatch, Task, and ScopedTask objects
    as shown in profiler.h's class documentation

See https://github.com/bazelbuild/bazel/issues/5444

Change-Id: I43f0afd124b486c694f451e8455a66ffca8137b6

Closes #5461.

Change-Id: I43f0afd124b486c694f451e8455a66ffca8137b6
PiperOrigin-RevId: 202314319

1 files changed, 43 insertions, 0 deletions

diff --git a/src/main/cpp/util/profiler_posix.cc b/src/main/cpp/util/profiler_posix.cc
new file mode 100644
index 0000000000..c86d509a2f
--- /dev/null
+++ b/src/main/cpp/util/profiler_posix.cc
@@ -0,0 +1,43 @@
+// Copyright 2018 The Bazel Authors. All rights reserved.
+//
+// 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 "src/main/cpp/util/profiler.h"
+
+#include <time.h>
+
+#include <string>
+
+#include "src/main/cpp/util/errors.h"
+#include "src/main/cpp/util/exit_code.h"
+#include "src/main/cpp/util/logging.h"
+
+namespace blaze_util {
+namespace profiler {
+
+Ticks Ticks::Now() {
+  struct timespec ts = {};
+  if (clock_gettime(CLOCK_MONOTONIC, &ts) == -1) {
+    std::string error = GetLastErrorString();
+    BAZEL_DIE(blaze_exit_code::LOCAL_ENVIRONMENTAL_ERROR)
+        << "clock_gettime failed: " << error;
+  }
+  return {ts.tv_sec * 1000LL * 1000LL * 1000LL + ts.tv_nsec};
+}
+
+Duration Duration::FromTicks(const Ticks ticks) {
+  return {ticks.value_ / 1000LL};
+}
+
+}  // namespace profiler
+}  // namespace blaze_util