Android systrace: Optimize memory dumps.

systrace/atrace_helper/jni/time_utils.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "time_utils.h"
+
+#include <sys/time.h>
+#include <sys/timerfd.h>
+#include <time.h>
+
+#include "logging.h"
+
+namespace time_utils {
+
+uint64_t GetTimestamp() {
+  struct timespec ts = {};
+  CHECK(clock_gettime(CLOCK_MONOTONIC_COARSE, &ts) == 0);
+  return ts.tv_sec * 1000 + ts.tv_nsec / 1000000ul;
+}
+
+PeriodicTimer::PeriodicTimer(int interval_ms) : interval_ms_(interval_ms) {
+  timer_fd_ = -1;
+}
+
+PeriodicTimer::~PeriodicTimer() {
+  Stop();
+}
+
+void PeriodicTimer::Start() {
+  Stop();
+  timer_fd_ = timerfd_create(CLOCK_MONOTONIC, 0);
+  CHECK(timer_fd_ >= 0);
+  int sec = interval_ms_ / 1000;
+  int nsec = (interval_ms_ % 1000) * 1000000;
+  struct itimerspec ts = {};
+  ts.it_value.tv_nsec = nsec;
+  ts.it_value.tv_sec = sec;
+  ts.it_interval.tv_nsec = nsec;
+  ts.it_interval.tv_sec = sec;
+  CHECK(timerfd_settime(timer_fd_, 0, &ts, nullptr) == 0);
+}
+
+void PeriodicTimer::Stop() {
+  if (timer_fd_ < 0)
+    return;
+  close(timer_fd_);
+  timer_fd_ = -1;
+}
+
+bool PeriodicTimer::Wait() {
+  if (timer_fd_ < 0)
+    return false;  // Not started yet.
+  uint64_t stub = 0;
+  int res = read(timer_fd_, &stub, sizeof(stub));
+  if (res < 0 && errno == EBADF)
+    return false;  // Interrupted by Stop().
+  CHECK(res > 0);
+  return true;
+}
+
+}  // namespace time_utils