Add, test, and use clock utilities

util/misc/clock.cc

Index: util/misc/clock.cc
diff --git a/util/misc/clock.cc b/util/misc/clock.cc
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+// Copyright 2014 The Crashpad 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 "util/misc/clock.h"
+
+#include <time.h>
+
+#include "base/logging.h"
+#include "base/posix/eintr_wrapper.h"
+#include "build/build_config.h"
+
+namespace {
+
+const uint64_t kNanosecondsPerSecond = 1E9;
+
+}  // namespace
+
+namespace crashpad {
+
+#if !defined(OS_MACOSX)
+
+uint64_t ClockMonotonicNanoseconds() {
+  timespec now;
+  int rv = clock_gettime(CLOCK_MONOTONIC, &now);
+  DPCHECK(rv == 0) << "clock_gettime";
+
+  return now.tv_sec * kNanosecondsPerSecond + now.tv_nsec;
+}
+
+#endif
+
+void SleepNanoseconds(uint64_t nanoseconds) {
+  timespec sleep_time;
+  sleep_time.tv_sec = nanoseconds / kNanosecondsPerSecond;
+  sleep_time.tv_nsec = nanoseconds % kNanosecondsPerSecond;
+  int rv = HANDLE_EINTR(nanosleep(&sleep_time, &sleep_time));
+  DPCHECK(rv == 0) << "nanosleep";
+}
+
+}  // namespace crashpad