bootstat: Refactor init/utils/boot_clock into base/chrono_utils.

Use this for bootstat and init. This replaces the custom uptime parser in
bootstat.

This is a reland of aosp/332854 with a fix for Darwin.

Bug: 34352037
Test: chrono_utils_test
Change-Id: Ib2567d8df0e460ab59753ac1c053dd7f9f1008a7

1 files changed, 43 insertions, 0 deletions

diff --git a/base/chrono_utils.cpp b/base/chrono_utils.cpp
new file mode 100644
index 0000000000..644fd28bb1
--- /dev/null
+++ b/base/chrono_utils.cpp
@@ -0,0 +1,43 @@
+/*
+ * Copyright (C) 2017 The Android Open Source Project
+ *
+ * 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 "android-base/chrono_utils.h"
+
+#include <time.h>
+
+namespace android {
+namespace base {
+
+boot_clock::time_point boot_clock::now() {
+  timespec ts;
+  clockid_t clk_id;
+
+#ifdef __ANDROID__
+  clk_id = CLOCK_BOOTTIME;
+#else
+  // Darwin does not support CLOCK_BOOTTIME.  CLOCK_MONOTONIC is a sufficient
+  // fallback; the only loss of precision is the time duration when the system
+  // is suspended.
+  clk_id = CLOCK_MONOTONIC;
+#endif  // __ANDROID__
+
+  clock_gettime(clk_id, &ts);
+  return boot_clock::time_point(std::chrono::seconds(ts.tv_sec) +
+                                std::chrono::nanoseconds(ts.tv_nsec));
+}
+
+}  // namespace base
+}  // namespace android