Merge "Print warnings when backwards timestamps are detected." into jb-mr1-dev (07e8134e) · Commits · e / os / android_frameworks_native

libs/utils/SystemClock.cpp

+55 −5

Original line number	Diff line number	Diff line
		@@ -109,6 +109,43 @@ int64_t elapsedRealtime()
		return nanoseconds_to_milliseconds(elapsedRealtimeNano());
		}

		#define METHOD_CLOCK_GETTIME 0
		#define METHOD_IOCTL 1
		#define METHOD_SYSTEMTIME 2

		static const char *gettime_method_names[] = {
		"clock_gettime",
		"ioctl",
		"systemTime",
		};

		static inline void checkTimeStamps(int64_t timestamp,
		int64_t volatile *prevTimestampPtr,
		int volatile *prevMethodPtr,
		int curMethod)
		{
		/*
		* Disable the check for SDK since the prebuilt toolchain doesn't contain
		* gettid, and int64_t is different on the ARM platform
		* (ie long vs long long).
		*/
		#ifdef ARCH_ARM
		int64_t prevTimestamp = *prevTimestampPtr;
		int prevMethod = *prevMethodPtr;

		if (timestamp < prevTimestamp) {
		ALOGW("time going backwards: prev %lld(%s) vs now %lld(%s), tid=%d",
		prevTimestamp, gettime_method_names[prevMethod],
		timestamp, gettime_method_names[curMethod],
		gettid());
		}
		// NOTE - not atomic and may generate spurious warnings if the 64-bit
		// write is interrupted or not observed as a whole.
		*prevTimestampPtr = timestamp;
		*prevMethodPtr = curMethod;
		#endif
		}

		/*
		* native public static long elapsedRealtimeNano();
		*/
		@@ -117,8 +154,15 @@ int64_t elapsedRealtimeNano()
		#ifdef HAVE_ANDROID_OS
		struct timespec ts;
		int result = clock_gettime(CLOCK_BOOTTIME, &ts);
		int64_t timestamp;
		static volatile int64_t prevTimestamp;
		static volatile int prevMethod;

		if (result == 0) {
		return seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
		timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
		checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
		METHOD_CLOCK_GETTIME);
		return timestamp;
		}

		// CLOCK_BOOTTIME doesn't exist, fallback to /dev/alarm
		@@ -129,18 +173,24 @@ int64_t elapsedRealtimeNano()
		if (android_atomic_cmpxchg(-1, fd, &s_fd)) {
		close(fd);
		}
		}

		result = ioctl(s_fd,
		ANDROID_ALARM_GET_TIME(ANDROID_ALARM_ELAPSED_REALTIME), &ts);
		}

		if (result == 0) {
		return seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
		timestamp = seconds_to_nanoseconds(ts.tv_sec) + ts.tv_nsec;
		checkTimeStamps(timestamp, &prevTimestamp, &prevMethod, METHOD_IOCTL);
		return timestamp;
		}

		// XXX: there was an error, probably because the driver didn't
		// exist ... this should return
		// a real error, like an exception!
		return systemTime(SYSTEM_TIME_MONOTONIC);
		timestamp = systemTime(SYSTEM_TIME_MONOTONIC);
		checkTimeStamps(timestamp, &prevTimestamp, &prevMethod,
		METHOD_SYSTEMTIME);
		return timestamp;
		#else
		return systemTime(SYSTEM_TIME_MONOTONIC);
		#endif