replicant-frameworks_native/libs/utils/Timers.cpp

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/*
* Copyright (C) 2005 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.
*/
//
// Timer functions.
//
#include <utils/Timers.h>
#include <utils/ported.h> // may need usleep
#include <utils/Log.h>
#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/time.h>
#include <time.h>
#include <errno.h>
#ifdef HAVE_WIN32_THREADS
#include <windows.h>
#endif
nsecs_t systemTime(int clock)
{
#if defined(HAVE_POSIX_CLOCKS)
static const clockid_t clocks[] = {
CLOCK_REALTIME,
CLOCK_MONOTONIC,
CLOCK_PROCESS_CPUTIME_ID,
CLOCK_THREAD_CPUTIME_ID
};
struct timespec t;
t.tv_sec = t.tv_nsec = 0;
clock_gettime(clocks[clock], &t);
return nsecs_t(t.tv_sec)*1000000000LL + t.tv_nsec;
#else
// we don't support the clocks here.
struct timeval t;
t.tv_sec = t.tv_usec = 0;
gettimeofday(&t, NULL);
return nsecs_t(t.tv_sec)*1000000000LL + nsecs_t(t.tv_usec)*1000LL;
#endif
}
//#define MONITOR_USLEEP
/*
* Sleep long enough that we'll wake up "interval" milliseconds after
* the previous snooze.
*
* The "nextTick" argument is updated on each call, and should be passed
* in every time. Set its fields to zero on the first call.
*
* Returns the #of intervals we have overslept, which will be zero if we're
* on time. [Currently just returns 0 or 1.]
*/
int sleepForInterval(long interval, struct timeval* pNextTick)
{
struct timeval now;
long long timeBeforeNext;
long sleepTime = 0;
bool overSlept = false;
//int usleepBias = 0;
#ifdef USLEEP_BIAS
/*
* Linux likes to add 9000ms or so.
* [not using this for now]
*/
//usleepBias = USLEEP_BIAS;
#endif
gettimeofday(&now, NULL);
if (pNextTick->tv_sec == 0) {
/* special-case for first time through */
*pNextTick = now;
sleepTime = interval;
android::DurationTimer::addToTimeval(pNextTick, interval);
} else {
/*
* Compute how much time there is before the next tick. If this
* value is negative, we've run over. If we've run over a little
* bit we can shorten the next frame to keep the pace steady, but
* if we've dramatically overshot we need to re-sync.
*/
timeBeforeNext = android::DurationTimer::subtractTimevals(pNextTick, &now);
//printf("TOP: now=%ld.%ld next=%ld.%ld diff=%ld\n",
// now.tv_sec, now.tv_usec, pNextTick->tv_sec, pNextTick->tv_usec,
// (long) timeBeforeNext);
if (timeBeforeNext < -interval) {
/* way over */
overSlept = true;
sleepTime = 0;
*pNextTick = now;
} else if (timeBeforeNext <= 0) {
/* slightly over, keep the pace steady */
overSlept = true;
sleepTime = 0;
} else if (timeBeforeNext <= interval) {
/* right on schedule */
sleepTime = timeBeforeNext;
} else if (timeBeforeNext > interval && timeBeforeNext <= 2*interval) {
/* sleep call returned early; do a longer sleep this time */
sleepTime = timeBeforeNext;
} else if (timeBeforeNext > interval) {
/* we went back in time -- somebody updated system clock? */
/* (could also be a *seriously* broken usleep()) */
LOG(LOG_DEBUG, "",
" Impossible: timeBeforeNext = %ld\n", (long)timeBeforeNext);
sleepTime = 0;
*pNextTick = now;
}
android::DurationTimer::addToTimeval(pNextTick, interval);
}
//printf(" Before sleep: now=%ld.%ld next=%ld.%ld sleepTime=%ld\n",
// now.tv_sec, now.tv_usec, pNextTick->tv_sec, pNextTick->tv_usec,
// sleepTime);
/*
* Sleep for the designated period of time.
*
* Linux tends to sleep for longer than requested, often by 17-18ms.
* MinGW tends to sleep for less than requested, by as much as 14ms,
* but occasionally oversleeps for 40+ms (looks like some external
* factors plus round-off on a 64Hz clock). Cygwin is pretty steady.
*
* If you start the MinGW version, and then launch the Cygwin version,
* the MinGW clock becomes more erratic. Not entirely sure why.
*
* (There's a lot of stuff here; it's really just a usleep() call with
* a bunch of instrumentation.)
*/
if (sleepTime > 0) {
#if defined(MONITOR_USLEEP)
struct timeval before, after;
long long actual;
gettimeofday(&before, NULL);
usleep((long) sleepTime);
gettimeofday(&after, NULL);
/* check usleep() accuracy; default Linux threads are pretty sloppy */
actual = android::DurationTimer::subtractTimevals(&after, &before);
if ((long) actual < sleepTime - 14000 /*(sleepTime/10)*/ ||
(long) actual > sleepTime + 20000 /*(sleepTime/10)*/)
{
LOG(LOG_DEBUG, "", " Odd usleep: req=%ld, actual=%ld\n", sleepTime,
(long) actual);
}
#else
#ifdef HAVE_WIN32_THREADS
Sleep( sleepTime/1000 );
#else
usleep((long) sleepTime);
#endif
#endif
}
//printf("slept %d\n", sleepTime);
if (overSlept)
return 1; // close enough
else
return 0;
}
/*
* ===========================================================================
* DurationTimer
* ===========================================================================
*/
using namespace android;
// Start the timer.
void DurationTimer::start(void)
{
gettimeofday(&mStartWhen, NULL);
}
// Stop the timer.
void DurationTimer::stop(void)
{
gettimeofday(&mStopWhen, NULL);
}
// Get the duration in microseconds.
long long DurationTimer::durationUsecs(void) const
{
return (long) subtractTimevals(&mStopWhen, &mStartWhen);
}
// Subtract two timevals. Returns the difference (ptv1-ptv2) in
// microseconds.
/*static*/ long long DurationTimer::subtractTimevals(const struct timeval* ptv1,
const struct timeval* ptv2)
{
long long stop = ((long long) ptv1->tv_sec) * 1000000LL +
((long long) ptv1->tv_usec);
long long start = ((long long) ptv2->tv_sec) * 1000000LL +
((long long) ptv2->tv_usec);
return stop - start;
}
// Add the specified amount of time to the timeval.
/*static*/ void DurationTimer::addToTimeval(struct timeval* ptv, long usec)
{
if (usec < 0) {
LOG(LOG_WARN, "", "Negative values not supported in addToTimeval\n");
return;
}
// normalize tv_usec if necessary
if (ptv->tv_usec >= 1000000) {
ptv->tv_sec += ptv->tv_usec / 1000000;
ptv->tv_usec %= 1000000;
}
ptv->tv_usec += usec % 1000000;
if (ptv->tv_usec >= 1000000) {
ptv->tv_usec -= 1000000;
ptv->tv_sec++;
}
ptv->tv_sec += usec / 1000000;
}