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1 /*
2  * Copyright (C) 2013 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 #define ATRACE_TAG ATRACE_TAG_GRAPHICS
18 //#define LOG_NDEBUG 0
19 
20 // This is needed for stdint.h to define INT64_MAX in C++
21 #define __STDC_LIMIT_MACROS
22 
23 #include <math.h>
24 
25 #include <cutils/log.h>
26 
27 #include <ui/Fence.h>
28 
29 #include <utils/String8.h>
30 #include <utils/Thread.h>
31 #include <utils/Trace.h>
32 #include <utils/Vector.h>
33 
34 #include "DispSync.h"
35 #include "EventLog/EventLog.h"
36 
37 #include <algorithm>
38 
39 using std::max;
40 using std::min;
41 
42 namespace android {
43 
44 // Setting this to true enables verbose tracing that can be used to debug
45 // vsync event model or phase issues.
46 static const bool kTraceDetailedInfo = false;
47 
48 // Setting this to true adds a zero-phase tracer for correlating with hardware
49 // vsync events
50 static const bool kEnableZeroPhaseTracer = false;
51 
52 // This is the threshold used to determine when hardware vsync events are
53 // needed to re-synchronize the software vsync model with the hardware.  The
54 // error metric used is the mean of the squared difference between each
55 // present time and the nearest software-predicted vsync.
56 static const nsecs_t kErrorThreshold = 160000000000;    // 400 usec squared
57 
58 // This is the offset from the present fence timestamps to the corresponding
59 // vsync event.
60 static const int64_t kPresentTimeOffset = PRESENT_TIME_OFFSET_FROM_VSYNC_NS;
61 
62 #undef LOG_TAG
63 #define LOG_TAG "DispSyncThread"
64 class DispSyncThread: public Thread {
65 public:
66 
DispSyncThread(const char * name)67     DispSyncThread(const char* name):
68             mName(name),
69             mStop(false),
70             mPeriod(0),
71             mPhase(0),
72             mReferenceTime(0),
73             mWakeupLatency(0),
74             mFrameNumber(0) {}
75 
~DispSyncThread()76     virtual ~DispSyncThread() {}
77 
updateModel(nsecs_t period,nsecs_t phase,nsecs_t referenceTime)78     void updateModel(nsecs_t period, nsecs_t phase, nsecs_t referenceTime) {
79         if (kTraceDetailedInfo) ATRACE_CALL();
80         Mutex::Autolock lock(mMutex);
81         mPeriod = period;
82         mPhase = phase;
83         mReferenceTime = referenceTime;
84         ALOGV("[%s] updateModel: mPeriod = %" PRId64 ", mPhase = %" PRId64
85                 " mReferenceTime = %" PRId64, mName, ns2us(mPeriod),
86                 ns2us(mPhase), ns2us(mReferenceTime));
87         mCond.signal();
88     }
89 
stop()90     void stop() {
91         if (kTraceDetailedInfo) ATRACE_CALL();
92         Mutex::Autolock lock(mMutex);
93         mStop = true;
94         mCond.signal();
95     }
96 
threadLoop()97     virtual bool threadLoop() {
98         status_t err;
99         nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
100 
101         while (true) {
102             Vector<CallbackInvocation> callbackInvocations;
103 
104             nsecs_t targetTime = 0;
105 
106             { // Scope for lock
107                 Mutex::Autolock lock(mMutex);
108 
109                 if (kTraceDetailedInfo) {
110                     ATRACE_INT64("DispSync:Frame", mFrameNumber);
111                 }
112                 ALOGV("[%s] Frame %" PRId64, mName, mFrameNumber);
113                 ++mFrameNumber;
114 
115                 if (mStop) {
116                     return false;
117                 }
118 
119                 if (mPeriod == 0) {
120                     err = mCond.wait(mMutex);
121                     if (err != NO_ERROR) {
122                         ALOGE("error waiting for new events: %s (%d)",
123                                 strerror(-err), err);
124                         return false;
125                     }
126                     continue;
127                 }
128 
129                 targetTime = computeNextEventTimeLocked(now);
130 
131                 bool isWakeup = false;
132 
133                 if (now < targetTime) {
134                     if (kTraceDetailedInfo) ATRACE_NAME("DispSync waiting");
135 
136                     if (targetTime == INT64_MAX) {
137                         ALOGV("[%s] Waiting forever", mName);
138                         err = mCond.wait(mMutex);
139                     } else {
140                         ALOGV("[%s] Waiting until %" PRId64, mName,
141                                 ns2us(targetTime));
142                         err = mCond.waitRelative(mMutex, targetTime - now);
143                     }
144 
145                     if (err == TIMED_OUT) {
146                         isWakeup = true;
147                     } else if (err != NO_ERROR) {
148                         ALOGE("error waiting for next event: %s (%d)",
149                                 strerror(-err), err);
150                         return false;
151                     }
152                 }
153 
154                 now = systemTime(SYSTEM_TIME_MONOTONIC);
155 
156                 // Don't correct by more than 1.5 ms
157                 static const nsecs_t kMaxWakeupLatency = us2ns(1500);
158 
159                 if (isWakeup) {
160                     mWakeupLatency = ((mWakeupLatency * 63) +
161                             (now - targetTime)) / 64;
162                     mWakeupLatency = min(mWakeupLatency, kMaxWakeupLatency);
163                     if (kTraceDetailedInfo) {
164                         ATRACE_INT64("DispSync:WakeupLat", now - targetTime);
165                         ATRACE_INT64("DispSync:AvgWakeupLat", mWakeupLatency);
166                     }
167                 }
168 
169                 callbackInvocations = gatherCallbackInvocationsLocked(now);
170             }
171 
172             if (callbackInvocations.size() > 0) {
173                 fireCallbackInvocations(callbackInvocations);
174             }
175         }
176 
177         return false;
178     }
179 
addEventListener(const char * name,nsecs_t phase,const sp<DispSync::Callback> & callback)180     status_t addEventListener(const char* name, nsecs_t phase,
181             const sp<DispSync::Callback>& callback) {
182         if (kTraceDetailedInfo) ATRACE_CALL();
183         Mutex::Autolock lock(mMutex);
184 
185         for (size_t i = 0; i < mEventListeners.size(); i++) {
186             if (mEventListeners[i].mCallback == callback) {
187                 return BAD_VALUE;
188             }
189         }
190 
191         EventListener listener;
192         listener.mName = name;
193         listener.mPhase = phase;
194         listener.mCallback = callback;
195 
196         // We want to allow the firstmost future event to fire without
197         // allowing any past events to fire
198         listener.mLastEventTime = systemTime() - mPeriod / 2 + mPhase -
199                 mWakeupLatency;
200 
201         mEventListeners.push(listener);
202 
203         mCond.signal();
204 
205         return NO_ERROR;
206     }
207 
removeEventListener(const sp<DispSync::Callback> & callback)208     status_t removeEventListener(const sp<DispSync::Callback>& callback) {
209         if (kTraceDetailedInfo) ATRACE_CALL();
210         Mutex::Autolock lock(mMutex);
211 
212         for (size_t i = 0; i < mEventListeners.size(); i++) {
213             if (mEventListeners[i].mCallback == callback) {
214                 mEventListeners.removeAt(i);
215                 mCond.signal();
216                 return NO_ERROR;
217             }
218         }
219 
220         return BAD_VALUE;
221     }
222 
223     // This method is only here to handle the kIgnorePresentFences case.
hasAnyEventListeners()224     bool hasAnyEventListeners() {
225         if (kTraceDetailedInfo) ATRACE_CALL();
226         Mutex::Autolock lock(mMutex);
227         return !mEventListeners.empty();
228     }
229 
230 private:
231 
232     struct EventListener {
233         const char* mName;
234         nsecs_t mPhase;
235         nsecs_t mLastEventTime;
236         sp<DispSync::Callback> mCallback;
237     };
238 
239     struct CallbackInvocation {
240         sp<DispSync::Callback> mCallback;
241         nsecs_t mEventTime;
242     };
243 
computeNextEventTimeLocked(nsecs_t now)244     nsecs_t computeNextEventTimeLocked(nsecs_t now) {
245         if (kTraceDetailedInfo) ATRACE_CALL();
246         ALOGV("[%s] computeNextEventTimeLocked", mName);
247         nsecs_t nextEventTime = INT64_MAX;
248         for (size_t i = 0; i < mEventListeners.size(); i++) {
249             nsecs_t t = computeListenerNextEventTimeLocked(mEventListeners[i],
250                     now);
251 
252             if (t < nextEventTime) {
253                 nextEventTime = t;
254             }
255         }
256 
257         ALOGV("[%s] nextEventTime = %" PRId64, mName, ns2us(nextEventTime));
258         return nextEventTime;
259     }
260 
gatherCallbackInvocationsLocked(nsecs_t now)261     Vector<CallbackInvocation> gatherCallbackInvocationsLocked(nsecs_t now) {
262         if (kTraceDetailedInfo) ATRACE_CALL();
263         ALOGV("[%s] gatherCallbackInvocationsLocked @ %" PRId64, mName,
264                 ns2us(now));
265 
266         Vector<CallbackInvocation> callbackInvocations;
267         nsecs_t onePeriodAgo = now - mPeriod;
268 
269         for (size_t i = 0; i < mEventListeners.size(); i++) {
270             nsecs_t t = computeListenerNextEventTimeLocked(mEventListeners[i],
271                     onePeriodAgo);
272 
273             if (t < now) {
274                 CallbackInvocation ci;
275                 ci.mCallback = mEventListeners[i].mCallback;
276                 ci.mEventTime = t;
277                 ALOGV("[%s] [%s] Preparing to fire", mName,
278                         mEventListeners[i].mName);
279                 callbackInvocations.push(ci);
280                 mEventListeners.editItemAt(i).mLastEventTime = t;
281             }
282         }
283 
284         return callbackInvocations;
285     }
286 
computeListenerNextEventTimeLocked(const EventListener & listener,nsecs_t baseTime)287     nsecs_t computeListenerNextEventTimeLocked(const EventListener& listener,
288             nsecs_t baseTime) {
289         if (kTraceDetailedInfo) ATRACE_CALL();
290         ALOGV("[%s] [%s] computeListenerNextEventTimeLocked(%" PRId64 ")",
291                 mName, listener.mName, ns2us(baseTime));
292 
293         nsecs_t lastEventTime = listener.mLastEventTime + mWakeupLatency;
294         ALOGV("[%s] lastEventTime: %" PRId64, mName, ns2us(lastEventTime));
295         if (baseTime < lastEventTime) {
296             baseTime = lastEventTime;
297             ALOGV("[%s] Clamping baseTime to lastEventTime -> %" PRId64, mName,
298                     ns2us(baseTime));
299         }
300 
301         baseTime -= mReferenceTime;
302         ALOGV("[%s] Relative baseTime = %" PRId64, mName, ns2us(baseTime));
303         nsecs_t phase = mPhase + listener.mPhase;
304         ALOGV("[%s] Phase = %" PRId64, mName, ns2us(phase));
305         baseTime -= phase;
306         ALOGV("[%s] baseTime - phase = %" PRId64, mName, ns2us(baseTime));
307 
308         // If our previous time is before the reference (because the reference
309         // has since been updated), the division by mPeriod will truncate
310         // towards zero instead of computing the floor. Since in all cases
311         // before the reference we want the next time to be effectively now, we
312         // set baseTime to -mPeriod so that numPeriods will be -1.
313         // When we add 1 and the phase, we will be at the correct event time for
314         // this period.
315         if (baseTime < 0) {
316             ALOGV("[%s] Correcting negative baseTime", mName);
317             baseTime = -mPeriod;
318         }
319 
320         nsecs_t numPeriods = baseTime / mPeriod;
321         ALOGV("[%s] numPeriods = %" PRId64, mName, numPeriods);
322         nsecs_t t = (numPeriods + 1) * mPeriod + phase;
323         ALOGV("[%s] t = %" PRId64, mName, ns2us(t));
324         t += mReferenceTime;
325         ALOGV("[%s] Absolute t = %" PRId64, mName, ns2us(t));
326 
327         // Check that it's been slightly more than half a period since the last
328         // event so that we don't accidentally fall into double-rate vsyncs
329         if (t - listener.mLastEventTime < (3 * mPeriod / 5)) {
330             t += mPeriod;
331             ALOGV("[%s] Modifying t -> %" PRId64, mName, ns2us(t));
332         }
333 
334         t -= mWakeupLatency;
335         ALOGV("[%s] Corrected for wakeup latency -> %" PRId64, mName, ns2us(t));
336 
337         return t;
338     }
339 
fireCallbackInvocations(const Vector<CallbackInvocation> & callbacks)340     void fireCallbackInvocations(const Vector<CallbackInvocation>& callbacks) {
341         if (kTraceDetailedInfo) ATRACE_CALL();
342         for (size_t i = 0; i < callbacks.size(); i++) {
343             callbacks[i].mCallback->onDispSyncEvent(callbacks[i].mEventTime);
344         }
345     }
346 
347     const char* const mName;
348 
349     bool mStop;
350 
351     nsecs_t mPeriod;
352     nsecs_t mPhase;
353     nsecs_t mReferenceTime;
354     nsecs_t mWakeupLatency;
355 
356     int64_t mFrameNumber;
357 
358     Vector<EventListener> mEventListeners;
359 
360     Mutex mMutex;
361     Condition mCond;
362 };
363 
364 #undef LOG_TAG
365 #define LOG_TAG "DispSync"
366 
367 class ZeroPhaseTracer : public DispSync::Callback {
368 public:
ZeroPhaseTracer()369     ZeroPhaseTracer() : mParity(false) {}
370 
onDispSyncEvent(nsecs_t)371     virtual void onDispSyncEvent(nsecs_t /*when*/) {
372         mParity = !mParity;
373         ATRACE_INT("ZERO_PHASE_VSYNC", mParity ? 1 : 0);
374     }
375 
376 private:
377     bool mParity;
378 };
379 
DispSync(const char * name)380 DispSync::DispSync(const char* name) :
381         mName(name),
382         mRefreshSkipCount(0),
383         mThread(new DispSyncThread(name)) {
384 
385     mThread->run("DispSync", PRIORITY_URGENT_DISPLAY + PRIORITY_MORE_FAVORABLE);
386     // set DispSync to SCHED_FIFO to minimize jitter
387     struct sched_param param = {0};
388     param.sched_priority = 2;
389     if (sched_setscheduler(mThread->getTid(), SCHED_FIFO, &param) != 0) {
390         ALOGE("Couldn't set SCHED_FIFO for DispSyncThread");
391     }
392 
393 
394     reset();
395     beginResync();
396 
397     if (kTraceDetailedInfo) {
398         // If we're not getting present fences then the ZeroPhaseTracer
399         // would prevent HW vsync event from ever being turned off.
400         // Even if we're just ignoring the fences, the zero-phase tracing is
401         // not needed because any time there is an event registered we will
402         // turn on the HW vsync events.
403         if (!kIgnorePresentFences && kEnableZeroPhaseTracer) {
404             addEventListener("ZeroPhaseTracer", 0, new ZeroPhaseTracer());
405         }
406     }
407 }
408 
~DispSync()409 DispSync::~DispSync() {}
410 
reset()411 void DispSync::reset() {
412     Mutex::Autolock lock(mMutex);
413 
414     mPhase = 0;
415     mReferenceTime = 0;
416     mModelUpdated = false;
417     mNumResyncSamples = 0;
418     mFirstResyncSample = 0;
419     mNumResyncSamplesSincePresent = 0;
420     resetErrorLocked();
421 }
422 
addPresentFence(const sp<Fence> & fence)423 bool DispSync::addPresentFence(const sp<Fence>& fence) {
424     Mutex::Autolock lock(mMutex);
425 
426     mPresentFences[mPresentSampleOffset] = fence;
427     mPresentTimes[mPresentSampleOffset] = 0;
428     mPresentSampleOffset = (mPresentSampleOffset + 1) % NUM_PRESENT_SAMPLES;
429     mNumResyncSamplesSincePresent = 0;
430 
431     for (size_t i = 0; i < NUM_PRESENT_SAMPLES; i++) {
432         const sp<Fence>& f(mPresentFences[i]);
433         if (f != NULL) {
434             nsecs_t t = f->getSignalTime();
435             if (t < INT64_MAX) {
436                 mPresentFences[i].clear();
437                 mPresentTimes[i] = t + kPresentTimeOffset;
438             }
439         }
440     }
441 
442     updateErrorLocked();
443 
444     return !mModelUpdated || mError > kErrorThreshold;
445 }
446 
beginResync()447 void DispSync::beginResync() {
448     Mutex::Autolock lock(mMutex);
449     ALOGV("[%s] beginResync", mName);
450     mModelUpdated = false;
451     mNumResyncSamples = 0;
452 }
453 
addResyncSample(nsecs_t timestamp)454 bool DispSync::addResyncSample(nsecs_t timestamp) {
455     Mutex::Autolock lock(mMutex);
456 
457     ALOGV("[%s] addResyncSample(%" PRId64 ")", mName, ns2us(timestamp));
458 
459     size_t idx = (mFirstResyncSample + mNumResyncSamples) % MAX_RESYNC_SAMPLES;
460     mResyncSamples[idx] = timestamp;
461     if (mNumResyncSamples == 0) {
462         mPhase = 0;
463         mReferenceTime = timestamp;
464         ALOGV("[%s] First resync sample: mPeriod = %" PRId64 ", mPhase = 0, "
465                 "mReferenceTime = %" PRId64, mName, ns2us(mPeriod),
466                 ns2us(mReferenceTime));
467         mThread->updateModel(mPeriod, mPhase, mReferenceTime);
468     }
469 
470     if (mNumResyncSamples < MAX_RESYNC_SAMPLES) {
471         mNumResyncSamples++;
472     } else {
473         mFirstResyncSample = (mFirstResyncSample + 1) % MAX_RESYNC_SAMPLES;
474     }
475 
476     updateModelLocked();
477 
478     if (mNumResyncSamplesSincePresent++ > MAX_RESYNC_SAMPLES_WITHOUT_PRESENT) {
479         resetErrorLocked();
480     }
481 
482     if (kIgnorePresentFences) {
483         // If we don't have the sync framework we will never have
484         // addPresentFence called.  This means we have no way to know whether
485         // or not we're synchronized with the HW vsyncs, so we just request
486         // that the HW vsync events be turned on whenever we need to generate
487         // SW vsync events.
488         return mThread->hasAnyEventListeners();
489     }
490 
491     // Check against kErrorThreshold / 2 to add some hysteresis before having to
492     // resync again
493     bool modelLocked = mModelUpdated && mError < (kErrorThreshold / 2);
494     ALOGV("[%s] addResyncSample returning %s", mName,
495             modelLocked ? "locked" : "unlocked");
496     return !modelLocked;
497 }
498 
endResync()499 void DispSync::endResync() {
500 }
501 
addEventListener(const char * name,nsecs_t phase,const sp<Callback> & callback)502 status_t DispSync::addEventListener(const char* name, nsecs_t phase,
503         const sp<Callback>& callback) {
504     Mutex::Autolock lock(mMutex);
505     return mThread->addEventListener(name, phase, callback);
506 }
507 
setRefreshSkipCount(int count)508 void DispSync::setRefreshSkipCount(int count) {
509     Mutex::Autolock lock(mMutex);
510     ALOGD("setRefreshSkipCount(%d)", count);
511     mRefreshSkipCount = count;
512     updateModelLocked();
513 }
514 
removeEventListener(const sp<Callback> & callback)515 status_t DispSync::removeEventListener(const sp<Callback>& callback) {
516     Mutex::Autolock lock(mMutex);
517     return mThread->removeEventListener(callback);
518 }
519 
setPeriod(nsecs_t period)520 void DispSync::setPeriod(nsecs_t period) {
521     Mutex::Autolock lock(mMutex);
522     mPeriod = period;
523     mPhase = 0;
524     mReferenceTime = 0;
525     mThread->updateModel(mPeriod, mPhase, mReferenceTime);
526 }
527 
getPeriod()528 nsecs_t DispSync::getPeriod() {
529     // lock mutex as mPeriod changes multiple times in updateModelLocked
530     Mutex::Autolock lock(mMutex);
531     return mPeriod;
532 }
533 
updateModelLocked()534 void DispSync::updateModelLocked() {
535     ALOGV("[%s] updateModelLocked %zu", mName, mNumResyncSamples);
536     if (mNumResyncSamples >= MIN_RESYNC_SAMPLES_FOR_UPDATE) {
537         ALOGV("[%s] Computing...", mName);
538         nsecs_t durationSum = 0;
539         nsecs_t minDuration = INT64_MAX;
540         nsecs_t maxDuration = 0;
541         for (size_t i = 1; i < mNumResyncSamples; i++) {
542             size_t idx = (mFirstResyncSample + i) % MAX_RESYNC_SAMPLES;
543             size_t prev = (idx + MAX_RESYNC_SAMPLES - 1) % MAX_RESYNC_SAMPLES;
544             nsecs_t duration = mResyncSamples[idx] - mResyncSamples[prev];
545             durationSum += duration;
546             minDuration = min(minDuration, duration);
547             maxDuration = max(maxDuration, duration);
548         }
549 
550         // Exclude the min and max from the average
551         durationSum -= minDuration + maxDuration;
552         mPeriod = durationSum / (mNumResyncSamples - 3);
553 
554         ALOGV("[%s] mPeriod = %" PRId64, mName, ns2us(mPeriod));
555 
556         double sampleAvgX = 0;
557         double sampleAvgY = 0;
558         double scale = 2.0 * M_PI / double(mPeriod);
559         // Intentionally skip the first sample
560         for (size_t i = 1; i < mNumResyncSamples; i++) {
561             size_t idx = (mFirstResyncSample + i) % MAX_RESYNC_SAMPLES;
562             nsecs_t sample = mResyncSamples[idx] - mReferenceTime;
563             double samplePhase = double(sample % mPeriod) * scale;
564             sampleAvgX += cos(samplePhase);
565             sampleAvgY += sin(samplePhase);
566         }
567 
568         sampleAvgX /= double(mNumResyncSamples - 1);
569         sampleAvgY /= double(mNumResyncSamples - 1);
570 
571         mPhase = nsecs_t(atan2(sampleAvgY, sampleAvgX) / scale);
572 
573         ALOGV("[%s] mPhase = %" PRId64, mName, ns2us(mPhase));
574 
575         if (mPhase < -(mPeriod / 2)) {
576             mPhase += mPeriod;
577             ALOGV("[%s] Adjusting mPhase -> %" PRId64, mName, ns2us(mPhase));
578         }
579 
580         if (kTraceDetailedInfo) {
581             ATRACE_INT64("DispSync:Period", mPeriod);
582             ATRACE_INT64("DispSync:Phase", mPhase + mPeriod / 2);
583         }
584 
585         // Artificially inflate the period if requested.
586         mPeriod += mPeriod * mRefreshSkipCount;
587 
588         mThread->updateModel(mPeriod, mPhase, mReferenceTime);
589         mModelUpdated = true;
590     }
591 }
592 
updateErrorLocked()593 void DispSync::updateErrorLocked() {
594     if (!mModelUpdated) {
595         return;
596     }
597 
598     // Need to compare present fences against the un-adjusted refresh period,
599     // since they might arrive between two events.
600     nsecs_t period = mPeriod / (1 + mRefreshSkipCount);
601 
602     int numErrSamples = 0;
603     nsecs_t sqErrSum = 0;
604 
605     for (size_t i = 0; i < NUM_PRESENT_SAMPLES; i++) {
606         nsecs_t sample = mPresentTimes[i] - mReferenceTime;
607         if (sample > mPhase) {
608             nsecs_t sampleErr = (sample - mPhase) % period;
609             if (sampleErr > period / 2) {
610                 sampleErr -= period;
611             }
612             sqErrSum += sampleErr * sampleErr;
613             numErrSamples++;
614         }
615     }
616 
617     if (numErrSamples > 0) {
618         mError = sqErrSum / numErrSamples;
619     } else {
620         mError = 0;
621     }
622 
623     if (kTraceDetailedInfo) {
624         ATRACE_INT64("DispSync:Error", mError);
625     }
626 }
627 
resetErrorLocked()628 void DispSync::resetErrorLocked() {
629     mPresentSampleOffset = 0;
630     mError = 0;
631     for (size_t i = 0; i < NUM_PRESENT_SAMPLES; i++) {
632         mPresentFences[i].clear();
633         mPresentTimes[i] = 0;
634     }
635 }
636 
computeNextRefresh(int periodOffset) const637 nsecs_t DispSync::computeNextRefresh(int periodOffset) const {
638     Mutex::Autolock lock(mMutex);
639     nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
640     nsecs_t phase = mReferenceTime + mPhase;
641     return (((now - phase) / mPeriod) + periodOffset + 1) * mPeriod + phase;
642 }
643 
dump(String8 & result) const644 void DispSync::dump(String8& result) const {
645     Mutex::Autolock lock(mMutex);
646     result.appendFormat("present fences are %s\n",
647             kIgnorePresentFences ? "ignored" : "used");
648     result.appendFormat("mPeriod: %" PRId64 " ns (%.3f fps; skipCount=%d)\n",
649             mPeriod, 1000000000.0 / mPeriod, mRefreshSkipCount);
650     result.appendFormat("mPhase: %" PRId64 " ns\n", mPhase);
651     result.appendFormat("mError: %" PRId64 " ns (sqrt=%.1f)\n",
652             mError, sqrt(mError));
653     result.appendFormat("mNumResyncSamplesSincePresent: %d (limit %d)\n",
654             mNumResyncSamplesSincePresent, MAX_RESYNC_SAMPLES_WITHOUT_PRESENT);
655     result.appendFormat("mNumResyncSamples: %zd (max %d)\n",
656             mNumResyncSamples, MAX_RESYNC_SAMPLES);
657 
658     result.appendFormat("mResyncSamples:\n");
659     nsecs_t previous = -1;
660     for (size_t i = 0; i < mNumResyncSamples; i++) {
661         size_t idx = (mFirstResyncSample + i) % MAX_RESYNC_SAMPLES;
662         nsecs_t sampleTime = mResyncSamples[idx];
663         if (i == 0) {
664             result.appendFormat("  %" PRId64 "\n", sampleTime);
665         } else {
666             result.appendFormat("  %" PRId64 " (+%" PRId64 ")\n",
667                     sampleTime, sampleTime - previous);
668         }
669         previous = sampleTime;
670     }
671 
672     result.appendFormat("mPresentFences / mPresentTimes [%d]:\n",
673             NUM_PRESENT_SAMPLES);
674     nsecs_t now = systemTime(SYSTEM_TIME_MONOTONIC);
675     previous = 0;
676     for (size_t i = 0; i < NUM_PRESENT_SAMPLES; i++) {
677         size_t idx = (i + mPresentSampleOffset) % NUM_PRESENT_SAMPLES;
678         bool signaled = mPresentFences[idx] == NULL;
679         nsecs_t presentTime = mPresentTimes[idx];
680         if (!signaled) {
681             result.appendFormat("  [unsignaled fence]\n");
682         } else if (presentTime == 0) {
683             result.appendFormat("  0\n");
684         } else if (previous == 0) {
685             result.appendFormat("  %" PRId64 "  (%.3f ms ago)\n", presentTime,
686                     (now - presentTime) / 1000000.0);
687         } else {
688             result.appendFormat("  %" PRId64 " (+%" PRId64 " / %.3f)  (%.3f ms ago)\n",
689                     presentTime, presentTime - previous,
690                     (presentTime - previous) / (double) mPeriod,
691                     (now - presentTime) / 1000000.0);
692         }
693         previous = presentTime;
694     }
695 
696     result.appendFormat("current monotonic time: %" PRId64 "\n", now);
697 }
698 
699 } // namespace android
700