1 /*
2 * Copyright 2014,2016 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 #include <inttypes.h>
18
19 #define LOG_TAG "Camera3StreamSplitter"
20 #define ATRACE_TAG ATRACE_TAG_CAMERA
21 //#define LOG_NDEBUG 0
22
23 #include <gui/BufferItem.h>
24 #include <gui/IGraphicBufferConsumer.h>
25 #include <gui/IGraphicBufferProducer.h>
26 #include <gui/BufferQueue.h>
27 #include <gui/Surface.h>
28
29 #include <ui/GraphicBuffer.h>
30
31 #include <binder/ProcessState.h>
32
33 #include <utils/Trace.h>
34
35 #include <cutils/atomic.h>
36
37 #include "Camera3StreamSplitter.h"
38
39 namespace android {
40
connect(const std::vector<sp<Surface>> & surfaces,uint64_t consumerUsage,size_t halMaxBuffers,sp<Surface> * consumer)41 status_t Camera3StreamSplitter::connect(const std::vector<sp<Surface> >& surfaces,
42 uint64_t consumerUsage, size_t halMaxBuffers, sp<Surface>* consumer) {
43 ATRACE_CALL();
44 if (consumer == nullptr) {
45 SP_LOGE("%s: consumer pointer is NULL", __FUNCTION__);
46 return BAD_VALUE;
47 }
48
49 Mutex::Autolock lock(mMutex);
50 status_t res = OK;
51
52 if (mOutputs.size() > 0 || mConsumer != nullptr) {
53 SP_LOGE("%s: already connected", __FUNCTION__);
54 return BAD_VALUE;
55 }
56 if (mBuffers.size() > 0) {
57 SP_LOGE("%s: still has %zu pending buffers", __FUNCTION__, mBuffers.size());
58 return BAD_VALUE;
59 }
60
61 mMaxHalBuffers = halMaxBuffers;
62 mConsumerName = getUniqueConsumerName();
63 // Add output surfaces. This has to be before creating internal buffer queue
64 // in order to get max consumer side buffers.
65 for (size_t i = 0; i < surfaces.size(); i++) {
66 if (surfaces[i] == nullptr) {
67 SP_LOGE("%s: Fatal: surface is NULL", __FUNCTION__);
68 return BAD_VALUE;
69 }
70 res = addOutputLocked(surfaces[i]);
71 if (res != OK) {
72 SP_LOGE("%s: Failed to add output surface: %s(%d)",
73 __FUNCTION__, strerror(-res), res);
74 return res;
75 }
76 }
77
78 // Create BufferQueue for input
79 BufferQueue::createBufferQueue(&mProducer, &mConsumer);
80
81 // Allocate 1 extra buffer to handle the case where all buffers are detached
82 // from input, and attached to the outputs. In this case, the input queue's
83 // dequeueBuffer can still allocate 1 extra buffer before being blocked by
84 // the output's attachBuffer().
85 mBufferItemConsumer = new BufferItemConsumer(mConsumer, consumerUsage,
86 mMaxConsumerBuffers+1);
87 if (mBufferItemConsumer == nullptr) {
88 return NO_MEMORY;
89 }
90 mConsumer->setConsumerName(mConsumerName);
91
92 *consumer = new Surface(mProducer);
93 if (*consumer == nullptr) {
94 return NO_MEMORY;
95 }
96
97 res = mConsumer->consumerConnect(this, /* controlledByApp */ false);
98
99 SP_LOGV("%s: connected", __FUNCTION__);
100 return res;
101 }
102
getOnFrameAvailableResult()103 status_t Camera3StreamSplitter::getOnFrameAvailableResult() {
104 ATRACE_CALL();
105 return mOnFrameAvailableRes.load();
106 }
107
disconnect()108 void Camera3StreamSplitter::disconnect() {
109 ATRACE_CALL();
110 Mutex::Autolock lock(mMutex);
111
112 for (auto& notifier : mNotifiers) {
113 sp<IGraphicBufferProducer> producer = notifier.first;
114 sp<OutputListener> listener = notifier.second;
115 IInterface::asBinder(producer)->unlinkToDeath(listener);
116 }
117 mNotifiers.clear();
118
119 for (auto& output : mOutputs) {
120 output->disconnect(NATIVE_WINDOW_API_CAMERA);
121 }
122 mOutputs.clear();
123 mOutputSlots.clear();
124
125 mConsumer->consumerDisconnect();
126
127 if (mBuffers.size() > 0) {
128 SP_LOGW("%zu buffers still being tracked", mBuffers.size());
129 mBuffers.clear();
130 }
131
132 mMaxHalBuffers = 0;
133 mMaxConsumerBuffers = 0;
134 SP_LOGV("%s: Disconnected", __FUNCTION__);
135 }
136
137
~Camera3StreamSplitter()138 Camera3StreamSplitter::~Camera3StreamSplitter() {
139 disconnect();
140 }
141
addOutput(const sp<Surface> & outputQueue)142 status_t Camera3StreamSplitter::addOutput(const sp<Surface>& outputQueue) {
143 ATRACE_CALL();
144 Mutex::Autolock lock(mMutex);
145 status_t res = addOutputLocked(outputQueue);
146
147 if (res != OK) {
148 SP_LOGE("%s: addOutputLocked failed %d", __FUNCTION__, res);
149 return res;
150 }
151
152 res = mConsumer->setMaxAcquiredBufferCount(mMaxConsumerBuffers+1);
153
154 return res;
155 }
156
addOutputLocked(const sp<Surface> & outputQueue)157 status_t Camera3StreamSplitter::addOutputLocked(const sp<Surface>& outputQueue) {
158 ATRACE_CALL();
159 if (outputQueue == nullptr) {
160 SP_LOGE("addOutput: outputQueue must not be NULL");
161 return BAD_VALUE;
162 }
163
164 sp<IGraphicBufferProducer> gbp = outputQueue->getIGraphicBufferProducer();
165 // Connect to the buffer producer
166 sp<OutputListener> listener(new OutputListener(this, gbp));
167 IInterface::asBinder(gbp)->linkToDeath(listener);
168 status_t res = outputQueue->connect(NATIVE_WINDOW_API_CAMERA, listener);
169 if (res != NO_ERROR) {
170 SP_LOGE("addOutput: failed to connect (%d)", res);
171 return res;
172 }
173
174 // Query consumer side buffer count, and update overall buffer count
175 int maxConsumerBuffers = 0;
176 res = static_cast<ANativeWindow*>(outputQueue.get())->query(
177 outputQueue.get(),
178 NATIVE_WINDOW_MIN_UNDEQUEUED_BUFFERS, &maxConsumerBuffers);
179 if (res != OK) {
180 SP_LOGE("%s: Unable to query consumer undequeued buffer count"
181 " for surface", __FUNCTION__);
182 return res;
183 }
184
185 SP_LOGV("%s: Consumer wants %d buffers, Producer wants %zu", __FUNCTION__,
186 maxConsumerBuffers, mMaxHalBuffers);
187 size_t totalBufferCount = maxConsumerBuffers + mMaxHalBuffers;
188 res = native_window_set_buffer_count(outputQueue.get(),
189 totalBufferCount);
190 if (res != OK) {
191 SP_LOGE("%s: Unable to set buffer count for surface %p",
192 __FUNCTION__, outputQueue.get());
193 return res;
194 }
195
196 // Set dequeueBuffer/attachBuffer timeout if the consumer is not hw composer or hw texture.
197 // We need skip these cases as timeout will disable the non-blocking (async) mode.
198 uint64_t usage = 0;
199 res = native_window_get_consumer_usage(static_cast<ANativeWindow*>(outputQueue.get()), &usage);
200 if (!(usage & (GRALLOC_USAGE_HW_COMPOSER | GRALLOC_USAGE_HW_TEXTURE))) {
201 outputQueue->setDequeueTimeout(kDequeueBufferTimeout);
202 }
203
204 res = gbp->allowAllocation(false);
205 if (res != OK) {
206 SP_LOGE("%s: Failed to turn off allocation for outputQueue", __FUNCTION__);
207 return res;
208 }
209
210 // Add new entry into mOutputs
211 mOutputs.push_back(gbp);
212 mNotifiers[gbp] = listener;
213 mOutputSlots[gbp] = std::make_unique<OutputSlots>(totalBufferCount);
214
215 mMaxConsumerBuffers += maxConsumerBuffers;
216 return NO_ERROR;
217 }
218
outputBufferLocked(const sp<IGraphicBufferProducer> & output,const BufferItem & bufferItem)219 status_t Camera3StreamSplitter::outputBufferLocked(const sp<IGraphicBufferProducer>& output,
220 const BufferItem& bufferItem) {
221 ATRACE_CALL();
222 status_t res;
223 IGraphicBufferProducer::QueueBufferInput queueInput(
224 bufferItem.mTimestamp, bufferItem.mIsAutoTimestamp,
225 bufferItem.mDataSpace, bufferItem.mCrop,
226 static_cast<int32_t>(bufferItem.mScalingMode),
227 bufferItem.mTransform, bufferItem.mFence);
228
229 IGraphicBufferProducer::QueueBufferOutput queueOutput;
230
231 uint64_t bufferId = bufferItem.mGraphicBuffer->getId();
232 const BufferTracker& tracker = *(mBuffers[bufferId]);
233 int slot = getSlotForOutputLocked(output, tracker.getBuffer());
234
235 // In case the output BufferQueue has its own lock, if we hold splitter lock while calling
236 // queueBuffer (which will try to acquire the output lock), the output could be holding its
237 // own lock calling releaseBuffer (which will try to acquire the splitter lock), running into
238 // circular lock situation.
239 mMutex.unlock();
240 res = output->queueBuffer(slot, queueInput, &queueOutput);
241 mMutex.lock();
242
243 SP_LOGV("%s: Queuing buffer to buffer queue %p slot %d returns %d",
244 __FUNCTION__, output.get(), slot, res);
245 if (res != OK) {
246 if (res != NO_INIT && res != DEAD_OBJECT) {
247 SP_LOGE("Queuing buffer to output failed (%d)", res);
248 }
249 // If we just discovered that this output has been abandoned, note
250 // that, increment the release count so that we still release this
251 // buffer eventually, and move on to the next output
252 onAbandonedLocked();
253 decrementBufRefCountLocked(bufferItem.mGraphicBuffer->getId(), output);
254 return res;
255 }
256
257 // If the queued buffer replaces a pending buffer in the async
258 // queue, no onBufferReleased is called by the buffer queue.
259 // Proactively trigger the callback to avoid buffer loss.
260 if (queueOutput.bufferReplaced) {
261 onBufferReleasedByOutputLocked(output);
262 }
263
264 return res;
265 }
266
getUniqueConsumerName()267 String8 Camera3StreamSplitter::getUniqueConsumerName() {
268 static volatile int32_t counter = 0;
269 return String8::format("Camera3StreamSplitter-%d", android_atomic_inc(&counter));
270 }
271
notifyBufferReleased(const sp<GraphicBuffer> & buffer)272 status_t Camera3StreamSplitter::notifyBufferReleased(const sp<GraphicBuffer>& buffer) {
273 ATRACE_CALL();
274 status_t res = OK;
275
276 Mutex::Autolock lock(mMutex);
277
278 uint64_t bufferId = buffer->getId();
279 std::unique_ptr<BufferTracker> tracker_ptr = std::move(mBuffers[bufferId]);
280 mBuffers.erase(bufferId);
281
282 for (const auto surface : tracker_ptr->requestedSurfaces()) {
283 sp<IGraphicBufferProducer>& gbp = mOutputs[surface];
284 OutputSlots& outputSlots = *(mOutputSlots[gbp]);
285 int slot = getSlotForOutputLocked(gbp, buffer);
286 if (slot != BufferItem::INVALID_BUFFER_SLOT) {
287 gbp->detachBuffer(slot);
288 outputSlots[slot].clear();
289 }
290 }
291
292 return res;
293 }
294
attachBufferToOutputs(ANativeWindowBuffer * anb,const std::vector<size_t> & surface_ids)295 status_t Camera3StreamSplitter::attachBufferToOutputs(ANativeWindowBuffer* anb,
296 const std::vector<size_t>& surface_ids) {
297 ATRACE_CALL();
298 status_t res = OK;
299
300 Mutex::Autolock lock(mMutex);
301
302 sp<GraphicBuffer> gb(static_cast<GraphicBuffer*>(anb));
303 uint64_t bufferId = gb->getId();
304
305 // Initialize buffer tracker for this input buffer
306 auto tracker = std::make_unique<BufferTracker>(gb, surface_ids);
307
308 for (auto& surface_id : surface_ids) {
309 sp<IGraphicBufferProducer>& gbp = mOutputs[surface_id];
310 int slot = BufferItem::INVALID_BUFFER_SLOT;
311 //Temporarly Unlock the mutex when trying to attachBuffer to the output
312 //queue, because attachBuffer could block in case of a slow consumer. If
313 //we block while holding the lock, onFrameAvailable and onBufferReleased
314 //will block as well because they need to acquire the same lock.
315 mMutex.unlock();
316 res = gbp->attachBuffer(&slot, gb);
317 mMutex.lock();
318 if (res != OK) {
319 SP_LOGE("%s: Cannot acquireBuffer from GraphicBufferProducer %p: %s (%d)",
320 __FUNCTION__, gbp.get(), strerror(-res), res);
321 return res;
322 }
323 auto& outputSlots = *mOutputSlots[gbp];
324 if (outputSlots[slot] != nullptr) {
325 // If the buffer is attached to a slot which already contains a buffer,
326 // the previous buffer will be removed from the output queue. Decrement
327 // the reference count accordingly.
328 decrementBufRefCountLocked(outputSlots[slot]->getId(), gbp);
329 }
330 SP_LOGV("%s: Attached buffer %p to slot %d on output %p.",__FUNCTION__, gb.get(),
331 slot, gbp.get());
332 outputSlots[slot] = gb;
333 }
334
335 mBuffers[bufferId] = std::move(tracker);
336
337 return res;
338 }
339
onFrameAvailable(const BufferItem &)340 void Camera3StreamSplitter::onFrameAvailable(const BufferItem& /*item*/) {
341 ATRACE_CALL();
342 Mutex::Autolock lock(mMutex);
343
344 // Acquire and detach the buffer from the input
345 BufferItem bufferItem;
346 status_t res = mConsumer->acquireBuffer(&bufferItem, /* presentWhen */ 0);
347 if (res != NO_ERROR) {
348 SP_LOGE("%s: Acquiring buffer from input failed (%d)", __FUNCTION__, res);
349 mOnFrameAvailableRes.store(res);
350 return;
351 }
352 if (mBuffers.find(bufferItem.mGraphicBuffer->getId()) == mBuffers.end()) {
353 SP_LOGE("%s: Acquired buffer doesn't exist in attached buffer map",
354 __FUNCTION__);
355 mOnFrameAvailableRes.store(INVALID_OPERATION);
356 return;
357 }
358
359 SP_LOGV("acquired buffer %" PRId64 " from input at slot %d",
360 bufferItem.mGraphicBuffer->getId(), bufferItem.mSlot);
361
362 res = mConsumer->detachBuffer(bufferItem.mSlot);
363 if (res != NO_ERROR) {
364 SP_LOGE("%s: detaching buffer from input failed (%d)", __FUNCTION__, res);
365 mOnFrameAvailableRes.store(res);
366 return;
367 }
368
369 // Attach and queue the buffer to each of the outputs
370 BufferTracker& tracker = *(mBuffers[bufferItem.mGraphicBuffer->getId()]);
371
372 SP_LOGV("%s: BufferTracker for buffer %" PRId64 ", number of requests %zu",
373 __FUNCTION__, bufferItem.mGraphicBuffer->getId(), tracker.requestedSurfaces().size());
374 for (const auto id : tracker.requestedSurfaces()) {
375
376 LOG_ALWAYS_FATAL_IF(id >= mOutputs.size(),
377 "requested surface id exceeding max registered ids");
378
379 res = outputBufferLocked(mOutputs[id], bufferItem);
380 if (res != OK) {
381 SP_LOGE("%s: outputBufferLocked failed %d", __FUNCTION__, res);
382 mOnFrameAvailableRes.store(res);
383 // If we fail to send buffer to certain output, keep sending to
384 // other outputs.
385 continue;
386 }
387 }
388
389 mOnFrameAvailableRes.store(res);
390 }
391
decrementBufRefCountLocked(uint64_t id,const sp<IGraphicBufferProducer> & from)392 void Camera3StreamSplitter::decrementBufRefCountLocked(uint64_t id,
393 const sp<IGraphicBufferProducer>& from) {
394 ATRACE_CALL();
395 size_t referenceCount = mBuffers[id]->decrementReferenceCountLocked();
396
397 removeSlotForOutputLocked(from, mBuffers[id]->getBuffer());
398 if (referenceCount > 0) {
399 return;
400 }
401
402 // We no longer need to track the buffer now that it is being returned to the
403 // input. Note that this should happen before we unlock the mutex and call
404 // releaseBuffer, to avoid the case where the same bufferId is acquired in
405 // attachBufferToOutputs resulting in a new BufferTracker with same bufferId
406 // overwrites the current one.
407 std::unique_ptr<BufferTracker> tracker_ptr = std::move(mBuffers[id]);
408 mBuffers.erase(id);
409
410 // Attach and release the buffer back to the input
411 int consumerSlot = BufferItem::INVALID_BUFFER_SLOT;
412 status_t res = mConsumer->attachBuffer(&consumerSlot, tracker_ptr->getBuffer());
413 if (res != NO_ERROR) {
414 SP_LOGE("%s: attaching buffer to input failed (%d)", __FUNCTION__, res);
415 return;
416 }
417
418 // Temporarily unlock mutex to avoid circular lock:
419 // 1. This function holds splitter lock, calls releaseBuffer which triggers
420 // onBufferReleased in Camera3OutputStream. onBufferReleased waits on the
421 // OutputStream lock
422 // 2. Camera3SharedOutputStream::getBufferLocked calls
423 // attachBufferToOutputs, which holds the stream lock, and waits for the
424 // splitter lock.
425 sp<IGraphicBufferConsumer> consumer(mConsumer);
426 mMutex.unlock();
427 if (consumer != nullptr) {
428 res = consumer->releaseBuffer(consumerSlot, /* frameNumber */ 0,
429 EGL_NO_DISPLAY, EGL_NO_SYNC_KHR, tracker_ptr->getMergedFence());
430 } else {
431 SP_LOGE("%s: consumer has become null!", __FUNCTION__);
432 }
433 mMutex.lock();
434 // If the producer of this queue is disconnected, -22 error will occur
435 if (res != NO_ERROR) {
436 SP_LOGE("%s: releaseBuffer returns %d", __FUNCTION__, res);
437 }
438 }
439
onBufferReleasedByOutput(const sp<IGraphicBufferProducer> & from)440 void Camera3StreamSplitter::onBufferReleasedByOutput(
441 const sp<IGraphicBufferProducer>& from) {
442 ATRACE_CALL();
443 Mutex::Autolock lock(mMutex);
444
445 onBufferReleasedByOutputLocked(from);
446 }
447
onBufferReleasedByOutputLocked(const sp<IGraphicBufferProducer> & from)448 void Camera3StreamSplitter::onBufferReleasedByOutputLocked(
449 const sp<IGraphicBufferProducer>& from) {
450 ATRACE_CALL();
451 sp<GraphicBuffer> buffer;
452 sp<Fence> fence;
453 status_t res = from->detachNextBuffer(&buffer, &fence);
454 if (res == NO_INIT) {
455 // If we just discovered that this output has been abandoned, note that,
456 // but we can't do anything else, since buffer is invalid
457 onAbandonedLocked();
458 return;
459 } else if (res == NO_MEMORY) {
460 SP_LOGV("%s: No free buffers", __FUNCTION__);
461 return;
462 } else if (res != OK) {
463 SP_LOGE("%s: detaching buffer from output failed (%d)", __FUNCTION__, res);
464 return;
465 }
466
467 BufferTracker& tracker = *(mBuffers[buffer->getId()]);
468 // Merge the release fence of the incoming buffer so that the fence we send
469 // back to the input includes all of the outputs' fences
470 if (fence != nullptr && fence->isValid()) {
471 tracker.mergeFence(fence);
472 }
473 SP_LOGV("detached buffer %" PRId64 " %p from output %p",
474 buffer->getId(), buffer.get(), from.get());
475
476 // Check to see if this is the last outstanding reference to this buffer
477 decrementBufRefCountLocked(buffer->getId(), from);
478 }
479
onAbandonedLocked()480 void Camera3StreamSplitter::onAbandonedLocked() {
481 // If this is called from binderDied callback, it means the app process
482 // holding the binder has died. CameraService will be notified of the binder
483 // death, and camera device will be closed, which in turn calls
484 // disconnect().
485 //
486 // If this is called from onBufferReleasedByOutput or onFrameAvailable, one
487 // consumer being abanoned shouldn't impact the other consumer. So we won't
488 // stop the buffer flow.
489 //
490 // In both cases, we don't need to do anything here.
491 SP_LOGV("One of my outputs has abandoned me");
492 }
493
getSlotForOutputLocked(const sp<IGraphicBufferProducer> & gbp,const sp<GraphicBuffer> & gb)494 int Camera3StreamSplitter::getSlotForOutputLocked(const sp<IGraphicBufferProducer>& gbp,
495 const sp<GraphicBuffer>& gb) {
496 auto& outputSlots = *mOutputSlots[gbp];
497
498 for (size_t i = 0; i < outputSlots.size(); i++) {
499 if (outputSlots[i] == gb) {
500 return (int)i;
501 }
502 }
503
504 SP_LOGE("%s: Cannot find slot for gb %p on output %p", __FUNCTION__, gb.get(),
505 gbp.get());
506 return BufferItem::INVALID_BUFFER_SLOT;
507 }
508
removeSlotForOutputLocked(const sp<IGraphicBufferProducer> & gbp,const sp<GraphicBuffer> & gb)509 status_t Camera3StreamSplitter::removeSlotForOutputLocked(const sp<IGraphicBufferProducer>& gbp,
510 const sp<GraphicBuffer>& gb) {
511 auto& outputSlots = *mOutputSlots[gbp];
512
513 for (size_t i = 0; i < outputSlots.size(); i++) {
514 if (outputSlots[i] == gb) {
515 outputSlots[i].clear();
516 return NO_ERROR;
517 }
518 }
519
520 SP_LOGE("%s: Cannot find slot for gb %p on output %p", __FUNCTION__, gb.get(),
521 gbp.get());
522 return BAD_VALUE;
523 }
524
OutputListener(wp<Camera3StreamSplitter> splitter,wp<IGraphicBufferProducer> output)525 Camera3StreamSplitter::OutputListener::OutputListener(
526 wp<Camera3StreamSplitter> splitter,
527 wp<IGraphicBufferProducer> output)
528 : mSplitter(splitter), mOutput(output) {}
529
onBufferReleased()530 void Camera3StreamSplitter::OutputListener::onBufferReleased() {
531 ATRACE_CALL();
532 sp<Camera3StreamSplitter> splitter = mSplitter.promote();
533 sp<IGraphicBufferProducer> output = mOutput.promote();
534 if (splitter != nullptr && output != nullptr) {
535 splitter->onBufferReleasedByOutput(output);
536 }
537 }
538
binderDied(const wp<IBinder> &)539 void Camera3StreamSplitter::OutputListener::binderDied(const wp<IBinder>& /* who */) {
540 sp<Camera3StreamSplitter> splitter = mSplitter.promote();
541 if (splitter != nullptr) {
542 Mutex::Autolock lock(splitter->mMutex);
543 splitter->onAbandonedLocked();
544 }
545 }
546
BufferTracker(const sp<GraphicBuffer> & buffer,const std::vector<size_t> & requestedSurfaces)547 Camera3StreamSplitter::BufferTracker::BufferTracker(
548 const sp<GraphicBuffer>& buffer, const std::vector<size_t>& requestedSurfaces)
549 : mBuffer(buffer), mMergedFence(Fence::NO_FENCE), mRequestedSurfaces(requestedSurfaces),
550 mReferenceCount(requestedSurfaces.size()) {}
551
mergeFence(const sp<Fence> & with)552 void Camera3StreamSplitter::BufferTracker::mergeFence(const sp<Fence>& with) {
553 mMergedFence = Fence::merge(String8("Camera3StreamSplitter"), mMergedFence, with);
554 }
555
decrementReferenceCountLocked()556 size_t Camera3StreamSplitter::BufferTracker::decrementReferenceCountLocked() {
557 if (mReferenceCount > 0)
558 --mReferenceCount;
559 return mReferenceCount;
560 }
561
562 } // namespace android
563