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| //frameworks/native/libs/gui/BufferQueueProducer.cpp
class BufferQueueProducer : public BnGraphicBufferProducer {
status_t BufferQueueProducer::dequeueBuffer(int* outSlot, sp<android::Fence>* outFence,
uint32_t width, uint32_t height, PixelFormat format,
uint64_t usage, uint64_t* outBufferAge,
FrameEventHistoryDelta* outTimestamps) {
ATRACE_CALL();
{ // Autolock scope
std::lock_guard<std::mutex> lock(mCore->mMutex);
mConsumerName = mCore->mConsumerName;
if (mCore->mIsAbandoned) {
BQ_LOGE("dequeueBuffer: BufferQueue has been abandoned");
return NO_INIT;
}
if (mCore->mConnectedApi == BufferQueueCore::NO_CONNECTED_API) {
BQ_LOGE("dequeueBuffer: BufferQueue has no connected producer");
return NO_INIT;
}
} // Autolock scope
BQ_LOGV("dequeueBuffer: w=%u h=%u format=%#x, usage=%#" PRIx64, width, height, format, usage);
if ((width && !height) || (!width && height)) {
BQ_LOGE("dequeueBuffer: invalid size: w=%u h=%u", width, height);
return BAD_VALUE;
}
status_t returnFlags = NO_ERROR;
EGLDisplay eglDisplay = EGL_NO_DISPLAY;
EGLSyncKHR eglFence = EGL_NO_SYNC_KHR;
bool attachedByConsumer = false;
{ // Autolock scope
std::unique_lock<std::mutex> lock(mCore->mMutex);
// If we don't have a free buffer, but we are currently allocating, we wait until allocation
// is finished such that we don't allocate in parallel.
if (mCore->mFreeBuffers.empty() && mCore->mIsAllocating) {
mDequeueWaitingForAllocation = true;
mCore->waitWhileAllocatingLocked(lock);
mDequeueWaitingForAllocation = false;
mDequeueWaitingForAllocationCondition.notify_all();
}
if (format == 0) {
format = mCore->mDefaultBufferFormat;
}
// Enable the usage bits the consumer requested
usage |= mCore->mConsumerUsageBits;
const bool useDefaultSize = !width && !height;
if (useDefaultSize) {
width = mCore->mDefaultWidth;
height = mCore->mDefaultHeight;
if (mCore->mAutoPrerotation &&
(mCore->mTransformHintInUse & NATIVE_WINDOW_TRANSFORM_ROT_90)) {
std::swap(width, height);
}
}
int found = BufferItem::INVALID_BUFFER_SLOT;
while (found == BufferItem::INVALID_BUFFER_SLOT) {
status_t status = waitForFreeSlotThenRelock(FreeSlotCaller::Dequeue, lock, &found);
if (status != NO_ERROR) {
return status;
}
// This should not happen
if (found == BufferQueueCore::INVALID_BUFFER_SLOT) {
BQ_LOGE("dequeueBuffer: no available buffer slots");
return -EBUSY;
}
const sp<GraphicBuffer>& buffer(mSlots[found].mGraphicBuffer);
// If we are not allowed to allocate new buffers,
// waitForFreeSlotThenRelock must have returned a slot containing a
// buffer. If this buffer would require reallocation to meet the
// requested attributes, we free it and attempt to get another one.
if (!mCore->mAllowAllocation) {
if (buffer->needsReallocation(width, height, format, BQ_LAYER_COUNT, usage)) { //检查是否已分配了GraphicBuffer
if (mCore->mSharedBufferSlot == found) {
BQ_LOGE("dequeueBuffer: cannot re-allocate a sharedbuffer");
return BAD_VALUE;
}
mCore->mFreeSlots.insert(found);
mCore->clearBufferSlotLocked(found);
found = BufferItem::INVALID_BUFFER_SLOT;
continue;
}
}
}
const sp<GraphicBuffer>& buffer(mSlots[found].mGraphicBuffer);
if (mCore->mSharedBufferSlot == found &&
buffer->needsReallocation(width, height, format, BQ_LAYER_COUNT, usage)) {
BQ_LOGE("dequeueBuffer: cannot re-allocate a shared"
"buffer");
return BAD_VALUE;
}
if (mCore->mSharedBufferSlot != found) {
mCore->mActiveBuffers.insert(found);
}
*outSlot = found;
ATRACE_BUFFER_INDEX(found);
attachedByConsumer = mSlots[found].mNeedsReallocation;
mSlots[found].mNeedsReallocation = false;
mSlots[found].mBufferState.dequeue();
if ((buffer == nullptr) ||
buffer->needsReallocation(width, height, format, BQ_LAYER_COUNT, usage))
{
mSlots[found].mAcquireCalled = false;
mSlots[found].mGraphicBuffer = nullptr;
mSlots[found].mRequestBufferCalled = false;
mSlots[found].mEglDisplay = EGL_NO_DISPLAY;
mSlots[found].mEglFence = EGL_NO_SYNC_KHR;
mSlots[found].mFence = Fence::NO_FENCE;
mCore->mBufferAge = 0;
mCore->mIsAllocating = true;
returnFlags |= BUFFER_NEEDS_REALLOCATION; //发现需要分配buffer,置个标记
} else {
// We add 1 because that will be the frame number when this buffer
// is queued
mCore->mBufferAge = mCore->mFrameCounter + 1 - mSlots[found].mFrameNumber;
}
BQ_LOGV("dequeueBuffer: setting buffer age to %" PRIu64,
mCore->mBufferAge);
if (CC_UNLIKELY(mSlots[found].mFence == nullptr)) {
BQ_LOGE("dequeueBuffer: about to return a NULL fence - "
"slot=%d w=%d h=%d format=%u",
found, buffer->width, buffer->height, buffer->format);
}
eglDisplay = mSlots[found].mEglDisplay;
eglFence = mSlots[found].mEglFence;
// Don't return a fence in shared buffer mode, except for the first
// frame.
*outFence = (mCore->mSharedBufferMode &&
mCore->mSharedBufferSlot == found) ?
Fence::NO_FENCE : mSlots[found].mFence;
mSlots[found].mEglFence = EGL_NO_SYNC_KHR;
mSlots[found].mFence = Fence::NO_FENCE;
// If shared buffer mode has just been enabled, cache the slot of the
// first buffer that is dequeued and mark it as the shared buffer.
if (mCore->mSharedBufferMode && mCore->mSharedBufferSlot ==
BufferQueueCore::INVALID_BUFFER_SLOT) {
mCore->mSharedBufferSlot = found;
mSlots[found].mBufferState.mShared = true;
}
if (!(returnFlags & BUFFER_NEEDS_REALLOCATION)) {
if (mCore->mConsumerListener != nullptr) {
mCore->mConsumerListener->onFrameDequeued(mSlots[*outSlot].mGraphicBuffer->getId());
}
}
} // Autolock scope
if (returnFlags & BUFFER_NEEDS_REALLOCATION) {
BQ_LOGV("dequeueBuffer: allocating a new buffer for slot %d", *outSlot);
//新创建一个新的GraphicBuffer给到对应的slot
//new GraphicBuffer 见新的说明[[Android13 GraphicBuffer 创建流程-CSDN博客]]
sp<GraphicBuffer> graphicBuffer = new GraphicBuffer(
width, height, format, BQ_LAYER_COUNT, usage,
{mConsumerName.string(), mConsumerName.size()});
status_t error = graphicBuffer->initCheck();
{ // Autolock scope
std::lock_guard<std::mutex> lock(mCore->mMutex);
if (error == NO_ERROR && !mCore->mIsAbandoned) {
graphicBuffer->setGenerationNumber(mCore->mGenerationNumber);
mSlots[*outSlot].mGraphicBuffer = graphicBuffer; //把GraphicBuffer给到对应的slot
if (mCore->mConsumerListener != nullptr) {
mCore->mConsumerListener->onFrameDequeued(
mSlots[*outSlot].mGraphicBuffer->getId());
}
}
mCore->mIsAllocating = false;
mCore->mIsAllocatingCondition.notify_all();
if (error != NO_ERROR) {
mCore->mFreeSlots.insert(*outSlot);
mCore->clearBufferSlotLocked(*outSlot);
BQ_LOGE("dequeueBuffer: createGraphicBuffer failed");
return error;
}
if (mCore->mIsAbandoned) {
mCore->mFreeSlots.insert(*outSlot);
mCore->clearBufferSlotLocked(*outSlot);
BQ_LOGE("dequeueBuffer: BufferQueue has been abandoned");
return NO_INIT;
}
VALIDATE_CONSISTENCY();
} // Autolock scope
}
if (attachedByConsumer) {
returnFlags |= BUFFER_NEEDS_REALLOCATION;
}
if (eglFence != EGL_NO_SYNC_KHR) {
EGLint result = eglClientWaitSyncKHR(eglDisplay, eglFence, 0,
1000000000);
// If something goes wrong, log the error, but return the buffer without
// synchronizing access to it. It's too late at this point to abort the
// dequeue operation.
if (result == EGL_FALSE) {
BQ_LOGE("dequeueBuffer: error %#x waiting for fence",
eglGetError());
} else if (result == EGL_TIMEOUT_EXPIRED_KHR) {
BQ_LOGE("dequeueBuffer: timeout waiting for fence");
}
eglDestroySyncKHR(eglDisplay, eglFence);
}
BQ_LOGV("dequeueBuffer: returning slot=%d/%" PRIu64 " buf=%p flags=%#x",
*outSlot,
mSlots[*outSlot].mFrameNumber,
mSlots[*outSlot].mGraphicBuffer->handle, returnFlags);
if (outBufferAge) {
*outBufferAge = mCore->mBufferAge;
}
addAndGetFrameTimestamps(nullptr, outTimestamps);
return returnFlags; //注意在应用第一次请求buffer, dequeueBuffer返回时对应的GraphicBuffer已经创建完成并给到了对应的slot上，但返回给应用的flags里还是带有BUFFER_NEEDS_REALLOCATION标记的
}
}
|
wentao