blob: 8f1f6fd1a10d856f033debed3c45760d72e1ba79 [file] [log] [blame]
/*
* Copyright 2020 Google LLC
*
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*/
#include "src/gpu/GrRingBuffer.h"
#include "src/gpu/GrDirectContextPriv.h"
#include "src/gpu/GrGpu.h"
#include "src/gpu/GrResourceProvider.h"
// Get offset into buffer that has enough space for size
// Returns fTotalSize if no space
size_t GrRingBuffer::getAllocationOffset(size_t size) {
// capture current state locally (because fTail could be overwritten by the completion handler)
size_t head, tail;
head = fHead;
tail = fTail;
// The head and tail indices increment without bound, wrapping with overflow,
// so we need to mod them down to the actual bounds of the allocation to determine
// which blocks are available.
size_t modHead = head & (fTotalSize - 1);
size_t modTail = tail & (fTotalSize - 1);
bool full = (head != tail && modHead == modTail);
if (full) {
return fTotalSize;
}
// case 1: free space lies at the beginning and/or the end of the buffer
if (modHead >= modTail) {
// check for room at the end
if (fTotalSize - modHead < size) {
// no room at the end, check the beginning
if (modTail < size) {
// no room at the beginning
return fTotalSize;
}
// we are going to allocate from the beginning, adjust head to '0' position
head += fTotalSize - modHead;
modHead = 0;
}
// case 2: free space lies in the middle of the buffer, check for room there
} else if (modTail - modHead < size) {
// no room in the middle
return fTotalSize;
}
fHead = SkAlignTo(head + size, fAlignment);
return modHead;
}
GrRingBuffer::Slice GrRingBuffer::suballocate(size_t size) {
fNewAllocation = true;
if (fCurrentBuffer) {
size_t offset = this->getAllocationOffset(size);
if (offset < fTotalSize) {
return { fCurrentBuffer.get(), offset };
}
// Try to grow allocation (old allocation will age out).
fTotalSize *= 2;
// Add current buffer to be tracked for next submit.
fPreviousBuffers.push_back(std::move(fCurrentBuffer));
}
GrResourceProvider* resourceProvider = fGpu->getContext()->priv().resourceProvider();
fCurrentBuffer = resourceProvider->createBuffer(fTotalSize, fType, kDynamic_GrAccessPattern);
SkASSERT(fCurrentBuffer);
fHead = 0;
fTail = 0;
fGenID++;
size_t offset = this->getAllocationOffset(size);
SkASSERT(offset < fTotalSize);
return { fCurrentBuffer.get(), offset };
}
// used when current command buffer/command list is submitted
void GrRingBuffer::startSubmit(GrGpu* gpu) {
for (unsigned int i = 0; i < fPreviousBuffers.size(); ++i) {
fPreviousBuffers[i]->unmap();
gpu->takeOwnershipOfBuffer(std::move(fPreviousBuffers[i]));
}
fPreviousBuffers.clear();
if (fNewAllocation) {
#ifdef SK_BUILD_FOR_MAC
// Since we're using a Managed buffer on MacOS we need to unmap to write back to GPU
// TODO: once we set up persistently mapped UPLOAD buffers on D3D, we can remove the
// platform restriction.
fCurrentBuffer->unmap();
#endif
SubmitData* submitData = new SubmitData();
submitData->fOwner = this;
submitData->fLastHead = fHead;
submitData->fGenID = fGenID;
gpu->addFinishedProc(FinishSubmit, submitData);
fNewAllocation = false;
}
}
// used when current command buffer/command list is completed
void GrRingBuffer::FinishSubmit(void* finishedContext) {
GrRingBuffer::SubmitData* submitData = (GrRingBuffer::SubmitData*)finishedContext;
if (submitData && submitData->fOwner && submitData->fGenID == submitData->fOwner->fGenID) {
submitData->fOwner->fTail = submitData->fLastHead;
submitData->fOwner = nullptr;
}
delete submitData;
}