1 /*
2 * Copyright 2020 Google LLC
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7 #include "src/gpu/ganesh/GrRingBuffer.h"
8
9 #include "include/gpu/ganesh/GrDirectContext.h"
10 #include "include/private/base/SkAlign.h"
11 #include "include/private/gpu/ganesh/GrTypesPriv.h"
12 #include "src/gpu/RefCntedCallback.h"
13 #include "src/gpu/ganesh/GrDirectContextPriv.h"
14 #include "src/gpu/ganesh/GrGpu.h"
15 #include "src/gpu/ganesh/GrResourceProvider.h"
16
17 #include <utility>
18
19 // Get offset into buffer that has enough space for size
20 // Returns fTotalSize if no space
getAllocationOffset(size_t size)21 size_t GrRingBuffer::getAllocationOffset(size_t size) {
22 // capture current state locally (because fTail could be overwritten by the completion handler)
23 size_t head, tail;
24 head = fHead;
25 tail = fTail;
26
27 // The head and tail indices increment without bound, wrapping with overflow,
28 // so we need to mod them down to the actual bounds of the allocation to determine
29 // which blocks are available.
30 size_t modHead = head & (fTotalSize - 1);
31 size_t modTail = tail & (fTotalSize - 1);
32
33 bool full = (head != tail && modHead == modTail);
34
35 if (full) {
36 return fTotalSize;
37 }
38
39 // case 1: free space lies at the beginning and/or the end of the buffer
40 if (modHead >= modTail) {
41 // check for room at the end
42 if (fTotalSize - modHead < size) {
43 // no room at the end, check the beginning
44 if (modTail < size) {
45 // no room at the beginning
46 return fTotalSize;
47 }
48 // we are going to allocate from the beginning, adjust head to '0' position
49 head += fTotalSize - modHead;
50 modHead = 0;
51 }
52 // case 2: free space lies in the middle of the buffer, check for room there
53 } else if (modTail - modHead < size) {
54 // no room in the middle
55 return fTotalSize;
56 }
57
58 fHead = SkAlignTo(head + size, fAlignment);
59 return modHead;
60 }
61
suballocate(size_t size)62 GrRingBuffer::Slice GrRingBuffer::suballocate(size_t size) {
63 fNewAllocation = true;
64 if (fCurrentBuffer) {
65 size_t offset = this->getAllocationOffset(size);
66 if (offset < fTotalSize) {
67 return { fCurrentBuffer.get(), offset };
68 }
69
70 // Try to grow allocation (old allocation will age out).
71 fTotalSize *= 2;
72 // Add current buffer to be tracked for next submit.
73 fPreviousBuffers.push_back(std::move(fCurrentBuffer));
74 }
75
76 GrResourceProvider* resourceProvider = fGpu->getContext()->priv().resourceProvider();
77 fCurrentBuffer = resourceProvider->createBuffer(fTotalSize,
78 fType,
79 kDynamic_GrAccessPattern,
80 GrResourceProvider::ZeroInit::kNo);
81
82 SkASSERT(fCurrentBuffer);
83 fHead = 0;
84 fTail = 0;
85 fGenID++;
86 size_t offset = this->getAllocationOffset(size);
87 SkASSERT(offset < fTotalSize);
88 return { fCurrentBuffer.get(), offset };
89 }
90
91 // used when current command buffer/command list is submitted
startSubmit(GrGpu * gpu)92 void GrRingBuffer::startSubmit(GrGpu* gpu) {
93 for (unsigned int i = 0; i < fPreviousBuffers.size(); ++i) {
94 fPreviousBuffers[i]->unmap();
95 gpu->takeOwnershipOfBuffer(std::move(fPreviousBuffers[i]));
96 }
97 fPreviousBuffers.clear();
98
99 if (fNewAllocation) {
100 #ifdef SK_BUILD_FOR_MAC
101 // Since we're using a Managed buffer on MacOS we need to unmap to write back to GPU
102 // TODO: once we set up persistently mapped UPLOAD buffers on D3D, we can remove the
103 // platform restriction.
104 fCurrentBuffer->unmap();
105 #endif
106 SubmitData* submitData = new SubmitData();
107 submitData->fOwner = this;
108 submitData->fLastHead = fHead;
109 submitData->fGenID = fGenID;
110 gpu->addFinishedCallback(skgpu::AutoCallback(FinishSubmit, submitData));
111 fNewAllocation = false;
112 }
113 }
114
115 // used when current command buffer/command list is completed
FinishSubmit(void * finishedContext)116 void GrRingBuffer::FinishSubmit(void* finishedContext) {
117 GrRingBuffer::SubmitData* submitData = (GrRingBuffer::SubmitData*)finishedContext;
118 if (submitData && submitData->fOwner && submitData->fGenID == submitData->fOwner->fGenID) {
119 submitData->fOwner->fTail = submitData->fLastHead;
120 submitData->fOwner = nullptr;
121 }
122 delete submitData;
123 }
124