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
8#ifndef GrRingBuffer_DEFINED
9#define GrRingBuffer_DEFINED
10
11#include "src/gpu/GrGpuBuffer.h"
12
13#include <vector>
14
15class GrGpu;
16
17/**
18 * A wrapper for a GPU buffer that allocates slices in a continuous ring.
19 *
20 * It's assumed that suballocate and startSubmit are always called in the same thread,
21 * and that finishSubmit could be called in a separate thread.
22 */
23class GrRingBuffer {
24public:
25 GrRingBuffer(GrGpu* gpu, size_t size, size_t alignment, GrGpuBufferType intendedType)
26 : fGpu(gpu)
27 , fTotalSize(size)
28 , fAlignment(alignment)
29 , fType(intendedType)
30 , fHead(0)
31 , fTail(0)
32 , fGenID(0) {
33 // We increment fHead and fTail without bound and let overflow handle any wrapping.
34 // Because of this, size needs to be a power of two.
35 SkASSERT(SkIsPow2(size));
36 }
37
38 struct Slice {
39 GrGpuBuffer* fBuffer;
40 size_t fOffset;
41 };
42 Slice suballocate(size_t size);
43
44 // Backends should call startSubmit() at submit time
45 void startSubmit(GrGpu*);
46
47 size_t size() const { return fTotalSize; }
48
49private:
50 size_t getAllocationOffset(size_t size);
51 struct SubmitData {
52 GrRingBuffer* fOwner;
53 size_t fLastHead;
54 size_t fGenID;
55 };
56 static void FinishSubmit(void*);
57
58 GrGpu* fGpu;
59 sk_sp<GrGpuBuffer> fCurrentBuffer;
60 std::vector<sk_sp<GrGpuBuffer>> fTrackedBuffers; // all buffers we've used in this submit
61 size_t fTotalSize;
62 size_t fAlignment;
63 GrGpuBufferType fType;
64 size_t fHead; // where we start allocating
65 size_t fTail; // where we start deallocating
66 uint64_t fGenID; // incremented when createBuffer is called
67};
68
69#endif
70