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1 /*
2  * Copyright 2022 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 skgpu_graphite_GlobalCache_DEFINED
9 #define skgpu_graphite_GlobalCache_DEFINED
10 
11 #include "include/core/SkRefCnt.h"
12 #include "include/private/SkSpinlock.h"
13 #include "src/core/SkLRUCache.h"
14 #include "src/gpu/ResourceKey.h"
15 
16 
17 namespace skgpu::graphite {
18 
19 class ComputePipeline;
20 class GraphicsPipeline;
21 class Resource;
22 class ShaderCodeDictionary;
23 
24 /**
25  * GlobalCache holds GPU resources that should be shared by every Recorder. The common requirement
26  * of these resources are they are static/read-only, have long lifetimes, and are likely to be used
27  * by multiple Recorders. The canonical example of this are pipelines.
28  *
29  * GlobalCache is thread safe, but intentionally splits queries and storing operations so that they
30  * are not atomic. The pattern is to query for a resource, which has a high likelihood of a cache
31  * hit. If it's not found, the Recorder creates the resource on its own, without locking the
32  * GlobalCache. After the resource is created, it is added to the GlobalCache, atomically returning
33  * the winning Resource in the event of a race between Recorders for the same UniqueKey.
34  */
35 class GlobalCache {
36 public:
37     GlobalCache();
38     ~GlobalCache();
39 
40     // Find a cached GraphicsPipeline that matches the associated key.
41     sk_sp<GraphicsPipeline> findGraphicsPipeline(const UniqueKey&) SK_EXCLUDES(fSpinLock);
42     // Associate the given pipeline with the key. If the key has already had a separate pipeline
43     // associated with the key, that pipeline is returned and the passed-in pipeline is discarded.
44     // Otherwise, the passed-in pipeline is held by the GlobalCache and also returned back.
45     sk_sp<GraphicsPipeline> addGraphicsPipeline(const UniqueKey&,
46                                                 sk_sp<GraphicsPipeline>) SK_EXCLUDES(fSpinLock);
47 
48 #if GRAPHITE_TEST_UTILS
49     int numGraphicsPipelines() const SK_EXCLUDES(fSpinLock);
50     void resetGraphicsPipelines() SK_EXCLUDES(fSpinLock);
51 #endif
52 
53     // Find amd add operations for ComputePipelines, with the same pattern as GraphicsPipelines.
54     sk_sp<ComputePipeline> findComputePipeline(const UniqueKey&) SK_EXCLUDES(fSpinLock);
55     sk_sp<ComputePipeline> addComputePipeline(const UniqueKey&,
56                                               sk_sp<ComputePipeline>) SK_EXCLUDES(fSpinLock);
57 
58     // The GlobalCache holds a ref on the given Resource until the cache is destroyed, keeping it
59     // alive for the lifetime of the SharedContext. This should be used only for Resources that are
60     // immutable after initialization so that anyone can use the resource without synchronization
61     // or reference tracking.
62     void addStaticResource(sk_sp<Resource>) SK_EXCLUDES(fSpinLock);
63 
64 private:
65     struct KeyHash {
operatorKeyHash66         uint32_t operator()(const UniqueKey& key) const { return key.hash(); }
67     };
68 
69     using GraphicsPipelineCache = SkLRUCache<UniqueKey, sk_sp<GraphicsPipeline>, KeyHash>;
70     using ComputePipelineCache  = SkLRUCache<UniqueKey, sk_sp<ComputePipeline>,  KeyHash>;
71 
72     // TODO: can we do something better given this should have write-seldom/read-often behavior?
73     mutable SkSpinlock fSpinLock;
74 
75     // GraphicsPipelines and ComputePipelines are expensive to create, likely to be used by multiple
76     // Recorders, and are ideally pre-compiled on process startup so thread write-contention is
77     // expected to be low. For these reasons we store pipelines globally instead of per-Recorder.
78     GraphicsPipelineCache fGraphicsPipelineCache SK_GUARDED_BY(fSpinLock);
79     ComputePipelineCache  fComputePipelineCache  SK_GUARDED_BY(fSpinLock);
80 
81     SkTArray<sk_sp<Resource>> fStaticResource SK_GUARDED_BY(fSpinLock);
82 };
83 
84 } // namespace skgpu::graphite
85 
86 #endif // skgpu_graphite_GlobalCache_DEFINED
87