ResourceCache.h

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/*
 * Copyright 2022 Google LLC
 *
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */
 
#ifndef skgpu_graphite_ResourceCache_DEFINED
#define skgpu_graphite_ResourceCache_DEFINED
 
#include "include/core/SkRefCnt.h"
#include "include/private/base/SkMutex.h"
#include "include/private/base/SkTArray.h"
#include "src/base/SkTDPQueue.h"
#include "src/core/SkTHash.h"
#include "src/core/SkTMultiMap.h"
#include "src/gpu/GpuTypesPriv.h"
#include "src/gpu/graphite/ResourceTypes.h"
 
#if defined(GRAPHITE_TEST_UTILS)
#include <functional>
#endif
#include <vector>
 
class SkTraceMemoryDump;
 
namespace skgpu {
class SingleOwner;
}
 
namespace skgpu::graphite {
 
class GraphiteResourceKey;
class ProxyCache;
class Resource;
 
#if defined(GRAPHITE_TEST_UTILS)
class Texture;
#endif
 
class ResourceCache : public SkRefCnt {
public:
    static sk_sp<ResourceCache> Make(SingleOwner*, uint32_t recorderID, size_t maxBytes);
    ~ResourceCache() override;
 
    ResourceCache(const ResourceCache&) = delete;
    ResourceCache(ResourceCache&&) = delete;
    ResourceCache& operator=(const ResourceCache&) = delete;
    ResourceCache& operator=(ResourceCache&&) = delete;
 
    // Returns the number of resources.
    int getResourceCount() const {
        return fPurgeableQueue.count() + fNonpurgeableResources.size();
    }
 
    void insertResource(Resource*);
 
    // Find a resource that matches a key.
    Resource* findAndRefResource(const GraphiteResourceKey& key, skgpu::Budgeted);
 
    // This is a thread safe call. If it fails the ResourceCache is no longer valid and the
    // Resource should clean itself up if it is the last ref.
    bool returnResource(Resource*, LastRemovedRef);
 
    // Purge resources not used since the passed point in time. Resources that have a gpu memory
    // size of zero will not be purged.
    // TODO: Should we add an optional flag to also allow purging of zero sized resources? Would we
    // want to be able to differentiate between things like Pipelines (probably never want to purge)
    // and things like descriptor sets.
    void purgeResourcesNotUsedSince(StdSteadyClock::time_point purgeTime);
 
    // Purge any unlocked resources. Resources that have a gpu memory size of zero will not be
    // purged.
    void purgeResources();
 
    // Called by the ResourceProvider when it is dropping its ref to the ResourceCache. After this
    // is called no more Resources can be returned to the ResourceCache (besides those already in
    // the return queue). Also no new Resources can be retrieved from the ResourceCache.
    void shutdown();
 
    size_t getMaxBudget() const { return fMaxBytes; }
 
    size_t currentBudgetedBytes() const { return fBudgetedBytes; }
 
    void dumpMemoryStatistics(SkTraceMemoryDump* traceMemoryDump) const;
 
#if defined(GRAPHITE_TEST_UTILS)
    void forceProcessReturnedResources() { this->processReturnedResources(); }
 
    void forcePurgeAsNeeded() { this->purgeAsNeeded(); }
 
    // Returns the numbers of Resources that can currently be found in the cache. This includes all
    // shared Resources and all non-shareable resources that have been returned to the cache.
    int numFindableResources() const;
 
    // This will probably end up being a public function to change the current budget size, but for
    // now just making this a testing only function.
    void setMaxBudget(size_t bytes);
 
    Resource* topOfPurgeableQueue();
 
    bool testingInPurgeableQueue(Resource* resource) { return this->inPurgeableQueue(resource); }
 
    void visitTextures(const std::function<void(const Texture*, bool purgeable)>&) const;
#endif
 
    ProxyCache* proxyCache() { return fProxyCache.get(); }
 
private:
    ResourceCache(SingleOwner*, uint32_t recorderID, size_t maxBytes);
 
    // All these private functions are not meant to be thread safe. We don't check for is single
    // owner in them as we assume that has already been checked by the public api calls.
    void refAndMakeResourceMRU(Resource*);
    void addToNonpurgeableArray(Resource* resource);
    void removeFromNonpurgeableArray(Resource* resource);
    void removeFromPurgeableQueue(Resource* resource);
 
    // This will return true if any resources were actually returned to the cache
    bool processReturnedResources();
    void returnResourceToCache(Resource*, LastRemovedRef);
 
    uint32_t getNextTimestamp();
    void setResourceTimestamp(Resource*, uint32_t timestamp);
 
    bool inPurgeableQueue(Resource*) const;
 
    bool overbudget() const { return fBudgetedBytes > fMaxBytes; }
    void purgeAsNeeded();
    void purgeResource(Resource*);
    // Passing in a nullptr for purgeTime will trigger us to try and free all unlocked resources.
    void purgeResources(const StdSteadyClock::time_point* purgeTime);
 
#ifdef SK_DEBUG
    bool isInCache(const Resource* r) const;
    void validate() const;
#else
    void validate() const {}
#endif
 
    struct MapTraits {
        static const GraphiteResourceKey& GetKey(const Resource& r);
 
        static uint32_t Hash(const GraphiteResourceKey& key);
        static void OnFree(Resource*) {}
    };
    typedef SkTMultiMap<Resource, GraphiteResourceKey, MapTraits> ResourceMap;
 
    static bool CompareTimestamp(Resource* const& a, Resource* const& b);
    static int* AccessResourceIndex(Resource* const& res);
 
    using PurgeableQueue = SkTDPQueue<Resource*, CompareTimestamp, AccessResourceIndex>;
    using ResourceArray = SkTDArray<Resource*>;
 
    // Whenever a resource is added to the cache or the result of a cache lookup, fTimestamp is
    // assigned as the resource's timestamp and then incremented. fPurgeableQueue orders the
    // purgeable resources by this value, and thus is used to purge resources in LRU order.
    // Resources with a size of zero are set to have max uint32_t value. This will also put them at
    // the end of the LRU priority queue. This will allow us to not purge these resources even when
    // we are over budget.
    uint32_t fTimestamp = 0;
    static const uint32_t kMaxTimestamp = 0xFFFFFFFF;
 
    PurgeableQueue fPurgeableQueue;
    ResourceArray fNonpurgeableResources;
    std::unique_ptr<ProxyCache> fProxyCache;
 
    SkDEBUGCODE(int fCount = 0;)
 
    ResourceMap fResourceMap;
 
    // Our budget
    size_t fMaxBytes;
    size_t fBudgetedBytes = 0;
 
    SingleOwner* fSingleOwner = nullptr;
 
    bool fIsShutdown = false;
 
    SkMutex fReturnMutex;
    using ReturnQueue = std::vector<std::pair<Resource*, LastRemovedRef>>;
    ReturnQueue fReturnQueue SK_GUARDED_BY(fReturnMutex);
};
 
} // namespace skgpu::graphite
 
#endif // skgpu_graphite_ResourceCache_DEFINED