src/gpu/ResourceKey.h - skia - Git at Google

 /*
  * Copyright 2014 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */

 #ifndef skgpu_ResourceKey_DEFINED
 #define skgpu_ResourceKey_DEFINED

 #include "include/core/SkData.h"
 #include "include/core/SkString.h"
 #include "include/private/SkOnce.h"
 #include "include/private/SkTemplates.h"
 #include "include/private/SkTo.h"

 #include <new>

 class TestResource;

 namespace skgpu {

 uint32_t ResourceKeyHash(const uint32_t* data, size_t size);

 /**
  * Base class for all gpu Resource cache keys. There are two types of cache keys. Refer to the
  * comments for each key type below.
  */
 class ResourceKey {
 public:
     uint32_t hash() const {
         this->validate();
         return fKey[kHash_MetaDataIdx];
     }

     size_t size() const {
         this->validate();
         SkASSERT(this->isValid());
         return this->internalSize();
     }

     /** Reset to an invalid key. */
     void reset() {
         fKey.reset(kMetaDataCnt);
         fKey[kHash_MetaDataIdx] = 0;
         fKey[kDomainAndSize_MetaDataIdx] = kInvalidDomain;
     }

     bool isValid() const { return kInvalidDomain != this->domain(); }

     /** Used to initialize a key. */
     class Builder {
     public:
         ~Builder() { this->finish(); }

         void finish() {
             if (nullptr == fKey) {
                 return;
             }
             uint32_t* hash = &fKey->fKey[kHash_MetaDataIdx];
             *hash = ResourceKeyHash(hash + 1, fKey->internalSize() - sizeof(uint32_t));
             fKey->validate();
             fKey = nullptr;
         }

         uint32_t& operator[](int dataIdx) {
             SkASSERT(fKey);
             SkDEBUGCODE(size_t dataCount = fKey->internalSize() / sizeof(uint32_t) - kMetaDataCnt;)
                     SkASSERT(SkToU32(dataIdx) < dataCount);
             return fKey->fKey[(int)kMetaDataCnt + dataIdx];
         }

     protected:
         Builder(ResourceKey* key, uint32_t domain, int data32Count) : fKey(key) {
             size_t count = SkToSizeT(data32Count);
             SkASSERT(domain != kInvalidDomain);
             key->fKey.reset(kMetaDataCnt + count);
             size_t size = (count + kMetaDataCnt) * sizeof(uint32_t);
             SkASSERT(SkToU16(size) == size);
             SkASSERT(SkToU16(domain) == domain);
             key->fKey[kDomainAndSize_MetaDataIdx] = domain | (size << 16);
         }

     private:
         ResourceKey* fKey;
     };

 protected:
     static const uint32_t kInvalidDomain = 0;

     ResourceKey() { this->reset(); }

     bool operator==(const ResourceKey& that) const {
         // Both keys should be sized to at least contain the meta data. The metadata contains each
         // key's length. So the second memcmp should only run if the keys have the same length.
         return 0 == memcmp(fKey.get(), that.fKey.get(), kMetaDataCnt*sizeof(uint32_t)) &&
                0 == memcmp(&fKey[kMetaDataCnt], &that.fKey[kMetaDataCnt], this->dataSize());
     }

     ResourceKey& operator=(const ResourceKey& that) {
         if (this != &that) {
             if (!that.isValid()) {
                 this->reset();
             } else {
                 size_t bytes = that.size();
                 SkASSERT(SkIsAlign4(bytes));
                 fKey.reset(bytes / sizeof(uint32_t));
                 memcpy(fKey.get(), that.fKey.get(), bytes);
                 this->validate();
             }
         }
         return *this;
     }

     uint32_t domain() const { return fKey[kDomainAndSize_MetaDataIdx] & 0xffff; }

     /** size of the key data, excluding meta-data (hash, domain, etc).  */
     size_t dataSize() const { return this->size() - 4 * kMetaDataCnt; }

     /** ptr to the key data, excluding meta-data (hash, domain, etc).  */
     const uint32_t* data() const {
         this->validate();
         return &fKey[kMetaDataCnt];
     }

 #ifdef SK_DEBUG
     void dump() const {
         if (!this->isValid()) {
             SkDebugf("Invalid Key\n");
         } else {
             SkDebugf("hash: %d ", this->hash());
             SkDebugf("domain: %d ", this->domain());
             SkDebugf("size: %zuB ", this->internalSize());
             size_t dataCount = this->internalSize() / sizeof(uint32_t) - kMetaDataCnt;
             for (size_t i = 0; i < dataCount; ++i) {
                 SkDebugf("%d ", fKey[SkTo<int>(kMetaDataCnt+i)]);
             }
             SkDebugf("\n");
         }
     }
 #endif

 private:
     enum MetaDataIdx {
         kHash_MetaDataIdx,
         // The key domain and size are packed into a single uint32_t.
         kDomainAndSize_MetaDataIdx,

         kLastMetaDataIdx = kDomainAndSize_MetaDataIdx
     };
     static const uint32_t kMetaDataCnt = kLastMetaDataIdx + 1;

     size_t internalSize() const { return fKey[kDomainAndSize_MetaDataIdx] >> 16; }

     void validate() const {
         SkASSERT(this->isValid());
         SkASSERT(fKey[kHash_MetaDataIdx] ==
                  ResourceKeyHash(&fKey[kHash_MetaDataIdx] + 1,
                                  this->internalSize() - sizeof(uint32_t)));
         SkASSERT(SkIsAlign4(this->internalSize()));
     }

     friend class ::TestResource;  // For unit test to access kMetaDataCnt.

     // bmp textures require 5 uint32_t values.
     SkAutoSTMalloc<kMetaDataCnt + 5, uint32_t> fKey;
 };

 /**
  * A key used for scratch resources. There are three important rules about scratch keys:
  *        * Multiple resources can share the same scratch key. Therefore resources assigned the same
  *          scratch key should be interchangeable with respect to the code that uses them.
  *        * A resource can have at most one scratch key and it is set at resource creation by the
  *          resource itself.
  *        * When a scratch resource is ref'ed it will not be returned from the
  *          cache for a subsequent cache request until all refs are released. This facilitates using
  *          a scratch key for multiple render-to-texture scenarios. An example is a separable blur:
  *
  *  GrTexture* texture[2];
  *  texture[0] = get_scratch_texture(scratchKey);
  *  texture[1] = get_scratch_texture(scratchKey); // texture[0] is already owned so we will get a
  *                                                // different one for texture[1]
  *  draw_mask(texture[0], path);        // draws path mask to texture[0]
  *  blur_x(texture[0], texture[1]);     // blurs texture[0] in y and stores result in texture[1]
  *  blur_y(texture[1], texture[0]);     // blurs texture[1] in y and stores result in texture[0]
  *  texture[1]->unref();  // texture 1 can now be recycled for the next request with scratchKey
  *  consume_blur(texture[0]);
  *  texture[0]->unref();  // texture 0 can now be recycled for the next request with scratchKey
  */
 class ScratchKey : public ResourceKey {
 public:
     /** Uniquely identifies the type of resource that is cached as scratch. */
     typedef uint32_t ResourceType;

     /** Generate a unique ResourceType. */
     static ResourceType GenerateResourceType();

     /** Creates an invalid scratch key. It must be initialized using a Builder object before use. */
     ScratchKey() {}

     ScratchKey(const ScratchKey& that) { *this = that; }

     ResourceType resourceType() const { return this->domain(); }

     ScratchKey& operator=(const ScratchKey& that) {
         this->ResourceKey::operator=(that);
         return *this;
     }

     bool operator==(const ScratchKey& that) const { return this->ResourceKey::operator==(that); }
     bool operator!=(const ScratchKey& that) const { return !(*this == that); }

     class Builder : public ResourceKey::Builder {
     public:
         Builder(ScratchKey* key, ResourceType type, int data32Count)
                 : ResourceKey::Builder(key, type, data32Count) {}
     };
 };

 /**
  * A key that allows for exclusive use of a resource for a use case (AKA "domain"). There are three
  * rules governing the use of unique keys:
  *        * Only one resource can have a given unique key at a time. Hence, "unique".
  *        * A resource can have at most one unique key at a time.
  *        * Unlike scratch keys, multiple requests for a unique key will return the same
  *          resource even if the resource already has refs.
  * This key type allows a code path to create cached resources for which it is the exclusive user.
  * The code path creates a domain which it sets on its keys. This guarantees that there are no
  * cross-domain collisions.
  *
  * Unique keys preempt scratch keys. While a resource has a unique key it is inaccessible via its
  * scratch key. It can become scratch again if the unique key is removed.
  */
 class UniqueKey : public ResourceKey {
 public:
     typedef uint32_t Domain;
     /** Generate a Domain for unique keys. */
     static Domain GenerateDomain();

     /** Creates an invalid unique key. It must be initialized using a Builder object before use. */
     UniqueKey() : fTag(nullptr) {}

     UniqueKey(const UniqueKey& that) { *this = that; }

     UniqueKey& operator=(const UniqueKey& that) {
         this->ResourceKey::operator=(that);
         this->setCustomData(sk_ref_sp(that.getCustomData()));
         fTag = that.fTag;
         return *this;
     }

     bool operator==(const UniqueKey& that) const { return this->ResourceKey::operator==(that); }
     bool operator!=(const UniqueKey& that) const { return !(*this == that); }

     void setCustomData(sk_sp<SkData> data) { fData = std::move(data); }
     SkData* getCustomData() const { return fData.get(); }
     sk_sp<SkData> refCustomData() const { return fData; }

     const char* tag() const { return fTag; }

 #ifdef SK_DEBUG
     void dump(const char* label) const {
         SkDebugf("%s tag: %s\n", label, fTag ? fTag : "None");
         this->ResourceKey::dump();
     }
 #endif

     class Builder : public ResourceKey::Builder {
     public:
         Builder(UniqueKey* key, Domain type, int data32Count, const char* tag = nullptr)
                 : ResourceKey::Builder(key, type, data32Count) {
             key->fTag = tag;
         }

         /** Used to build a key that wraps another key and adds additional data. */
         Builder(UniqueKey* key, const UniqueKey& innerKey, Domain domain, int extraData32Cnt,
                 const char* tag = nullptr)
                 : ResourceKey::Builder(key,
                                        domain,
                                        Data32CntForInnerKey(innerKey) + extraData32Cnt) {
             SkASSERT(&innerKey != key);
             // add the inner key to the end of the key so that op[] can be indexed normally.
             uint32_t* innerKeyData = &this->operator[](extraData32Cnt);
             const uint32_t* srcData = innerKey.data();
             (*innerKeyData++) = innerKey.domain();
             memcpy(innerKeyData, srcData, innerKey.dataSize());
             key->fTag = tag;
         }

     private:
         static int Data32CntForInnerKey(const UniqueKey& innerKey) {
             // key data + domain
             return SkToInt((innerKey.dataSize() >> 2) + 1);
         }
     };

 private:
     sk_sp<SkData> fData;
     const char* fTag;
 };

 /**
  * It is common to need a frequently reused UniqueKey where the only requirement is that the key
  * is unique. These macros create such a key in a thread safe manner so the key can be truly global
  * and only constructed once.
  */

 /** Place outside of function/class definitions. */
 #define SKGPU_DECLARE_STATIC_UNIQUE_KEY(name) static SkOnce name##_once

 /** Place inside function where the key is used. */
 #define SKGPU_DEFINE_STATIC_UNIQUE_KEY(name)                                \
     static SkAlignedSTStorage<1, skgpu::UniqueKey> name##_storage;          \
     name##_once(skgpu::skgpu_init_static_unique_key_once, &name##_storage); \
     static const skgpu::UniqueKey& name =                                   \
         *reinterpret_cast<skgpu::UniqueKey*>(name##_storage.get())

 static inline void skgpu_init_static_unique_key_once(SkAlignedSTStorage<1, UniqueKey>* keyStorage) {
     UniqueKey* key = new (keyStorage->get()) UniqueKey;
     UniqueKey::Builder builder(key, UniqueKey::GenerateDomain(), 0);
 }

 // The cache listens for these messages to purge junk resources proactively.
 class UniqueKeyInvalidatedMessage {
 public:
     UniqueKeyInvalidatedMessage() = default;
     UniqueKeyInvalidatedMessage(const UniqueKey& key,
                                 uint32_t contextUniqueID,
                                 bool inThreadSafeCache = false)
             : fKey(key), fContextID(contextUniqueID), fInThreadSafeCache(inThreadSafeCache) {
         SkASSERT(SK_InvalidUniqueID != contextUniqueID);
     }

     UniqueKeyInvalidatedMessage(const UniqueKeyInvalidatedMessage&) = default;

     UniqueKeyInvalidatedMessage& operator=(const UniqueKeyInvalidatedMessage&) = default;

     const UniqueKey& key() const { return fKey; }
     uint32_t contextID() const { return fContextID; }
     bool inThreadSafeCache() const { return fInThreadSafeCache; }

 private:
     UniqueKey fKey;
     uint32_t fContextID = SK_InvalidUniqueID;
     bool fInThreadSafeCache = false;
 };

 static inline bool SkShouldPostMessageToBus(const UniqueKeyInvalidatedMessage& msg,
                                             uint32_t msgBusUniqueID) {
     return msg.contextID() == msgBusUniqueID;
 }

 } // namespace skgpu

 #endif // skgpu_ResourceKey_DEFINED
	/*
	* Copyright 2014 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/

	#ifndef skgpu_ResourceKey_DEFINED
	#define skgpu_ResourceKey_DEFINED

	#include "include/core/SkData.h"
	#include "include/core/SkString.h"
	#include "include/private/SkOnce.h"
	#include "include/private/SkTemplates.h"
	#include "include/private/SkTo.h"

	#include <new>

	class TestResource;

	namespace skgpu {

	uint32_t ResourceKeyHash(const uint32_t* data, size_t size);

	/**
	* Base class for all gpu Resource cache keys. There are two types of cache keys. Refer to the
	* comments for each key type below.
	*/
	class ResourceKey {
	public:
	uint32_t hash() const {
	this->validate();
	return fKey[kHash_MetaDataIdx];
	}

	size_t size() const {
	this->validate();
	SkASSERT(this->isValid());
	return this->internalSize();
	}

	/** Reset to an invalid key. */
	void reset() {
	fKey.reset(kMetaDataCnt);
	fKey[kHash_MetaDataIdx] = 0;
	fKey[kDomainAndSize_MetaDataIdx] = kInvalidDomain;
	}

	bool isValid() const { return kInvalidDomain != this->domain(); }

	/** Used to initialize a key. */
	class Builder {
	public:
	~Builder() { this->finish(); }

	void finish() {
	if (nullptr == fKey) {
	return;
	}
	uint32_t* hash = &fKey->fKey[kHash_MetaDataIdx];
	*hash = ResourceKeyHash(hash + 1, fKey->internalSize() - sizeof(uint32_t));
	fKey->validate();
	fKey = nullptr;
	}

	uint32_t& operator[](int dataIdx) {
	SkASSERT(fKey);
	SkDEBUGCODE(size_t dataCount = fKey->internalSize() / sizeof(uint32_t) - kMetaDataCnt;)
	SkASSERT(SkToU32(dataIdx) < dataCount);
	return fKey->fKey[(int)kMetaDataCnt + dataIdx];
	}

	protected:
	Builder(ResourceKey* key, uint32_t domain, int data32Count) : fKey(key) {
	size_t count = SkToSizeT(data32Count);
	SkASSERT(domain != kInvalidDomain);
	key->fKey.reset(kMetaDataCnt + count);
	size_t size = (count + kMetaDataCnt) * sizeof(uint32_t);
	SkASSERT(SkToU16(size) == size);
	SkASSERT(SkToU16(domain) == domain);
	key->fKey[kDomainAndSize_MetaDataIdx] = domain \| (size << 16);
	}

	private:
	ResourceKey* fKey;
	};

	protected:
	static const uint32_t kInvalidDomain = 0;

	ResourceKey() { this->reset(); }

	bool operator==(const ResourceKey& that) const {
	// Both keys should be sized to at least contain the meta data. The metadata contains each
	// key's length. So the second memcmp should only run if the keys have the same length.
	return 0 == memcmp(fKey.get(), that.fKey.get(), kMetaDataCnt*sizeof(uint32_t)) &&
	0 == memcmp(&fKey[kMetaDataCnt], &that.fKey[kMetaDataCnt], this->dataSize());
	}

	ResourceKey& operator=(const ResourceKey& that) {
	if (this != &that) {
	if (!that.isValid()) {
	this->reset();
	} else {
	size_t bytes = that.size();
	SkASSERT(SkIsAlign4(bytes));
	fKey.reset(bytes / sizeof(uint32_t));
	memcpy(fKey.get(), that.fKey.get(), bytes);
	this->validate();
	}
	}
	return *this;
	}

	uint32_t domain() const { return fKey[kDomainAndSize_MetaDataIdx] & 0xffff; }

	/** size of the key data, excluding meta-data (hash, domain, etc). */
	size_t dataSize() const { return this->size() - 4 * kMetaDataCnt; }

	/** ptr to the key data, excluding meta-data (hash, domain, etc). */
	const uint32_t* data() const {
	this->validate();
	return &fKey[kMetaDataCnt];
	}

	#ifdef SK_DEBUG
	void dump() const {
	if (!this->isValid()) {
	SkDebugf("Invalid Key\n");
	} else {
	SkDebugf("hash: %d ", this->hash());
	SkDebugf("domain: %d ", this->domain());
	SkDebugf("size: %zuB ", this->internalSize());
	size_t dataCount = this->internalSize() / sizeof(uint32_t) - kMetaDataCnt;
	for (size_t i = 0; i < dataCount; ++i) {
	SkDebugf("%d ", fKey[SkTo<int>(kMetaDataCnt+i)]);
	}
	SkDebugf("\n");
	}
	}
	#endif

	private:
	enum MetaDataIdx {
	kHash_MetaDataIdx,
	// The key domain and size are packed into a single uint32_t.
	kDomainAndSize_MetaDataIdx,

	kLastMetaDataIdx = kDomainAndSize_MetaDataIdx
	};
	static const uint32_t kMetaDataCnt = kLastMetaDataIdx + 1;

	size_t internalSize() const { return fKey[kDomainAndSize_MetaDataIdx] >> 16; }

	void validate() const {
	SkASSERT(this->isValid());
	SkASSERT(fKey[kHash_MetaDataIdx] ==
	ResourceKeyHash(&fKey[kHash_MetaDataIdx] + 1,
	this->internalSize() - sizeof(uint32_t)));
	SkASSERT(SkIsAlign4(this->internalSize()));
	}

	friend class ::TestResource; // For unit test to access kMetaDataCnt.

	// bmp textures require 5 uint32_t values.
	SkAutoSTMalloc<kMetaDataCnt + 5, uint32_t> fKey;
	};

	/**
	* A key used for scratch resources. There are three important rules about scratch keys:
	* * Multiple resources can share the same scratch key. Therefore resources assigned the same
	* scratch key should be interchangeable with respect to the code that uses them.
	* * A resource can have at most one scratch key and it is set at resource creation by the
	* resource itself.
	* * When a scratch resource is ref'ed it will not be returned from the
	* cache for a subsequent cache request until all refs are released. This facilitates using
	* a scratch key for multiple render-to-texture scenarios. An example is a separable blur:
	*
	* GrTexture* texture[2];
	* texture[0] = get_scratch_texture(scratchKey);
	* texture[1] = get_scratch_texture(scratchKey); // texture[0] is already owned so we will get a
	* // different one for texture[1]
	* draw_mask(texture[0], path); // draws path mask to texture[0]
	* blur_x(texture[0], texture[1]); // blurs texture[0] in y and stores result in texture[1]
	* blur_y(texture[1], texture[0]); // blurs texture[1] in y and stores result in texture[0]
	* texture[1]->unref(); // texture 1 can now be recycled for the next request with scratchKey
	* consume_blur(texture[0]);
	* texture[0]->unref(); // texture 0 can now be recycled for the next request with scratchKey
	*/
	class ScratchKey : public ResourceKey {
	public:
	/** Uniquely identifies the type of resource that is cached as scratch. */
	typedef uint32_t ResourceType;

	/** Generate a unique ResourceType. */
	static ResourceType GenerateResourceType();

	/** Creates an invalid scratch key. It must be initialized using a Builder object before use. */
	ScratchKey() {}

	ScratchKey(const ScratchKey& that) { *this = that; }

	ResourceType resourceType() const { return this->domain(); }

	ScratchKey& operator=(const ScratchKey& that) {
	this->ResourceKey::operator=(that);
	return *this;
	}

	bool operator==(const ScratchKey& that) const { return this->ResourceKey::operator==(that); }
	bool operator!=(const ScratchKey& that) const { return !(*this == that); }

	class Builder : public ResourceKey::Builder {
	public:
	Builder(ScratchKey* key, ResourceType type, int data32Count)
	: ResourceKey::Builder(key, type, data32Count) {}
	};
	};

	/**
	* A key that allows for exclusive use of a resource for a use case (AKA "domain"). There are three
	* rules governing the use of unique keys:
	* * Only one resource can have a given unique key at a time. Hence, "unique".
	* * A resource can have at most one unique key at a time.
	* * Unlike scratch keys, multiple requests for a unique key will return the same
	* resource even if the resource already has refs.
	* This key type allows a code path to create cached resources for which it is the exclusive user.
	* The code path creates a domain which it sets on its keys. This guarantees that there are no
	* cross-domain collisions.
	*
	* Unique keys preempt scratch keys. While a resource has a unique key it is inaccessible via its
	* scratch key. It can become scratch again if the unique key is removed.
	*/
	class UniqueKey : public ResourceKey {
	public:
	typedef uint32_t Domain;
	/** Generate a Domain for unique keys. */
	static Domain GenerateDomain();

	/** Creates an invalid unique key. It must be initialized using a Builder object before use. */
	UniqueKey() : fTag(nullptr) {}

	UniqueKey(const UniqueKey& that) { *this = that; }

	UniqueKey& operator=(const UniqueKey& that) {
	this->ResourceKey::operator=(that);
	this->setCustomData(sk_ref_sp(that.getCustomData()));
	fTag = that.fTag;
	return *this;
	}

	bool operator==(const UniqueKey& that) const { return this->ResourceKey::operator==(that); }
	bool operator!=(const UniqueKey& that) const { return !(*this == that); }

	void setCustomData(sk_sp<SkData> data) { fData = std::move(data); }
	SkData* getCustomData() const { return fData.get(); }
	sk_sp<SkData> refCustomData() const { return fData; }

	const char* tag() const { return fTag; }

	#ifdef SK_DEBUG
	void dump(const char* label) const {
	SkDebugf("%s tag: %s\n", label, fTag ? fTag : "None");
	this->ResourceKey::dump();
	}
	#endif

	class Builder : public ResourceKey::Builder {
	public:
	Builder(UniqueKey* key, Domain type, int data32Count, const char* tag = nullptr)
	: ResourceKey::Builder(key, type, data32Count) {
	key->fTag = tag;
	}

	/** Used to build a key that wraps another key and adds additional data. */
	Builder(UniqueKey* key, const UniqueKey& innerKey, Domain domain, int extraData32Cnt,
	const char* tag = nullptr)
	: ResourceKey::Builder(key,
	domain,
	Data32CntForInnerKey(innerKey) + extraData32Cnt) {
	SkASSERT(&innerKey != key);
	// add the inner key to the end of the key so that op[] can be indexed normally.
	uint32_t* innerKeyData = &this->operator[](extraData32Cnt);
	const uint32_t* srcData = innerKey.data();
	(*innerKeyData++) = innerKey.domain();
	memcpy(innerKeyData, srcData, innerKey.dataSize());
	key->fTag = tag;
	}

	private:
	static int Data32CntForInnerKey(const UniqueKey& innerKey) {
	// key data + domain
	return SkToInt((innerKey.dataSize() >> 2) + 1);
	}
	};

	private:
	sk_sp<SkData> fData;
	const char* fTag;
	};

	/**
	* It is common to need a frequently reused UniqueKey where the only requirement is that the key
	* is unique. These macros create such a key in a thread safe manner so the key can be truly global
	* and only constructed once.
	*/

	/** Place outside of function/class definitions. */
	#define SKGPU_DECLARE_STATIC_UNIQUE_KEY(name) static SkOnce name##_once

	/** Place inside function where the key is used. */
	#define SKGPU_DEFINE_STATIC_UNIQUE_KEY(name) \
	static SkAlignedSTStorage<1, skgpu::UniqueKey> name##_storage; \
	name##_once(skgpu::skgpu_init_static_unique_key_once, &name##_storage); \
	static const skgpu::UniqueKey& name = \
	reinterpret_cast<skgpu::UniqueKey>(name##_storage.get())

	static inline void skgpu_init_static_unique_key_once(SkAlignedSTStorage<1, UniqueKey>* keyStorage) {
	UniqueKey* key = new (keyStorage->get()) UniqueKey;
	UniqueKey::Builder builder(key, UniqueKey::GenerateDomain(), 0);
	}

	// The cache listens for these messages to purge junk resources proactively.
	class UniqueKeyInvalidatedMessage {
	public:
	UniqueKeyInvalidatedMessage() = default;
	UniqueKeyInvalidatedMessage(const UniqueKey& key,
	uint32_t contextUniqueID,
	bool inThreadSafeCache = false)
	: fKey(key), fContextID(contextUniqueID), fInThreadSafeCache(inThreadSafeCache) {
	SkASSERT(SK_InvalidUniqueID != contextUniqueID);
	}

	UniqueKeyInvalidatedMessage(const UniqueKeyInvalidatedMessage&) = default;

	UniqueKeyInvalidatedMessage& operator=(const UniqueKeyInvalidatedMessage&) = default;

	const UniqueKey& key() const { return fKey; }
	uint32_t contextID() const { return fContextID; }
	bool inThreadSafeCache() const { return fInThreadSafeCache; }

	private:
	UniqueKey fKey;
	uint32_t fContextID = SK_InvalidUniqueID;
	bool fInThreadSafeCache = false;
	};

	static inline bool SkShouldPostMessageToBus(const UniqueKeyInvalidatedMessage& msg,
	uint32_t msgBusUniqueID) {
	return msg.contextID() == msgBusUniqueID;
	}

	} // namespace skgpu

	#endif // skgpu_ResourceKey_DEFINED