src/gpu/GrResourceCache.h - platform/external/skia - Git at Google


 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */


 #ifndef GrResourceCache_DEFINED
 #define GrResourceCache_DEFINED

 #include "GrTypes.h"
 #include "GrTHashCache.h"

 class GrResource;

 // return true if a<b, or false if b<a
 //
 #define RET_IF_LT_OR_GT(a, b)   \
     do {                        \
         if ((a) < (b)) {        \
             return true;        \
         }                       \
         if ((b) < (a)) {        \
             return false;       \
         }                       \
     } while (0)

 /**
  *  Helper class for GrResourceCache, the Key is used to identify src data for
  *  a resource. It is identified by 2 32bit data fields which can hold any
  *  data (uninterpreted by the cache) and a width/height.
  */
 class GrResourceKey {
 public:
     enum {
         kHashBits   = 7,
         kHashCount  = 1 << kHashBits,
         kHashMask   = kHashCount - 1
     };

     GrResourceKey(uint32_t p0, uint32_t p1, uint32_t p2, uint32_t p3) {
         fP[0] = p0;
         fP[1] = p1;
         fP[2] = p2;
         fP[3] = p3;
         this->computeHashIndex();
     }

     GrResourceKey(uint32_t v[4]) {
         memcpy(fP, v, 4 * sizeof(uint32_t));
         this->computeHashIndex();
     }

     GrResourceKey(const GrResourceKey& src) {
         memcpy(fP, src.fP, 4 * sizeof(uint32_t));
 #if GR_DEBUG
         this->computeHashIndex();
         GrAssert(fHashIndex == src.fHashIndex);
 #endif
         fHashIndex = src.fHashIndex;
     }

     //!< returns hash value [0..kHashMask] for the key
     int hashIndex() const { return fHashIndex; }

     friend bool operator==(const GrResourceKey& a, const GrResourceKey& b) {
         GR_DEBUGASSERT(-1 != a.fHashIndex && -1 != b.fHashIndex);
         return 0 == memcmp(a.fP, b.fP, 4 * sizeof(uint32_t));
     }

     friend bool operator!=(const GrResourceKey& a, const GrResourceKey& b) {
         GR_DEBUGASSERT(-1 != a.fHashIndex && -1 != b.fHashIndex);
         return !(a == b);
     }

     friend bool operator<(const GrResourceKey& a, const GrResourceKey& b) {
         RET_IF_LT_OR_GT(a.fP[0], b.fP[0]);
         RET_IF_LT_OR_GT(a.fP[1], b.fP[1]);
         RET_IF_LT_OR_GT(a.fP[2], b.fP[2]);
         return a.fP[3] < b.fP[3];
     }

     uint32_t getValue32(int i) const {
         GrAssert(i >=0 && i < 4);
         return fP[i];
     }
 private:

     static uint32_t rol(uint32_t x) {
         return (x >> 24) | (x << 8);
     }
     static uint32_t ror(uint32_t x) {
         return (x >> 8) | (x << 24);
     }
     static uint32_t rohalf(uint32_t x) {
         return (x >> 16) | (x << 16);
     }

     void computeHashIndex() {
         uint32_t hash = fP[0] ^ rol(fP[1]) ^ ror(fP[2]) ^ rohalf(fP[3]);
         // this way to mix and reduce hash to its index may have to change
         // depending on how many bits we allocate to the index
         hash ^= hash >> 16;
         hash ^= hash >> 8;
         fHashIndex = hash & kHashMask;
     }

     uint32_t    fP[4];

     // this is computed from the fP... fields
     int         fHashIndex;

     friend class GrContext;
 };

 ///////////////////////////////////////////////////////////////////////////////

 class GrResourceEntry {
 public:
     GrResource* resource() const { return fResource; }
     const GrResourceKey& key() const { return fKey; }

 #if GR_DEBUG
     GrResourceEntry* next() const { return fNext; }
     GrResourceEntry* prev() const { return fPrev; }
 #endif

 #if GR_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif

 private:
     GrResourceEntry(const GrResourceKey& key, GrResource* resource);
     ~GrResourceEntry();

     bool isLocked() const { return fLockCount != 0; }
     void lock() { ++fLockCount; }
     void unlock() {
         GrAssert(fLockCount > 0);
         --fLockCount;
     }

     GrResourceKey    fKey;
     GrResource*      fResource;

     // track if we're in use, used when we need to purge
     // we only purge unlocked entries
     int fLockCount;

     // we're a dlinklist
     GrResourceEntry* fPrev;
     GrResourceEntry* fNext;

     friend class GrResourceCache;
 };

 ///////////////////////////////////////////////////////////////////////////////

 #include "GrTHashCache.h"

 /**
  *  Cache of GrResource objects.
  *
  *  These have a corresponding GrResourceKey, built from 128bits identifying the
  *  resource.
  *
  *  The cache stores the entries in a double-linked list, which is its LRU.
  *  When an entry is "locked" (i.e. given to the caller), it is moved to the
  *  head of the list. If/when we must purge some of the entries, we walk the
  *  list backwards from the tail, since those are the least recently used.
  *
  *  For fast searches, we maintain a sorted array (based on the GrResourceKey)
  *  which we can bsearch. When a new entry is added, it is inserted into this
  *  array.
  *
  *  For even faster searches, a hash is computed from the Key. If there is
  *  a collision between two keys with the same hash, we fall back on the
  *  bsearch, and update the hash to reflect the most recent Key requested.
  */
 class GrResourceCache {
 public:
     GrResourceCache(int maxCount, size_t maxBytes);
     ~GrResourceCache();

     /**
      *  Return the current resource cache limits.
      *
      *  @param maxResource If non-null, returns maximum number of resources
      *                     that can be held in the cache.
      *  @param maxBytes    If non-null, returns maximum number of bytes of
      *                         gpu memory that can be held in the cache.
      */
     void getLimits(int* maxResources, size_t* maxBytes) const;

     /**
      *  Specify the resource cache limits. If the current cache exceeds either
      *  of these, it will be purged (LRU) to keep the cache within these limits.
      *
      *  @param maxResources The maximum number of resources that can be held in
      *                      the cache.
      *  @param maxBytes     The maximum number of bytes of resource memory that
      *                      can be held in the cache.
      */
     void setLimits(int maxResource, size_t maxResourceBytes);

     /**
      * Returns the number of bytes consumed by cached resources.
      */
     size_t getCachedResourceBytes() const { return fEntryBytes; }

     /**
      * Controls whether locks should be nestable or not.
      */
     enum LockType {
         kNested_LockType,
         kSingle_LockType,
     };

     /**
      *  Search for an entry with the same Key. If found, "lock" it and return it.
      *  If not found, return null.
      */
     GrResourceEntry* findAndLock(const GrResourceKey&, LockType style);

     /**
      *  Create a new entry, based on the specified key and resource, and return
      *  its "locked" entry.
      *
      *  Ownership of the resource is transferred to the Entry, which will unref()
      *  it when we are purged or deleted.
      */
     GrResourceEntry* createAndLock(const GrResourceKey&, GrResource*);

     /**
      * Determines if the cache contains an entry matching a key. If a matching
      * entry exists but was detached then it will not be found.
      */
     bool hasKey(const GrResourceKey& key) const;

     /**
      * Detach removes an entry from the cache. This prevents the entry from
      * being found by a subsequent findAndLock() until it is reattached. The
      * entry still counts against the cache's budget and should be reattached
      * when exclusive access is no longer needed.
      */
     void detach(GrResourceEntry*);

     /**
      * Reattaches a resource to the cache and unlocks it. Allows it to be found
      * by a subsequent findAndLock or be purged (provided its lock count is
      * now 0.)
      */
     void reattachAndUnlock(GrResourceEntry*);

     /**
      *  When done with an entry, call unlock(entry) on it, which returns it to
      *  a purgable state.
      */
     void unlock(GrResourceEntry*);

     void removeAll();

 #if GR_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif

 private:
     void internalDetach(GrResourceEntry*, bool);
     void attachToHead(GrResourceEntry*, bool);
     void purgeAsNeeded();

     class Key;
     GrTHashTable<GrResourceEntry, Key, 8> fCache;

     // manage the dlink list
     GrResourceEntry* fHead;
     GrResourceEntry* fTail;

     // our budget, used in purgeAsNeeded()
     int fMaxCount;
     size_t fMaxBytes;

     // our current stats, related to our budget
     int fEntryCount;
     int fUnlockedEntryCount;
     size_t fEntryBytes;
     int fClientDetachedCount;
     size_t fClientDetachedBytes;

     // prevents recursive purging
     bool fPurging;
 };

 ///////////////////////////////////////////////////////////////////////////////

 #if GR_DEBUG
     class GrAutoResourceCacheValidate {
     public:
         GrAutoResourceCacheValidate(GrResourceCache* cache) : fCache(cache) {
             cache->validate();
         }
         ~GrAutoResourceCacheValidate() {
             fCache->validate();
         }
     private:
         GrResourceCache* fCache;
     };
 #else
     class GrAutoResourceCacheValidate {
     public:
         GrAutoResourceCacheValidate(GrResourceCache*) {}
     };
 #endif

 #endif

	/*
	* Copyright 2011 Google Inc.
	*
	* Use of this source code is governed by a BSD-style license that can be
	* found in the LICENSE file.
	*/



	#ifndef GrResourceCache_DEFINED
	#define GrResourceCache_DEFINED

	#include "GrTypes.h"
	#include "GrTHashCache.h"

	class GrResource;

	// return true if a<b, or false if b<a
	//
	#define RET_IF_LT_OR_GT(a, b) \
	do { \
	if ((a) < (b)) { \
	return true; \
	} \
	if ((b) < (a)) { \
	return false; \
	} \
	} while (0)

	/**
	* Helper class for GrResourceCache, the Key is used to identify src data for
	* a resource. It is identified by 2 32bit data fields which can hold any
	* data (uninterpreted by the cache) and a width/height.
	*/
	class GrResourceKey {
	public:
	enum {
	kHashBits = 7,
	kHashCount = 1 << kHashBits,
	kHashMask = kHashCount - 1
	};

	GrResourceKey(uint32_t p0, uint32_t p1, uint32_t p2, uint32_t p3) {
	fP[0] = p0;
	fP[1] = p1;
	fP[2] = p2;
	fP[3] = p3;
	this->computeHashIndex();
	}

	GrResourceKey(uint32_t v[4]) {
	memcpy(fP, v, 4 * sizeof(uint32_t));
	this->computeHashIndex();
	}

	GrResourceKey(const GrResourceKey& src) {
	memcpy(fP, src.fP, 4 * sizeof(uint32_t));
	#if GR_DEBUG
	this->computeHashIndex();
	GrAssert(fHashIndex == src.fHashIndex);
	#endif
	fHashIndex = src.fHashIndex;
	}

	//!< returns hash value [0..kHashMask] for the key
	int hashIndex() const { return fHashIndex; }

	friend bool operator==(const GrResourceKey& a, const GrResourceKey& b) {
	GR_DEBUGASSERT(-1 != a.fHashIndex && -1 != b.fHashIndex);
	return 0 == memcmp(a.fP, b.fP, 4 * sizeof(uint32_t));
	}

	friend bool operator!=(const GrResourceKey& a, const GrResourceKey& b) {
	GR_DEBUGASSERT(-1 != a.fHashIndex && -1 != b.fHashIndex);
	return !(a == b);
	}

	friend bool operator<(const GrResourceKey& a, const GrResourceKey& b) {
	RET_IF_LT_OR_GT(a.fP[0], b.fP[0]);
	RET_IF_LT_OR_GT(a.fP[1], b.fP[1]);
	RET_IF_LT_OR_GT(a.fP[2], b.fP[2]);
	return a.fP[3] < b.fP[3];
	}

	uint32_t getValue32(int i) const {
	GrAssert(i >=0 && i < 4);
	return fP[i];
	}
	private:

	static uint32_t rol(uint32_t x) {
	return (x >> 24) \| (x << 8);
	}
	static uint32_t ror(uint32_t x) {
	return (x >> 8) \| (x << 24);
	}
	static uint32_t rohalf(uint32_t x) {
	return (x >> 16) \| (x << 16);
	}

	void computeHashIndex() {
	uint32_t hash = fP[0] ^ rol(fP[1]) ^ ror(fP[2]) ^ rohalf(fP[3]);
	// this way to mix and reduce hash to its index may have to change
	// depending on how many bits we allocate to the index
	hash ^= hash >> 16;
	hash ^= hash >> 8;
	fHashIndex = hash & kHashMask;
	}

	uint32_t fP[4];

	// this is computed from the fP... fields
	int fHashIndex;

	friend class GrContext;
	};

	///////////////////////////////////////////////////////////////////////////////

	class GrResourceEntry {
	public:
	GrResource* resource() const { return fResource; }
	const GrResourceKey& key() const { return fKey; }

	#if GR_DEBUG
	GrResourceEntry* next() const { return fNext; }
	GrResourceEntry* prev() const { return fPrev; }
	#endif

	#if GR_DEBUG
	void validate() const;
	#else
	void validate() const {}
	#endif

	private:
	GrResourceEntry(const GrResourceKey& key, GrResource* resource);
	~GrResourceEntry();

	bool isLocked() const { return fLockCount != 0; }
	void lock() { ++fLockCount; }
	void unlock() {
	GrAssert(fLockCount > 0);
	--fLockCount;
	}

	GrResourceKey fKey;
	GrResource* fResource;

	// track if we're in use, used when we need to purge
	// we only purge unlocked entries
	int fLockCount;

	// we're a dlinklist
	GrResourceEntry* fPrev;
	GrResourceEntry* fNext;

	friend class GrResourceCache;
	};

	///////////////////////////////////////////////////////////////////////////////

	#include "GrTHashCache.h"

	/**
	* Cache of GrResource objects.
	*
	* These have a corresponding GrResourceKey, built from 128bits identifying the
	* resource.
	*
	* The cache stores the entries in a double-linked list, which is its LRU.
	* When an entry is "locked" (i.e. given to the caller), it is moved to the
	* head of the list. If/when we must purge some of the entries, we walk the
	* list backwards from the tail, since those are the least recently used.
	*
	* For fast searches, we maintain a sorted array (based on the GrResourceKey)
	* which we can bsearch. When a new entry is added, it is inserted into this
	* array.
	*
	* For even faster searches, a hash is computed from the Key. If there is
	* a collision between two keys with the same hash, we fall back on the
	* bsearch, and update the hash to reflect the most recent Key requested.
	*/
	class GrResourceCache {
	public:
	GrResourceCache(int maxCount, size_t maxBytes);
	~GrResourceCache();

	/**
	* Return the current resource cache limits.
	*
	* @param maxResource If non-null, returns maximum number of resources
	* that can be held in the cache.
	* @param maxBytes If non-null, returns maximum number of bytes of
	* gpu memory that can be held in the cache.
	*/
	void getLimits(int* maxResources, size_t* maxBytes) const;

	/**
	* Specify the resource cache limits. If the current cache exceeds either
	* of these, it will be purged (LRU) to keep the cache within these limits.
	*
	* @param maxResources The maximum number of resources that can be held in
	* the cache.
	* @param maxBytes The maximum number of bytes of resource memory that
	* can be held in the cache.
	*/
	void setLimits(int maxResource, size_t maxResourceBytes);

	/**
	* Returns the number of bytes consumed by cached resources.
	*/
	size_t getCachedResourceBytes() const { return fEntryBytes; }

	/**
	* Controls whether locks should be nestable or not.
	*/
	enum LockType {
	kNested_LockType,
	kSingle_LockType,
	};

	/**
	* Search for an entry with the same Key. If found, "lock" it and return it.
	* If not found, return null.
	*/
	GrResourceEntry* findAndLock(const GrResourceKey&, LockType style);

	/**
	* Create a new entry, based on the specified key and resource, and return
	* its "locked" entry.
	*
	* Ownership of the resource is transferred to the Entry, which will unref()
	* it when we are purged or deleted.
	*/
	GrResourceEntry* createAndLock(const GrResourceKey&, GrResource*);

	/**
	* Determines if the cache contains an entry matching a key. If a matching
	* entry exists but was detached then it will not be found.
	*/
	bool hasKey(const GrResourceKey& key) const;

	/**
	* Detach removes an entry from the cache. This prevents the entry from
	* being found by a subsequent findAndLock() until it is reattached. The
	* entry still counts against the cache's budget and should be reattached
	* when exclusive access is no longer needed.
	*/
	void detach(GrResourceEntry*);

	/**
	* Reattaches a resource to the cache and unlocks it. Allows it to be found
	* by a subsequent findAndLock or be purged (provided its lock count is
	* now 0.)
	*/
	void reattachAndUnlock(GrResourceEntry*);

	/**
	* When done with an entry, call unlock(entry) on it, which returns it to
	* a purgable state.
	*/
	void unlock(GrResourceEntry*);

	void removeAll();

	#if GR_DEBUG
	void validate() const;
	#else
	void validate() const {}
	#endif

	private:
	void internalDetach(GrResourceEntry*, bool);
	void attachToHead(GrResourceEntry*, bool);
	void purgeAsNeeded();

	class Key;
	GrTHashTable<GrResourceEntry, Key, 8> fCache;

	// manage the dlink list
	GrResourceEntry* fHead;
	GrResourceEntry* fTail;

	// our budget, used in purgeAsNeeded()
	int fMaxCount;
	size_t fMaxBytes;

	// our current stats, related to our budget
	int fEntryCount;
	int fUnlockedEntryCount;
	size_t fEntryBytes;
	int fClientDetachedCount;
	size_t fClientDetachedBytes;

	// prevents recursive purging
	bool fPurging;
	};

	///////////////////////////////////////////////////////////////////////////////

	#if GR_DEBUG
	class GrAutoResourceCacheValidate {
	public:
	GrAutoResourceCacheValidate(GrResourceCache* cache) : fCache(cache) {
	cache->validate();
	}
	~GrAutoResourceCacheValidate() {
	fCache->validate();
	}
	private:
	GrResourceCache* fCache;
	};
	#else
	class GrAutoResourceCacheValidate {
	public:
	GrAutoResourceCacheValidate(GrResourceCache*) {}
	};
	#endif

	#endif