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 /*

  * 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 "GrConfig.h"

 #include "GrTypes.h"

 #include "GrTMultiMap.h"

 #include "GrBinHashKey.h"

 #include "SkMessageBus.h"

 #include "SkTInternalLList.h"

 class GrResource;

 class GrResourceEntry;

 class GrResourceKey {

 public:

     static GrCacheID::Domain ScratchDomain() {

         static const GrCacheID::Domain gDomain = GrCacheID::GenerateDomain();

         return gDomain;

     }

     /** Uniquely identifies the GrResource subclass in the key to avoid collisions

         across resource types. */

     typedef uint8_t ResourceType;

     /** Flags set by the GrResource subclass. */

     typedef uint8_t ResourceFlags;

     /** Generate a unique ResourceType */

     static ResourceType GenerateResourceType();

     /** Creates a key for resource */

     GrResourceKey(const GrCacheID& id, ResourceType type, ResourceFlags flags) {

         this->init(id.getDomain(), id.getKey(), type, flags);

     };

     GrResourceKey(const GrResourceKey& src) {

         fKey = src.fKey;

     }

     GrResourceKey() {

         fKey.reset();

     }

     void reset(const GrCacheID& id, ResourceType type, ResourceFlags flags) {

         this->init(id.getDomain(), id.getKey(), type, flags);

     }

     uint32_t getHash() const {

         return fKey.getHash();

     }

     bool isScratch() const {

         return ScratchDomain() ==

             *reinterpret_cast<const GrCacheID::Domain*>(fKey.getData() +

                                                         kCacheIDDomainOffset);

     }

     ResourceType getResourceType() const {

         return *reinterpret_cast<const ResourceType*>(fKey.getData() +

                                                       kResourceTypeOffset);

     }

     ResourceFlags getResourceFlags() const {

         return *reinterpret_cast<const ResourceFlags*>(fKey.getData() +

                                                        kResourceFlagsOffset);

     }

     bool operator==(const GrResourceKey& other) const { return fKey == other.fKey; }

 private:

     enum {

         kCacheIDKeyOffset = 0,

         kCacheIDDomainOffset = kCacheIDKeyOffset + sizeof(GrCacheID::Key),

         kResourceTypeOffset = kCacheIDDomainOffset + sizeof(GrCacheID::Domain),

         kResourceFlagsOffset = kResourceTypeOffset + sizeof(ResourceType),

         kPadOffset = kResourceFlagsOffset + sizeof(ResourceFlags),

         kKeySize = SkAlign4(kPadOffset),

         kPadSize = kKeySize - kPadOffset

     };

     void init(const GrCacheID::Domain domain,

               const GrCacheID::Key& key,

               ResourceType type,

               ResourceFlags flags) {

         union {

             uint8_t  fKey8[kKeySize];

             uint32_t fKey32[kKeySize / 4];

         } keyData;

         uint8_t* k = keyData.fKey8;

         memcpy(k + kCacheIDKeyOffset, key.fData8, sizeof(GrCacheID::Key));

         memcpy(k + kCacheIDDomainOffset, &domain, sizeof(GrCacheID::Domain));

         memcpy(k + kResourceTypeOffset, &type, sizeof(ResourceType));

         memcpy(k + kResourceFlagsOffset, &flags, sizeof(ResourceFlags));

         memset(k + kPadOffset, 0, kPadSize);

         fKey.setKeyData(keyData.fKey32);

     }

     GrBinHashKey<kKeySize> fKey;

 };

 // The cache listens for these messages to purge junk resources proactively.

 struct GrResourceInvalidatedMessage {

     GrResourceKey key;

 };

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

 class GrResourceEntry {

 public:

     GrResource* resource() const { return fResource; }

     const GrResourceKey& key() const { return fKey; }

     static const GrResourceKey& GetKey(const GrResourceEntry& e) { return e.key(); }

     static uint32_t Hash(const GrResourceKey& key) { return key.getHash(); }

     static bool Equal(const GrResourceEntry& a, const GrResourceKey& b) {

         return a.key() == b;

     }

 #ifdef SK_DEBUG

     void validate() const;

 #else

     void validate() const {}

 #endif

 private:

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

     ~GrResourceEntry();

     GrResourceKey    fKey;

     GrResource*      fResource;

     // Linked list for the LRU ordering.

     SK_DECLARE_INTERNAL_LLIST_INTERFACE(GrResourceEntry);

     friend class GrResourceCache;

 };

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

 /**

  *  Cache of GrResource objects.

  *

  *  These have a corresponding GrResourceKey, built from 128bits identifying the

  *  resource. Multiple resources can map to same GrResourceKey.

  *

  *  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 hash map based on the GrResourceKey.

  *

  *  It is a goal to make the GrResourceCache the central repository and bookkeeper

  *  of all resources. It should replace the linked list of GrResources that

  *  GrGpu uses to call abandon/release.

  */

 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 maxResources, size_t maxResourceBytes);

     /**

      *  The callback function used by the cache when it is still over budget

      *  after a purge. The passed in 'data' is the same 'data' handed to

      *  setOverbudgetCallback. The callback returns true if some resources

      *  have been freed.

      */

     typedef bool (*PFOverbudgetCB)(void* data);

     /**

      *  Set the callback the cache should use when it is still over budget

      *  after a purge. The 'data' provided here will be passed back to the

      *  callback. Note that the cache will attempt to purge any resources newly

      *  freed by the callback.

      */

     void setOverbudgetCallback(PFOverbudgetCB overbudgetCB, void* data) {

         fOverbudgetCB = overbudgetCB;

         fOverbudgetData = data;

     }

     /**

      * Returns the number of bytes consumed by cached resources.

      */

     size_t getCachedResourceBytes() const { return fEntryBytes; }

     // For a found or added resource to be completely exclusive to the caller

     // both the kNoOtherOwners and kHide flags need to be specified

     enum OwnershipFlags {

         kNoOtherOwners_OwnershipFlag = 0x1, // found/added resource has no other owners

         kHide_OwnershipFlag = 0x2  // found/added resource is hidden from future 'find's

     };

     /**

      *  Search for an entry with the same Key. If found, return it.

      *  If not found, return null.

      *  If ownershipFlags includes kNoOtherOwners and a resource is returned

      *  then that resource has no other refs to it.

      *  If ownershipFlags includes kHide and a resource is returned then that

      *  resource will not be returned from future 'find' calls until it is

      *  'freed' (and recycled) or makeNonExclusive is called.

      *  For a resource to be completely exclusive to a caller both kNoOtherOwners

      *  and kHide must be specified.

      */

     GrResource* find(const GrResourceKey& key,

                      uint32_t ownershipFlags = 0);

     /**

      *  Add the new resource to the cache (by creating a new cache entry based

      *  on the provided key and resource).

      *

      *  Ownership of the resource is transferred to the resource cache,

      *  which will unref() it when it is purged or deleted.

      *

      *  If ownershipFlags includes kHide, subsequent calls to 'find' will not

      *  return 'resource' until it is 'freed' (and recycled) or makeNonExclusive

      *  is called.

      */

     void addResource(const GrResourceKey& key,

                      GrResource* resource,

                      uint32_t ownershipFlags = 0);

     /**

      * 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 { return NULL != fCache.find(key); }

     /**

      * Hide 'entry' so that future searches will not find it. Such

      * hidden entries will not be purged. The entry still counts against

      * the cache's budget and should be made non-exclusive when exclusive access

      * is no longer needed.

      */

     void makeExclusive(GrResourceEntry* entry);

     /**

      * Restore 'entry' so that it can be found by future searches. 'entry'

      * will also be purgeable (provided its lock count is now 0.)

      */

     void makeNonExclusive(GrResourceEntry* entry);

     /**

      * Remove a resource from the cache and delete it!

      */

     void deleteResource(GrResourceEntry* entry);

     /**

      * Removes every resource in the cache that isn't locked.

      */

     void purgeAllUnlocked();

     /**

      * Allow cache to purge unused resources to obey resource limitations

      * Note: this entry point will be hidden (again) once totally ref-driven

      * cache maintenance is implemented. Note that the overbudget callback

      * will be called if the initial purge doesn't get the cache under

      * its budget.

      *

      * extraCount and extraBytes are added to the current resource allocation

      * to make sure enough room is available for future additions (e.g,

      * 10MB across 10 textures is about to be added).

      */

     void purgeAsNeeded(int extraCount = 0, size_t extraBytes = 0);

 #ifdef SK_DEBUG

     void validate() const;

 #else

     void validate() const {}

 #endif

 #if GR_CACHE_STATS

     void printStats();

 #endif

 private:

     enum BudgetBehaviors {

         kAccountFor_BudgetBehavior,

         kIgnore_BudgetBehavior

     };

     void internalDetach(GrResourceEntry*, BudgetBehaviors behavior = kAccountFor_BudgetBehavior);

     void attachToHead(GrResourceEntry*, BudgetBehaviors behavior = kAccountFor_BudgetBehavior);

     void removeInvalidResource(GrResourceEntry* entry);

     GrTMultiMap<GrResourceEntry,

                 GrResourceKey,

                 GrResourceEntry::GetKey,

                 GrResourceEntry::Hash,

                 GrResourceEntry::Equal> fCache;

     // We're an internal doubly linked list

     typedef SkTInternalLList<GrResourceEntry> EntryList;

     EntryList      fList;

 #ifdef SK_DEBUG

     // These objects cannot be returned by a search

     EntryList      fExclusiveList;

 #endif

     // our budget, used in purgeAsNeeded()

     int            fMaxCount;

     size_t         fMaxBytes;

     // our current stats, related to our budget

 #if GR_CACHE_STATS

     int            fHighWaterEntryCount;

     size_t         fHighWaterEntryBytes;

     int            fHighWaterClientDetachedCount;

     size_t         fHighWaterClientDetachedBytes;

 #endif

     int            fEntryCount;

     size_t         fEntryBytes;

     int            fClientDetachedCount;

     size_t         fClientDetachedBytes;

     // prevents recursive purging

     bool           fPurging;

     PFOverbudgetCB fOverbudgetCB;

     void*          fOverbudgetData;

     void internalPurge(int extraCount, size_t extraBytes);

     // Listen for messages that a resource has been invalidated and purge cached junk proactively.

     SkMessageBus<GrResourceInvalidatedMessage>::Inbox fInvalidationInbox;

     void purgeInvalidated();

 #ifdef SK_DEBUG

     static size_t countBytes(const SkTInternalLList<GrResourceEntry>& list);

 #endif

 };

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

 #ifdef SK_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