notify resource caches when pixelref genID goes stale

src/core/SkResourceCache.h

 /*
  * Copyright 2013 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #ifndef SkResourceCache_DEFINED
 #define SkResourceCache_DEFINED
 
@@ skipping 17 matching lines @@
 public:
     struct Key {
         // Call this to access your private contents. Must not use the address after calling init()
         void* writableContents() { return this + 1; }
 
         // must call this after your private data has been written.
         // nameSpace must be unique per Key subclass.
         // length must be a multiple of 4
         void init(void* nameSpace, size_t length);
 
+        void* getNamespace() const { return fNamespace; }
+
         // This is only valid after having called init().
         uint32_t hash() const { return fHash; }
 
         bool operator==(const Key& other) const {
             const uint32_t* a = this->as32();
             const uint32_t* b = other.as32();
             for (int i = 0; i < fCount32; ++i) {  // (This checks fCount == other.fCount first.)
                 if (a[i] != b[i]) {
                     return false;
                 }
@@ skipping 37 matching lines @@
     /**
      *  Callback function for find(). If called, the cache will have found a match for the
      *  specified Key, and will pass in the corresponding Rec, along with a caller-specified
      *  context. The function can read the data in Rec, and copy whatever it likes into context
      *  (casting context to whatever it really is).
      *
      *  The return value determines what the cache will do with the Rec. If the function returns
      *  true, then the Rec is considered "valid". If false is returned, the Rec will be considered
      *  "stale" and will be purged from the cache.
      */
-    typedef bool (*VisitorProc)(const Rec&, void* context);
+    typedef bool (*FindVisitor)(const Rec&, void* context);
+
+    enum PurgeVisitorResult {
+        kRetainAndContinue_PurgeVisitorResult,
+        kPurgeAndContinue_PurgeVisitorResult,
+        kRetainAndStop_PurgeVisitorResult,
+        kPurgeAndStop_PurgeVisitorResult,
+    };
+
+    /**
+     *  Callback function for purge(). If called, the cache will have found a match for the
+     *  specified Key, and will pass in the corresponding Rec, along with a caller-specified
+     *  context. The function can read the data in Rec.
+     */
+    typedef PurgeVisitorResult (*PurgeVisitor)(const Rec&, void* context);
 
     /**
      *  Returns a locked/pinned SkDiscardableMemory instance for the specified
      *  number of bytes, or NULL on failure.
      */
     typedef SkDiscardableMemory* (*DiscardableFactory)(size_t bytes);
 
     /*
      *  The following static methods are thread-safe wrappers around a global
      *  instance of this cache.
      */
 
     /**
      *  Returns true if the visitor was called on a matching Key, and the visitor returned true.
      *
      *  Find() will search the cache for the specified Key. If no match is found, return false and
      *  do not call the VisitorProc. If a match is found, return whatever the visitor returns.
      *  Its return value is interpreted to mean:
      *      true  : Rec is valid
      *      false : Rec is "stale" -- the cache will purge it.
      */
-    static bool Find(const Key& key, VisitorProc, void* context);
+    static bool Find(const Key& key, FindVisitor, void* context);
     static void Add(Rec*);
 
     static size_t GetTotalBytesUsed();
     static size_t GetTotalByteLimit();
     static size_t SetTotalByteLimit(size_t newLimit);
 
     static size_t SetSingleAllocationByteLimit(size_t);
     static size_t GetSingleAllocationByteLimit();
     static size_t GetEffectiveSingleAllocationByteLimit();
 
+    /**
+     *  Visit all Rec that match the specified namespace, and purge entries as indicated by the
+     *  visitor.
+     */
+    static void Purge(const void* nameSpace, PurgeVisitor, void* context);
+
     static void PurgeAll();
 
     /**
      *  Returns the DiscardableFactory used by the global cache, or NULL.
      */
     static DiscardableFactory GetDiscardableFactory();
 
     /**
      * Use this allocator for bitmaps, so they can use ashmem when available.
      * Returns NULL if the ResourceCache has not been initialized with a DiscardableFactory.
@@ skipping 29 matching lines @@
 
     /**
      *  Returns true if the visitor was called on a matching Key, and the visitor returned true.
      *
      *  find() will search the cache for the specified Key. If no match is found, return false and
      *  do not call the VisitorProc. If a match is found, return whatever the visitor returns.
      *  Its return value is interpreted to mean:
      *      true  : Rec is valid
      *      false : Rec is "stale" -- the cache will purge it.
      */
-    bool find(const Key&, VisitorProc, void* context);
+    bool find(const Key&, FindVisitor, void* context);
     void add(Rec*);
 
     size_t getTotalBytesUsed() const { return fTotalBytesUsed; }
     size_t getTotalByteLimit() const { return fTotalByteLimit; }
 
     /**
      *  This is respected by SkBitmapProcState::possiblyScaleImage.
      *  0 is no maximum at all; this is the default.
      *  setSingleAllocationByteLimit() returns the previous value.
      */
     size_t setSingleAllocationByteLimit(size_t maximumAllocationSize);
     size_t getSingleAllocationByteLimit() const;
     // returns the logical single allocation size (pinning against the budget when the cache
     // is not backed by discardable memory.
     size_t getEffectiveSingleAllocationByteLimit() const;
 
     /**
      *  Set the maximum number of bytes available to this cache. If the current
      *  cache exceeds this new value, it will be purged to try to fit within
      *  this new limit.
      */
     size_t setTotalByteLimit(size_t newLimit);
 
+    void purge(const void* nameSpace, PurgeVisitor, void* context);
+
     void purgeAll() {
+        fInsidePurgeAllCounter += 1;
         this->purgeAsNeeded(true);
+        fInsidePurgeAllCounter -= 1;
     }
 
     DiscardableFactory discardableFactory() const { return fDiscardableFactory; }
     SkBitmap::Allocator* allocator() const { return fAllocator; };
 
     SkCachedData* newCachedData(size_t bytes);
 
     /**
      *  Call SkDebugf() with diagnostic information about the state of the cache
      */
     void dump() const;
 
 private:
     Rec*    fHead;
     Rec*    fTail;
 
     class Hash;
     Hash*   fHash;
 
     DiscardableFactory  fDiscardableFactory;
     // the allocator is NULL or one that matches discardables
     SkBitmap::Allocator* fAllocator;
 
     size_t  fTotalBytesUsed;
     size_t  fTotalByteLimit;
     size_t  fSingleAllocationByteLimit;
     int     fCount;
 
+    bool insidePurgeAll() const {
+        SkASSERT(fInsidePurgeAllCounter >= 0);
+        return fInsidePurgeAllCounter > 0;
+    }
+    int fInsidePurgeAllCounter;
+
     void purgeAsNeeded(bool forcePurge = false);
 
     // linklist management
     void moveToHead(Rec*);
     void addToHead(Rec*);
     void detach(Rec*);
     void remove(Rec*);
 
     void init();    // called by constructors
 
 #ifdef SK_DEBUG
     void validate() const;
 #else
     void validate() const {}
 #endif
 };
 #endif