Line data    Source code

       1             : /*
       2             :  * Copyright 2014 Google Inc.
       3             :  *
       4             :  * Use of this source code is governed by a BSD-style license that can be
       5             :  * found in the LICENSE file.
       6             :  */
       7             : 
       8             : #ifndef SkCachedData_DEFINED
       9             : #define SkCachedData_DEFINED
      10             : 
      11             : #include "SkMutex.h"
      12             : #include "SkTypes.h"
      13             : 
      14             : class SkDiscardableMemory;
      15             : 
      16             : class SkCachedData : ::SkNoncopyable {
      17             : public:
      18             :     SkCachedData(void* mallocData, size_t size);
      19             :     SkCachedData(size_t size, SkDiscardableMemory*);
      20             :     virtual ~SkCachedData();
      21             : 
      22           0 :     size_t size() const { return fSize; }
      23           0 :     const void* data() const { return fData; }
      24             : 
      25           0 :     void* writable_data() { return fData; }
      26             : 
      27           0 :     void ref() const { this->internalRef(false); }
      28           0 :     void unref() const { this->internalUnref(false); }
      29             : 
      30             :     int testing_only_getRefCnt() const { return fRefCnt; }
      31             :     bool testing_only_isLocked() const { return fIsLocked; }
      32             :     bool testing_only_isInCache() const { return fInCache; }
      33             : 
      34           0 :     SkDiscardableMemory* diagnostic_only_getDiscardable() const {
      35           0 :         return kDiscardableMemory_StorageType == fStorageType ? fStorage.fDM : nullptr;
      36             :     }
      37             : 
      38             : protected:
      39             :     // called when fData changes. could be nullptr.
      40           0 :     virtual void onDataChange(void* oldData, void* newData) {}
      41             : 
      42             : private:
      43             :     SkMutex fMutex;     // could use a pool of these...
      44             : 
      45             :     enum StorageType {
      46             :         kDiscardableMemory_StorageType,
      47             :         kMalloc_StorageType
      48             :     };
      49             : 
      50             :     union {
      51             :         SkDiscardableMemory*    fDM;
      52             :         void*                   fMalloc;
      53             :     } fStorage;
      54             :     void*       fData;
      55             :     size_t      fSize;
      56             :     int         fRefCnt;    // low-bit means we're owned by the cache
      57             :     StorageType fStorageType;
      58             :     bool        fInCache;
      59             :     bool        fIsLocked;
      60             : 
      61             :     void internalRef(bool fromCache) const;
      62             :     void internalUnref(bool fromCache) const;
      63             : 
      64             :     void inMutexRef(bool fromCache);
      65             :     bool inMutexUnref(bool fromCache);  // returns true if we should delete "this"
      66             :     void inMutexLock();
      67             :     void inMutexUnlock();
      68             : 
      69             :     // called whenever our fData might change (lock or unlock)
      70           0 :     void setData(void* newData) {
      71           0 :         if (newData != fData) {
      72             :             // notify our subclasses of the change
      73           0 :             this->onDataChange(fData, newData);
      74           0 :             fData = newData;
      75             :         }
      76           0 :     }
      77             : 
      78             :     class AutoMutexWritable;
      79             : 
      80             : public:
      81             : #ifdef SK_DEBUG
      82             :     void validate() const;
      83             : #else
      84             :     void validate() const {}
      85             : #endif
      86             : 
      87             :    /*
      88             :      *  Attaching a data to to a SkResourceCache (only one at a time) enables the data to be
      89             :      *  unlocked when the cache is the only owner, thus freeing it to be purged (assuming the
      90             :      *  data is backed by a SkDiscardableMemory).
      91             :      *
      92             :      *  When attached, it also automatically attempts to "lock" the data when the first client
      93             :      *  ref's the data (typically from a find(key, visitor) call).
      94             :      *
      95             :      *  Thus the data will always be "locked" when a non-cache has a ref on it (whether or not
      96             :      *  the lock succeeded to recover the memory -- check data() to see if it is nullptr).
      97             :      */
      98             : 
      99             :     /*
     100             :      *  Call when adding this instance to a SkResourceCache::Rec subclass
     101             :      *  (typically in the Rec's constructor).
     102             :      */
     103           0 :     void attachToCacheAndRef() const { this->internalRef(true); }
     104             : 
     105             :     /*
     106             :      *  Call when removing this instance from a SkResourceCache::Rec subclass
     107             :      *  (typically in the Rec's destructor).
     108             :      */
     109           0 :     void detachFromCacheAndUnref() const { this->internalUnref(true); }
     110             : };
     111             : 
     112             : #endif