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      1 /*
      2  * Copyright 2015 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 GrNonAtomicRef_DEFINED
      9 #define GrNonAtomicRef_DEFINED
     10 
     11 #include "SkRefCnt.h"
     12 #include "SkTArray.h"
     13 
     14 /**
     15  * A simple non-atomic ref used in the GrBackend when we don't want to pay for the overhead of a
     16  * threadsafe ref counted object
     17  */
     18 template<typename TSubclass> class GrNonAtomicRef : public SkNoncopyable {
     19 public:
     20     GrNonAtomicRef() : fRefCnt(1) {}
     21 
     22 #ifdef SK_DEBUG
     23     ~GrNonAtomicRef() {
     24         // fRefCnt can be one when a subclass is created statically
     25         SkASSERT((0 == fRefCnt || 1 == fRefCnt));
     26         // Set to invalid values.
     27         fRefCnt = -10;
     28     }
     29 #endif
     30 
     31     void ref() const {
     32         // Once the ref cnt reaches zero it should never be ref'ed again.
     33         SkASSERT(fRefCnt > 0);
     34         ++fRefCnt;
     35     }
     36 
     37     void unref() const {
     38         SkASSERT(fRefCnt > 0);
     39         --fRefCnt;
     40         if (0 == fRefCnt) {
     41             GrTDeleteNonAtomicRef(static_cast<const TSubclass*>(this));
     42             return;
     43         }
     44     }
     45 
     46 private:
     47     mutable int32_t fRefCnt;
     48 
     49     typedef SkNoncopyable INHERITED;
     50 };
     51 
     52 template<typename T> inline void GrTDeleteNonAtomicRef(const T* ref) {
     53     delete ref;
     54 }
     55 
     56 #endif
     57