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 "include/core/SkRefCnt.h"
12 #include "include/private/SkNoncopyable.h"
13 #include "include/private/SkTArray.h"
14 
15 /**
16  * A simple non-atomic ref used in the GrBackendApi when we don't want to pay for the overhead of a
17  * threadsafe ref counted object
18  */
19 template<typename TSubclass> class GrNonAtomicRef : public SkNoncopyable {
20 public:
GrNonAtomicRef()21     GrNonAtomicRef() : fRefCnt(1) {}
22 
23 #ifdef SK_DEBUG
~GrNonAtomicRef()24     ~GrNonAtomicRef() {
25         // fRefCnt can be one when a subclass is created statically
26         SkASSERT((0 == fRefCnt || 1 == fRefCnt));
27         // Set to invalid values.
28         fRefCnt = -10;
29     }
30 #endif
31 
unique()32     bool unique() const { return 1 == fRefCnt; }
33 
34     // We allow this getter because this type is not thread-safe, meaning only one thread should
35     // have ownership and be manipulating the ref count or querying this.
refCnt()36     int refCnt() const { return fRefCnt; }
37 
ref()38     void ref() const {
39         // Once the ref cnt reaches zero it should never be ref'ed again.
40         SkASSERT(fRefCnt > 0);
41         ++fRefCnt;
42     }
43 
unref()44     void unref() const {
45         SkASSERT(fRefCnt > 0);
46         --fRefCnt;
47         if (0 == fRefCnt) {
48             GrTDeleteNonAtomicRef(static_cast<const TSubclass*>(this));
49             return;
50         }
51     }
52 
53 private:
54     mutable int32_t fRefCnt;
55 
56     using INHERITED = SkNoncopyable;
57 };
58 
GrTDeleteNonAtomicRef(const T * ref)59 template<typename T> inline void GrTDeleteNonAtomicRef(const T* ref) {
60     delete ref;
61 }
62 
63 #endif
64