gfx/2d/GenericRefCounted.h@6474c204b198 (annotated)
gfx/2d/GenericRefCounted.h
Wed, 31 Dec 2014 06:09:35 +0100
- author
- Michael Schloh von Bennewitz <michael@schloh.com>
- date
- Wed, 31 Dec 2014 06:09:35 +0100
- changeset 0
- 6474c204b198
- permissions
- -rw-r--r--
Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.
| michael@0 | 1 | /* -*- Mode: C++; tab-width: 20; indent-tabs-mode: nil; c-basic-offset: 2 -*- |
| michael@0 | 2 | * This Source Code Form is subject to the terms of the Mozilla Public |
| michael@0 | 3 | * License, v. 2.0. If a copy of the MPL was not distributed with this |
| michael@0 | 4 | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ |
| michael@0 | 5 | |
| michael@0 | 6 | // This header provides virtual, non-templated alternatives to MFBT's RefCounted<T>. |
| michael@0 | 7 | // It intentionally uses MFBT coding style with the intention of moving there |
| michael@0 | 8 | // should there be other use cases for it. |
| michael@0 | 9 | |
| michael@0 | 10 | #ifndef MOZILLA_GENERICREFCOUNTED_H_ |
| michael@0 | 11 | #define MOZILLA_GENERICREFCOUNTED_H_ |
| michael@0 | 12 | |
| michael@0 | 13 | #include "mozilla/RefPtr.h" |
| michael@0 | 14 | |
| michael@0 | 15 | namespace mozilla { |
| michael@0 | 16 | |
| michael@0 | 17 | /** |
| michael@0 | 18 | * Common base class for GenericRefCounted and GenericAtomicRefCounted. |
| michael@0 | 19 | * |
| michael@0 | 20 | * Having this shared base class, common to both the atomic and non-atomic |
| michael@0 | 21 | * cases, allows to have RefPtr's that don't care about whether the |
| michael@0 | 22 | * objects they're managing have atomic refcounts or not. |
| michael@0 | 23 | */ |
| michael@0 | 24 | class GenericRefCountedBase |
| michael@0 | 25 | { |
| michael@0 | 26 | protected: |
| michael@0 | 27 | virtual ~GenericRefCountedBase() {}; |
| michael@0 | 28 | |
| michael@0 | 29 | public: |
| michael@0 | 30 | // AddRef() and Release() method names are for compatibility with nsRefPtr. |
| michael@0 | 31 | virtual void AddRef() = 0; |
| michael@0 | 32 | |
| michael@0 | 33 | virtual void Release() = 0; |
| michael@0 | 34 | |
| michael@0 | 35 | // ref() and deref() method names are for compatibility with wtf::RefPtr. |
| michael@0 | 36 | // No virtual keywords here: if a subclass wants to override the refcounting |
| michael@0 | 37 | // mechanism, it is welcome to do so by overriding AddRef() and Release(). |
| michael@0 | 38 | void ref() { AddRef(); } |
| michael@0 | 39 | void deref() { Release(); } |
| michael@0 | 40 | |
| michael@0 | 41 | #ifdef MOZ_REFCOUNTED_LEAK_CHECKING |
| michael@0 | 42 | virtual const char* typeName() const = 0; |
| michael@0 | 43 | virtual size_t typeSize() const = 0; |
| michael@0 | 44 | #endif |
| michael@0 | 45 | }; |
| michael@0 | 46 | |
| michael@0 | 47 | namespace detail { |
| michael@0 | 48 | |
| michael@0 | 49 | template<RefCountAtomicity Atomicity> |
| michael@0 | 50 | class GenericRefCounted : public GenericRefCountedBase |
| michael@0 | 51 | { |
| michael@0 | 52 | protected: |
| michael@0 | 53 | GenericRefCounted() : refCnt(0) { } |
| michael@0 | 54 | |
| michael@0 | 55 | virtual ~GenericRefCounted() { |
| michael@0 | 56 | MOZ_ASSERT(refCnt == detail::DEAD); |
| michael@0 | 57 | } |
| michael@0 | 58 | |
| michael@0 | 59 | public: |
| michael@0 | 60 | virtual void AddRef() { |
| michael@0 | 61 | // Note: this method must be thread safe for GenericAtomicRefCounted. |
| michael@0 | 62 | MOZ_ASSERT(int32_t(refCnt) >= 0); |
| michael@0 | 63 | #ifndef MOZ_REFCOUNTED_LEAK_CHECKING |
| michael@0 | 64 | ++refCnt; |
| michael@0 | 65 | #else |
| michael@0 | 66 | const char* type = typeName(); |
| michael@0 | 67 | uint32_t size = typeSize(); |
| michael@0 | 68 | const void* ptr = this; |
| michael@0 | 69 | MozRefCountType cnt = ++refCnt; |
| michael@0 | 70 | detail::RefCountLogger::logAddRef(ptr, cnt, type, size); |
| michael@0 | 71 | #endif |
| michael@0 | 72 | } |
| michael@0 | 73 | |
| michael@0 | 74 | virtual void Release() { |
| michael@0 | 75 | // Note: this method must be thread safe for GenericAtomicRefCounted. |
| michael@0 | 76 | MOZ_ASSERT(int32_t(refCnt) > 0); |
| michael@0 | 77 | #ifndef MOZ_REFCOUNTED_LEAK_CHECKING |
| michael@0 | 78 | MozRefCountType cnt = --refCnt; |
| michael@0 | 79 | #else |
| michael@0 | 80 | const char* type = typeName(); |
| michael@0 | 81 | const void* ptr = this; |
| michael@0 | 82 | MozRefCountType cnt = --refCnt; |
| michael@0 | 83 | // Note: it's not safe to touch |this| after decrementing the refcount, |
| michael@0 | 84 | // except for below. |
| michael@0 | 85 | detail::RefCountLogger::logRelease(ptr, cnt, type); |
| michael@0 | 86 | #endif |
| michael@0 | 87 | if (0 == cnt) { |
| michael@0 | 88 | // Because we have atomically decremented the refcount above, only |
| michael@0 | 89 | // one thread can get a 0 count here, so as long as we can assume that |
| michael@0 | 90 | // everything else in the system is accessing this object through |
| michael@0 | 91 | // RefPtrs, it's safe to access |this| here. |
| michael@0 | 92 | #ifdef DEBUG |
| michael@0 | 93 | refCnt = detail::DEAD; |
| michael@0 | 94 | #endif |
| michael@0 | 95 | delete this; |
| michael@0 | 96 | } |
| michael@0 | 97 | } |
| michael@0 | 98 | |
| michael@0 | 99 | MozRefCountType refCount() const { return refCnt; } |
| michael@0 | 100 | bool hasOneRef() const { |
| michael@0 | 101 | MOZ_ASSERT(refCnt > 0); |
| michael@0 | 102 | return refCnt == 1; |
| michael@0 | 103 | } |
| michael@0 | 104 | |
| michael@0 | 105 | private: |
| michael@0 | 106 | typename Conditional<Atomicity == AtomicRefCount, Atomic<MozRefCountType>, MozRefCountType>::Type refCnt; |
| michael@0 | 107 | }; |
| michael@0 | 108 | |
| michael@0 | 109 | } // namespace detail |
| michael@0 | 110 | |
| michael@0 | 111 | /** |
| michael@0 | 112 | * This reference-counting base class is virtual instead of |
| michael@0 | 113 | * being templated, which is useful in cases where one needs |
| michael@0 | 114 | * genericity at binary code level, but comes at the cost |
| michael@0 | 115 | * of a moderate performance and size overhead, like anything virtual. |
| michael@0 | 116 | */ |
| michael@0 | 117 | class GenericRefCounted : public detail::GenericRefCounted<detail::NonAtomicRefCount> |
| michael@0 | 118 | { |
| michael@0 | 119 | }; |
| michael@0 | 120 | |
| michael@0 | 121 | /** |
| michael@0 | 122 | * GenericAtomicRefCounted is like GenericRefCounted, with an atomically updated |
| michael@0 | 123 | * reference counter. |
| michael@0 | 124 | */ |
| michael@0 | 125 | class GenericAtomicRefCounted : public detail::GenericRefCounted<detail::AtomicRefCount> |
| michael@0 | 126 | { |
| michael@0 | 127 | }; |
| michael@0 | 128 | |
| michael@0 | 129 | } // namespace mozilla |
| michael@0 | 130 | |
| michael@0 | 131 | #endif |
