| /* |
| * Copyright (C) 2006 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| #ifndef SkRefCnt_DEFINED |
| #define SkRefCnt_DEFINED |
| |
| #include "SkThread.h" |
| |
| /** \class SkRefCnt |
| |
| SkRefCnt is the base class for objects that may be shared by multiple |
| objects. When a new owner wants a reference, it calls ref(). When an owner |
| wants to release its reference, it calls unref(). When the shared object's |
| reference count goes to zero as the result of an unref() call, its (virtual) |
| destructor is called. It is an error for the destructor to be called |
| explicitly (or via the object going out of scope on the stack or calling |
| delete) if getRefCnt() > 1. |
| */ |
| class SkRefCnt : SkNoncopyable { |
| public: |
| /** Default construct, initializing the reference count to 1. |
| */ |
| SkRefCnt() : fRefCnt(1) {} |
| |
| /** Destruct, asserting that the reference count is 1. |
| */ |
| virtual ~SkRefCnt() { SkASSERT(fRefCnt == 1); } |
| |
| /** Return the reference count. |
| */ |
| int32_t getRefCnt() const { return fRefCnt; } |
| |
| /** Increment the reference count. Must be balanced by a call to unref(). |
| */ |
| void ref() const { |
| SkASSERT(fRefCnt > 0); |
| sk_atomic_inc(&fRefCnt); |
| } |
| |
| /** Decrement the reference count. If the reference count is 1 before the |
| decrement, then call delete on the object. Note that if this is the |
| case, then the object needs to have been allocated via new, and not on |
| the stack. |
| */ |
| void unref() const { |
| SkASSERT(fRefCnt > 0); |
| if (sk_atomic_dec(&fRefCnt) == 1) { |
| fRefCnt = 1; // so our destructor won't complain |
| SkDELETE(this); |
| } |
| } |
| |
| /** Helper version of ref(), that first checks to see if this is not null. |
| If this is null, then do nothing. |
| */ |
| void safeRef() const { |
| if (this) { |
| this->ref(); |
| } |
| } |
| |
| /** Helper version of unref(), that first checks to see if this is not null. |
| If this is null, then do nothing. |
| */ |
| void safeUnref() const { |
| if (this) { |
| this->unref(); |
| } |
| } |
| |
| private: |
| mutable int32_t fRefCnt; |
| }; |
| |
| /** \class SkAutoUnref |
| |
| SkAutoUnref is a stack-helper class that will automatically call unref() on |
| the object it points to when the SkAutoUnref object goes out of scope. |
| If obj is null, do nothing. |
| */ |
| class SkAutoUnref : SkNoncopyable { |
| public: |
| SkAutoUnref(SkRefCnt* obj) : fObj(obj) {} |
| ~SkAutoUnref(); |
| |
| SkRefCnt* get() const { return fObj; } |
| |
| /** If the hosted object is null, do nothing and return false, else call |
| ref() on it and return true |
| */ |
| bool ref(); |
| |
| /** If the hosted object is null, do nothing and return false, else call |
| unref() on it, set its reference to null, and return true |
| */ |
| bool unref(); |
| |
| /** If the hosted object is null, do nothing and return NULL, else call |
| unref() on it, set its reference to null, and return the object |
| */ |
| SkRefCnt* detach(); |
| |
| private: |
| SkRefCnt* fObj; |
| }; |
| |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| /** Helper macro to safely assign one SkRefCnt[TS]* to another, checking for |
| null in on each side of the assignment, and ensuring that ref() is called |
| before unref(), in case the two pointers point to the same object. |
| */ |
| #define SkRefCnt_SafeAssign(dst, src) \ |
| do { \ |
| if (src) src->ref(); \ |
| if (dst) dst->unref(); \ |
| dst = src; \ |
| } while (0) |
| |
| |
| /** Check if the argument is non-null, and if so, call obj->ref() |
| */ |
| template <typename T> static inline void SkSafeRef(T* obj) { |
| if (obj) { |
| obj->ref(); |
| } |
| } |
| |
| /** Check if the argument is non-null, and if so, call obj->unref() |
| */ |
| template <typename T> static inline void SkSafeUnref(T* obj) { |
| if (obj) { |
| obj->unref(); |
| } |
| } |
| |
| #endif |
| |