diff options
author | reed <reed@chromium.org> | 2015-08-15 08:46:27 -0700 |
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committer | Commit bot <commit-bot@chromium.org> | 2015-08-15 08:46:27 -0700 |
commit | fb28cd2b13d76c324570341e1155aaadc1b532b6 (patch) | |
tree | 643c879f8dbb89e89dd65d5dba720a7eca5dc7b3 /include/private/SkWeakRefCnt.h | |
parent | bb886749feb444edfd8fbf053a9ea815e3605f8a (diff) |
Revert[7] "move some public headers into private"
This reverts commit e02716908fe82c7c4ae9b415793277620a22bcd6.
BUG=skia:
TBR=
Review URL: https://codereview.chromium.org/1300523002
Diffstat (limited to 'include/private/SkWeakRefCnt.h')
-rw-r--r-- | include/private/SkWeakRefCnt.h | 159 |
1 files changed, 0 insertions, 159 deletions
diff --git a/include/private/SkWeakRefCnt.h b/include/private/SkWeakRefCnt.h deleted file mode 100644 index a550951970..0000000000 --- a/include/private/SkWeakRefCnt.h +++ /dev/null @@ -1,159 +0,0 @@ -/* - * Copyright 2012 Google Inc. - * - * Use of this source code is governed by a BSD-style license that can be - * found in the LICENSE file. - */ - -#ifndef SkWeakRefCnt_DEFINED -#define SkWeakRefCnt_DEFINED - -#include "SkRefCnt.h" -#include "SkAtomics.h" - -/** \class SkWeakRefCnt - - SkWeakRefCnt is the base class for objects that may be shared by multiple - objects. When an existing strong owner wants to share a reference, it calls - ref(). When a strong owner wants to release its reference, it calls - unref(). When the shared object's strong reference count goes to zero as - the result of an unref() call, its (virtual) weak_dispose method 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. - - In addition to strong ownership, an owner may instead obtain a weak - reference by calling weak_ref(). A call to weak_ref() must be balanced by a - call to weak_unref(). To obtain a strong reference from a weak reference, - call try_ref(). If try_ref() returns true, the owner's pointer is now also - a strong reference on which unref() must be called. Note that this does not - affect the original weak reference, weak_unref() must still be called. When - the weak reference count goes to zero, the object is deleted. While the - weak reference count is positive and the strong reference count is zero the - object still exists, but will be in the disposed state. It is up to the - object to define what this means. - - Note that a strong reference implicitly implies a weak reference. As a - result, it is allowable for the owner of a strong ref to call try_ref(). - This will have the same effect as calling ref(), but may be more expensive. - - Example: - - SkWeakRefCnt myRef = strongRef.weak_ref(); - ... // strongRef.unref() may or may not be called - if (myRef.try_ref()) { - ... // use myRef - myRef.unref(); - } else { - // myRef is in the disposed state - } - myRef.weak_unref(); -*/ -class SK_API SkWeakRefCnt : public SkRefCnt { -public: - /** Default construct, initializing the reference counts to 1. - The strong references collectively hold one weak reference. When the - strong reference count goes to zero, the collectively held weak - reference is released. - */ - SkWeakRefCnt() : SkRefCnt(), fWeakCnt(1) {} - - /** Destruct, asserting that the weak reference count is 1. - */ - virtual ~SkWeakRefCnt() { -#ifdef SK_DEBUG - SkASSERT(fWeakCnt == 1); - fWeakCnt = 0; -#endif - } - - /** Return the weak reference count. - */ - int32_t getWeakCnt() const { return fWeakCnt; } - -#ifdef SK_DEBUG - void validate() const { - this->INHERITED::validate(); - SkASSERT(fWeakCnt > 0); - } -#endif - - /** Creates a strong reference from a weak reference, if possible. The - caller must already be an owner. If try_ref() returns true the owner - is in posession of an additional strong reference. Both the original - reference and new reference must be properly unreferenced. If try_ref() - returns false, no strong reference could be created and the owner's - reference is in the same state as before the call. - */ - bool SK_WARN_UNUSED_RESULT try_ref() const { - if (sk_atomic_conditional_inc(&fRefCnt) != 0) { - // Acquire barrier (L/SL), if not provided above. - // Prevents subsequent code from happening before the increment. - sk_membar_acquire__after_atomic_conditional_inc(); - return true; - } - return false; - } - - /** Increment the weak reference count. Must be balanced by a call to - weak_unref(). - */ - void weak_ref() const { - SkASSERT(fRefCnt > 0); - SkASSERT(fWeakCnt > 0); - sk_atomic_inc(&fWeakCnt); // No barrier required. - } - - /** Decrement the weak reference count. If the weak 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 weak_unref() const { - SkASSERT(fWeakCnt > 0); - // Release barrier (SL/S), if not provided below. - if (sk_atomic_dec(&fWeakCnt) == 1) { - // Acquire barrier (L/SL), if not provided above. - // Prevents code in destructor from happening before the decrement. - sk_membar_acquire__after_atomic_dec(); -#ifdef SK_DEBUG - // so our destructor won't complain - fWeakCnt = 1; -#endif - this->INHERITED::internal_dispose(); - } - } - - /** Returns true if there are no strong references to the object. When this - is the case all future calls to try_ref() will return false. - */ - bool weak_expired() const { - return fRefCnt == 0; - } - -protected: - /** Called when the strong reference count goes to zero. This allows the - object to free any resources it may be holding. Weak references may - still exist and their level of allowed access to the object is defined - by the object's class. - */ - virtual void weak_dispose() const { - } - -private: - /** Called when the strong reference count goes to zero. Calls weak_dispose - on the object and releases the implicit weak reference held - collectively by the strong references. - */ - void internal_dispose() const override { - weak_dispose(); - weak_unref(); - } - - /* Invariant: fWeakCnt = #weak + (fRefCnt > 0 ? 1 : 0) */ - mutable int32_t fWeakCnt; - - typedef SkRefCnt INHERITED; -}; - -#endif |