Index: include/core/SkWeakRefCnt.h |
diff --git a/include/core/SkWeakRefCnt.h b/include/core/SkWeakRefCnt.h |
deleted file mode 100644 |
index a550951970c925eb93d86bb6aa9869c52fa054ca..0000000000000000000000000000000000000000 |
--- a/include/core/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 |