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Unified Diff: include/private/SkWeakRefCnt.h

Issue 1300523002: Revert[7] "move some public headers into private" (Closed) Base URL: https://skia.googlesource.com/skia.git@master
Patch Set: Created 5 years, 4 months ago
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Index: include/private/SkWeakRefCnt.h
diff --git a/include/private/SkWeakRefCnt.h b/include/private/SkWeakRefCnt.h
deleted file mode 100644
index a550951970c925eb93d86bb6aa9869c52fa054ca..0000000000000000000000000000000000000000
--- 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
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