Revert[3] "move some public headers into private"

include/private/SkWeakRefCnt.h

-/*
- * 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