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bd0f2fccab
The virtual call to this method shows up in profiles, and therefore would be nice to avoid if possible. We can do that by making nsIWeakReference hold the weak reference itself and therefore implementing a non-virtual QueryReferent method.
122 lines
3.6 KiB
Plaintext
122 lines
3.6 KiB
Plaintext
/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "nsISupports.idl"
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%{C++
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#include "mozilla/Attributes.h"
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#include "mozilla/MemoryReporting.h"
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// For MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED.
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#include "nsDebug.h"
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#ifdef MOZ_THREAD_SAFETY_OWNERSHIP_CHECKS_SUPPORTED
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#define MOZ_WEAKREF_DECL_OWNINGTHREAD nsAutoOwningThread _mWeakRefOwningThread;
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#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD \
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_mWeakRefOwningThread.AssertOwnership("nsWeakReference not thread-safe")
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#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(that) \
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(that)->_mWeakRefOwningThread.AssertOwnership("nsWeakReference not thread-safe")
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#else
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#define MOZ_WEAKREF_DECL_OWNINGTHREAD
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#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD do { } while (false)
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#define MOZ_WEAKREF_ASSERT_OWNINGTHREAD_DELEGATED(that) do { } while (false)
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#endif
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%}
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/**
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* An instance of |nsIWeakReference| is a proxy object that cooperates with
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* its referent to give clients a non-owning, non-dangling reference. Clients
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* own the proxy, and should generally manage it with an |nsCOMPtr| (see the
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* type |nsWeakPtr| for a |typedef| name that stands out) as they would any
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* other XPCOM object. The |QueryReferent| member function provides a
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* (hopefully short-lived) owning reference on demand, through which clients
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* can get useful access to the referent, while it still exists.
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*
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* @version 1.0
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* @see nsISupportsWeakReference
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* @see nsWeakReference
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* @see nsWeakPtr
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*/
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[scriptable, uuid(9188bc85-f92e-11d2-81ef-0060083a0bcf)]
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interface nsIWeakReference : nsISupports
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{
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/**
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* |QueryReferent| queries the referent, if it exists, and like |QueryInterface|, produces
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* an owning reference to the desired interface. It is designed to look and act exactly
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* like (a proxied) |QueryInterface|. Don't hold on to the produced interface permanently;
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* that would defeat the purpose of using a non-owning |nsIWeakReference| in the first place.
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*/
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[binaryname(QueryReferentFromScript)]
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void QueryReferent( in nsIIDRef uuid, [iid_is(uuid), retval] out nsQIResult result );
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%{C++
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virtual size_t SizeOfOnlyThis(mozilla::MallocSizeOf aMallocSizeOf) const = 0;
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/**
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* Returns true if the referring object is alive. Otherwise, false.
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*/
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bool IsAlive() const
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{
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return !!mObject;
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}
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nsresult QueryReferent(const nsIID& aIID, void** aInstancePtr);
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protected:
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friend class nsSupportsWeakReference;
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nsIWeakReference(nsISupports* aObject)
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: mObject(aObject)
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{
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}
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nsIWeakReference() = delete;
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MOZ_WEAKREF_DECL_OWNINGTHREAD
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// The object we're holding a weak reference to.
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nsISupports* MOZ_NON_OWNING_REF mObject;
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%}
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};
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/**
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* |nsISupportsWeakReference| is a factory interface which produces appropriate
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* instances of |nsIWeakReference|. Weak references in this scheme can only be
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* produced for objects that implement this interface.
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*
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* @version 1.0
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* @see nsIWeakReference
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* @see nsSupportsWeakReference
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*/
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[scriptable, uuid(9188bc86-f92e-11d2-81ef-0060083a0bcf)]
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interface nsISupportsWeakReference : nsISupports
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{
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/**
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* |GetWeakReference| produces an appropriate instance of |nsIWeakReference|.
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* As with all good XPCOM `getters', you own the resulting interface and should
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* manage it with an |nsCOMPtr|.
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*
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* @see nsIWeakReference
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* @see nsWeakPtr
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* @see nsCOMPtr
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*/
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nsIWeakReference GetWeakReference();
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};
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%{C++
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#ifdef MOZILLA_INTERNAL_API
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#include "nsIWeakReferenceUtils.h"
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#endif
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%}
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