forked from mirrors/gecko-dev
7aa3564a28
Much like the component manager, many of the strings that we use for category manager entries are statically allocated. There's no need to duplicate these strings. This patch changes the category manager APIs to take nsACStrings rather than raw pointers, and to pass literal nsCStrings when we know we have a literal string to begin with. When adding the category entry, it then skips making copies of any strings with the LITERAL flag. MozReview-Commit-ID: EJEcYSdNMWs *** amend-catman --HG-- extra : source : aa9a8f18e98f930a3d8359565eef02f3f6efc5f9 extra : absorb_source : 81a22ab26ee8017ac43321ff2c987d8096182d37
139 lines
3.5 KiB
C++
139 lines
3.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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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#ifndef nsCategoryCache_h_
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#define nsCategoryCache_h_
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#include "mozilla/Attributes.h"
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#include "nsICategoryManager.h"
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#include "nsIObserver.h"
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#include "nsISimpleEnumerator.h"
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#include "nsISupportsPrimitives.h"
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#include "nsServiceManagerUtils.h"
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#include "nsAutoPtr.h"
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#include "nsCOMArray.h"
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#include "nsInterfaceHashtable.h"
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#include "nsXPCOM.h"
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#include "MainThreadUtils.h"
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class nsCategoryObserver final : public nsIObserver
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{
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~nsCategoryObserver();
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public:
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explicit nsCategoryObserver(const nsACString& aCategory);
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void ListenerDied();
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void SetListener(void(aCallback)(void*), void* aClosure);
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nsInterfaceHashtable<nsCStringHashKey, nsISupports>& GetHash()
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{
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return mHash;
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}
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NS_DECL_ISUPPORTS
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NS_DECL_NSIOBSERVER
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private:
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void RemoveObservers();
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nsInterfaceHashtable<nsCStringHashKey, nsISupports> mHash;
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nsCString mCategory;
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void(*mCallback)(void*);
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void *mClosure;
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bool mObserversRemoved;
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};
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/**
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* This is a helper class that caches services that are registered in a certain
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* category. The intended usage is that a service stores a variable of type
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* nsCategoryCache<nsIFoo> in a member variable, where nsIFoo is the interface
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* that these services should implement. The constructor of this class should
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* then get the name of the category.
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*/
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template<class T>
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class nsCategoryCache final
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{
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public:
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explicit nsCategoryCache(const char* aCategory)
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: mCategoryName(aCategory)
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{
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MOZ_ASSERT(NS_IsMainThread());
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}
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~nsCategoryCache()
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{
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MOZ_ASSERT(NS_IsMainThread());
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if (mObserver) {
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mObserver->ListenerDied();
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}
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}
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void GetEntries(nsCOMArray<T>& aResult)
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{
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MOZ_ASSERT(NS_IsMainThread());
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LazyInit();
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AddEntries(aResult);
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}
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/**
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* This function returns an nsCOMArray of interface pointers to the cached
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* category enries for the requested category. This was added in order to be
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* used in call sites where the overhead of excessive allocations can be
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* unacceptable. See bug 1360971 for an example.
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*/
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const nsCOMArray<T>& GetCachedEntries()
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{
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MOZ_ASSERT(NS_IsMainThread());
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LazyInit();
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if (mCachedEntries.IsEmpty()) {
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AddEntries(mCachedEntries);
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}
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return mCachedEntries;
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}
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private:
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void LazyInit()
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{
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// Lazy initialization, so that services in this category can't
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// cause reentrant getService (bug 386376)
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if (!mObserver) {
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mObserver = new nsCategoryObserver(mCategoryName);
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mObserver->SetListener(nsCategoryCache<T>::OnCategoryChanged, this);
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}
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}
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void AddEntries(nsCOMArray<T>& aResult)
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{
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for (auto iter = mObserver->GetHash().Iter(); !iter.Done(); iter.Next()) {
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nsISupports* entry = iter.UserData();
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nsCOMPtr<T> service = do_QueryInterface(entry);
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if (service) {
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aResult.AppendElement(service.forget());
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}
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}
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}
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static void OnCategoryChanged(void* aClosure)
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{
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MOZ_ASSERT(NS_IsMainThread());
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auto self = static_cast<nsCategoryCache<T>*>(aClosure);
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self->mCachedEntries.Clear();
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}
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private:
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// Not to be implemented
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nsCategoryCache(const nsCategoryCache<T>&);
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nsCString mCategoryName;
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RefPtr<nsCategoryObserver> mObserver;
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nsCOMArray<T> mCachedEntries;
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};
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#endif
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