gecko/xpcom/glue/nsCategoryCache.h

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2012-05-21 04:12:37 -07:00
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#ifndef nsCategoryCache_h_
#define nsCategoryCache_h_
#include "mozilla/Attributes.h"
#include "nsICategoryManager.h"
#include "nsIObserver.h"
#include "nsISimpleEnumerator.h"
#include "nsISupportsPrimitives.h"
#include "nsServiceManagerUtils.h"
#include "nsAutoPtr.h"
#include "nsCOMArray.h"
#include "nsInterfaceHashtable.h"
#include "nsXPCOM.h"
class NS_COM_GLUE nsCategoryObserver MOZ_FINAL : public nsIObserver
{
public:
nsCategoryObserver(const char* aCategory);
~nsCategoryObserver();
void ListenerDied();
nsInterfaceHashtable<nsCStringHashKey, nsISupports>& GetHash()
{
return mHash;
}
NS_DECL_ISUPPORTS
NS_DECL_NSIOBSERVER
private:
void RemoveObservers();
nsInterfaceHashtable<nsCStringHashKey, nsISupports> mHash;
nsCString mCategory;
bool mObserversRemoved;
};
/**
* This is a helper class that caches services that are registered in a certain
* category. The intended usage is that a service stores a variable of type
* nsCategoryCache<nsIFoo> in a member variable, where nsIFoo is the interface
* that these services should implement. The constructor of this class should
* then get the name of the category.
*/
template<class T>
class nsCategoryCache MOZ_FINAL
{
public:
explicit nsCategoryCache(const char* aCategory)
: mCategoryName(aCategory)
{
}
~nsCategoryCache() {
if (mObserver)
mObserver->ListenerDied();
}
void GetEntries(nsCOMArray<T>& result) {
// Lazy initialization, so that services in this category can't
// cause reentrant getService (bug 386376)
if (!mObserver)
mObserver = new nsCategoryObserver(mCategoryName.get());
mObserver->GetHash().EnumerateRead(EntriesToArray, &result);
}
private:
// Not to be implemented
nsCategoryCache(const nsCategoryCache<T>&);
static PLDHashOperator EntriesToArray(const nsACString& key,
nsISupports* entry, void* arg)
{
nsCOMArray<T>& entries = *static_cast<nsCOMArray<T>*>(arg);
nsCOMPtr<T> service = do_QueryInterface(entry);
if (service) {
entries.AppendObject(service);
}
return PL_DHASH_NEXT;
}
nsCString mCategoryName;
nsRefPtr<nsCategoryObserver> mObserver;
};
#endif