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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <list>
#include <map>
#include "mongo/db/namespace_string.h"
#include "mongo/platform/mutex.h"
#include "mongo/util/concurrency/notification.h"
namespace mongo {
class OperationContext;
/**
* Map of one-snot notifications for changes to a particular namespace.
*/
class NamespaceMetadataChangeNotifications {
NamespaceMetadataChangeNotifications(const NamespaceMetadataChangeNotifications&) = delete;
NamespaceMetadataChangeNotifications& operator=(const NamespaceMetadataChangeNotifications&) =
delete;
struct NotificationToken;
friend class ScopedNotification;
public:
NamespaceMetadataChangeNotifications();
~NamespaceMetadataChangeNotifications();
/**
* Holds the token for a registered metadata change notification and unregisters it when it gets
* out of scope, if it has not been signalled yet.
*/
class ScopedNotification {
ScopedNotification(const ScopedNotification&) = delete;
ScopedNotification& operator=(const ScopedNotification&) = delete;
public:
ScopedNotification(NamespaceMetadataChangeNotifications* notifications,
std::shared_ptr<NotificationToken> token)
: _notifications(notifications), _token(std::move(token)) {}
ScopedNotification(ScopedNotification&&) = default;
~ScopedNotification() {
if (_token) {
_notifications->_unregisterNotificationToken(std::move(_token));
}
}
void get(OperationContext* opCtx) {
_token->notify.get(opCtx);
}
private:
NamespaceMetadataChangeNotifications* _notifications;
std::shared_ptr<NamespaceMetadataChangeNotifications::NotificationToken> _token;
};
/**
* Creates and registers a new pending notification for the specified namespace.
*/
ScopedNotification createNotification(const NamespaceString& nss);
/**
* Goes through all registered notifications for this namespace signals them and removes them
* from the registry atomically.
*/
void notifyChange(const NamespaceString& nss);
private:
using NotificationsList = std::list<std::shared_ptr<NotificationToken>>;
struct NotificationToken {
NotificationToken(NamespaceString inNss) : nss(std::move(inNss)) {}
NamespaceString nss;
Notification<void> notify;
boost::optional<NamespaceMetadataChangeNotifications::NotificationsList::iterator>
itToErase;
};
void _unregisterNotificationToken(std::shared_ptr<NotificationToken> token);
Mutex _mutex = MONGO_MAKE_LATCH("NamespaceMetadataChangeNotifications::_mutex");
std::map<NamespaceString, NotificationsList> _notificationsList;
};
} // namespace mongo
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