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/**
* Copyright (C) 2014 MongoDB Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* 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 GNU Affero General 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 <string>
#include "mongo/base/string_data.h"
#include "mongo/db/catalog/database.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/util/timer.h"
namespace mongo {
class Collection;
/**
* RAII-style class, which acquires a lock on the specified database in the requested mode and
* obtains a reference to the database. Used as a shortcut for calls to dbHolder().get().
*
* It is guaranteed that the lock will be released when this object goes out of scope, therefore
* the database reference returned by this class should not be retained.
*/
class AutoGetDb {
MONGO_DISALLOW_COPYING(AutoGetDb);
public:
AutoGetDb(OperationContext* txn, StringData ns, LockMode mode);
Database* getDb() const {
return _db;
}
private:
const Lock::DBLock _dbLock;
Database* const _db;
};
/**
* RAII-style class, which acquires a locks on the specified database and collection in the
* requested mode and obtains references to both.
*
* It is guaranteed that locks will be released when this object goes out of scope, therefore
* the database and the collection references returned by this class should not be retained.
*/
class AutoGetCollection {
MONGO_DISALLOW_COPYING(AutoGetCollection);
public:
AutoGetCollection(OperationContext* txn, const NamespaceString& nss, LockMode mode);
Database* getDb() const {
return _autoDb.getDb();
}
Collection* getCollection() const {
return _coll;
}
private:
const AutoGetDb _autoDb;
const Lock::CollectionLock _collLock;
Collection* const _coll;
};
/**
* RAII-style class, which acquires a lock on the specified database in the requested mode and
* obtains a reference to the database, creating it was non-existing. Used as a shortcut for
* calls to dbHolder().openDb(), taking care of locking details. The requested mode must be
* MODE_IX or MODE_X. If the database needs to be created, the lock will automatically be
* reacquired as MODE_X.
*
* It is guaranteed that locks will be released when this object goes out of scope, therefore
* the database reference returned by this class should not be retained.
*/
class AutoGetOrCreateDb {
MONGO_DISALLOW_COPYING(AutoGetOrCreateDb);
public:
AutoGetOrCreateDb(OperationContext* txn, StringData ns, LockMode mode);
Database* getDb() const {
return _db;
}
bool justCreated() const {
return _justCreated;
}
Lock::DBLock& lock() {
return _dbLock;
}
private:
ScopedTransaction _transaction;
Lock::DBLock _dbLock; // not const, as we may need to relock for implicit create
Database* _db;
bool _justCreated;
};
/**
* RAII-style class, which would acquire the appropritate hierarchy of locks for obtaining
* a particular collection and would retrieve a reference to the collection. In addition, this
* utility validates the shard version for the specified namespace and sets the current operation's
* namespace for the duration while this object is alive.
*
* It is guaranteed that locks will be released when this object goes out of scope, therefore
* database and collection references returned by this class should not be retained.
*/
class AutoGetCollectionForRead {
MONGO_DISALLOW_COPYING(AutoGetCollectionForRead);
public:
AutoGetCollectionForRead(OperationContext* txn, const std::string& ns);
AutoGetCollectionForRead(OperationContext* txn, const NamespaceString& nss);
~AutoGetCollectionForRead();
Database* getDb() const {
return _autoColl->getDb();
}
Collection* getCollection() const {
return _autoColl->getCollection();
}
private:
void _init(const std::string& ns, StringData coll);
void _ensureMajorityCommittedSnapshotIsValid(const NamespaceString& nss);
const Timer _timer;
OperationContext* const _txn;
const ScopedTransaction _transaction;
boost::optional<AutoGetCollection> _autoColl;
};
/**
* Opens the database that we want to use and sets the appropriate namespace on the
* current operation.
*/
class OldClientContext {
MONGO_DISALLOW_COPYING(OldClientContext);
public:
/** this is probably what you want */
OldClientContext(OperationContext* txn, const std::string& ns, bool doVersion = true);
/**
* Below still calls _finishInit, but assumes database has already been acquired
* or just created.
*/
OldClientContext(OperationContext* txn, const std::string& ns, Database* db, bool justCreated);
~OldClientContext();
Database* db() const {
return _db;
}
const char* ns() const {
return _ns.c_str();
}
/** @return if the db was created by this OldClientContext */
bool justCreated() const {
return _justCreated;
}
private:
friend class CurOp;
void _finishInit();
void _checkNotStale() const;
bool _justCreated;
bool _doVersion;
const std::string _ns;
Database* _db;
OperationContext* _txn;
Timer _timer;
};
class OldClientWriteContext {
MONGO_DISALLOW_COPYING(OldClientWriteContext);
public:
OldClientWriteContext(OperationContext* opCtx, const std::string& ns);
Database* db() const {
return _c.db();
}
Collection* getCollection() const {
return _c.db()->getCollection(_nss.ns());
}
private:
OperationContext* const _txn;
const NamespaceString _nss;
AutoGetOrCreateDb _autodb;
Lock::CollectionLock _collk;
OldClientContext _c;
Collection* _collection;
};
} // namespace mongo
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