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/**
* Copyright (C) 2017 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 <set>
#include <string>
#include "mongo/base/string_data.h"
#include "mongo/db/namespace_string.h"
#include "mongo/stdx/functional.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/concurrency/mutex.h"
#include "mongo/util/string_map.h"
namespace mongo {
class Database;
class OperationContext;
/**
* Registry of opened databases.
*/
class DatabaseHolder {
public:
class Impl {
public:
virtual ~Impl() = 0;
virtual Database* get(OperationContext* opCtx, StringData ns) const = 0;
virtual Database* openDb(OperationContext* opCtx, StringData ns, bool* justCreated) = 0;
virtual void close(OperationContext* opCtx, StringData ns, const std::string& reason) = 0;
virtual void closeAll(OperationContext* opCtx, const std::string& reason) = 0;
virtual std::set<std::string> getNamesWithConflictingCasing(StringData name) = 0;
};
private:
static std::unique_ptr<Impl> makeImpl();
public:
using factory_function_type = decltype(makeImpl);
static void registerFactory(stdx::function<factory_function_type> factory);
inline ~DatabaseHolder() = default;
inline explicit DatabaseHolder() : _pimpl(makeImpl()) {}
/**
* Retrieves an already opened database or returns NULL. Must be called with the database
* locked in at least IS-mode.
*/
inline Database* get(OperationContext* const opCtx, const StringData ns) const {
return this->_impl().get(opCtx, ns);
}
/**
* Retrieves a database reference if it is already opened, or opens it if it hasn't been
* opened/created yet. Must be called with the database locked in X-mode.
*
* @param justCreated Returns whether the database was newly created (true) or it already
* existed (false). Can be NULL if this information is not necessary.
*/
inline Database* openDb(OperationContext* const opCtx,
const StringData ns,
bool* const justCreated = nullptr) {
return this->_impl().openDb(opCtx, ns, justCreated);
}
/**
* Closes the specified database. Must be called with the database locked in X-mode.
* No background jobs must be in progress on the database when this function is called.
*/
inline void close(OperationContext* const opCtx,
const StringData ns,
const std::string& reason) {
return this->_impl().close(opCtx, ns, reason);
}
/**
* Closes all opened databases. Must be called with the global lock acquired in X-mode.
* Will uassert if any background jobs are running when this function is called.
*
* @param reason The reason for close.
*/
inline void closeAll(OperationContext* const opCtx, const std::string& reason) {
this->_impl().closeAll(opCtx, reason);
}
/**
* Returns the set of existing database names that differ only in casing.
*/
inline std::set<std::string> getNamesWithConflictingCasing(const StringData name) {
return this->_impl().getNamesWithConflictingCasing(name);
}
private:
// This structure exists to give us a customization point to decide how to force users of this
// class to depend upon the corresponding `database_holder.cpp` Translation Unit (TU). All
// public forwarding functions call `_impl(), and `_impl` creates an instance of this structure.
struct TUHook {
static void hook() noexcept;
explicit inline TUHook() noexcept {
if (kDebugBuild)
this->hook();
}
};
inline const Impl& _impl() const {
TUHook{};
return *this->_pimpl;
}
inline Impl& _impl() {
TUHook{};
return *this->_pimpl;
}
std::unique_ptr<Impl> _pimpl;
};
extern DatabaseHolder& dbHolder();
extern void registerDbHolderImpl(stdx::function<decltype(dbHolder)> impl);
} // namespace mongo
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