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/**
* Copyright (C) 2010-2015 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 <vector>
#include "mongo/db/server_options.h"
#include "mongo/s/query/cluster_cursor_manager.h"
#include "mongo/stdx/memory.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/concurrency/rwlock.h"
namespace mongo {
class BSONObj;
class CatalogCache;
class CatalogManager;
class DBConfig;
class OperationContext;
class SettingsType;
class ShardRegistry;
template <typename T>
class StatusWith;
/**
* Holds the global sharding context. Single instance exists for a running server. Exists on
* both MongoD and MongoS.
*/
class Grid {
public:
class CatalogManagerGuard;
Grid();
/**
* Called at startup time so the global sharding services can be set. This method must be called
* once and once only for the lifetime of the service.
*
* NOTE: Unit-tests are allowed to call it more than once, provided they reset the object's
* state using clearForUnitTests.
*/
void init(std::unique_ptr<CatalogManager> catalogManager,
std::unique_ptr<ShardRegistry> shardRegistry,
std::unique_ptr<ClusterCursorManager> cursorManager);
/**
* Implicitly creates the specified database as non-sharded.
*/
StatusWith<std::shared_ptr<DBConfig>> implicitCreateDb(OperationContext* txn,
const std::string& dbName);
/**
* @return true if shards and config servers are allowed to use 'localhost' in address
*/
bool allowLocalHost() const;
/**
* @param whether to allow shards and config servers to use 'localhost' in address
*/
void setAllowLocalHost(bool allow);
/**
* Returns true if the balancer should be running. Caller is responsible
* for making sure settings has the balancer key.
*/
bool shouldBalance(const SettingsType& balancerSettings) const;
/**
* Returns true if the config server settings indicate that the balancer should be active.
*/
bool getConfigShouldBalance(OperationContext* txn) const;
Grid::CatalogManagerGuard catalogManager(OperationContext* txn);
Grid::CatalogManagerGuard catalogManager(); // TODO(spencer): remove
CatalogCache* catalogCache() {
return _catalogCache.get();
}
ShardRegistry* shardRegistry() {
return _shardRegistry.get();
}
ClusterCursorManager* getCursorManager() {
return _cursorManager.get();
}
/**
* Compares desiredMode against _catalogManagerMode. Returns Status::OK() if they match,
* returns ErrorCodes::IncompatibleCatalogManger if desiredMode is CSRS and the current mode is
* SCCC. If desiredMode is SCCC and current mode is CSRS returns InvalidOperation as we do not
* support downgrade.
* TODO(spencer): Support downgrade.
*/
Status checkIfCatalogNeedsSwapping(ServerGlobalParams::ConfigServerMode desiredMode);
/**
* Clears the grid object so that it can be reused between test executions. This will not
* be necessary if grid is hanging off the global ServiceContext and each test gets its
* own service context.
*
* NOTE: Do not use this outside of unit-tests.
*/
void clearForUnitTests();
private:
std::unique_ptr<CatalogCache> _catalogCache;
std::unique_ptr<ShardRegistry> _shardRegistry;
std::unique_ptr<ClusterCursorManager> _cursorManager;
// can 'localhost' be used in shard addresses?
bool _allowLocalShard;
// Concurrency control around access the _catalogManager is as follows.
// In order to read _catalogManager, one must either lock _catalogManagerLock in shared mode
// or hold _catalogManagerMutex. In order to change _catalogManager, one must hold
// both _catalogManagerLock in exclusive mode and _catalogManagerMutex.
// Guards access to _catalogManager
stdx::mutex _catalogManagerMutex;
/**
* Protects access to _catalogManager.
* All normal accessors of the current CatalogManager will go through Grid::CatalogManagerGuard,
* which always takes the lock in shared mode. In order to swap the active catalog manager,
* the lock must be held in exclusive mode.
* TODO(SERVER-19875) Use a new lock manager resource for this instead.
*/
RWLock _catalogManagerLock;
// Current active catalog manager
std::unique_ptr<CatalogManager> _catalogManager;
};
/**
* Guard object that protects access to the current active CatalogManager to enable switching the
* active catalog manager at runtime.
* Note: Never contstruct a CatalogManagerGuard directly, they should only be given out by calling
* grid.catalogManager().
*/
class Grid::CatalogManagerGuard {
MONGO_DISALLOW_COPYING(CatalogManagerGuard);
public:
CatalogManagerGuard(OperationContext* txn, Grid* grid);
~CatalogManagerGuard();
CatalogManager* operator->() const;
explicit operator bool() const;
CatalogManager* get() const;
#if defined(_MSC_VER) && _MSC_VER < 1900
CatalogManagerGuard(CatalogManagerGuard&& other) : _grid(other._grid) {}
CatalogManagerGuard& operator=(CatalogManagerGuard&& other) {
_grid = other._grid;
return *this;
}
#else
CatalogManagerGuard(CatalogManagerGuard&& other) = default;
CatalogManagerGuard& operator=(CatalogManagerGuard&& other) = default;
#endif
private:
Grid* _grid;
};
extern Grid grid;
} // namespace mongo
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