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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 <functional>
#include "mongo/db/repl/optime.h"
#include "mongo/executor/task_executor_pool.h"
#include "mongo/platform/mutex.h"
#include "mongo/s/catalog/sharding_catalog_client.h"
#include "mongo/s/catalog_cache.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/util/hierarchical_acquisition.h"
namespace mongo {
class BalancerConfiguration;
class ClusterCursorManager;
class OperationContext;
class ServiceContext;
namespace executor {
class NetworkInterface;
} // namespace executor
/**
* Contains the sharding context for a running server. Exists on both MongoD and MongoS.
*/
class Grid {
public:
Grid();
~Grid();
using CustomConnectionPoolStatsFn = std::function<void(executor::ConnectionPoolStats* stats)>;
/**
* Retrieves the instance of Grid associated with the current service/operation context.
*/
static Grid* get(ServiceContext* serviceContext);
static Grid* get(OperationContext* operationContext);
/**
* 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<ShardingCatalogClient> catalogClient,
std::unique_ptr<CatalogCache> catalogCache,
std::unique_ptr<ShardRegistry> shardRegistry,
std::unique_ptr<ClusterCursorManager> cursorManager,
std::unique_ptr<BalancerConfiguration> balancerConfig,
std::unique_ptr<executor::TaskExecutorPool> executorPool,
executor::NetworkInterface* network);
/**
* Used to check if sharding is initialized for usage of global sharding services. Protected by
* an atomic access guard.
*/
bool isShardingInitialized() const;
/**
* Used to indicate the sharding initialization process is complete. Should only be called once
* in the lifetime of a server. Protected by an atomic access guard.
*/
void setShardingInitialized();
/**
* If the instance as which this sharding component is running (config/shard/mongos) uses
* additional connection pools other than the default, this function will be present and can be
* used to obtain statistics about them. Otherwise, the value will be unset.
*/
CustomConnectionPoolStatsFn getCustomConnectionPoolStatsFn() const;
void setCustomConnectionPoolStatsFn(CustomConnectionPoolStatsFn statsFn);
ShardingCatalogClient* catalogClient() const {
return _catalogClient.get();
}
CatalogCache* catalogCache() const {
return _catalogCache.get();
}
ShardRegistry* shardRegistry() const {
return _shardRegistry.get();
}
ClusterCursorManager* getCursorManager() const {
return _cursorManager.get();
}
executor::TaskExecutorPool* getExecutorPool() const {
return _executorPool.get();
}
executor::NetworkInterface* getNetwork() {
return _network;
}
BalancerConfiguration* getBalancerConfiguration() const {
return _balancerConfig.get();
}
/**
* Returns a readConcern at the specified level for reading after the current ConfigTime.
*/
repl::ReadConcernArgs readConcernWithConfigTime(repl::ReadConcernLevel readConcernLevel) const;
/**
* Returns a readPreference (based on the given one) for targeting a config server that is at or
* after the current ConfigTime.
*/
ReadPreferenceSetting readPreferenceWithConfigTime(
const ReadPreferenceSetting& readPreference) const;
/**
* Returns the the last optime that a shard or config server has reported as the current
* committed optime on the config server.
* NOTE: This is not valid to call on a config server instance.
*/
repl::OpTime configOpTime() const;
/**
* Called whenever a mongos or shard gets a response from a config server or shard and updates
* what we've seen as the last config server optime.
* If the config optime was updated, returns the previous value.
* NOTE: This is not valid to call on a config server instance.
*/
boost::optional<repl::OpTime> advanceConfigOpTime(OperationContext* opCtx,
repl::OpTime opTime,
StringData what);
/**
* 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: shardRegistry()->shutdown() must be called before this method is called.
*
* NOTE: Do not use this outside of unit-tests.
*/
void clearForUnitTests();
private:
std::unique_ptr<ShardingCatalogClient> _catalogClient;
std::unique_ptr<CatalogCache> _catalogCache;
std::unique_ptr<ShardRegistry> _shardRegistry;
std::unique_ptr<ClusterCursorManager> _cursorManager;
std::unique_ptr<BalancerConfiguration> _balancerConfig;
// Executor pool for scheduling work and remote commands to shards and config servers. Each
// contained executor has a connection hook set on it for sending/receiving sharding metadata.
std::unique_ptr<executor::TaskExecutorPool> _executorPool;
// Network interface being used by the fixed executor in _executorPool. Used for asking
// questions about the network configuration, such as getting the current server's hostname.
executor::NetworkInterface* _network{nullptr};
CustomConnectionPoolStatsFn _customConnectionPoolStatsFn;
AtomicWord<bool> _shardingInitialized{false};
// Protects _configOpTime.
mutable Mutex _mutex = MONGO_MAKE_LATCH(HierarchicalAcquisitionLevel(0), "Grid::_mutex");
// Last known highest opTime from the config server that should be used when doing reads.
// This value is updated any time a shard or mongos talks to a config server or a shard.
repl::OpTime _configOpTime;
/**
* Called to update what we've seen as the last config server optime.
* If the config optime was updated, returns the previous value.
* NOTE: This is not valid to call on a config server instance.
*/
boost::optional<repl::OpTime> _advanceConfigOpTime(const repl::OpTime& opTime);
};
} // namespace mongo
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