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/**
* Copyright (C) 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 "mongo/db/concurrency/d_concurrency.h"
#include "mongo/executor/task_executor.h"
#include "mongo/s/catalog/sharding_catalog_manager.h"
#include "mongo/s/client/shard.h"
#include "mongo/stdx/mutex.h"
namespace mongo {
class RemoteCommandTargeter;
/**
* Implements the catalog manager for writing to replica set config servers.
*/
class ShardingCatalogManagerImpl final : public ShardingCatalogManager {
public:
ShardingCatalogManagerImpl(std::unique_ptr<executor::TaskExecutor> addShardExecutor);
virtual ~ShardingCatalogManagerImpl();
/**
* Safe to call multiple times as long as the calls are externally synchronized to be
* non-overlapping.
*/
Status startup() override;
void shutDown(OperationContext* txn) override;
Status initializeConfigDatabaseIfNeeded(OperationContext* txn) override;
void discardCachedConfigDatabaseInitializationState() override;
Status addShardToZone(OperationContext* txn,
const std::string& shardName,
const std::string& zoneName) override;
Status removeShardFromZone(OperationContext* txn,
const std::string& shardName,
const std::string& zoneName) override;
Status assignKeyRangeToZone(OperationContext* txn,
const NamespaceString& ns,
const ChunkRange& range,
const std::string& zoneName) override;
Status removeKeyRangeFromZone(OperationContext* txn,
const NamespaceString& ns,
const ChunkRange& range) override;
Status commitChunkSplit(OperationContext* txn,
const NamespaceString& ns,
const OID& requestEpoch,
const ChunkRange& range,
const std::vector<BSONObj>& splitPoints,
const std::string& shardName) override;
Status commitChunkMerge(OperationContext* txn,
const NamespaceString& ns,
const OID& requestEpoch,
const std::vector<BSONObj>& chunkBoundaries,
const std::string& shardName) override;
StatusWith<BSONObj> commitChunkMigration(OperationContext* txn,
const NamespaceString& nss,
const ChunkType& migratedChunk,
const boost::optional<ChunkType>& controlChunk,
const OID& collectionEpoch,
const ShardId& fromShard,
const ShardId& toShard) override;
void appendConnectionStats(executor::ConnectionPoolStats* stats) override;
StatusWith<std::string> addShard(OperationContext* txn,
const std::string* shardProposedName,
const ConnectionString& shardConnectionString,
const long long maxSize) override;
BSONObj createShardIdentityUpsertForAddShard(OperationContext* txn,
const std::string& shardName) override;
Status setFeatureCompatibilityVersionOnShards(OperationContext* txn,
const std::string& version) override;
private:
/**
* Performs the necessary checks for version compatibility and creates a new config.version
* document if the current cluster config is empty.
*/
Status _initConfigVersion(OperationContext* txn);
/**
* Builds all the expected indexes on the config server.
*/
Status _initConfigIndexes(OperationContext* txn);
/**
* Used during addShard to determine if there is already an existing shard that matches the
* shard that is currently being added. An OK return with boost::none indicates that there
* is no conflicting shard, and we can proceed trying to add the new shard. An OK return
* with a ShardType indicates that there is an existing shard that matches the shard being added
* but since the options match, this addShard request can do nothing and return success. A
* non-OK return either indicates a problem reading the existing shards from disk or more likely
* indicates that an existing shard conflicts with the shard being added and they have different
* options, so the addShard attempt must be aborted.
*/
StatusWith<boost::optional<ShardType>> _checkIfShardExists(
OperationContext* txn,
const ConnectionString& propsedShardConnectionString,
const std::string* shardProposedName,
long long maxSize);
/**
* Validates that the specified endpoint can serve as a shard server. In particular, this
* this function checks that the shard can be contacted and that it is not already member of
* another sharded cluster.
*
* @param targeter For sending requests to the shard-to-be.
* @param shardProposedName Optional proposed name for the shard. Can be omitted in which case
* a unique name for the shard will be generated from the shard's connection string. If it
* is not omitted, the value cannot be the empty string.
*
* On success returns a partially initialized ShardType object corresponding to the requested
* shard. It will have the hostName field set and optionally the name, if the name could be
* generated from either the proposed name or the connection string set name. The returned
* shard's name should be checked and if empty, one should be generated using some uniform
* algorithm.
*/
StatusWith<ShardType> _validateHostAsShard(OperationContext* txn,
std::shared_ptr<RemoteCommandTargeter> targeter,
const std::string* shardProposedName,
const ConnectionString& connectionString);
/**
* Runs the listDatabases command on the specified host and returns the names of all databases
* it returns excluding those named local, config and admin, since they serve administrative
* purposes.
*/
StatusWith<std::vector<std::string>> _getDBNamesListFromShard(
OperationContext* txn, std::shared_ptr<RemoteCommandTargeter> targeter);
/**
* Runs a command against a "shard" that is not yet in the cluster and thus not present in the
* ShardRegistry.
*/
StatusWith<Shard::CommandResponse> _runCommandForAddShard(OperationContext* txn,
RemoteCommandTargeter* targeter,
const std::string& dbName,
const BSONObj& cmdObj);
//
// All member variables are labeled with one of the following codes indicating the
// synchronization rules for accessing them.
//
// (M) Must hold _mutex for access.
// (R) Read only, can only be written during initialization.
// (S) Self-synchronizing; access in any way from any context.
//
stdx::mutex _mutex;
// True if shutDown() has been called. False, otherwise.
bool _inShutdown{false}; // (M)
// True if startup() has been called.
bool _started{false}; // (M)
// True if initializeConfigDatabaseIfNeeded() has been called and returned successfully.
bool _configInitialized{false}; // (M)
// Executor specifically used for sending commands to servers that are in the process of being
// added as shards. Does not have any connection hook set on it, thus it can be used to talk
// to servers that are not yet in the ShardRegistry.
std::unique_ptr<executor::TaskExecutor> _executorForAddShard; // (R)
/**
* Lock for shard zoning operations. This should be acquired when doing any operations that
* can affect the config.tags collection or the tags field of the config.shards collection.
* No other locks should be held when locking this. If an operation needs to take database
* locks (for example to write to a local collection) those locks should be taken after
* taking this.
*/
Lock::ResourceMutex _kZoneOpLock;
/**
* Lock for chunk split/merge/move operations. This should be acquired when doing split/merge/
* move operations that can affect the config.chunks collection.
* No other locks should be held when locking this. If an operation needs to take database
* locks (for example to write to a local collection) those locks should be taken after
* taking this.
*/
Lock::ResourceMutex _kChunkOpLock;
/**
* Lock that guards changes to the set of shards in the cluster (ie addShard and removeShard
* requests).
* TODO: Currently only taken during addShard requests, this should also be taken in X mode
* during removeShard, once removeShard is moved to run on the config server primary instead of
* on mongos. At that point we should also change any operations that expect the shard not to
* be removed while they are running (such as removeShardFromZone) to take this in shared mode.
*/
Lock::ResourceMutex _kShardMembershipLock;
};
} // namespace mongo
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