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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 "mongo/base/status_with.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/logical_session_cache.h"
#include "mongo/db/repl/optime_with.h"
#include "mongo/executor/task_executor.h"
#include "mongo/platform/mutex.h"
#include "mongo/s/catalog/type_chunk.h"
#include "mongo/s/catalog/type_collection.h"
#include "mongo/s/catalog/type_database.h"
#include "mongo/s/catalog/type_shard.h"
#include "mongo/s/client/shard.h"
#include "mongo/s/client/shard_registry.h"
#include "mongo/s/shard_key_pattern.h"
namespace mongo {
struct RemoveShardProgress {
/**
* Used to indicate to the caller of the removeShard method whether draining of chunks for
* a particular shard has started, is ongoing, or has been completed.
*/
enum DrainingShardStatus {
STARTED,
ONGOING,
COMPLETED,
};
/**
* Used to indicate to the caller of the removeShard method the remaining amount of chunks,
* jumbo chunks and databases within the shard
*/
struct DrainingShardUsage {
const long long totalChunks;
const long long databases;
const long long jumboChunks;
};
DrainingShardStatus status;
boost::optional<DrainingShardUsage> remainingCounts;
};
/**
* Implements modifications to the sharding catalog metadata.
*
* TODO: Currently the code responsible for writing the sharding catalog metadata is split between
* this class and ShardingCatalogClient. Eventually all methods that write catalog data should be
* moved out of ShardingCatalogClient and into this class.
*/
class ShardingCatalogManager {
ShardingCatalogManager(const ShardingCatalogManager&) = delete;
ShardingCatalogManager& operator=(const ShardingCatalogManager&) = delete;
public:
ShardingCatalogManager(ServiceContext* serviceContext,
std::unique_ptr<executor::TaskExecutor> addShardExecutor);
~ShardingCatalogManager();
/**
* Instantiates an instance of the sharding catalog manager and installs it on the specified
* service context. This method is not thread-safe and must be called only once when the service
* is starting.
*/
static void create(ServiceContext* serviceContext,
std::unique_ptr<executor::TaskExecutor> addShardExecutor);
/**
* Retrieves the per-service instance of the ShardingCatalogManager. This instance is only
* available if the node is running as a config server.
*/
static ShardingCatalogManager* get(ServiceContext* serviceContext);
static ShardingCatalogManager* get(OperationContext* operationContext);
/**
* Safe to call multiple times as long as the calls are externally synchronized to be
* non-overlapping.
*/
void startup();
/**
* Performs necessary cleanup when shutting down cleanly.
*/
void shutDown();
//
// Sharded cluster initialization logic
//
/**
* Checks if this is the first start of a newly instantiated config server and if so pre-creates
* the catalog collections and their indexes. Also generates and persists the cluster's
* identity.
*/
Status initializeConfigDatabaseIfNeeded(OperationContext* opCtx);
/**
* Invoked on cluster identity metadata rollback after replication step down. Throws out any
* cached identity information and causes it to be reloaded/re-created on the next attempt.
*/
void discardCachedConfigDatabaseInitializationState();
//
// Zone Operations
//
/**
* Adds the given shardName to the zone. Returns ErrorCodes::ShardNotFound if a shard by that
* name does not exist.
*/
Status addShardToZone(OperationContext* opCtx,
const std::string& shardName,
const std::string& zoneName);
/**
* Removes the given shardName from the zone. Returns ErrorCodes::ShardNotFound if a shard by
* that name does not exist.
*/
Status removeShardFromZone(OperationContext* opCtx,
const std::string& shardName,
const std::string& zoneName);
/**
* Assigns a range of a sharded collection to a particular shard zone. If range is a prefix of
* the shard key, the range will be converted into a new range with full shard key filled with
* MinKey values.
*/
void assignKeyRangeToZone(OperationContext* opCtx,
const NamespaceString& nss,
const ChunkRange& range,
const std::string& zoneName);
/**
* Removes a range from a zone.
*
* NOTE: unlike assignKeyRangeToZone, the given range will never be converted to include the
* full shard key.
*/
void removeKeyRangeFromZone(OperationContext* opCtx,
const NamespaceString& nss,
const ChunkRange& range);
//
// General utilities related to the ShardingCatalogManager
//
/**
* Starts and commits a transaction on the config server, with a no-op find on the specified
* namespace in order to internally start the transaction. All writes done inside the
* passed-in function must assume that they are run inside a transaction that will be commited
* after the function itself has completely finished.
*/
static void withTransaction(OperationContext* opCtx,
const NamespaceString& namespaceForInitialFind,
unique_function<void(OperationContext*, TxnNumber)> func);
/**
* Runs the write 'request' on namespace 'nss' in a transaction with 'txnNumber'. Write must be
* on a collection in the config database. If expectedNumModified is specified, the number of
* documents modified must match expectedNumModified - throws otherwise.
*/
BSONObj writeToConfigDocumentInTxn(OperationContext* opCtx,
const NamespaceString& nss,
const BatchedCommandRequest& request,
TxnNumber txnNumber);
/**
* Inserts 'docs' to namespace 'nss' in a transaction with 'txnNumber'. Breaks into multiple
* batches if 'docs' is larger than the max batch size. Write must be on a collection in the
* config database.
*/
void insertConfigDocumentsInTxn(OperationContext* opCtx,
const NamespaceString& nss,
std::vector<BSONObj> docs,
TxnNumber txnNumber);
//
// Chunk Operations
//
/**
* Updates metadata in the config.chunks collection to show the given chunk as split into
* smaller chunks at the specified split points.
*
* Returns a BSON object with the newly produced chunk versions after the migration:
* - shardVersion - The new shard version of the source shard
* - collectionVersion - The new collection version after the commit
*/
StatusWith<BSONObj> commitChunkSplit(OperationContext* opCtx,
const NamespaceString& nss,
const OID& requestEpoch,
const ChunkRange& range,
const std::vector<BSONObj>& splitPoints,
const std::string& shardName);
/**
* Updates metadata in the config.chunks collection so the chunks with given boundaries are seen
* merged into a single larger chunk.
* If 'validAfter' is not set, this means the commit request came from an older server version,
* which is not history-aware.
*
* Returns a BSON object with the newly produced chunk versions after the migration:
* - shardVersion - The new shard version of the source shard
* - collectionVersion - The new collection version after the commit
*/
StatusWith<BSONObj> commitChunkMerge(OperationContext* opCtx,
const NamespaceString& nss,
const OID& requestEpoch,
const std::vector<BSONObj>& chunkBoundaries,
const std::string& shardName,
const boost::optional<Timestamp>& validAfter);
/**
* Updates metadata in the config.chunks collection so the chunks within the specified key range
* are seen merged into a single larger chunk.
* If 'validAfter' is not set, this means the commit request came from an older server version,
* which is not history-aware.
*
* Returns a BSON object with the newly produced chunk versions after the migration:
* - shardVersion - The new shard version of the source shard
* - collectionVersion - The new collection version after the commit
*/
StatusWith<BSONObj> commitChunksMerge(OperationContext* opCtx,
const NamespaceString& nss,
const UUID& requestCollectionUUID,
const ChunkRange& chunkRange,
const ShardId& shardId,
const boost::optional<Timestamp>& validAfter);
/**
* Updates metadata in config.chunks collection to show the given chunk in its new shard.
* If 'validAfter' is not set, this means the commit request came from an older server version,
* which is not history-aware.
*
* Returns a BSON object with the newly produced chunk versions after the migration:
* - shardVersion - The new shard version of the source shard
* - collectionVersion - The new collection version after the commit
*/
StatusWith<BSONObj> commitChunkMigration(OperationContext* opCtx,
const NamespaceString& nss,
const ChunkType& migratedChunk,
const OID& collectionEpoch,
const ShardId& fromShard,
const ShardId& toShard,
const boost::optional<Timestamp>& validAfter);
/**
* Removes the jumbo flag from the specified chunk.
*/
void clearJumboFlag(OperationContext* opCtx,
const NamespaceString& nss,
const OID& collectionEpoch,
const ChunkRange& chunk);
/**
* If a chunk matching 'requestedChunk' exists, bumps the chunk's version to one greater than
* the current collection version.
*
* 'nss' and 'collUUID' were added to the ConfigsvrEnsureChunkVersionIsGreaterThanCommand
* in 5.0. They are optional in 5.0 because the request may come from a previous version (4.4)
* that doesn't pass these extra fields.
*/
void ensureChunkVersionIsGreaterThan(OperationContext* opCtx,
const boost::optional<NamespaceString>& nss,
const boost::optional<UUID>& collUUID,
const BSONObj& minKey,
const BSONObj& maxKey,
const ChunkVersion& version);
/**
* In a single transaction, effectively bumps the shard version for each shard in the collection
* to be the current collection version's major version + 1 inside an already-running
* transaction.
*/
void bumpCollectionVersionAndChangeMetadataInTxn(
OperationContext* opCtx,
const NamespaceString& nss,
unique_function<void(OperationContext*, TxnNumber)> changeMetadataFunc);
/**
* Same as bumpCollectionVersionAndChangeMetadataInTxn, but bumps the version for several
* collections in a single transaction.
*/
void bumpMultipleCollectionVersionsAndChangeMetadataInTxn(
OperationContext* opCtx,
const std::vector<NamespaceString>& collNames,
unique_function<void(OperationContext*, TxnNumber)> changeMetadataFunc);
/**
* Performs a split on the chunk with min value "minKey". If the split fails, it is marked as
* jumbo.
*/
void splitOrMarkJumbo(OperationContext* opCtx,
const NamespaceString& nss,
const BSONObj& minKey);
/**
* In a transaction, sets the 'allowMigrations' to the requested state and bumps the collection
* version.
*/
void setAllowMigrationsAndBumpOneChunk(OperationContext* opCtx,
const NamespaceString& nss,
const boost::optional<UUID>& collectionUUID,
bool allowMigrations);
//
// Database Operations
//
/**
* Checks if a database with the same name, optPrimaryShard and enableSharding state already
* exists, and if not, creates a new one that matches these prerequisites. If a database already
* exists and matches all the prerequisites returns success, otherwise throws NamespaceNotFound.
*/
DatabaseType createDatabase(OperationContext* opCtx,
StringData dbName,
const boost::optional<ShardId>& optPrimaryShard,
bool enableSharding);
//
// Collection Operations
//
/**
* Refines the shard key of an existing collection with namespace 'nss'. Here, 'shardKey'
* denotes the new shard key, which must contain the old shard key as a prefix.
*
* Throws exception on errors.
*/
void refineCollectionShardKey(OperationContext* opCtx,
const NamespaceString& nss,
const ShardKeyPattern& newShardKey);
/**
* Runs a replacement update on config.collections for the collection entry for 'nss' in a
* transaction with 'txnNumber'. 'coll' is used as the replacement doc.
*
* Throws exception on errors.
*/
void updateShardingCatalogEntryForCollectionInTxn(OperationContext* opCtx,
const NamespaceString& nss,
const CollectionType& coll,
const bool upsert,
TxnNumber txnNumber);
//
// Shard Operations
//
/**
*
* Adds a new shard. It expects a standalone mongod process or replica set to be running on the
* provided address.
*
* 'shardProposedName' is an optional string with the proposed name of the shard. If it is
* nullptr, a name will be automatically generated; if not nullptr, it cannot
* contain the empty string.
* 'shardConnectionString' is the complete connection string of the shard being added.
* 'maxSize' is the optional space quota in bytes. Zero means there's no limitation to space
* usage.
*
* On success returns the name of the newly added shard.
*/
StatusWith<std::string> addShard(OperationContext* opCtx,
const std::string* shardProposedName,
const ConnectionString& shardConnectionString,
const long long maxSize);
/**
* Tries to remove a shard. To completely remove a shard from a sharded cluster,
* the data residing in that shard must be moved to the remaining shards in the
* cluster by "draining" chunks from that shard.
*
* Because of the asynchronous nature of the draining mechanism, this method returns
* the current draining status. See ShardDrainingStatus enum definition for more details.
*/
RemoveShardProgress removeShard(OperationContext* opCtx, const ShardId& shardId);
//
// Cluster Upgrade Operations
//
/**
* Runs the setFeatureCompatibilityVersion command on all shards.
*/
Status setFeatureCompatibilityVersionOnShards(OperationContext* opCtx, const BSONObj& cmdObj);
/**
* Patches-up persistent metadata for 5.0.
*
* It shall be called when upgrading to 5.0 or newer versions, when shards are in phase-1 of the
* setFCV protocol.
* TODO SERVER-53283: Remove once 5.0 has been released.
*/
void upgradeMetadataFor50Phase1(OperationContext* opCtx);
/**
* Patches-up persistent metadata for 5.0.
*
* It shall be called when upgrading to 5.0 or newer versions, when shards are in phase-2 of the
* setFCV protocol.
* TODO SERVER-53283: Remove once 5.0 has been released.
*/
void upgradeMetadataFor50Phase2(OperationContext* opCtx);
/**
* Patches-up persistent metadata for downgrade from 5.0.
*
* It shall be called when downgrading from 5.0 to an earlier version, when shards are in
* phase-1 of the setFCV protocol.
* TODO SERVER-53283: Remove once 5.0 has been released.
*/
void downgradeMetadataToPre50Phase1(OperationContext* opCtx);
/**
* Patches-up persistent metadata for downgrade from 5.0.
*
* It shall be called when downgrading from 5.0 to an earlier version, when shards are in
* phase-2 of the setFCV protocol.
* TODO SERVER-53283: Remove once 5.0 has been released.
*/
void downgradeMetadataToPre50Phase2(OperationContext* opCtx);
/*
* Rename collection metadata as part of a renameCollection operation.
*
* - Updates the FROM collection entry if the source collection is sharded
* - Removes the TO collection entry if the target collection was sharded
*/
void renameShardedMetadata(OperationContext* opCtx,
const NamespaceString& from,
const NamespaceString& to,
const WriteConcernOptions& writeConcern,
boost::optional<CollectionType> optFromCollType);
//
// For Diagnostics
//
/**
* Append information about the connection pools owned by the CatalogManager.
*/
void appendConnectionStats(executor::ConnectionPoolStats* stats);
/**
* Only used for unit-tests, clears a previously-created catalog manager from the specified
* service context, so that 'create' can be called again.
*/
static void clearForTests(ServiceContext* serviceContext);
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* opCtx);
/**
* Builds all the expected indexes on the config server.
*/
Status _initConfigIndexes(OperationContext* opCtx);
/**
* Ensure that config.collections exists upon configsvr startup
*/
Status _initConfigCollections(OperationContext* opCtx);
/**
* 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* opCtx,
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* opCtx,
std::shared_ptr<RemoteCommandTargeter> targeter,
const std::string* shardProposedName,
const ConnectionString& connectionString);
/**
* Drops the sessions collection on the specified host.
*/
Status _dropSessionsCollection(OperationContext* opCtx,
std::shared_ptr<RemoteCommandTargeter> targeter);
/**
* 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* opCtx, 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* opCtx,
RemoteCommandTargeter* targeter,
StringData dbName,
const BSONObj& cmdObj);
/**
* Helper method for running a count command against the config server with appropriate error
* handling.
*/
StatusWith<long long> _runCountCommandOnConfig(OperationContext* opCtx,
const NamespaceString& nss,
BSONObj query);
/**
* Appends a read committed read concern to the request object.
*/
void _appendReadConcern(BSONObjBuilder* builder);
/**
* Retrieve the full chunk description from the config.
*/
StatusWith<ChunkType> _findChunkOnConfig(OperationContext* opCtx,
const NamespaceStringOrUUID& nsOrUUID,
const OID& epoch,
const boost::optional<Timestamp>& timestamp,
const BSONObj& key);
/**
* Returns true if the zone with the given name has chunk ranges associated with it and the
* shard with the given name is the only shard that it belongs to.
*/
StatusWith<bool> _isShardRequiredByZoneStillInUse(OperationContext* opCtx,
const ReadPreferenceSetting& readPref,
const std::string& shardName,
const std::string& zoneName);
/**
* Removes all entries from the config server's config.collections where 'dropped' is true.
*
* Before 5.0, when a collection was dropped, its entry in config.collections remained, tagged
* as 'dropped: true'. As those are no longer needed, this method cleans up the leftover
* metadata.
*
* It shall be called when upgrading to 5.0 or newer versions.
*
* TODO SERVER-53283: Remove once 5.0 has becomes last-lts.
*/
void _removePre50LegacyMetadata(OperationContext* opCtx);
/**
* Creates a 'version.timestamp' for each one of the entries in the config server's
* config.databases where it didn't already exist before.
*
* TODO SERVER-53283: Remove once 5.0 becomes last-lts.
*/
void _upgradeDatabasesEntriesTo50(OperationContext* opCtx);
/**
* Downgrades the config.databases entries to prior 4.9 version. More specifically, it removes
* the 'version.timestamp' field from all the documents in config.databases.
*
* TODO SERVER-53283: Remove once 5.0 becomes last-lts.
*/
void _downgradeDatabasesEntriesToPre50(OperationContext* opCtx);
/**
* For each one of the entries in config.collections where there is no 'timestamp':
* - Patches-up the entries in config.chunks to set their 'collectionUUID' and 'timestamp'
* fields.
* - Creates a 'timestamp' in its entry in config.collections.
* , and builds the uuid_* indexes and drops the ns_* indexes on config.chunks.
*
* TODO SERVER-53283: Remove once 5.0 becomes last-lts.
*/
void _upgradeCollectionsAndChunksEntriesTo50Phase1(OperationContext* opCtx);
/**
* Unsets the 'ns' field from all documents in config.chunks
*
* TODO SERVER-53283: Remove once 5.0 becomes last-lts.
*/
void _upgradeCollectionsAndChunksEntriesTo50Phase2(OperationContext* opCtx);
/**
* For each one of the entries in config.collections where there is a 'timestamp':
* - Patches-up the entries in config.chunks to set their 'ns' field.
* - Unsets the 'timestamp' field from its entry in config.collections.
* , and builds the ns_* indexes and drops the uuid_* indexes on config.chunks.
*
* TODO SERVER-53283: Remove once 5.0 becomes last-lts.
*/
void _downgradeCollectionsAndChunksEntriesToPre50Phase1(OperationContext* opCtx);
/**
* Unsets the 'collectionUUID' and 'timestamp' fields from all documents in config.chunks
*
* TODO SERVER-53283: Remove once 5.0 becomes last-lts.
*/
void _downgradeCollectionsAndChunksEntriesToPre50Phase2(OperationContext* opCtx);
// The owning service context
ServiceContext* const _serviceContext;
// 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.
const std::unique_ptr<executor::TaskExecutor> _executorForAddShard;
//
// 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.
//
Mutex _mutex = MONGO_MAKE_LATCH("ShardingCatalogManager::_mutex");
// True if startup() has been called.
bool _started{false}; // (M)
// True if initializeConfigDatabaseIfNeeded() has been called and returned successfully.
bool _configInitialized{false}; // (M)
// Resource lock order:
// _kShardMembershipLock -> _kChunkOpLock
// _kZoneOpLock
/**
* Lock that guards changes to the set of shards in the cluster (ie addShard and removeShard
* requests).
*/
Lock::ResourceMutex _kShardMembershipLock;
/**
* 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 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 local database operations. This should be acquired when executing
* 'commitMovePrimary' and 'setFeatureCompatibilityVersion' commands which affect the
* config.databases 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.
* TODO (SERVER-53283): Remove once version 5.0 has been released.
*/
Lock::ResourceMutex _kDatabaseOpLock;
};
} // namespace mongo
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