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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 <string>
#include "mongo/bson/oid.h"
#include "mongo/s/shard_id.h"
#include "mongo/stdx/mutex.h"
namespace mongo {
class OperationContext;
class ServiceContext;
/**
* Contains information about the shardingness of a running mongod. This is a passive class and its
* state and concurrency control is driven from outside (specifically ShardingInitializationMongoD,
* which should be its only caller).
*
* There is one instance of this object per service context and once 'setInitialized' is called, it
* never gets destroyed or uninitialized.
*/
class ShardingState {
ShardingState(const ShardingState&) = delete;
ShardingState& operator=(const ShardingState&) = delete;
public:
ShardingState();
~ShardingState();
static ShardingState* get(ServiceContext* serviceContext);
static ShardingState* get(OperationContext* operationContext);
/**
* Puts the sharding state singleton in the "initialization completed" state with either
* successful initialization or an error. This method may only be called once for the lifetime
* of the object.
*/
void setInitialized(ShardId shardId, OID clusterId);
void setInitialized(Status failedStatus);
/**
* If 'setInitialized' has not been called, returns boost::none. Otherwise, returns the status
* with which 'setInitialized' was called. This is used by the initialization sequence to decide
* whether to set up the sharding services.
*/
boost::optional<Status> initializationStatus();
/**
* Returns true if 'setInitialized' has been called with shardId and clusterId.
*
* Code that needs to perform extra actions if sharding is initialized, but does not need to
* error if not, should use this. Alternatively, see ShardingState::canAcceptShardedCommands().
*/
bool enabled() const;
/**
* Returns Status::OK if the ShardingState is enabled; if not, returns an error describing
* whether the ShardingState is just not yet initialized, or if this shard is not running with
* --shardsvr at all.
*
* Code that should error if sharding state has not been initialized should use this to report
* a more descriptive error. Alternatively, see ShardingState::enabled().
*/
Status canAcceptShardedCommands() const;
/**
* Returns the shard id to which this node belongs. May only be called if 'enabled()' above
* returns true.
*/
ShardId shardId();
/**
* Returns the cluster id of the cluster to which this node belongs. May only be called if
* 'enabled()' above returns true.
*/
OID clusterId();
/**
* For testing only. This is a workaround for the fact that it is not possible to get a clean
* ServiceContext in between test executions. Because of this, tests which require that they get
* started with a clean (uninitialized) ShardingState must invoke this in their tearDown method.
*/
void clearForTests();
private:
// Progress of the sharding state initialization
enum class InitializationState : uint32_t {
// Initial state. The server must be under exclusive lock when this state is entered. No
// metadata is available yet and it is not known whether there is any min optime metadata,
// which needs to be recovered. From this state, the server may enter INITIALIZING, if a
// recovey document is found or stay in it until initialize has been called.
kNew,
// Sharding state is fully usable.
kInitialized,
// Some initialization error occurred. The _initializationStatus variable will contain the
// error.
kError,
};
/**
* Returns the initialization state.
*/
InitializationState _getInitializationState() const {
return static_cast<InitializationState>(_initializationState.load());
}
// Protects state below
stdx::mutex _mutex;
// State of the initialization of the sharding state along with any potential errors
AtomicWord<unsigned> _initializationState{static_cast<uint32_t>(InitializationState::kNew)};
// Sets the shard name for this host (comes through setShardVersion)
ShardId _shardId;
// The id for the cluster this shard belongs to.
OID _clusterId;
// Only valid if _initializationState is kError. Contains the reason for initialization failure.
Status _initializationStatus{ErrorCodes::InternalError, "Uninitialized value"};
};
} // namespace mongo
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