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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 <boost/optional.hpp>
#include "mongo/base/disallow_copying.h"
#include "mongo/db/namespace_string.h"
#include "mongo/s/chunk_version.h"
#include "mongo/s/database_version_gen.h"
#include "mongo/util/concurrency/notification.h"
#include "mongo/util/string_map.h"
namespace mongo {
class OperationContext;
/**
* A decoration on OperationContext representing per-operation shard version metadata sent to mongod
* from mongos as a command parameter.
*
* The metadata for a particular operation can be retrieved using the get() method.
*
* Note: This only supports storing the version for a single namespace.
*/
class OperationShardingState {
MONGO_DISALLOW_COPYING(OperationShardingState);
public:
OperationShardingState();
~OperationShardingState();
/**
* Retrieves a reference to the shard version decorating the OperationContext, 'opCtx'.
*/
static OperationShardingState& get(OperationContext* opCtx);
/**
* Requests on a sharded collection that are broadcast without a shardVersion should not cause
* the collection to be created on a shard that does not know about the collection already,
* since the collection options will not be propagated. Such requests specify to disallow
* collection creation, which is saved here.
*/
void setAllowImplicitCollectionCreation(const BSONElement& allowImplicitCollectionCreationElem);
/**
* Specifies whether the request is allowed to create database/collection implicitly.
*/
bool allowImplicitCollectionCreation() const;
/**
* Parses shardVersion and databaseVersion from 'cmdObj' and stores the results in this object
* along with the given namespace that is associated with the versions. Does nothing if no
* shardVersion or databaseVersion is attached to the command.
*
* Expects 'cmdObj' to have format
* { ...,
* shardVersion: [<version>, <epoch>],
* databaseVersion: { uuid: <UUID>, version: <int> },
* ...}
*
* This initialization may only be performed once for the lifetime of the object, which
* coincides with the lifetime of the client's request.
*/
void initializeClientRoutingVersions(NamespaceString nss, const BSONObj& cmdObj);
/**
* Returns whether or not there is a shard version associated with this operation.
*/
bool hasShardVersion() const;
/**
* Returns the shard version (i.e. maximum chunk version) of a namespace being used by the
* operation. Documents in chunks which did not belong on this shard at this shard version
* will be filtered out.
*
* Returns ChunkVersion::UNSHARDED() if this operation has no shard version information
* for the requested namespace.
*/
ChunkVersion getShardVersion(const NamespaceString& nss) const;
/**
* Returns true if the client sent a databaseVersion for any namespace.
*/
bool hasDbVersion() const;
/**
* If 'db' matches the 'db' in the namespace the client sent versions for, returns the database
* version sent by the client (if any), else returns boost::none.
*/
boost::optional<DatabaseVersion> getDbVersion(const StringData dbName) const;
/**
* Makes the OperationShardingState behave as if an UNSHARDED shardVersion was sent for every
* possible namespace.
*/
void setGlobalUnshardedShardVersion();
/**
* This call is a no op if there isn't a currently active migration critical section. Otherwise
* it will wait for the critical section to complete up to the remaining operation time.
*
* Returns true if the call actually waited because of migration critical section (regardless if
* whether it timed out or not), false if there was no active migration critical section.
*/
bool waitForMigrationCriticalSectionSignal(OperationContext* opCtx);
/**
* Setting this value indicates that when the version check failed, there was an active
* migration for the namespace and that it would be prudent to wait for the critical section to
* complete before retrying so the router doesn't make wasteful requests.
*/
void setMigrationCriticalSectionSignal(std::shared_ptr<Notification<void>> critSecSignal);
/**
* This call is a no op if there isn't a currently active movePrimary critical section.
* Otherwise it will wait for the critical section to complete up to the remaining operation
* time.
*
* Returns true if the call actually waited because of movePrimary critical section (regardless
* whether it timed out or not), false if there was no active movePrimary critical section.
*/
bool waitForMovePrimaryCriticalSectionSignal(OperationContext* opCtx);
/**
* Setting this value indicates that when the version check failed, there was an active
* movePrimary for the namespace and that it would be prudent to wait for the critical section
* to complete before retrying so the router doesn't make wasteful requests.
*/
void setMovePrimaryCriticalSectionSignal(std::shared_ptr<Notification<void>> critSecSignal);
/**
* Stores the failed status in _shardingOperationFailedStatus.
*
* This method may only be called once when a rerouting exception occurs. The caller
* must process the status at exit.
*/
void setShardingOperationFailedStatus(const Status& status);
/**
* Returns the failed status stored in _shardingOperationFailedStatus if any, and reset the
* status to none.
*
* This method may only be called when the caller wants to process the status.
*/
boost::optional<Status> resetShardingOperationFailedStatus();
private:
// Specifies whether the request is allowed to create database/collection implicitly
bool _allowImplicitCollectionCreation{true};
// Should be set to true if all collections accessed are expected to be unsharded.
bool _globalUnshardedShardVersion = false;
// The OperationShardingState class supports storing shardVersions for multiple namespaces (and
// databaseVersions for multiple databases), even though client code has not been written yet to
// *send* multiple shardVersions or databaseVersions.
StringMap<ChunkVersion> _shardVersions;
StringMap<DatabaseVersion> _databaseVersions;
// This value will only be non-null if version check during the operation execution failed due
// to stale version and there was a migration for that namespace, which was in critical section.
std::shared_ptr<Notification<void>> _migrationCriticalSectionSignal;
// This value will only be non-null if version check during the operation execution failed due
// to stale version and there was a movePrimary for that namespace, which was in critical
// section.
std::shared_ptr<Notification<void>> _movePrimaryCriticalSectionSignal;
// This value can only be set when a rerouting exception occurs during a write operation, and
// must be handled before this object gets destructed.
boost::optional<Status> _shardingOperationFailedStatus;
};
} // namespace mongo
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