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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/db/namespace_string.h"
#include "mongo/db/operation_context.h"
#include "mongo/s/database_version.h"
#include "mongo/s/shard_version.h"
#include "mongo/util/future.h"
#include "mongo/util/string_map.h"
namespace mongo {
/**
* Marks the opCtx during scope in which it has been instantiated as running in the shard role for
* the specified collection. This indicates to the underlying storage system that the caller has
* performed 'routing', in the sense that it is aware of what data is located on this node.
*/
class ScopedSetShardRole {
public:
ScopedSetShardRole(OperationContext* opCtx,
NamespaceString nss,
boost::optional<ShardVersion> shardVersion,
boost::optional<DatabaseVersion> databaseVersion);
~ScopedSetShardRole();
private:
OperationContext* const _opCtx;
NamespaceString _nss;
boost::optional<ShardVersion> _shardVersion;
boost::optional<DatabaseVersion> _databaseVersion;
};
/**
* 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 {
OperationShardingState(const OperationShardingState&) = delete;
OperationShardingState& operator=(const OperationShardingState&) = delete;
public:
OperationShardingState();
~OperationShardingState();
/**
* Retrieves a reference to the shard version decorating the OperationContext, 'opCtx'.
*/
static OperationShardingState& get(OperationContext* opCtx);
/**
* Returns true if the the current operation was sent from an upstream router, rather than it
* being a direct connection against the shard. The way this decision is made is based on
* whether there is shard version declared for any namespace.
*/
static bool isComingFromRouter(OperationContext* opCtx);
/**
* NOTE: DO NOT ADD any new usages of this class without including someone from the Sharding
* Team on the code review.
*
* Instantiating this object on the stack indicates to the storage execution subsystem that it
* is allowed to create any collection in this context and that the caller will be responsible
* for notifying the shard Sharding subsystem of the collection creation. Note that in most of
* cases the CollectionShardingRuntime associated to that nss will be set as UNSHARDED. However,
* there are some scenarios in which it is required to set is as UNKNOWN: that's the reason why
* the constructor has the 'forceCSRAsUnknownAfterCollectionCreation' parameter. You can find
* more information about how the CSR is modified in ShardServerOpObserver::onCreateCollection.
*/
class ScopedAllowImplicitCollectionCreate_UNSAFE {
public:
/* Please read the comment associated to this class */
ScopedAllowImplicitCollectionCreate_UNSAFE(
OperationContext* opCtx, bool forceCSRAsUnknownAfterCollectionCreation = false);
~ScopedAllowImplicitCollectionCreate_UNSAFE();
private:
OperationContext* const _opCtx;
};
/**
* Same semantics as ScopedSetShardRole above, but the role remains set for the lifetime of the
* opCtx.
*/
static void setShardRole(OperationContext* opCtx,
const NamespaceString& nss,
const boost::optional<ShardVersion>& shardVersion,
const boost::optional<DatabaseVersion>& dbVersion);
/**
* Used to clear the shard role from the opCtx for ddl operations which are not required to send
* the index version (ex. split, merge). These operations will do their own metadata checks
* rather than us the collection sharding runtime checks.
*/
static void unsetShardRoleForLegacyDDLOperationsSentWithShardVersionIfNeeded(
OperationContext* opCtx, const NamespaceString& nss);
/**
* 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.
*/
boost::optional<ShardVersion> getShardVersion(const NamespaceString& nss);
/**
* 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(StringData dbName) const;
/**
* This method implements a best-effort attempt to wait for the critical section to complete
* before returning to the router at the previous step in order to prevent it from busy spinning
* while the critical section is in progress.
*
* All waits for migration critical section should go through this code path, because it also
* accounts for transactions and locking.
*/
static Status waitForCriticalSectionToComplete(OperationContext* opCtx,
SharedSemiFuture<void> critSecSignal) noexcept;
/**
* 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:
friend class ScopedSetShardRole;
friend class ShardServerOpObserver; // For access to _allowCollectionCreation below
// Specifies whether the request is allowed to create database/collection implicitly
bool _allowCollectionCreation{false};
// Specifies whether the CollectionShardingRuntime should be set as unknown after collection
// creation
bool _forceCSRAsUnknownAfterCollectionCreation{false};
// Stores the shard version expected for each collection that will be accessed
struct ShardVersionTracker {
ShardVersionTracker(ShardVersion v) : v(v) {}
ShardVersionTracker(ShardVersionTracker&&) = default;
ShardVersionTracker(const ShardVersionTracker&) = delete;
ShardVersionTracker& operator=(const ShardVersionTracker&) = delete;
ShardVersion v;
int recursion{0};
};
StringMap<ShardVersionTracker> _shardVersions;
// Stores the database version expected for each database that will be accessed
struct DatabaseVersionTracker {
DatabaseVersionTracker(DatabaseVersion v) : v(v) {}
DatabaseVersionTracker(DatabaseVersionTracker&&) = default;
DatabaseVersionTracker(const DatabaseVersionTracker&) = delete;
DatabaseVersionTracker& operator=(const DatabaseVersionTracker&) = delete;
DatabaseVersion v;
int recursion{0};
};
StringMap<DatabaseVersionTracker> _databaseVersions;
// 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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