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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 <string>
#include <vector>
#include "mongo/base/status.h"
#include "mongo/base/string_data.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/db/jsobj.h"
#include "mongo/s/async_requests_sender.h"
#include "mongo/s/chunk_version.h"
#include "mongo/s/commands/strategy.h"
#include "mongo/stdx/memory.h"
namespace mongo {
class CachedCollectionRoutingInfo;
class CachedDatabaseInfo;
class OperationContext;
class ShardId;
/*
* Allows callers of routing functions to specify a preferred targeting policy. See scatterGather
* for a usage example.
*/
enum class ShardTargetingPolicy { UseRoutingTable, BroadcastToAllShards };
/**
* This function appends the provided writeConcernError BSONElement to the sharded response.
*/
void appendWriteConcernErrorToCmdResponse(const ShardId& shardID,
const BSONElement& wcErrorElem,
BSONObjBuilder& responseBuilder);
/**
* Returns a copy of 'cmdObj' with 'version' appended.
*/
BSONObj appendShardVersion(BSONObj cmdObj, ChunkVersion version);
/**
* Generic function for dispatching commands to the cluster.
*
* If 'targetPolicy' is ShardTargetingPolicy::BroadcastToAllShards, the command will be sent
* unversioned to all shards and run on database 'dbName'. The 'query', 'collation' and
* 'appendShardVersion' arguments, if supplied, will be ignored.
*
* If 'targetPolicy' is ShardTargetingPolicy::UseRoutingTable, the routing table cache will be used
* to determine which shards the command should be dispatched to. If the namespace specified by
* 'nss' is an unsharded collection, the command will be sent to the Primary shard for the database.
* If 'query' is specified, only shards that own data needed by the query are targeted; otherwise,
* all shards are targeted. By default, shardVersions are attached to the outgoing requests, and the
* function will re-target and retry if it receives a stale shardVersion error from any shard.
*
* Returns a non-OK status if a failure occurs on *this* node during execution or on seeing an error
* from a shard that means the operation as a whole should fail, such as a exceeding retries for
* stale shardVersion errors.
*
* If a shard returns an error saying that the request was on a view, the shard will also return a
* view definition. This will be stored in the BSONObj* viewDefinition argument, if non-null, so
* that the caller can re-run the operation as an aggregation.
*
* Otherwise, returns success and a list of responses from shards (including errors from the shards
* or errors reaching the shards).
*/
StatusWith<std::vector<AsyncRequestsSender::Response>> scatterGather(
OperationContext* opCtx,
const std::string& dbName,
const boost::optional<NamespaceString> nss,
const BSONObj& cmdObj,
const ReadPreferenceSetting& readPref,
Shard::RetryPolicy retryPolicy,
const ShardTargetingPolicy targetPolicy = ShardTargetingPolicy::UseRoutingTable,
const boost::optional<BSONObj> query = boost::none,
const boost::optional<BSONObj> collation = boost::none,
const bool appendShardVersion = true,
const bool retryOnStaleShardVersion = true,
BSONObj* viewDefinition = nullptr);
/**
* Attaches each shard's response or error status by the shard's connection string in a top-level
* field called 'raw' in 'output'.
*
* If all shards that errored had the same error, writes the common error code to 'output'. Writes a
* string representation of all errors to 'errmsg.'
*
* Returns true if all the shards reported success.
*/
bool appendRawResponses(OperationContext* opCtx,
std::string* errmsg,
BSONObjBuilder* output,
std::vector<AsyncRequestsSender::Response> shardResponses);
/**
* Utility function to compute a single error code from a vector of command results.
*
* @return If there is an error code common to all of the error results, returns that error
* code; otherwise, returns 0.
*/
int getUniqueCodeFromCommandResults(const std::vector<Strategy::CommandResult>& results);
/**
* Utility function to return an empty result set from a command.
*/
bool appendEmptyResultSet(BSONObjBuilder& result, Status status, const std::string& ns);
/**
* Returns the set of collections for the specified database, which have been marked as sharded.
* Goes directly to the config server's metadata, without checking the local cache so it should not
* be used in frequently called code paths.
*
* Throws exception on errors.
*/
std::vector<NamespaceString> getAllShardedCollectionsForDb(OperationContext* opCtx,
StringData dbName);
/**
* Abstracts the common pattern of refreshing a collection and checking if it is sharded used across
* multiple commands.
*/
CachedCollectionRoutingInfo getShardedCollection(OperationContext* opCtx,
const NamespaceString& nss);
/**
* If the specified database exists already, loads it in the cache (if not already there) and
* returns it. Otherwise, if it does not exist, this call will implicitly create it as non-sharded.
*/
StatusWith<CachedDatabaseInfo> createShardDatabase(OperationContext* opCtx, StringData dbName);
} // namespace mongo
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