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/** @file dbclient_rs.h Connect to a Replica Set, from C++ */
/* Copyright 2009 10gen 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 <utility>
#include "mongo/client/dbclientinterface.h"
#include "mongo/util/net/hostandport.h"
namespace mongo {
class ReplicaSetMonitor;
class TagSet;
struct ReadPreferenceSetting;
typedef std::shared_ptr<ReplicaSetMonitor> ReplicaSetMonitorPtr;
/** Use this class to connect to a replica set of servers. The class will manage
checking for which server in a replica set is master, and do failover automatically.
This can also be used to connect to replica pairs since pairs are a subset of sets
On a failover situation, expect at least one operation to return an error (throw
an exception) before the failover is complete. Operations are not retried.
*/
class DBClientReplicaSet : public DBClientBase {
public:
using DBClientBase::query;
using DBClientBase::update;
using DBClientBase::remove;
/** Call connect() after constructing. autoReconnect is always on for DBClientReplicaSet
* connections. */
DBClientReplicaSet(const std::string& name,
const std::vector<HostAndPort>& servers,
double so_timeout = 0);
virtual ~DBClientReplicaSet();
/**
* Returns false if no member of the set were reachable. This object
* can still be used even when false was returned as it will try to
* reconnect when you use it later.
*/
bool connect();
/**
* Logs out the connection for the given database.
*
* @param dbname the database to logout from.
* @param info the result object for the logout command (provided for backwards
* compatibility with mongo shell)
*/
virtual void logout(const std::string& dbname, BSONObj& info);
// ----------- simple functions --------------
/** throws userassertion "no master found" */
virtual std::unique_ptr<DBClientCursor> query(const std::string& ns,
Query query,
int nToReturn = 0,
int nToSkip = 0,
const BSONObj* fieldsToReturn = 0,
int queryOptions = 0,
int batchSize = 0);
/** throws userassertion "no master found" */
virtual BSONObj findOne(const std::string& ns,
const Query& query,
const BSONObj* fieldsToReturn = 0,
int queryOptions = 0);
virtual void insert(const std::string& ns, BSONObj obj, int flags = 0);
/** insert multiple objects. Note that single object insert is asynchronous, so this version
is only nominally faster and not worth a special effort to try to use. */
virtual void insert(const std::string& ns, const std::vector<BSONObj>& v, int flags = 0);
virtual void remove(const std::string& ns, Query obj, int flags);
virtual void update(const std::string& ns, Query query, BSONObj obj, int flags);
virtual void killCursor(long long cursorID);
// ---- access raw connections ----
/**
* WARNING: this method is very dangerous - this object can decide to free the
* returned master connection any time.
*
* @return the reference to the address that points to the master connection.
*/
DBClientConnection& masterConn();
/**
* WARNING: this method is very dangerous - this object can decide to free the
* returned master connection any time. This can also unpin the cached
* slaveOk/read preference connection.
*
* @return the reference to the address that points to a secondary connection.
*/
DBClientConnection& slaveConn();
// ---- callback pieces -------
virtual void say(Message& toSend, bool isRetry = false, std::string* actualServer = 0);
virtual bool recv(Message& toRecv);
virtual void checkResponse(const char* data,
int nReturned,
bool* retry = NULL,
std::string* targetHost = NULL);
/* this is the callback from our underlying connections to notify us that we got a "not master"
* error.
*/
void isntMaster();
/* this is used to indicate we got a "not master or secondary" error from a secondary.
*/
void isntSecondary();
// ----- status ------
virtual bool isFailed() const {
return !_master || _master->isFailed();
}
bool isStillConnected();
// ----- informational ----
/**
* Gets the replica set name of the set we are connected to.
*/
const std::string& getSetName() const {
return _setName;
}
/**
* Returns the HostAndPort of the server this connection believes belongs to the primary,
* or returns an empty HostAndPort if it doesn't know about a current primary.
*/
HostAndPort getSuspectedPrimaryHostAndPort() const;
double getSoTimeout() const {
return _so_timeout;
}
std::string toString() const {
return getServerAddress();
}
std::string getServerAddress() const;
virtual ConnectionString::ConnectionType type() const {
return ConnectionString::SET;
}
virtual bool lazySupported() const {
return true;
}
rpc::UniqueReply runCommandWithMetadata(StringData database,
StringData command,
const BSONObj& metadata,
const BSONObj& commandArgs) final;
void setRequestMetadataWriter(rpc::RequestMetadataWriter writer) final;
void setReplyMetadataReader(rpc::ReplyMetadataReader reader) final;
// ---- low level ------
virtual bool call(Message& toSend,
Message& response,
bool assertOk = true,
std::string* actualServer = 0);
virtual bool callRead(Message& toSend, Message& response) {
return checkMaster()->callRead(toSend, response);
}
/**
* Returns whether a query or command can be sent to secondaries based on the query object
* and options.
*
* @param ns the namespace of the query.
* @param queryObj the query object to check.
* @param queryOptions the query options
*
* @return true if the query/cmd could potentially be sent to a secondary, false otherwise
*/
static bool isSecondaryQuery(const std::string& ns, const BSONObj& queryObj, int queryOptions);
/**
* Performs a "soft reset" by clearing all states relating to secondary nodes and
* returning secondary connections to the pool.
*/
virtual void reset();
/**
* @bool setting if true, DBClientReplicaSet connections will make sure that secondary
* connections are authenticated and log them before returning them to the pool.
*/
static void setAuthPooledSecondaryConn(bool setting);
protected:
/** Authorize. Authorizes all nodes as needed
*/
virtual void _auth(const BSONObj& params);
virtual void sayPiggyBack(Message& toSend) {
checkMaster()->say(toSend);
}
private:
/**
* Used to simplify slave-handling logic on errors
*
* @return back the passed cursor
* @throws DBException if the directed node cannot accept the query because it
* is not a master
*/
std::unique_ptr<DBClientCursor> checkSlaveQueryResult(std::unique_ptr<DBClientCursor> result);
DBClientConnection* checkMaster();
/**
* Helper method for selecting a node based on the read preference. Will advance
* the tag tags object if it cannot find a node that matches the current tag.
*
* @param readPref the preference to use for selecting a node.
*
* @return a pointer to the new connection object if it can find a good connection.
* Otherwise it returns NULL.
*
* @throws DBException when an error occurred either when trying to connect to
* a node that was thought to be ok or when an assertion happened.
*/
DBClientConnection* selectNodeUsingTags(std::shared_ptr<ReadPreferenceSetting> readPref);
/**
* @return true if the last host used in the last slaveOk query is still in the
* set and can be used for the given read preference.
*/
bool checkLastHost(const ReadPreferenceSetting* readPref);
/**
* Destroys all cached information about the last slaveOk operation.
*/
void invalidateLastSlaveOkCache();
void _auth(DBClientConnection* conn);
/**
* Calls logout on the connection for all known database this DBClientRS instance has
* logged in.
*/
void logoutAll(DBClientConnection* conn);
/**
* Clears the master connection.
*/
void resetMaster();
/**
* Clears the slaveOk connection and returns it to the pool if not the same as _master.
*/
void resetSlaveOkConn();
/**
* Maximum number of retries to make for auto-retry logic when performing a slave ok
* operation.
*/
static const size_t MAX_RETRY;
// TODO: remove this when processes other than mongos uses the driver version.
static bool _authPooledSecondaryConn;
// Throws a DBException if the monitor doesn't exist and there isn't a cached seed to use.
ReplicaSetMonitorPtr _getMonitor() const;
std::string _setName;
HostAndPort _masterHost;
std::unique_ptr<DBClientConnection> _master;
// Last used host in a slaveOk query (can be a primary).
HostAndPort _lastSlaveOkHost;
// Last used connection in a slaveOk query (can be a primary).
// Connection can either be owned here or returned to the connection pool. Note that
// if connection is primary, it is owned by _master so it is incorrect to return
// it to the pool.
std::unique_ptr<DBClientConnection> _lastSlaveOkConn;
std::shared_ptr<ReadPreferenceSetting> _lastReadPref;
double _so_timeout;
// we need to store so that when we connect to a new node on failure
// we can re-auth
// this could be a security issue, as the password is stored in memory
// not sure if/how we should handle
std::map<std::string, BSONObj> _auths; // dbName -> auth parameters
protected:
/**
* for storing (non-threadsafe) information between lazy calls
*/
class LazyState {
public:
LazyState() : _lastClient(NULL), _lastOp(-1), _secondaryQueryOk(false), _retries(0) {}
DBClientConnection* _lastClient;
int _lastOp;
bool _secondaryQueryOk;
int _retries;
} _lazyState;
};
}
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