path: root/db/cloner.cpp

// cloner.cpp - copy a database (export/import basically)

/**
*    Copyright (C) 2008 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/>.
*/

#include "stdafx.h"
#include "pdfile.h"
#include "../client/dbclient.h"
#include "../util/builder.h"
#include "jsobj.h"
#include "query.h"
#include "commands.h"
#include "db.h"
#include "instance.h"
#include "repl.h"

namespace mongo {

    void ensureHaveIdIndex(const char *ns);
    extern int port;

    class Cloner: boost::noncopyable {
        auto_ptr< DBClientInterface > conn;
        void copy(const char *from_ns, const char *to_ns, bool isindex, bool logForRepl,
                  bool masterSameProcess, bool slaveOk);
    public:
        Cloner() { }

        /* slaveOk - if true it is ok if the source of the data is !ismaster.
        */
        bool go(const char *masterHost, string& errmsg, const string& fromdb, bool logForRepl, bool slaveOk);
    };

    /* for index info object:
         { "name" : "name_1" , "ns" : "foo.index3" , "key" :  { "name" : 1.0 } }
       we need to fix up the value in the "ns" parameter so that the name prefix is correct on a
       copy to a new name.
    */
    BSONObj fixindex(BSONObj o) {
        BSONObjBuilder b;
        BSONObjIterator i(o);
        while ( i.more() ) {
            BSONElement e = i.next();
            if ( e.eoo() )
                break;
            if ( string("ns") == e.fieldName() ) {
                uassert("bad ns field for index during dbcopy", e.type() == String);
                const char *p = strchr(e.valuestr(), '.');
                uassert("bad ns field for index during dbcopy [2]", p);
                string newname = database->name + p;
                b.append("ns", newname);
            }
            else
                b.append(e);
        }
        BSONObj res= b.doneAndDecouple();

        /*    if( mod ) {
            out() << "before: " << o.toString() << endl;
            o.dump();
            out() << "after:  " << res.toString() << endl;
            res.dump();
            }*/

        return res;
    }

    /* copy the specified collection
       isindex - if true, this is system.indexes collection, in which we do some transformation when copying.
    */
    void Cloner::copy(const char *from_collection, const char *to_collection, bool isindex, bool logForRepl, bool masterSameProcess, bool slaveOk) {
        auto_ptr<DBClientCursor> c;
        {
            dbtemprelease r;
            c = conn->query( from_collection, emptyObj, 0, 0, 0, slaveOk ? Option_SlaveOk : 0 );
        }
        assert( c.get() );
        while ( 1 ) {
            {
                dbtemprelease r;
                if ( !c->more() )
                    break;
            }
            BSONObj tmp = c->next();

            /* assure object is valid.  note this will slow us down a good bit. */
            if ( !tmp.valid() ) {
                out() << "skipping corrupt object from " << from_collection << '\n';
                continue;
            }

            BSONObj js = tmp;
            if ( isindex ) {
                assert( strstr(from_collection, "system.indexes") );
                js = fixindex(tmp);
            }

            theDataFileMgr.insert(to_collection, (void*) js.objdata(), js.objsize());
            if ( logForRepl )
                logOp("i", to_collection, js);
        }
    }

    bool Cloner::go(const char *masterHost, string& errmsg, const string& fromdb, bool logForRepl, bool slaveOk) {
        string todb = database->name;
        stringstream a,b;
        a << "localhost:" << port;
        b << "127.0.0.1:" << port;
        bool masterSameProcess = ( a.str() == masterHost || b.str() == masterHost );
        if ( masterSameProcess ) {
            if ( fromdb == todb && database->path == dbpath ) {
                // guard against an "infinite" loop
                /* if you are replicating, the local.sources config may be wrong if you get this */
                errmsg = "can't clone from self (localhost).";
                return false;
            }
        }
        /* todo: we can put thesee releases inside dbclient or a dbclient specialization.
           or just wait until we get rid of global lock anyway.
           */
        string ns = fromdb + ".system.namespaces";
        auto_ptr<DBClientCursor> c;
        {
            dbtemprelease r;
            if ( !masterSameProcess ) {
                auto_ptr< DBClientConnection > c( new DBClientConnection() );
                if ( !c->connect( masterHost, errmsg ) )
                    return false;
                conn = c;
            } else {
                conn = auto_ptr< DBClientInterface >( new DBDirectClient() );
            }
            c = conn->query( ns.c_str(), emptyObj, 0, 0, 0, slaveOk ? Option_SlaveOk : 0 );
        }
        if ( c.get() == 0 ) {
            errmsg = "query failed " + ns;
            return false;
        }

        while ( 1 ) {
            {
                dbtemprelease r;
                if ( !c->more() )
                    break;
            }
            BSONObj collection = c->next();
            BSONElement e = collection.findElement("name");
            if ( e.eoo() ) {
                string s = "bad system.namespaces object " + collection.toString();

                /* temp
                out() << masterHost << endl;
                out() << ns << endl;
                out() << e.toString() << endl;
                exit(1);*/

                massert(s.c_str(), false);
            }
            assert( !e.eoo() );
            assert( e.type() == String );
            const char *from_name = e.valuestr();
            if ( strstr(from_name, ".system.") || strchr(from_name, '$') ) {
                continue;
            }
            BSONObj options = collection.getObjectField("options");

            /* change name "<fromdb>.collection" -> <todb>.collection */
            const char *p = strchr(from_name, '.');
            assert(p);
            string to_name = todb + p;

            //if( !options.isEmpty() )
            {
                string err;
                const char *toname = to_name.c_str();
                userCreateNS(toname, options, err, logForRepl);

                /* chunks are big enough that we should create the _id index up front, that should
                   be faster. perhaps we should do that for everything?  Not doing that yet -- not sure
                   how we want to handle _id-less collections, and we might not want to create the index
                   there.
                   */
                if ( strstr(toname, "._chunks") )
                    ensureHaveIdIndex(toname);
            }
            copy(from_name, to_name.c_str(), false, logForRepl, masterSameProcess, slaveOk);
        }

        // now build the indexes
        string system_indexes_from = fromdb + ".system.indexes";
        string system_indexes_to = todb + ".system.indexes";
        copy(system_indexes_from.c_str(), system_indexes_to.c_str(), true, logForRepl, masterSameProcess, slaveOk);

        return true;
    }

    bool cloneFrom(const char *masterHost, string& errmsg, const string& fromdb, bool logForReplication, bool slaveOk)
    {
        Cloner c;
        return c.go(masterHost, errmsg, fromdb, logForReplication, slaveOk);
    }

    /* Usage:
       mydb.$cmd.findOne( { clone: "fromhost" } );
    */
    class CmdClone : public Command {
    public:
        virtual bool slaveOk() {
            return false;
        }
        CmdClone() : Command("clone") { }
        virtual bool run(const char *ns, BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            string from = cmdObj.getStringField("clone");
            if ( from.empty() )
                return false;
            /* replication note: we must logOp() not the command, but the cloned data -- if the slave
               were to clone it would get a different point-in-time and not match.
               */
            return cloneFrom(from.c_str(), errmsg, database->name, /*logForReplication=*/!fromRepl, /*slaveok*/false);
        }
    } cmdclone;

    /* Usage:
       admindb.$cmd.findOne( { copydb: 1, fromhost: <hostname>, fromdb: <db>, todb: <db> } );
    */
    class CmdCopyDb : public Command {
    public:
        CmdCopyDb() : Command("copydb") { }
        virtual bool adminOnly() {
            return true;
        }
        virtual bool slaveOk() {
            return false;
        }
        virtual bool run(const char *ns, BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool fromRepl) {
            string fromhost = cmdObj.getStringField("fromhost");
            if ( fromhost.empty() ) {
                /* copy from self */
                stringstream ss;
                ss << "localhost:" << port;
                fromhost = ss.str();
            }
            string fromdb = cmdObj.getStringField("fromdb");
            string todb = cmdObj.getStringField("todb");
            if ( fromhost.empty() || todb.empty() || fromdb.empty() ) {
                errmsg = "parms missing - {copydb: 1, fromhost: <hostname>, fromdb: <db>, todb: <db>}";
                return false;
            }
            setClient(todb.c_str());
            bool res = cloneFrom(fromhost.c_str(), errmsg, fromdb, /*logForReplication=*/!fromRepl, /*slaveok*/false);
            database = 0;
            return res;
        }
    } cmdcopydb;

} // namespace mongo