mongo/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 "dbclient.h"
#include "../util/builder.h"
#include "jsobj.h"
#include "query.h"
#include "commands.h"
#include "db.h"

extern int port;
bool userCreateNS(const char *ns, JSObj& j, string& err);

class Cloner: boost::noncopyable { 
	DBClientConnection conn;
	void copy(const char *from_ns, const char *to_ns);
public:
	Cloner() { }
	bool go(const char *masterHost, string& errmsg, const string& fromdb);
};

void Cloner::copy(const char *from_collection, const char *to_collection) {
//    cout << "COPY: " << from_collection << " -> " << to_collection << endl;
//    cout << "      client: " << client->name << endl;
    auto_ptr<DBClientCursor> c;
    {
        dbtemprelease r;
        c = auto_ptr<DBClientCursor>( conn.query(from_collection, emptyObj) );
    }
	assert( c.get() );
    while( 1 ) {
        {
            dbtemprelease r;
            if( !c->more() )
                break;
        }
		JSObj js = c->next();
		theDataFileMgr.insert(to_collection, (void*) js.objdata(), js.objsize());
	}
}

bool Cloner::go(const char *masterHost, string& errmsg, const string& fromdb) { 
    string todb = client->name;
	if( (string("localhost") == masterHost || string("127.0.0.1") == masterHost) && port == DBPort ) { 
        if( fromdb == todb ) {
            // 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 lcok anyway. 
       */
	string ns = fromdb + ".system.namespaces";
	auto_ptr<DBClientCursor> c;
    {
        dbtemprelease r;
        if( !conn.connect(masterHost, errmsg) )
            return false;
        c = auto_ptr<DBClientCursor>( conn.query(ns.c_str(), emptyObj) );
    }
	if( c.get() == 0 ) {
		errmsg = "query failed " + ns;
		return false;
	}

    while( 1 ) {
        {
            dbtemprelease r;
            if( !c->more() )
                break;
        }
		JSObj collection = c->next();
		Element e = collection.findElement("name");
		assert( !e.eoo() );
		assert( e.type() == String );
		const char *from_name = e.valuestr();
        if( strstr(from_name, ".system.") || strchr(from_name, '$') ) {
//            cout << "TEMP: skip " << from_name << endl;
			continue;
        }
		JSObj 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;
//            cout << "TEMP: usercreatens " << to_name << " client:" << client->name << endl;
			userCreateNS(to_name.c_str(), options, err);
		}
		copy(from_name, to_name.c_str());
	}

	// 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());

	return true;
}

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

/* Usage:
   mydb.$cmd.findOne( { clone: "fromhost" } ); 
*/
class CmdClone : public Command { 
public:
    CmdClone() : Command("clone") { }

    virtual bool run(const char *ns, JSObj& cmdObj, string& errmsg, JSObjBuilder& result) {
        string from = cmdObj.getStringField("clone");
        if( from.empty() ) 
            return false;
        return cloneFrom(from.c_str(), errmsg, client->name);
    }
} 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 run(const char *ns, JSObj& cmdObj, string& errmsg, JSObjBuilder& result) {
        string fromhost = cmdObj.getStringField("fromhost");
        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);
        client = 0;
        return res;
    }
} cmdcopydb;