// @file s/client_info.cpp

/**
 *    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/>.
 *
 *    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.
 */

#include "mongo/pch.h"

#include "mongo/client/connpool.h"
#include "mongo/db/auth/authorization_manager_global.h"
#include "mongo/db/auth/authorization_session.h"
#include "mongo/db/auth/authz_session_external_state_s.h"
#include "mongo/db/commands.h"
#include "mongo/db/commands/server_status.h"
#include "mongo/db/dbmessage.h"
#include "mongo/db/stats/counters.h"
#include "mongo/db/stats/timer_stats.h"
#include "mongo/s/client_info.h"
#include "mongo/s/config.h"
#include "mongo/s/chunk.h"
#include "mongo/s/cursors.h"
#include "mongo/s/grid.h"
#include "mongo/s/request.h"
#include "mongo/s/writeback_listener.h"
#include "mongo/server.h"
#include "mongo/util/mongoutils/str.h"
#include "mongo/util/scopeguard.h"

namespace mongo {

    ClientInfo::ClientInfo(AbstractMessagingPort* messagingPort) : ClientBasic(messagingPort) {
        _cur = &_a;
        _prev = &_b;
        _autoSplitOk = true;
        if (messagingPort) {
            _remote = messagingPort->remote();
        }
    }

    ClientInfo::~ClientInfo() {
    }

    void ClientInfo::addShard( const string& shard ) {
        _cur->insert( shard );
        _sinceLastGetError.insert( shard );
    }

    void ClientInfo::newPeerRequest( const HostAndPort& peer ) {
        if ( ! _remote.hasPort() )
            _remote = peer;
        else if ( _remote != peer ) {
            stringstream ss;
            ss << "remotes don't match old [" << _remote.toString() << "] new [" << peer.toString() << "]";
            throw UserException( 13134 , ss.str() );
        }

        newRequest();
    }

    void ClientInfo::newRequest() {
        _lastAccess = (int) time(0);

        set<string> * temp = _cur;
        _cur = _prev;
        _prev = temp;
        _cur->clear();
    }

    ClientInfo* ClientInfo::create(AbstractMessagingPort* messagingPort) {
        ClientInfo * info = _tlInfo.get();
        massert(16472, "A ClientInfo already exists for this thread", !info);
        info = new ClientInfo(messagingPort);
        info->setAuthorizationSession(new AuthorizationSession(
                new AuthzSessionExternalStateMongos(getGlobalAuthorizationManager())));
        _tlInfo.reset( info );
        info->newRequest();
        return info;
    }

    ClientInfo * ClientInfo::get(AbstractMessagingPort* messagingPort) {
        ClientInfo * info = _tlInfo.get();
        if (!info) {
            info = create(messagingPort);
        }
        massert(16483,
                mongoutils::str::stream() << "AbstractMessagingPort was provided to ClientInfo::get"
                        << " but differs from the one stored in the current ClientInfo object. "
                        << "Current ClientInfo messaging port "
                        << (info->port() ? "is not" : "is")
                        << " NULL",
                messagingPort == NULL || messagingPort == info->port());
        return info;
    }

    bool ClientInfo::exists() {
        return _tlInfo.get();
    }

    bool ClientBasic::hasCurrent() {
        return ClientInfo::exists();
    }

    ClientBasic* ClientBasic::getCurrent() {
        return ClientInfo::get();
    }


    void ClientInfo::disconnect() {
        // should be handled by TL cleanup
        _lastAccess = 0;
    }

    void ClientInfo::_addWriteBack( vector<WBInfo>& all, const BSONObj& gle, bool fromLastOperation ) {
        BSONElement w = gle["writeback"];

        if ( w.type() != jstOID )
            return;

        BSONElement cid = gle["connectionId"];

        if ( cid.eoo() ) {
            error() << "getLastError writeback can't work because of version mismatch" << endl;
            return;
        }

        string ident = "";
        if ( gle["instanceIdent"].type() == String )
            ident = gle["instanceIdent"].String();

        all.push_back( WBInfo( WriteBackListener::ConnectionIdent( ident , cid.numberLong() ),
                               w.OID(),
                               fromLastOperation ) );
    }

    vector<BSONObj> ClientInfo::_handleWriteBacks( const vector<WBInfo>& all , bool fromWriteBackListener ) {
        vector<BSONObj> res;

        if ( all.size() == 0 )
            return res;

        if ( fromWriteBackListener ) {
            LOG(1) << "not doing recursive writeback" << endl;
            return res;
        }

        for ( unsigned i=0; i<all.size(); i++ ) {
            res.push_back( WriteBackListener::waitFor( all[i].ident , all[i].id ) );
        }

        return res;
    }

    void ClientInfo::disableForCommand() {
        set<string> * temp = _cur;
        _cur = _prev;
        _prev = temp;
    }

    static TimerStats gleWtimeStats;
    static ServerStatusMetricField<TimerStats> displayGleLatency( "getLastError.wtime", &gleWtimeStats );

    bool ClientInfo::getLastError( const string& dbName,
                                   const BSONObj& options,
                                   BSONObjBuilder& result,
                                   string& errmsg,
                                   bool fromWriteBackListener)
    {

        scoped_ptr<TimerHolder> gleTimerHolder;
        if ( ! fromWriteBackListener ) {
            bool doTiming = false;
            const BSONElement& e = options["w"];
            if ( e.isNumber() ) {
                doTiming = e.numberInt() > 1;
            }
            else if ( e.type() == String ) {
                doTiming = true;
            }
            if ( doTiming ) {
                gleTimerHolder.reset( new TimerHolder( &gleWtimeStats ) );
            }
        }


        set<string> * shards = getPrev();

        if ( shards->size() == 0 ) {
            result.appendNull( "err" );
            return true;
        }

        vector<WBInfo> writebacks;

        //
        // TODO: These branches should be collapsed into a single codepath
        //

        // handle single server
        if ( shards->size() == 1 ) {
            string theShard = *(shards->begin() );

            BSONObj res;
            bool ok = false;
            {
                LOG(5) << "gathering response for gle from: " << theShard << endl;

                ShardConnection conn( theShard , "" );
                try {
                    ok = conn->runCommand( dbName , options , res );
                }
                catch( std::exception &e ) {

                    string message =
                            str::stream() << "could not get last error from shard " << theShard
                                          << causedBy( e );

                    warning() << message << endl;
                    errmsg = message;

                    // Catch everything that happens here, since we need to ensure we return our connection when we're
                    // finished.
                    conn.done();

                    return false;
                }


                res = res.getOwned();
                conn.done();
            }

            _addWriteBack( writebacks, res, true );

            LOG(4) << "gathering writebacks from " << sinceLastGetError().size() << " hosts for"
                   << " gle (" << theShard << ")" << endl;

            // hit other machines just to block
            for ( set<string>::const_iterator i=sinceLastGetError().begin(); i!=sinceLastGetError().end(); ++i ) {
                string temp = *i;
                if ( temp == theShard )
                    continue;

                LOG(5) << "gathering writebacks for single-shard gle from: " << temp << endl;

                try {
                    ShardConnection conn( temp , "" );
                    ON_BLOCK_EXIT_OBJ( conn, &ShardConnection::done );
                    _addWriteBack( writebacks, conn->getLastErrorDetailed(), false );

                }
                catch( std::exception &e ){
                    warning() << "could not clear last error from shard " << temp << causedBy( e ) << endl;
                }

            }
            clearSinceLastGetError();

            LOG(4) << "checking " << writebacks.size() << " writebacks for"
                   << " gle (" << theShard << ")" << endl;

            if ( writebacks.size() ){
                vector<BSONObj> v = _handleWriteBacks( writebacks , fromWriteBackListener );
                if ( v.size() == 0 && fromWriteBackListener ) {
                    // ok
                }
                else {
                    // this will usually be 1
                    // it can be greater than 1 if a write to a different shard
                    // than the last write op had a writeback
                    // all we're going to report is the first
                    // since that's the current write
                    // but we block for all
                    verify( v.size() >= 1 );

                    if ( res["writebackSince"].numberInt() > 0 ) {
                        // got writeback from older op
                        // ignore the result from it, just needed to wait
                        result.appendElements( res );
                    }
                    else if ( writebacks[0].fromLastOperation ) {
                        result.appendElements( v[0] );
                        result.appendElementsUnique( res );
                        result.append( "writebackGLE" , v[0] );
                        result.append( "initialGLEHost" , theShard );
                        result.append( "initialGLE", res );
                    }
                    else {
                        // there was a writeback
                        // but its from an old operations
                        // so all that's important is that we block, not that we return stats
                        result.appendElements( res );
                    }
                }
            }
            else {
                result.append( "singleShard" , theShard );
                result.appendElements( res );
            }

            return ok;
        }

        BSONArrayBuilder bbb( result.subarrayStart( "shards" ) );
        BSONObjBuilder shardRawGLE;

        long long n = 0;

        int updatedExistingStat = 0; // 0 is none, -1 has but false, 1 has true

        // hit each shard
        vector<string> errors;
        vector<BSONObj> errorObjects;
        for ( set<string>::iterator i = shards->begin(); i != shards->end(); i++ ) {
            string theShard = *i;
            bbb.append( theShard );

            LOG(5) << "gathering a response for gle from: " << theShard << endl;

            boost::scoped_ptr<ShardConnection> conn;
            BSONObj res;
            bool ok = false;
            try {
                conn.reset( new ShardConnection( theShard , "" ) ); // constructor can throw if shard is down
                ok = (*conn)->runCommand( dbName , options , res );
                shardRawGLE.append( theShard , res );
            }
            catch( std::exception &e ){

                // Safe to return here, since we haven't started any extra processing yet, just collecting
                // responses.

                string message =
                        str::stream() << "could not get last error from a shard " << theShard
                                      << causedBy( e );

                warning() << message << endl;
                errmsg = message;

                if (conn)
                    conn->done();

                return false;
            }

            _addWriteBack( writebacks, res, true );

            string temp = DBClientWithCommands::getLastErrorString( res );
            if ( (*conn)->type() != ConnectionString::SYNC && ( ok == false || temp.size() ) ) {
                errors.push_back( temp );
                errorObjects.push_back( res );
            }

            n += res["n"].numberLong();
            if ( res["updatedExisting"].type() ) {
                if ( res["updatedExisting"].trueValue() )
                    updatedExistingStat = 1;
                else if ( updatedExistingStat == 0 )
                    updatedExistingStat = -1;
            }

            conn->done();
        }

        bbb.done();
        result.append( "shardRawGLE" , shardRawGLE.obj() );

        result.appendNumber( "n" , n );
        if ( updatedExistingStat )
            result.appendBool( "updatedExisting" , updatedExistingStat > 0 );

        LOG(4) << "gathering writebacks from " << sinceLastGetError().size() << " hosts for"
               << " gle (" << shards->size() << " shards)" << endl;

        // hit other machines just to block
        for ( set<string>::const_iterator i=sinceLastGetError().begin(); i!=sinceLastGetError().end(); ++i ) {
            string temp = *i;
            if ( shards->count( temp ) )
                continue;

            LOG(5) << "gathering writebacks for multi-shard gle from: " << temp << endl;

            ShardConnection conn( temp , "" );
            try {
                _addWriteBack( writebacks, conn->getLastErrorDetailed(), false );
            }
            catch( std::exception &e ){
                warning() << "could not clear last error from a shard " << temp << causedBy( e ) << endl;
            }
            conn.done();
        }
        clearSinceLastGetError();

        LOG(4) << "checking " << writebacks.size() << " writebacks for"
                << " gle (" << shards->size() << " shards)" << endl;

        if ( errors.size() == 0 ) {
            result.appendNull( "err" );
            _handleWriteBacks( writebacks , fromWriteBackListener );
            return true;
        }

        result.append( "err" , errors[0].c_str() );

        {
            // errs
            BSONArrayBuilder all( result.subarrayStart( "errs" ) );
            for ( unsigned i=0; i<errors.size(); i++ ) {
                all.append( errors[i].c_str() );
            }
            all.done();
        }

        {
            // errObjects
            BSONArrayBuilder all( result.subarrayStart( "errObjects" ) );
            for ( unsigned i=0; i<errorObjects.size(); i++ ) {
                all.append( errorObjects[i] );
            }
            all.done();
        }

        _handleWriteBacks( writebacks , fromWriteBackListener );
        return true;
    }

    boost::thread_specific_ptr<ClientInfo> ClientInfo::_tlInfo;

} // namespace mongo