C++ OplogReader::haveCursor方法代码示例

    void ReplSetImpl::_getOplogDiagsAsHtml(unsigned server_id, stringstream& ss) const {
        const Member *m = findById(server_id);
        if( m == 0 ) {
            ss << "Error : can't find a member with id: " << server_id << '\n';
            return;
        }

        ss << p("Server : " + m->fullName() + "<br>ns : " + rsoplog );

        //const bo fields = BSON( "o" << false << "o2" << false );
        const bo fields;

        /** todo fix we might want an so timeout here */
        OplogReader reader;

        if (reader.connect(m->h()) == false) {
            ss << "couldn't connect to " << m->fullName();
            return;
        }

        reader.query(rsoplog, Query().sort("$natural",1), 20, 0, &fields);
        if ( !reader.haveCursor() ) {
            ss << "couldn't query " << rsoplog;
            return;
        }
        static const char *h[] = {"ts","optime","h","op","ns","rest",0};

        ss << "<style type=\"text/css\" media=\"screen\">"
           "table { font-size:75% }\n"
           // "th { background-color:#bbb; color:#000 }\n"
           // "td,th { padding:.25em }\n"
           "</style>\n";

        ss << table(h, true);
        //ss << "<pre>\n";
        int n = 0;
        OpTime otFirst;
        OpTime otLast;
        OpTime otEnd;
        while( reader.more() ) {
            bo o = reader.next();
            otLast = o["ts"]._opTime();
            if( otFirst.isNull() )
                otFirst = otLast;
            say(ss, o);
            n++;
        }
        if( n == 0 ) {
            ss << rsoplog << " is empty\n";
        }
        else {
            reader.query(rsoplog, Query().sort("$natural",-1), 20, 0, &fields);
            if( !reader.haveCursor() ) {
                ss << "couldn't query [2] " << rsoplog;
                return;
            }
            string x;
            bo o = reader.next();
            otEnd = o["ts"]._opTime();
            while( 1 ) {
                stringstream z;
                if( o["ts"]._opTime() == otLast )
                    break;
                say(z, o);
                x = z.str() + x;
                if( !reader.more() )
                    break;
                o = reader.next();
            }
            if( !x.empty() ) {
                ss << "<tr><td>...</td><td>...</td><td>...</td><td>...</td><td>...</td></tr>\n" << x;
                //ss << "\n...\n\n" << x;
            }
        }
        ss << _table();
        ss << p(time_t_to_String_short(time(0)) + " current time");

        if( !otEnd.isNull() ) {
            ss << "<p>Log length in time: ";
            unsigned d = otEnd.getSecs() - otFirst.getSecs();
            double h = d / 3600.0;
            ss.precision(3);
            if( h < 72 )
                ss << h << " hours";
            else
                ss << h / 24.0 << " days";
            ss << "</p>\n";
        }
    }

    void BackgroundSync::produce() {
        // this oplog reader does not do a handshake because we don't want the server it's syncing
        // from to track how far it has synced
        OplogReader r;
        OpTime lastOpTimeFetched;
        // find a target to sync from the last op time written
        getOplogReader(r);

        // no server found
        {
            boost::unique_lock<boost::mutex> lock(_mutex);

            if (_currentSyncTarget == NULL) {
                lock.unlock();
                sleepsecs(1);
                // if there is no one to sync from
                return;
            }
            lastOpTimeFetched = _lastOpTimeFetched;
        }

        r.tailingQueryGTE(rsoplog, lastOpTimeFetched);

        // if target cut connections between connecting and querying (for
        // example, because it stepped down) we might not have a cursor
        if (!r.haveCursor()) {
            return;
        }

        uassert(1000, "replSet source for syncing doesn't seem to be await capable -- is it an older version of mongodb?", r.awaitCapable() );

        if (isRollbackRequired(r)) {
            stop();
            return;
        }

        while (!inShutdown()) {
            if (!r.moreInCurrentBatch()) {
                // Check some things periodically
                // (whenever we run out of items in the
                // current cursor batch)

                int bs = r.currentBatchMessageSize();
                if( bs > 0 && bs < BatchIsSmallish ) {
                    // on a very low latency network, if we don't wait a little, we'll be 
                    // getting ops to write almost one at a time.  this will both be expensive
                    // for the upstream server as well as potentially defeating our parallel 
                    // application of batches on the secondary.
                    //
                    // the inference here is basically if the batch is really small, we are 
                    // "caught up".
                    //
                    dassert( !Lock::isLocked() );
                    sleepmillis(SleepToAllowBatchingMillis);
                }
  
                if (theReplSet->gotForceSync()) {
                    return;
                }
                // If we are transitioning to primary state, we need to leave
                // this loop in order to go into bgsync-pause mode.
                if (isAssumingPrimary() || theReplSet->isPrimary()) {
                    return;
                }

                // re-evaluate quality of sync target
                if (shouldChangeSyncTarget()) {
                    return;
                }


                {
                    //record time for each getmore
                    TimerHolder batchTimer(&getmoreReplStats);
                    
                    // This calls receiveMore() on the oplogreader cursor.
                    // It can wait up to five seconds for more data.
                    r.more();
                }
                networkByteStats.increment(r.currentBatchMessageSize());

                if (!r.moreInCurrentBatch()) {
                    // If there is still no data from upstream, check a few more things
                    // and then loop back for another pass at getting more data
                    {
                        boost::unique_lock<boost::mutex> lock(_mutex);
                        if (_pause || 
                            !_currentSyncTarget || 
                            !_currentSyncTarget->hbinfo().hbstate.readable()) {
                            return;
                        }
                    }

                    r.tailCheck();
                    if( !r.haveCursor() ) {
                        LOG(1) << "replSet end syncTail pass" << rsLog;
                        return;
                    }

                    continue;
//.........这里部分代码省略.........

    /* initial oplog application, during initial sync, after cloning. 
       @return false on failure.  
       this method returns an error and doesn't throw exceptions (i think).
    */
    bool ReplSetImpl::initialSyncOplogApplication(
        const Member *source,
        OpTime applyGTE,
        OpTime minValid)
    { 
        if( source == 0 ) return false;

        const string hn = source->h().toString();
        OpTime ts;
        try {
            OplogReader r;
            if( !r.connect(hn) ) { 
                log() << "replSet initial sync error can't connect to " << hn << " to read " << rsoplog << rsLog;
                return false;
            }

            {
                BSONObjBuilder q;
                q.appendDate("$gte", applyGTE.asDate());
                BSONObjBuilder query;
                query.append("ts", q.done());
                BSONObj queryObj = query.done();
                r.query(rsoplog, queryObj);
            }
            assert( r.haveCursor() );

            /* we lock outside the loop to avoid the overhead of locking on every operation.  server isn't usable yet anyway! */
            writelock lk("");

            {
                if( !r.more() ) { 
                    sethbmsg("replSet initial sync error reading remote oplog");
                    log() << "replSet initial sync error remote oplog (" << rsoplog << ") on host " << hn << " is empty?" << rsLog;
                    return false;
                }
                bo op = r.next();
                OpTime t = op["ts"]._opTime();
                r.putBack(op);

                if( op.firstElement().fieldName() == string("$err") ) { 
                    log() << "replSet initial sync error querying " << rsoplog << " on " << hn << " : " << op.toString() << rsLog;
                    return false;
                }

                uassert( 13508 , str::stream() << "no 'ts' in first op in oplog: " << op , !t.isNull() );
                if( t > applyGTE ) {
                    sethbmsg(str::stream() << "error " << hn << " oplog wrapped during initial sync");
                    log() << "replSet initial sync expected first optime of " << applyGTE << rsLog;
                    log() << "replSet initial sync but received a first optime of " << t << " from " << hn << rsLog;
                    return false;
                }
            }

            // todo : use exhaust
            unsigned long long n = 0;
            while( 1 ) { 

                if( !r.more() )
                    break;
                BSONObj o = r.nextSafe(); /* note we might get "not master" at some point */
                {
                    ts = o["ts"]._opTime();

                    /* if we have become primary, we dont' want to apply things from elsewhere
                        anymore. assumePrimary is in the db lock so we are safe as long as 
                        we check after we locked above. */
                    if( (source->state() != MemberState::RS_PRIMARY &&
                         source->state() != MemberState::RS_SECONDARY) ||
                        replSetForceInitialSyncFailure ) {
                        
                        int f = replSetForceInitialSyncFailure;
                        if( f > 0 ) {
                            replSetForceInitialSyncFailure = f-1;
                            log() << "replSet test code invoked, replSetForceInitialSyncFailure" << rsLog;
                            throw DBException("forced error",0);
                        }
                        log() << "replSet we are now primary" << rsLog;
                        throw DBException("primary changed",0);
                    }

                    if( ts >= applyGTE ) {
                        // optimes before we started copying need not be applied.
                        syncApply(o);
                    }
                    _logOpObjRS(o);   /* with repl sets we write the ops to our oplog too */
                }
                if( ++n % 100000 == 0 ) { 
                    // simple progress metering
                    log() << "replSet initialSyncOplogApplication " << n << rsLog;
                }
            }
        }
        catch(DBException& e) { 
            if( ts <= minValid ) {
                // didn't make it far enough
                log() << "replSet initial sync failing, error applying oplog " << e.toString() << rsLog;
//.........这里部分代码省略.........

    bool ReplSetImpl::_initialSyncOplogApplication(OplogReader& r, const Member *source,
        const OpTime& applyGTE, const OpTime& minValid) {

        const string hn = source->fullName();
        OplogReader missingObjReader;
        try {
            r.tailingQueryGTE( rsoplog, applyGTE );
            if ( !r.haveCursor() ) {
                log() << "replSet initial sync oplog query error" << rsLog;
                return false;
            }

            {
                if( !r.more() ) {
                    sethbmsg("replSet initial sync error reading remote oplog");
                    log() << "replSet initial sync error remote oplog (" << rsoplog << ") on host " << hn << " is empty?" << rsLog;
                    return false;
                }
                bo op = r.next();
                OpTime t = op["ts"]._opTime();
                r.putBack(op);

                if( op.firstElementFieldName() == string("$err") ) {
                    log() << "replSet initial sync error querying " << rsoplog << " on " << hn << " : " << op.toString() << rsLog;
                    return false;
                }

                uassert( 13508 , str::stream() << "no 'ts' in first op in oplog: " << op , !t.isNull() );
                if( t > applyGTE ) {
                    sethbmsg(str::stream() << "error " << hn << " oplog wrapped during initial sync");
                    log() << "replSet initial sync expected first optime of " << applyGTE << rsLog;
                    log() << "replSet initial sync but received a first optime of " << t << " from " << hn << rsLog;
                    return false;
                }

                sethbmsg(str::stream() << "initial oplog application from " << hn << " starting at "
                         << t.toStringPretty() << " to " << minValid.toStringPretty());
            }
        }
        catch(DBException& e) {
            log() << "replSet initial sync failing: " << e.toString() << rsLog;
            return false;
        }

        /* we lock outside the loop to avoid the overhead of locking on every operation. */
        writelock lk("");

        // todo : use exhaust
        OpTime ts;
        time_t start = time(0);
        unsigned long long n = 0;
        while( 1 ) {
            try {
                if( !r.more() )
                    break;
                BSONObj o = r.nextSafe(); /* note we might get "not master" at some point */
                ts = o["ts"]._opTime();

                {
                    if( (source->state() != MemberState::RS_PRIMARY &&
                            source->state() != MemberState::RS_SECONDARY) ||
                            replSetForceInitialSyncFailure ) {

                        int f = replSetForceInitialSyncFailure;
                        if( f > 0 ) {
                            replSetForceInitialSyncFailure = f-1;
                            log() << "replSet test code invoked, replSetForceInitialSyncFailure" << rsLog;
                            throw DBException("forced error",0);
                        }
                        log() << "replSet we are now primary" << rsLog;
                        throw DBException("primary changed",0);
                    }

                    if( ts >= applyGTE ) { // optimes before we started copying need not be applied.
                        bool failedUpdate = syncApply(o);
                        if( failedUpdate ) {
                            // we don't have the object yet, which is possible on initial sync.  get it.
                            log() << "replSet info adding missing object" << endl; // rare enough we can log
                            if( !missingObjReader.connect(hn) ) { // ok to call more than once
                                log() << "replSet initial sync fails, couldn't connect to " << hn << endl;
                                return false;
                            }
                            const char *ns = o.getStringField("ns");
                            BSONObj query = BSONObjBuilder().append(o.getObjectField("o2")["_id"]).obj(); // might be more than just _id in the update criteria
                            BSONObj missingObj;
                            try {
                                missingObj = missingObjReader.findOne(
                                    ns, 
                                    query );
                            } catch(...) { 
                                log() << "replSet assertion fetching missing object" << endl;
                                throw;
                            }
                            if( missingObj.isEmpty() ) { 
                                log() << "replSet missing object not found on source. presumably deleted later in oplog" << endl;
                                log() << "replSet o2: " << o.getObjectField("o2").toString() << endl;
                                log() << "replSet o firstfield: " << o.getObjectField("o").firstElementFieldName() << endl;
                            }
                            else {
                                Client::Context ctx(ns);
//.........这里部分代码省略.........

    bool replset::InitialSync::oplogApplication(OplogReader& r, const Member* source,
        const OpTime& applyGTE, const OpTime& minValid) {

        const string hn = source->fullName();
        try {
            r.tailingQueryGTE( rsoplog, applyGTE );
            if ( !r.haveCursor() ) {
                log() << "replSet initial sync oplog query error" << rsLog;
                return false;
            }

            {
                if( !r.more() ) {
                    sethbmsg("replSet initial sync error reading remote oplog");
                    log() << "replSet initial sync error remote oplog (" << rsoplog << ") on host " << hn << " is empty?" << rsLog;
                    return false;
                }
                bo op = r.next();
                OpTime t = op["ts"]._opTime();
                r.putBack(op);

                if( op.firstElementFieldName() == string("$err") ) {
                    log() << "replSet initial sync error querying " << rsoplog << " on " << hn << " : " << op.toString() << rsLog;
                    return false;
                }

                uassert( 13508 , str::stream() << "no 'ts' in first op in oplog: " << op , !t.isNull() );
                if( t > applyGTE ) {
                    sethbmsg(str::stream() << "error " << hn << " oplog wrapped during initial sync");
                    log() << "replSet initial sync expected first optime of " << applyGTE << rsLog;
                    log() << "replSet initial sync but received a first optime of " << t << " from " << hn << rsLog;
                    return false;
                }

                sethbmsg(str::stream() << "initial oplog application from " << hn << " starting at "
                         << t.toStringPretty() << " to " << minValid.toStringPretty());
            }
        }
        catch(DBException& e) {
            log() << "replSet initial sync failing: " << e.toString() << rsLog;
            return false;
        }

        /* we lock outside the loop to avoid the overhead of locking on every operation. */
        writelock lk("");

        // todo : use exhaust
        OpTime ts;
        time_t start = time(0);
        unsigned long long n = 0;
        int fails = 0;
        while( ts < minValid ) {
            try {
                // There are some special cases with initial sync (see the catch block), so we
                // don't want to break out of this while until we've reached minvalid. Thus, we'll
                // keep trying to requery.
                if( !r.more() ) {
                    OCCASIONALLY log() << "replSet initial sync oplog: no more records" << endl;
                    sleepsecs(1);

                    r.resetCursor();
                    r.tailingQueryGTE(rsoplog, theReplSet->lastOpTimeWritten);
                    if ( !r.haveCursor() ) {
                        if (fails++ > 30) {
                            log() << "replSet initial sync tried to query oplog 30 times, giving up" << endl;
                            return false;
                        }
                    }

                    continue;
                }

                BSONObj o = r.nextSafe(); /* note we might get "not master" at some point */
                ts = o["ts"]._opTime();

                {
                    if( (source->state() != MemberState::RS_PRIMARY &&
                            source->state() != MemberState::RS_SECONDARY) ||
                            replSetForceInitialSyncFailure ) {

                        int f = replSetForceInitialSyncFailure;
                        if( f > 0 ) {
                            replSetForceInitialSyncFailure = f-1;
                            log() << "replSet test code invoked, replSetForceInitialSyncFailure" << rsLog;
                            throw DBException("forced error",0);
                        }
                        log() << "replSet we are now primary" << rsLog;
                        throw DBException("primary changed",0);
                    }

                    applyOp(o, applyGTE);
                }

                if ( ++n % 1000 == 0 ) {
                    time_t now = time(0);
                    if (now - start > 10) {
                        // simple progress metering
                        log() << "replSet initialSyncOplogApplication applied " << n << " operations, synced to "
                              << ts.toStringPretty() << rsLog;
                        start = now;
//.........这里部分代码省略.........

    /* initial oplog application, during initial sync, after cloning.
       @return false on failure.
       this method returns an error and doesn't throw exceptions (i think).
    */
    bool ReplSetImpl::initialSyncOplogApplication(
        const Member *source,
        OpTime applyGTE,
        OpTime minValid) {
        if( source == 0 ) return false;

        const string hn = source->h().toString();
        OplogReader r;
        try {
            if( !r.connect(hn) ) {
                log() << "replSet initial sync error can't connect to " << hn << " to read " << rsoplog << rsLog;
                return false;
            }

            r.queryGTE( rsoplog, applyGTE );
            assert( r.haveCursor() );

            {
                if( !r.more() ) {
                    sethbmsg("replSet initial sync error reading remote oplog");
                    log() << "replSet initial sync error remote oplog (" << rsoplog << ") on host " << hn << " is empty?" << rsLog;
                    return false;
                }
                bo op = r.next();
                OpTime t = op["ts"]._opTime();
                r.putBack(op);

                if( op.firstElement().fieldName() == string("$err") ) {
                    log() << "replSet initial sync error querying " << rsoplog << " on " << hn << " : " << op.toString() << rsLog;
                    return false;
                }

                uassert( 13508 , str::stream() << "no 'ts' in first op in oplog: " << op , !t.isNull() );
                if( t > applyGTE ) {
                    sethbmsg(str::stream() << "error " << hn << " oplog wrapped during initial sync");
                    log() << "replSet initial sync expected first optime of " << applyGTE << rsLog;
                    log() << "replSet initial sync but received a first optime of " << t << " from " << hn << rsLog;
                    return false;
                }

                sethbmsg(str::stream() << "initial oplog application from " << hn << " starting at "
                         << t.toStringPretty() << " to " << minValid.toStringPretty());
            }
        }
        catch(DBException& e) {
            log() << "replSet initial sync failing: " << e.toString() << rsLog;
            return false;
        }

        /* we lock outside the loop to avoid the overhead of locking on every operation. */
        writelock lk("");

        // todo : use exhaust
        OpTime ts;
        time_t start = time(0);
        unsigned long long n = 0;
        while( 1 ) {
            try {
                if( !r.more() )
                    break;
                BSONObj o = r.nextSafe(); /* note we might get "not master" at some point */
                {
                    ts = o["ts"]._opTime();

                    /* if we have become primary, we dont' want to apply things from elsewhere
                        anymore. assumePrimary is in the db lock so we are safe as long as
                        we check after we locked above. */
                    if( (source->state() != MemberState::RS_PRIMARY &&
                            source->state() != MemberState::RS_SECONDARY) ||
                            replSetForceInitialSyncFailure ) {

                        int f = replSetForceInitialSyncFailure;
                        if( f > 0 ) {
                            replSetForceInitialSyncFailure = f-1;
                            log() << "replSet test code invoked, replSetForceInitialSyncFailure" << rsLog;
                            throw DBException("forced error",0);
                        }
                        log() << "replSet we are now primary" << rsLog;
                        throw DBException("primary changed",0);
                    }

                    if( ts >= applyGTE ) {
                        // optimes before we started copying need not be applied.
                        syncApply(o);
                    }
                    _logOpObjRS(o);   /* with repl sets we write the ops to our oplog too */
                }

                if ( ++n % 1000 == 0 ) {
                    time_t now = time(0);
                    if (now - start > 10) {
                        // simple progress metering
                        log() << "replSet initialSyncOplogApplication applied " << n << " operations, synced to "
                              << ts.toStringPretty() << rsLog;
                        start = now;
                    }
//.........这里部分代码省略.........