Examples with ReadEventCycleSummary com.linkedin.databus2.producers.db.ReadEventCycleSummary used on opensource projects

Example 6 with ReadEventCycleSummary

use of com.linkedin.databus2.producers.db.ReadEventCycleSummary in project databus by linkedin.

the class BootstrapSrcDBEventReader method readEventsFromAllSources.

@Override
public ReadEventCycleSummary readEventsFromAllSources(long sinceSCN) throws DatabusException, EventCreationException, UnsupportedKeyException {
    List<EventReaderSummary> summaries = new ArrayList<EventReaderSummary>();
    long maxScn = EventReaderSummary.NO_EVENTS_SCN;
    long endScn = maxScn;
    boolean error = false;
    long startTS = System.currentTimeMillis();
    try {
        _rate.start();
        _rate.suspend();
        Connection conn = null;
        try {
            conn = _dataSource.getConnection();
            LOG.info("Oracle JDBC Version :" + conn.getMetaData().getDriverVersion());
        } finally {
            DBHelper.close(conn);
        }
        if (!_sources.isEmpty()) {
            // Script assumes seeding is done for one schema at a time
            // just use one source to get the schema name for sy$txlog
            maxScn = getMaxScn(_sources.get(0));
        }
        for (OracleTriggerMonitoredSourceInfo sourceInfo : _sources) {
            LOG.info("Bootstrapping " + sourceInfo.getEventView());
            _bootstrapSeedWriter.start(maxScn);
            EventReaderSummary summary = readEventsForSource(sourceInfo, maxScn);
            // Script assumes seeding is done for one schema at a time
            // just use one source to get the schema name for sy$txlog
            endScn = getMaxScn(_sources.get(0));
            _bootstrapSeedWriter.endEvents(BootstrapEventBuffer.END_OF_SOURCE, endScn, null);
            summaries.add(summary);
        }
    } catch (Exception ex) {
        error = true;
        throw new DatabusException(ex);
    } finally {
        // Notify writer that I am done
        if (error) {
            _bootstrapSeedWriter.endEvents(BootstrapEventBuffer.ERROR_CODE, endScn, null);
            LOG.error("Seeder stopping unexpectedly !!");
        } else {
            _bootstrapSeedWriter.endEvents(BootstrapEventBuffer.END_OF_FILE, endScn, null);
            LOG.info("Completed Seeding !!");
        }
        LOG.info("Start SCN :" + maxScn);
        LOG.info("End SCN :" + endScn);
    }
    long endTS = System.currentTimeMillis();
    ReadEventCycleSummary cycleSummary = new ReadEventCycleSummary("seeder", summaries, maxScn, (endTS - startTS));
    return cycleSummary;
}

Example 7 with ReadEventCycleSummary

use of com.linkedin.databus2.producers.db.ReadEventCycleSummary in project databus by linkedin.

the class OracleTxlogEventReader method readEventsFromAllSources.

@Override
public ReadEventCycleSummary readEventsFromAllSources(long sinceSCN) throws DatabusException, EventCreationException, UnsupportedKeyException {
    boolean eventBufferNeedsRollback = true;
    boolean debugEnabled = _log.isDebugEnabled();
    List<EventReaderSummary> summaries = new ArrayList<EventReaderSummary>();
    try {
        long cycleStartTS = System.currentTimeMillis();
        _eventBuffer.startEvents();
        // Open the database connection if it is closed (at start or after an SQLException)
        if (_eventSelectConnection == null || _eventSelectConnection.isClosed()) {
            resetConnections();
        }
        /**
         * Chunking in Relay:
         * =================
         *
         *  Variables used:
         *  ===============
         *
         *  1. _inChunking : Flag to indicate if the relay is in chunking mode
         *  2. _chunkingType : Type of chunking supported
         *  3. _chunkedScnThreshold :
         *               The threshold Scn diff which triggers chunking. If the relay's maxScn is older
         *               than DB's maxScn by this threshold, then chunking will be enabled.
         *  4. _txnsPerChunk : Chunk size of txns for txn based chunking.
         *  5. _scnChunkSize : Chunk Size for scn based chunking.
         *  6. _catchupTargetMaxScn : Cached copy of DB's maxScn used as chunking's target SCN.
         *
         *  =========================================
         *  Behavior of Chunking for Slow Sources:
         *  =========================================
         *
         *  The slow sources case that is illustrated here is when all the sources in the sourcesList (fetched by relay) is slow.
         *  In this case, the endOfPeriodSCN will not increase on its own whereas in all other cases, it will.
         *
         *  At startup, if the _catchupTargetMaxScn - currScn > _chunkedScnThreshold, then chunking is enabled.
         *  1. Txn_based_chunking
         *
         *    a) If chunking is on at startup, then txn-based chunking query is used. Otherwise, regular query is used.
         *    b) For a period till SLOW_SOURCE_QUERY_THRESHOLD msec, the endOfPeriodSCN/SinceSCN will not increase.
         *    c) After SLOW_SOURCE_QUERY_THRESHOLD msec, the sinceScn/endOfPeriodSCN will be increased to current MaxScn. If chunking was previously enabled
         *        at this time, it will be disabled upto MAX_SCN_DELAY_MS msec after which _catchupTargetMaxScn will be refreshed.
         *    d) if the new _catchupTargetMaxScn - currScn > _chunkedScnThreshold, then chunking is again enabled.
         *    e) go to (b)
         *
         *  2. SCN based Chunking
         *    a) If chunking is on at startup, then scn-based chunking query is used. Otherwise, regular query is used.
         *    b) For a period till SLOW_SOURCE_QUERY_THRESHOLD msec, the endOfPeriodSCN/SinceSCN keep increasing by _scnChunkSize with no rows fetched.
         *    c) When _catchupTargetMaxScn - endOfPeriodSCN <  _chunkedScnThreshold, then chunking is disabled and regular query kicks in and in this
         *       phase sinceSCN/endOfPeriodSCN will not increase. After MAX_SCN_DELAY_MS interval, _catchupTargetSCN will be refreshed.
         *    d) If the new _catchupTargetMaxScn - currScn > _chunkedScnThreshold, then SCN chunking is again enabled.
         *    e) go to (b)       *
         */
        if (sinceSCN <= 0) {
            _catchupTargetMaxScn = sinceSCN = getMaxTxlogSCN(_eventSelectConnection);
            _log.debug("sinceSCN was <= 0. Overriding with the current max SCN=" + sinceSCN);
            _eventBuffer.setStartSCN(sinceSCN);
            try {
                DBHelper.commit(_eventSelectConnection);
            } catch (SQLException s) {
                DBHelper.rollback(_eventSelectConnection);
            }
        } else if ((_chunkingType.isChunkingEnabled()) && (_catchupTargetMaxScn <= 0)) {
            _catchupTargetMaxScn = getMaxTxlogSCN(_eventSelectConnection);
            _log.debug("catchupTargetMaxScn was <= 0. Overriding with the current max SCN=" + _catchupTargetMaxScn);
        }
        if (_catchupTargetMaxScn <= 0)
            _inChunkingMode = false;
        // Get events for each source
        List<OracleTriggerMonitoredSourceInfo> filteredSources = filterSources(sinceSCN);
        long endOfPeriodScn = EventReaderSummary.NO_EVENTS_SCN;
        for (OracleTriggerMonitoredSourceInfo source : _sources) {
            if (filteredSources.contains(source)) {
                long startTS = System.currentTimeMillis();
                EventReaderSummary summary = readEventsFromOneSource(_eventSelectConnection, source, sinceSCN);
                summaries.add(summary);
                endOfPeriodScn = Math.max(endOfPeriodScn, summary.getEndOfPeriodSCN());
                long endTS = System.currentTimeMillis();
                source.getStatisticsBean().addTimeOfLastDBAccess(endTS);
                if (_eventsLog.isDebugEnabled() || (_eventsLog.isInfoEnabled() && summary.getNumberOfEvents() > 0)) {
                    _eventsLog.info(summary.toString());
                }
                // Update statistics for the source
                if (summary.getNumberOfEvents() > 0) {
                    source.getStatisticsBean().addEventCycle(summary.getNumberOfEvents(), endTS - startTS, summary.getSizeOfSerializedEvents(), summary.getEndOfPeriodSCN());
                } else {
                    source.getStatisticsBean().addEmptyEventCycle();
                }
            } else {
                source.getStatisticsBean().addEmptyEventCycle();
            }
        }
        _lastSeenEOP = Math.max(_lastSeenEOP, Math.max(endOfPeriodScn, sinceSCN));
        // If we did not read any events in this cycle then get the max SCN from the txlog. This
        // is for slow sources so that the endOfPeriodScn never lags too far behind the max scn
        // in the txlog table.
        long curtime = System.currentTimeMillis();
        if (endOfPeriodScn == EventReaderSummary.NO_EVENTS_SCN) {
            // If in SCN Chunking mode, its possible to get empty batches for a SCN range,
            if ((sinceSCN + _scnChunkSize <= _catchupTargetMaxScn) && (ChunkingType.SCN_CHUNKING == _chunkingType)) {
                endOfPeriodScn = sinceSCN + _scnChunkSize;
                _lastquerytime = curtime;
            } else if (ChunkingType.TXN_CHUNKING == _chunkingType && _inChunkingMode) {
                long nextBatchScn = getMaxScnSkippedForTxnChunked(_eventSelectConnection, sinceSCN, _txnsPerChunk);
                _log.info("No events while in txn chunking. CurrScn : " + sinceSCN + ", jumping to :" + nextBatchScn);
                endOfPeriodScn = nextBatchScn;
                _lastquerytime = curtime;
            } else if ((curtime - _lastquerytime) > _slowQuerySourceThreshold) {
                _lastquerytime = curtime;
                // get new start scn for subsequent calls;
                final long maxTxlogSCN = getMaxTxlogSCN(_eventSelectConnection);
                // For performance reasons, getMaxTxlogSCN() returns the max scn only among txlog rows
                // which have their scn rewritten (i.e. scn < infinity). This allows the getMaxTxlogSCN
                // query to be evaluated using only the SCN index. Getting the true max SCN requires
                // scanning the rows where scn == infinity which is expensive.
                // On the other hand, readEventsFromOneSource will read the latter events. So it is
                // possible that maxTxlogSCN < scn of the last event in the buffer!
                // We use max() to guarantee that there are no SCN regressions.
                endOfPeriodScn = Math.max(maxTxlogSCN, sinceSCN);
                _log.info("SlowSourceQueryThreshold hit. currScn : " + sinceSCN + ". Advanced endOfPeriodScn to " + endOfPeriodScn + " and added the event to relay");
                if (debugEnabled) {
                    _log.debug("No events processed. Read max SCN from txlog table for endOfPeriodScn. endOfPeriodScn=" + endOfPeriodScn);
                }
            }
            if (endOfPeriodScn != EventReaderSummary.NO_EVENTS_SCN && endOfPeriodScn > sinceSCN) {
                // If the SCN has moved forward in the above if/else loop, then
                _log.info("The endOfPeriodScn has advanced from to " + endOfPeriodScn);
                _eventBuffer.endEvents(endOfPeriodScn, _relayInboundStatsCollector);
                eventBufferNeedsRollback = false;
            } else {
                eventBufferNeedsRollback = true;
            }
        } else {
            // we have appended some events; and a new end of period has been found
            _lastquerytime = curtime;
            _eventBuffer.endEvents(endOfPeriodScn, _relayInboundStatsCollector);
            if (debugEnabled) {
                _log.debug("End of events: " + endOfPeriodScn + " windown range= " + _eventBuffer.getMinScn() + "," + _eventBuffer.lastWrittenScn());
            }
            // no need to roll back
            eventBufferNeedsRollback = false;
        }
        // save endOfPeriodScn if new one has been discovered
        if (endOfPeriodScn != EventReaderSummary.NO_EVENTS_SCN) {
            if (null != _maxScnWriter && (endOfPeriodScn != sinceSCN)) {
                _maxScnWriter.saveMaxScn(endOfPeriodScn);
            }
            for (OracleTriggerMonitoredSourceInfo source : _sources) {
                // update maxDBScn here
                source.getStatisticsBean().addMaxDBScn(endOfPeriodScn);
                source.getStatisticsBean().addTimeOfLastDBAccess(System.currentTimeMillis());
            }
        }
        long cycleEndTS = System.currentTimeMillis();
        // check if we should refresh _catchupTargetMaxScn
        if (_chunkingType.isChunkingEnabled() && (_lastSeenEOP >= _catchupTargetMaxScn) && (curtime - _lastMaxScnTime >= _maxScnDelayMs)) {
            // reset it to -1 so it gets refreshed next time around
            _catchupTargetMaxScn = -1;
        }
        boolean chunkMode = _chunkingType.isChunkingEnabled() && (_catchupTargetMaxScn > 0) && (_lastSeenEOP < _catchupTargetMaxScn);
        if (!chunkMode && _inChunkingMode)
            _log.info("Disabling chunking for sources !!");
        _inChunkingMode = chunkMode;
        if (_inChunkingMode && debugEnabled)
            _log.debug("_inChunkingMode = true, _catchupTargetMaxScn=" + _catchupTargetMaxScn + ", endOfPeriodScn=" + endOfPeriodScn + ", _lastSeenEOP=" + _lastSeenEOP);
        ReadEventCycleSummary summary = new ReadEventCycleSummary(_name, summaries, Math.max(endOfPeriodScn, sinceSCN), (cycleEndTS - cycleStartTS));
        // Have to commit the transaction since we are in serializable isolation level
        DBHelper.commit(_eventSelectConnection);
        // Return the event summaries
        return summary;
    } catch (SQLException ex) {
        try {
            DBHelper.rollback(_eventSelectConnection);
        } catch (SQLException s) {
            throw new DatabusException(s.getMessage());
        }
        ;
        handleExceptionInReadEvents(ex);
        throw new DatabusException(ex);
    } catch (Exception e) {
        handleExceptionInReadEvents(e);
        throw new DatabusException(e);
    } finally {
        // If that happens, rollback the event buffer.
        if (eventBufferNeedsRollback) {
            if (_log.isDebugEnabled()) {
                _log.debug("Rolling back the event buffer because eventBufferNeedsRollback is true.");
            }
            _eventBuffer.rollbackEvents();
        }
    }
}