Examples with ReadAheadLogChannel org.neo4j.kernel.impl.transaction.log.ReadAheadLogChannel used on opensource projects

Example 1 with ReadAheadLogChannel

use of org.neo4j.kernel.impl.transaction.log.ReadAheadLogChannel in project neo4j by neo4j.

the class LatestCheckPointFinder method find.

public LatestCheckPoint find(long fromVersionBackwards) throws IOException {
    long version = fromVersionBackwards;
    long versionToSearchForCommits = fromVersionBackwards;
    LogEntryStart latestStartEntry = null;
    LogEntryStart oldestStartEntry = null;
    long oldestVersionFound = -1;
    while (version >= INITIAL_LOG_VERSION) {
        LogVersionedStoreChannel channel = PhysicalLogFile.tryOpenForVersion(logFiles, fileSystem, version, false);
        if (channel == null) {
            break;
        }
        oldestVersionFound = version;
        CheckPoint latestCheckPoint = null;
        ReadableLogChannel recoveredDataChannel = new ReadAheadLogChannel(channel, NO_MORE_CHANNELS);
        boolean firstStartEntry = true;
        try (LogEntryCursor cursor = new LogEntryCursor(logEntryReader, recoveredDataChannel)) {
            LogEntry entry;
            while (cursor.next()) {
                entry = cursor.get();
                if (entry instanceof CheckPoint) {
                    latestCheckPoint = entry.as();
                }
                if (entry instanceof LogEntryStart) {
                    LogEntryStart startEntry = entry.as();
                    if (version == versionToSearchForCommits) {
                        latestStartEntry = startEntry;
                    }
                    // Oldest start entry will be the first in the last log version scanned.
                    if (firstStartEntry) {
                        oldestStartEntry = startEntry;
                        firstStartEntry = false;
                    }
                }
            }
        }
        if (latestCheckPoint != null) {
            return latestCheckPoint(fromVersionBackwards, version, latestStartEntry, oldestVersionFound, latestCheckPoint);
        }
        version--;
        // if we have found no commits in the latest log, keep searching in the next one
        if (latestStartEntry == null) {
            versionToSearchForCommits--;
        }
    }
    boolean commitsAfterCheckPoint = oldestStartEntry != null;
    long firstTxAfterPosition = commitsAfterCheckPoint ? extractFirstTxIdAfterPosition(oldestStartEntry.getStartPosition(), fromVersionBackwards) : LatestCheckPoint.NO_TRANSACTION_ID;
    return new LatestCheckPoint(null, commitsAfterCheckPoint, firstTxAfterPosition, oldestVersionFound);
}

Example 2 with ReadAheadLogChannel

use of org.neo4j.kernel.impl.transaction.log.ReadAheadLogChannel in project neo4j by neo4j.

the class LatestCheckPointFinder method extractFirstTxIdAfterPosition.

/**
     * Extracts txId from first commit entry, when starting reading at the given {@code position}.
     * If no commit entry found in the version, the reader will continue into next version(s) up till
     * {@code maxLogVersion} until finding one.
     *
     * @param initialPosition {@link LogPosition} to start scan from.
     * @param maxLogVersion max log version to scan.
     * @return txId of closes commit entry to {@code initialPosition}, or {@link LatestCheckPoint#NO_TRANSACTION_ID}
     * if not found.
     * @throws IOException on I/O error.
     */
private long extractFirstTxIdAfterPosition(LogPosition initialPosition, long maxLogVersion) throws IOException {
    LogPosition currentPosition = initialPosition;
    while (currentPosition.getLogVersion() <= maxLogVersion) {
        LogVersionedStoreChannel storeChannel = PhysicalLogFile.tryOpenForVersion(logFiles, fileSystem, currentPosition.getLogVersion(), false);
        if (storeChannel != null) {
            try {
                storeChannel.position(currentPosition.getByteOffset());
                try (ReadAheadLogChannel logChannel = new ReadAheadLogChannel(storeChannel, NO_MORE_CHANNELS);
                    LogEntryCursor cursor = new LogEntryCursor(logEntryReader, logChannel)) {
                    while (cursor.next()) {
                        LogEntry entry = cursor.get();
                        if (entry instanceof LogEntryCommit) {
                            return ((LogEntryCommit) entry).getTxId();
                        }
                    }
                }
            } finally {
                storeChannel.close();
            }
        }
        currentPosition = LogPosition.start(currentPosition.getLogVersion() + 1);
    }
    return LatestCheckPoint.NO_TRANSACTION_ID;
}

Example 3 with ReadAheadLogChannel

use of org.neo4j.kernel.impl.transaction.log.ReadAheadLogChannel in project neo4j by neo4j.

the class LogTestUtils method openLogEntryCursor.

private static LogEntryCursor openLogEntryCursor(FileSystemAbstraction fs, File firstFile, LogVersionBridge versionBridge) {
    StoreChannel channel = null;
    try {
        channel = fs.open(firstFile, "r");
        ByteBuffer buffer = ByteBuffer.allocate(LogHeader.LOG_HEADER_SIZE);
        LogHeader header = LogHeaderReader.readLogHeader(buffer, channel, true, firstFile);
        PhysicalLogVersionedStoreChannel logVersionedChannel = new PhysicalLogVersionedStoreChannel(channel, header.logVersion, header.logFormatVersion);
        ReadableLogChannel logChannel = new ReadAheadLogChannel(logVersionedChannel, versionBridge, ReadAheadLogChannel.DEFAULT_READ_AHEAD_SIZE);
        return new LogEntryCursor(new VersionAwareLogEntryReader<>(), logChannel);
    } catch (Throwable t) {
        if (channel != null) {
            try {
                channel.close();
            } catch (IOException e) {
                t.addSuppressed(e);
            }
        }
        throw new RuntimeException(t);
    }
}

Example 4 with ReadAheadLogChannel

use of org.neo4j.kernel.impl.transaction.log.ReadAheadLogChannel in project neo4j by neo4j.

the class LogMatchers method logEntries.

public static List<LogEntry> logEntries(FileSystemAbstraction fileSystem, String logPath) throws IOException {
    File logFile = new File(logPath);
    StoreChannel fileChannel = fileSystem.open(logFile, "r");
    // Always a header
    LogHeader header = readLogHeader(ByteBuffer.allocateDirect(LOG_HEADER_SIZE), fileChannel, true, logFile);
    // Read all log entries
    PhysicalLogVersionedStoreChannel versionedStoreChannel = new PhysicalLogVersionedStoreChannel(fileChannel, header.logVersion, header.logFormatVersion);
    ReadableLogChannel logChannel = new ReadAheadLogChannel(versionedStoreChannel, NO_MORE_CHANNELS);
    LogEntryCursor logEntryCursor = new LogEntryCursor(new VersionAwareLogEntryReader<>(), logChannel);
    return Iterables.asList(new IOCursorAsResourceIterable<>(logEntryCursor));
}

Example 5 with ReadAheadLogChannel

use of org.neo4j.kernel.impl.transaction.log.ReadAheadLogChannel in project neo4j by neo4j.

the class LegacyLogEntryReader method openReadableChannel.

public Pair<LogHeader, IOCursor<LogEntry>> openReadableChannel(File logFile) throws IOException {
    final StoreChannel rawChannel = fs.open(logFile, "r");
    final LogHeader header = readLogHeader(ByteBuffer.allocate(LOG_HEADER_SIZE), rawChannel, false, logFile);
    LogEntryReader<ReadableLogChannel> reader = readerFactory.apply(header);
    // this ensures that the last committed txId field in the header is initialized properly
    long lastCommittedTxId = Math.max(BASE_TX_ID, header.lastCommittedTxId);
    final PhysicalLogVersionedStoreChannel channel = new PhysicalLogVersionedStoreChannel(rawChannel, header.logVersion, header.logFormatVersion);
    final ReadableLogChannel readableChannel = new ReadAheadLogChannel(channel, NO_MORE_CHANNELS);
    final IOCursor<LogEntry> cursor = new LogEntrySortingCursor(reader, readableChannel);
    return Pair.of(new LogHeader(CURRENT_LOG_VERSION, header.logVersion, lastCommittedTxId), cursor);
}