Examples with TxnStart org.exist.storage.txn.TxnStart used on opensource projects

Example 1 with TxnStart

use of org.exist.storage.txn.TxnStart in project exist by eXist-db.

the class Journal method writeToLog.

/**
 * Write a log entry to the journal.
 *
 * @param entry the journal entry to write
 * @throws JournalException if the entry could not be written
 */
public synchronized void writeToLog(final Loggable entry) throws JournalException {
    if (currentBuffer == null) {
        throw new JournalException("Database is shut down.");
    }
    SanityCheck.ASSERT(!inRecovery, "Write to log during recovery. Should not happen!");
    final int size = entry.getLogSize();
    if (size > Short.MAX_VALUE) {
        throw new JournalException("Journal can only write log entries of less that 32KB");
    }
    final int required = size + LOG_ENTRY_BASE_LEN;
    if (required > currentBuffer.remaining()) {
        flushToLog(false);
    }
    try {
        // TODO(AR) this is needed as the journal is initialised by starting a transaction for loading the SymbolTable... before recovery! which is likely wrong!!! as Recovery Cannot run if the Journal file has been switched!
        final long pos = channel != null ? channel.position() : 0;
        currentLsn = new Lsn(currentJournalFileNumber, pos + currentBuffer.position() + 1);
    } catch (final IOException e) {
        throw new JournalException("Unable to create LSN for: " + entry.dump());
    }
    entry.setLsn(currentLsn);
    try {
        final int currentBufferEntryOffset = currentBuffer.position();
        // write entryHeader
        currentBuffer.put(entry.getLogType());
        currentBuffer.putLong(entry.getTransactionId());
        currentBuffer.putShort((short) size);
        // write entry data
        entry.write(currentBuffer);
        // write backlink
        currentBuffer.putShort((short) (size + LOG_ENTRY_HEADER_LEN));
        // write checksum
        final long checksum = xxHash64.hash(currentBuffer, currentBufferEntryOffset, currentBuffer.position() - currentBufferEntryOffset, XXHASH64_SEED);
        currentBuffer.putLong(checksum);
    } catch (final BufferOverflowException e) {
        throw new JournalException("Buffer overflow while writing log record: " + entry.dump(), e);
    }
    // NOTE: we don't track operations on txnStart or checkpoints!
    if (!(entry instanceof TxnStart || entry instanceof Checkpoint)) {
        pool.getTransactionManager().trackOperation(entry.getTransactionId());
    }
}