Examples with LogCounter org.apache.derby.impl.store.raw.log.LogCounter used on opensource projects

Example 6 with LogCounter

use of org.apache.derby.impl.store.raw.log.LogCounter in project derby by apache.

the class FileLogger method undo.

/**
 *		Undo a part of or the entire transaction.  Begin rolling back the log
 *		record at undoStartAt and stopping at (inclusive) the log record at
 *		undoStopAt.
 *
 *		<P>MT - Not needed. A transaction must be single threaded thru undo,
 *        each RawTransaction has its own logger, therefore no need to
 *        synchronize.  The RawTransaction must handle synchronizing with
 *        multiple threads during rollback.
 *
 *		@param t 			the transaction that needs to be rolled back
 *		@param undoId 		the transaction ID
 *		@param undoStopAt	the last log record that should be rolled back
 *		@param undoStartAt	the first log record that should be rolled back
 *
 *		@exception StandardException	Standard Derby error policy
 *
 *		@see Logger#undo
 */
public void undo(RawTransaction t, TransactionId undoId, LogInstant undoStopAt, LogInstant undoStartAt) throws StandardException {
    if (SanityManager.DEBUG) {
        if (SanityManager.DEBUG_ON(LogToFile.DBG_FLAG)) {
            if (undoStartAt != null) {
                SanityManager.DEBUG(LogToFile.DBG_FLAG, "\nUndo transaction: " + undoId.toString() + "start at " + undoStartAt.toString() + " stop at " + undoStopAt.toString());
            } else {
                SanityManager.DEBUG(LogToFile.DBG_FLAG, "\nUndo transaction: " + undoId.toString() + "start at end of log stop at " + undoStopAt.toString());
            }
        }
    }
    // statistics
    int clrgenerated = 0;
    int clrskipped = 0;
    int logrecordseen = 0;
    StreamLogScan scanLog;
    Compensation compensation = null;
    Undoable lop = null;
    // stream to read the log record - initial size 4096, scanLog needs
    // to resize if the log record is larget than that.
    ArrayInputStream rawInput = null;
    try {
        if (undoStartAt == null) {
            // don't know where to start, rollback from end of log
            scanLog = (StreamLogScan) logFactory.openBackwardsScan(undoStopAt);
        } else {
            if (undoStartAt.lessThan(undoStopAt)) {
                // nothing to undo!
                return;
            }
            long undoStartInstant = ((LogCounter) undoStartAt).getValueAsLong();
            scanLog = (StreamLogScan) logFactory.openBackwardsScan(undoStartInstant, undoStopAt);
        }
        if (SanityManager.DEBUG)
            SanityManager.ASSERT(scanLog != null, "cannot open log for undo");
        rawInput = new ArrayInputStream(new byte[4096]);
        LogRecord record;
        while ((record = scanLog.getNextRecord(rawInput, undoId, 0)) != null) {
            if (SanityManager.DEBUG) {
                SanityManager.ASSERT(record.getTransactionId().equals(undoId), "getNextRecord return unqualified log record for undo");
            }
            logrecordseen++;
            if (record.isCLR()) {
                clrskipped++;
                // the loggable is still in the input stream, get rid of it
                record.skipLoggable();
                // read the undoInstant
                long undoInstant = rawInput.readLong();
                if (SanityManager.DEBUG) {
                    if (SanityManager.DEBUG_ON(LogToFile.DBG_FLAG)) {
                        SanityManager.DEBUG(LogToFile.DBG_FLAG, "Skipping over CLRs, reset scan to " + LogCounter.toDebugString(undoInstant));
                    }
                }
                scanLog.resetPosition(new LogCounter(undoInstant));
                continue;
            }
            lop = record.getUndoable();
            if (lop != null) {
                int optionalDataLength = rawInput.readInt();
                int savePosition = rawInput.getPosition();
                rawInput.setLimit(optionalDataLength);
                compensation = lop.generateUndo(t, rawInput);
                if (SanityManager.DEBUG) {
                    if (SanityManager.DEBUG_ON(LogToFile.DBG_FLAG)) {
                        SanityManager.DEBUG(LogToFile.DBG_FLAG, "Rollback log record at instant " + LogCounter.toDebugString(scanLog.getInstant()) + " : " + lop);
                    }
                }
                clrgenerated++;
                if (compensation != null) {
                    // generateUndo may have read stuff off the
                    // stream, reset it for the undo operation.
                    rawInput.setLimit(savePosition, optionalDataLength);
                    // log the compensation op that rolls back the
                    // operation at this instant
                    t.logAndUndo(compensation, new LogCounter(scanLog.getInstant()), rawInput);
                    compensation.releaseResource(t);
                    compensation = null;
                }
            // if compensation is null, log operation is redo only
            }
        // if this is not an undoable operation, continue with next log
        // record
        }
    } catch (ClassNotFoundException cnfe) {
        throw logFactory.markCorrupt(StandardException.newException(SQLState.LOG_CORRUPTED, cnfe));
    } catch (IOException ioe) {
        throw logFactory.markCorrupt(StandardException.newException(SQLState.LOG_READ_LOG_FOR_UNDO, ioe));
    } catch (StandardException se) {
        throw logFactory.markCorrupt(StandardException.newException(SQLState.LOG_UNDO_FAILED, se, undoId, lop, compensation));
    } finally {
        if (compensation != null) {
            // errored out
            compensation.releaseResource(t);
        }
        if (rawInput != null) {
            try {
                rawInput.close();
            } catch (IOException ioe) {
                throw logFactory.markCorrupt(StandardException.newException(SQLState.LOG_READ_LOG_FOR_UNDO, ioe, undoId));
            }
        }
    }
    if (SanityManager.DEBUG) {
        if (SanityManager.DEBUG_ON(LogToFile.DBG_FLAG)) {
            SanityManager.DEBUG(LogToFile.DBG_FLAG, "Finish undo" + ", clr generated = " + clrgenerated + ", clr skipped = " + clrskipped + ", record seen = " + logrecordseen + "\n");
        }
    }
}