com.bigdata.ha.halog

Interface IHALogWriter

All Known Implementing Classes:

HALogWriter

public interface IHALogWriter

A constrained interface providing access to limited operations on the live HALog.

Author:

Martyn Cutcher, Bryan Thompson

Method Summary

Methods

Modifier and Type	Method and Description
void	closeHALog(IRootBlockView rootBlock) Write the final root block on the HA log and close the file.
void	disableHALog() Disable (and remove) the current log file if one is open (an HALog file which has been committed by applying its closing root block is NOT removed).
long	getCommitCounter() Return the commit counter that is expected for the writes that will be logged (the same commit counter that is on the opening root block).
long	getSequence() Return the sequence number that is expected for the next write.
boolean	isHALogOpen() Return true iff there is an HALog file that is currently open for writing.
void	writeOnHALog(IHAWriteMessage msg, ByteBuffer data) Write the message and the data on the live HALog.

Method Detail

isHALogOpen

boolean isHALogOpen()

Return true iff there is an HALog file that is currently open for writing.

getCommitCounter

long getCommitCounter()

Return the commit counter that is expected for the writes that will be logged (the same commit counter that is on the opening root block).

Note: Once the HALog is sealed, the closing root block will have a commitCounter that is equal to getCommitCounter() + 1.

Note: The HALog filename contains the closing commit counter - that is, the HALog file is named for the commit counter associated with the closing root block for a given write set.

getSequence

long getSequence()

Return the sequence number that is expected for the next write.

writeOnHALog

void writeOnHALog(IHAWriteMessage msg,
                ByteBuffer data)
                  throws IOException

Write the message and the data on the live HALog.

Parameters:

msg - The message.

data - The data.

Throws:

IllegalStateException - if the message is not appropriate for the state of the log.

IOException - if we can not write on the log.

closeHALog

void closeHALog(IRootBlockView rootBlock)
                throws IOException

Write the final root block on the HA log and close the file. This "seals" the file, which now represents the entire write set associated with the commit point in the given root block.

Parameters:

rootBlock - The final root block for the write set.

Throws:

IOException

disableHALog

void disableHALog()
                  throws IOException

Disable (and remove) the current log file if one is open (an HALog file which has been committed by applying its closing root block is NOT removed).

Throws:

IOException

See Also:

HAJournalServer reports "follower" but is in SeekConsensus and is not participating in commits