alluxio.master.journalv0.ufs

Class UfsJournalWriter.EntryOutputStream

java.lang.Object

alluxio.master.journalv0.ufs.UfsJournalWriter.EntryOutputStream

All Implemented Interfaces:

JournalOutputStream, AutoCloseable

Enclosing class:

UfsJournalWriter

@ThreadSafe
protected static class UfsJournalWriter.EntryOutputStream
extends Object
implements JournalOutputStream

This is the output stream for the journal entries after the checkpoint. This output stream handles rotating log files, and creating the next log file. Log files are rotated in the following scenarios:

 1. The log size reaches mMaxLogSize
 2. flush() is called but the journal is in a UFS which doesn't support flush.
    Closing the file is the only way to simulate a flush.
 3. An IO exception occurs while writing to or flushing an entry. We must rotate here in case
    corrupted data was written. When reading the log we will detect corruption and assume that
    it's at the end of the log.
 

Constructor Summary

Constructors

Constructor and Description
EntryOutputStream(UnderFileSystem ufs, URI log, JournalFormatter journalFormatter, UfsJournalWriter journalWriter)

Method Summary

Modifier and Type	Method and Description
void	close() Closes the stream.
void	flush() Flushes the stream.
void	write(Journal.JournalEntry entry) The given entry should not have its sequence number set.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

EntryOutputStream

public EntryOutputStream(UnderFileSystem ufs,
                         URI log,
                         JournalFormatter journalFormatter,
                         UfsJournalWriter journalWriter)
                  throws IOException

Parameters:

ufs - the under storage holding the journal

log - the location to write the log to

journalFormatter - the journal formatter to use when writing journal entries

journalWriter - the journal writer to use to get journal entry sequence numbers and complete the log when it needs to be rotated

Throws:

IOException

Method Detail

write

public void write(Journal.JournalEntry entry)
           throws IOException

The given entry should not have its sequence number set. This method will add the proper sequence number to the passed in entry.

Specified by:

write in interface JournalOutputStream

Parameters:

entry - an entry to write to the journal checkpoint file

Throws:

IOException

close

public void close()
           throws IOException

Description copied from interface: JournalOutputStream

Closes the stream.

Specified by:

close in interface JournalOutputStream

Specified by:

close in interface AutoCloseable

Throws:

IOException

flush

public void flush()
           throws IOException

Description copied from interface: JournalOutputStream

Flushes the stream.

Specified by:

flush in interface JournalOutputStream

Throws:

IOException