org.neo4j.causalclustering.core.consensus.log

Class InMemoryRaftLog

java.lang.Object

org.neo4j.causalclustering.core.consensus.log.InMemoryRaftLog

All Implemented Interfaces:

RaftLog, ReadableRaftLog

public class InMemoryRaftLog
extends Object
implements RaftLog

Field Summary

Fields inherited from interface org.neo4j.causalclustering.core.consensus.log.RaftLog

PHYSICAL_LOG_DIRECTORY_NAME

Constructor Summary

Constructors

Constructor and Description
InMemoryRaftLog()

Method Summary

Modifier and Type	Method and Description
long	append(RaftLogEntry... entries) Appends entry to the end of the log.
long	appendIndex()
boolean	equals(Object o)
RaftLogCursor	getEntryCursor(long fromIndex) Returns a RaftLogCursor of RaftLogEntrys from the specified index until the end of the log
int	hashCode()
long	prevIndex()
long	prune(long safeIndex) Attempt to prune (delete) a prefix of the log, no further than the safeIndex.
long	readEntryTerm(long logIndex) Reads the term associated with the entry at the supplied index.
long	skip(long index, long term) Skip up to the supplied index if it is not already present.
void	truncate(long fromIndex) Truncates the log starting from the supplied index.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

InMemoryRaftLog

public InMemoryRaftLog()

Method Detail

append

public long append(RaftLogEntry... entries)
            throws IOException

Description copied from interface: RaftLog

Appends entry to the end of the log. The first log index is 0.

The entries must be uniquely identifiable and already appended entries must not be re-appended (unless they have been removed through truncation).

Specified by:

append in interface RaftLog

Parameters:

entries - The log entry.

Returns:

the index at which the entry was appended.

Throws:

IOException

prune

public long prune(long safeIndex)

Description copied from interface: RaftLog

Attempt to prune (delete) a prefix of the log, no further than the safeIndex.

Implementations can choose to prune a shorter prefix if this is convenient for their storage mechanism. The return value tells the caller how much was actually pruned.

Specified by:

prune in interface RaftLog

Parameters:

safeIndex - Highest index that may be pruned.

Returns:

The new prevIndex for the log, which will be at most safeIndex.

appendIndex

public long appendIndex()

Specified by:

appendIndex in interface ReadableRaftLog

Returns:

The index of the last appended entry.

prevIndex

public long prevIndex()

Specified by:

prevIndex in interface ReadableRaftLog

Returns:

The index immediately preceding entries in the log.

readEntryTerm

public long readEntryTerm(long logIndex)

Description copied from interface: ReadableRaftLog

Reads the term associated with the entry at the supplied index.

Specified by:

readEntryTerm in interface ReadableRaftLog

Parameters:

logIndex - The index of the log entry.

Returns:

The term of the entry, or -1 if the entry does not exist

truncate

public void truncate(long fromIndex)

Description copied from interface: RaftLog

Truncates the log starting from the supplied index. Committed entries can never be truncated.

Specified by:

truncate in interface RaftLog

Parameters:

fromIndex - The start index (inclusive).

getEntryCursor

public RaftLogCursor getEntryCursor(long fromIndex)
                             throws IOException

Description copied from interface: ReadableRaftLog

Returns a RaftLogCursor of RaftLogEntrys from the specified index until the end of the log

Specified by:

getEntryCursor in interface ReadableRaftLog

Parameters:

fromIndex - The log index at which the cursor should be positioned

Throws:

IOException

skip

public long skip(long index,
                 long term)

Description copied from interface: RaftLog

Skip up to the supplied index if it is not already present.

If the entry was not present then it gets defined with the supplied term, but without content, and thus can be used only for log matching from a later index.

This is useful when a snapshot starting from a later index has been downloaded and thus earlier entries are irrelevant and possibly non-existent in the cluster.

Specified by:

skip in interface RaftLog

Parameters:

index - the index we want to skip to

term - the term of the index

Returns:

The appendIndex after this call, which will be at least index.

equals

public boolean equals(Object o)

Overrides:

equals in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class Object