Package org.eclipse.jgit.internal.storage.reftable

Class MergedReftable

java.lang.Object

org.eclipse.jgit.internal.storage.reftable.Reftable

org.eclipse.jgit.internal.storage.reftable.MergedReftable

public class MergedReftable
extends Reftable

Merges multiple reference tables together.

A MergedReftable merge-joins multiple ReftableReader on the fly. Tables higher/later in the stack shadow lower/earlier tables, hiding references that been updated/replaced.

By default deleted references are skipped and not returned to the caller. Reftable.setIncludeDeletes(boolean) can be used to modify this behavior if the caller needs to preserve deletions during partial compaction.

A MergedReftable is not thread-safe.

Field Summary

Fields inherited from class org.eclipse.jgit.internal.storage.reftable.Reftable

includeDeletes

Constructor Summary

Constructors

Constructor	Description
MergedReftable(List<ReftableReader> tableStack)	Initialize a merged table reader.

Method Summary

Modifier and Type	Method	Description
LogCursor	allLogs()	Seek reader to read log records.
RefCursor	allRefs()	Seek to the first reference, to iterate in order.
RefCursor	byObjectId(AnyObjectId name)	Match references pointing to a specific object.
boolean	hasObjectMap()
long	maxUpdateIndex()	Get the maximum update index for ref entries that appear in this reftable.
long	minUpdateIndex()	Get the minimum update index for ref entries that appear in this reftable.
LogCursor	seekLog(String refName, long updateIdx)	Seek to an update index in a reference's log.
RefCursor	seekRef(String name)	Seek to a reference.
RefCursor	seekRefsWithPrefix(String prefix)	Seek references with prefix.

Methods inherited from class org.eclipse.jgit.internal.storage.reftable.Reftable

exactRef, from, hasId, hasRef, hasRefsWithPrefix, resolve, seekLog, setIncludeDeletes

Methods inherited from class java.lang.Object

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

Constructor Detail

MergedReftable

public MergedReftable(List<ReftableReader> tableStack)

Initialize a merged table reader.

Parameters:

tableStack - stack of tables to read from. The base of the stack is at index 0, the most recent should be at the top of the stack at tableStack.size() - 1. The top of the stack (higher index) shadows the base of the stack (lower index).

Method Detail

maxUpdateIndex

public long maxUpdateIndex()
                    throws IOException

Get the maximum update index for ref entries that appear in this reftable.

Specified by:

maxUpdateIndex in class Reftable

Returns:

the maximum update index for ref entries that appear in this reftable.

Throws:

IOException - file cannot be read.

minUpdateIndex

public long minUpdateIndex()
                    throws IOException

Get the minimum update index for ref entries that appear in this reftable.

Specified by:

minUpdateIndex in class Reftable

Returns:

the minimum update index for ref entries that appear in this reftable.

Throws:

IOException - file cannot be read.

hasObjectMap

public boolean hasObjectMap()
                     throws IOException

Specified by:

hasObjectMap in class Reftable

Returns:

whether this reftable can do a fast SHA1 => ref lookup.

Throws:

IOException - on I/O problems.

allRefs

public RefCursor allRefs()
                  throws IOException

Seek to the first reference, to iterate in order.

Specified by:

allRefs in class Reftable

Returns:

cursor to iterate.

Throws:

IOException - if references cannot be read.

seekRef

public RefCursor seekRef(String name)
                  throws IOException

Seek to a reference.

This method will seek to the reference refName. If present, the returned cursor will iterate exactly one entry. If not found, an empty cursor is returned.

Specified by:

seekRef in class Reftable

Parameters:

name - reference name.

Returns:

cursor to iterate; empty cursor if no references match.

Throws:

IOException - if references cannot be read.

seekRefsWithPrefix

public RefCursor seekRefsWithPrefix(String prefix)
                             throws IOException

Seek references with prefix.

The method will seek all the references starting with prefix as a prefix. If no references start with this prefix, an empty cursor is returned.

Specified by:

seekRefsWithPrefix in class Reftable

Parameters:

prefix - prefix to find.

Returns:

cursor to iterate; empty cursor if no references match.

Throws:

IOException - if references cannot be read.

byObjectId

public RefCursor byObjectId(AnyObjectId name)
                     throws IOException

Match references pointing to a specific object.

Specified by:

byObjectId in class Reftable

Parameters:

name - object to find.

Returns:

cursor to iterate; empty cursor if no references match.

Throws:

IOException - if references cannot be read.

allLogs

public LogCursor allLogs()
                  throws IOException

Seek reader to read log records.

Specified by:

allLogs in class Reftable

Returns:

cursor to iterate; empty cursor if no logs are present.

Throws:

IOException - if logs cannot be read.

seekLog

public LogCursor seekLog(String refName,
                         long updateIdx)
                  throws IOException

Seek to an update index in a reference's log.

Specified by:

seekLog in class Reftable

Parameters:

refName - exact name of the reference whose log to read.

updateIdx - most recent index to return first in the log cursor. Log records at or before updateIndex will be returned.

Returns:

cursor to iterate; empty cursor if no logs match.

Throws:

IOException - if logs cannot be read.