org.eclipse.jgit.dircache

Class DirCacheBuilder

java.lang.Object

org.eclipse.jgit.dircache.DirCacheBuilder

public class DirCacheBuilder
extends Object

Updates a DirCache by adding individual DirCacheEntrys.

A builder always starts from a clean slate and appends in every single DirCacheEntry which the final updated index must have to reflect its new content.

For maximum performance applications should add entries in path name order. Adding entries out of order is permitted, however a final sorting pass will be implicitly performed during finish() to correct any out-of-order entries. Duplicate detection is also delayed until the sorting is complete.

See Also:

DirCacheEditor

Field Summary

Fields

Modifier and Type	Field and Description
protected DirCache	cache The cache instance this editor updates during finish().
protected DirCacheEntry[]	entries Entry table this builder will eventually replace into cache.
protected int	entryCnt Total number of valid entries in entries.

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	DirCacheBuilder(DirCache dc, int ecnt) Construct a new builder.

Method Summary

Methods

Modifier and Type	Method and Description
void	add(DirCacheEntry newEntry) Append one entry into the resulting entry list.
void	addTree(byte[] pathPrefix, int stage, ObjectReader reader, AnyObjectId tree) Recursively add an entire tree into this builder.
boolean	commit() Finish, write, commit this change, and release the index lock.
protected void	fastAdd(DirCacheEntry newEntry) Append one entry into the resulting entry list.
protected void	fastKeep(int pos, int cnt) Add a range of existing entries from the destination cache.
void	finish() Finish this builder and update the destination DirCache.
DirCache	getDirCache()
void	keep(int pos, int cnt) Add a range of existing entries from the destination cache.
protected void	replace() Update the DirCache with the contents of entries.

Methods inherited from class java.lang.Object

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

Field Detail

cache

protected DirCache cache

The cache instance this editor updates during finish().

entries

protected DirCacheEntry[] entries

Entry table this builder will eventually replace into cache.

Use fastAdd(DirCacheEntry) or fastKeep(int, int) to make additions to this table. The table is automatically expanded if it is too small for a new addition.

Typically the entries in here are sorted by their path names, just like they are in the DirCache instance.

entryCnt

protected int entryCnt

Total number of valid entries in entries.

Constructor Detail

DirCacheBuilder

protected DirCacheBuilder(DirCache dc,
               int ecnt)

Construct a new builder.

Parameters:

dc - the cache this builder will eventually update.

ecnt - estimated number of entries the builder will have upon completion. This sizes the initial entry table.

Method Detail

add

public void add(DirCacheEntry newEntry)

Append one entry into the resulting entry list.

The entry is placed at the end of the entry list. If the entry causes the list to now be incorrectly sorted a final sorting phase will be automatically enabled within finish().

The internal entry table is automatically expanded if there is insufficient space for the new addition.

Parameters:

newEntry - the new entry to add.

Throws:

IllegalArgumentException - If the FileMode of the entry was not set by the caller.

keep

public void keep(int pos,
        int cnt)

Add a range of existing entries from the destination cache.

The entries are placed at the end of the entry list. If any of the entries causes the list to now be incorrectly sorted a final sorting phase will be automatically enabled within finish().

This method copies from the destination cache, which has not yet been updated with this editor's new table. So all offsets into the destination cache are not affected by any updates that may be currently taking place in this editor.

The internal entry table is automatically expanded if there is insufficient space for the new additions.

Parameters:

pos - first entry to copy from the destination cache.

cnt - number of entries to copy.

addTree

public void addTree(byte[] pathPrefix,
           int stage,
           ObjectReader reader,
           AnyObjectId tree)
             throws IOException

Recursively add an entire tree into this builder.

If pathPrefix is "a/b" and the tree contains file "c" then the resulting DirCacheEntry will have the path "a/b/c".

All entries are inserted at stage 0, therefore assuming that the application will not insert any other paths with the same pathPrefix.

Parameters:

pathPrefix - UTF-8 encoded prefix to mount the tree's entries at. If the path does not end with '/' one will be automatically inserted as necessary.

stage - stage of the entries when adding them.

reader - reader the tree(s) will be read from during recursive traversal. This must be the same repository that the resulting DirCache would be written out to (or used in) otherwise the caller is simply asking for deferred MissingObjectExceptions. Caller is responsible for releasing this reader when done.

tree - the tree to recursively add. This tree's contents will appear under pathPrefix. The ObjectId must be that of a tree; the caller is responsible for dereferencing a tag or commit (if necessary).

Throws:

IOException - a tree cannot be read to iterate through its entries.

finish

public void finish()

Finish this builder and update the destination DirCache.

When this method completes this builder instance is no longer usable by the calling application. A new builder must be created to make additional changes to the index entries.

After completion the DirCache returned by getDirCache() will contain all modifications.

Note to implementors: Make sure entries is fully sorted then invoke replace() to update the DirCache with the new table.

getDirCache

public DirCache getDirCache()

Returns:

the cache we will update on finish().

fastAdd

protected void fastAdd(DirCacheEntry newEntry)

Append one entry into the resulting entry list.

The entry is placed at the end of the entry list. The caller is responsible for making sure the final table is correctly sorted.

The entries table is automatically expanded if there is insufficient space for the new addition.

Parameters:

newEntry - the new entry to add.

fastKeep

protected void fastKeep(int pos,
            int cnt)

Add a range of existing entries from the destination cache.

The entries are placed at the end of the entry list, preserving their current order. The caller is responsible for making sure the final table is correctly sorted.

This method copies from the destination cache, which has not yet been updated with this editor's new table. So all offsets into the destination cache are not affected by any updates that may be currently taking place in this editor.

The entries table is automatically expanded if there is insufficient space for the new additions.

Parameters:

pos - first entry to copy from the destination cache.

cnt - number of entries to copy.

replace

protected void replace()

Update the DirCache with the contents of entries.

This method should be invoked only during an implementation of finish(), and only after entries is sorted.

commit

public boolean commit()
               throws IOException

Finish, write, commit this change, and release the index lock.

If this method fails (returns false) the lock is still released.

This is a utility method for applications as the finish-write-commit pattern is very common after using a builder to update entries.

Returns:

true if the commit was successful and the file contains the new data; false if the commit failed and the file remains with the old data.

Throws:

IllegalStateException - the lock is not held.

IOException - the output file could not be created. The caller no longer holds the lock.