Package org.eclipse.jgit.treewalk

Class NameConflictTreeWalk

java.lang.Object

org.eclipse.jgit.treewalk.TreeWalk

org.eclipse.jgit.treewalk.NameConflictTreeWalk

All Implemented Interfaces:

java.lang.AutoCloseable, AttributesProvider

public class NameConflictTreeWalk
extends TreeWalk

Specialized TreeWalk to detect directory-file (D/F) name conflicts.

Due to the way a Git tree is organized the standard TreeWalk won't easily find a D/F conflict when merging two or more trees together. In the standard TreeWalk the file will be returned first, and then much later the directory will be returned. This makes it impossible for the application to efficiently detect and handle the conflict.

Using this walk implementation causes the directory to report earlier than usual, at the same time as the non-directory entry. This permits the application to handle the D/F conflict in a single step. The directory is returned only once, so it does not get returned later in the iteration.

When a D/F conflict is detected TreeWalk.isSubtree() will return true and TreeWalk.enterSubtree() will recurse into the subtree, no matter which iterator originally supplied the subtree.

Because conflicted directories report early, using this walk implementation to populate a DirCacheBuilder may cause the automatic resorting to run and fix the entry ordering.

This walk implementation requires more CPU to implement a look-ahead and a look-behind to merge a D/F pair together, or to skip a previously reported directory. In typical Git repositories the look-ahead cost is 0 and the look-behind doesn't trigger, as users tend not to create trees which contain both "foo" as a directory and "foo.c" as a file.

In the worst-case however several thousand look-ahead steps per walk step may be necessary, making the overhead quite significant. Since this worst-case should never happen this walk implementation has made the time/space tradeoff in favor of more-time/less-space, as that better suits the typical case.

Nested Class Summary

Nested classes/interfaces inherited from class org.eclipse.jgit.treewalk.TreeWalk

TreeWalk.OperationType

Field Summary

Fields

Modifier and Type	Field	Description
private AbstractTreeIterator	dfConflict
private boolean	fastMinHasMatch
private static int	TREE_MODE

Fields inherited from class org.eclipse.jgit.treewalk.TreeWalk

currentHead, depth, trees

Constructor Summary

Constructors

Constructor	Description
NameConflictTreeWalk(ObjectReader or)	Create a new tree walker for a given repository.
NameConflictTreeWalk(Repository repo)	Create a new tree walker for a given repository.
NameConflictTreeWalk(Repository repo, ObjectReader or)	Create a new tree walker for a given repository.

Method Summary

Modifier and Type	Method	Description
private AbstractTreeIterator	combineDF(AbstractTreeIterator minRef)
private AbstractTreeIterator	fastMin()
boolean	isDirectoryFileConflict()	True if the current entry is covered by a directory/file conflict.
private boolean	isGitlink(AbstractTreeIterator p)
private static boolean	isTree(AbstractTreeIterator p)
(package private) AbstractTreeIterator	min()
private static boolean	nameEqual(AbstractTreeIterator a, AbstractTreeIterator b)
private boolean	needsStopWalk()
(package private) void	popEntriesEqual()
(package private) void	skipEntriesEqual()
private boolean	skipEntry(AbstractTreeIterator minRef)
(package private) void	stopWalk()	Notify iterators the walk is aborting.

Methods inherited from class org.eclipse.jgit.treewalk.TreeWalk

addTree, addTree, close, enterSubtree, exitSubtree, forPath, forPath, forPath, forPath, getAttributes, getAttributesNodeProvider, getDepth, getEolStreamType, getFileMode, getFileMode, getFilter, getFilterCommand, getNameString, getObjectId, getObjectId, getObjectReader, getOperationType, getPathLength, getPathString, getRawMode, getRawPath, getTree, getTree, getTreeCount, idEqual, isPathMatch, isPathPrefix, isPathSuffix, isPostChildren, isPostOrderTraversal, isRecursive, isSubtree, next, pathOf, pathOf, reset, reset, reset, setAttributesNodeProvider, setFilter, setOperationType, setPostOrderTraversal, setRecursive

Methods inherited from class java.lang.Object

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

Field Detail

TREE_MODE

private static final int TREE_MODE

fastMinHasMatch

private boolean fastMinHasMatch

dfConflict

private AbstractTreeIterator dfConflict

Constructor Detail

NameConflictTreeWalk

public NameConflictTreeWalk(Repository repo)

Create a new tree walker for a given repository.

Parameters:

repo - the repository the walker will obtain data from.

NameConflictTreeWalk

public NameConflictTreeWalk(@Nullable
                            Repository repo,
                            ObjectReader or)

Create a new tree walker for a given repository.

Parameters:

repo - the repository the walker will obtain data from.

or - the reader the walker will obtain tree data from.

Since:

4.3

NameConflictTreeWalk

public NameConflictTreeWalk(ObjectReader or)

Create a new tree walker for a given repository.

Parameters:

or - the reader the walker will obtain tree data from.

Method Detail

min

AbstractTreeIterator min()
                  throws CorruptObjectException

Overrides:

min in class TreeWalk

Throws:

CorruptObjectException

fastMin

private AbstractTreeIterator fastMin()

nameEqual

private static boolean nameEqual(AbstractTreeIterator a,
                                 AbstractTreeIterator b)

isGitlink

private boolean isGitlink(AbstractTreeIterator p)

isTree

private static boolean isTree(AbstractTreeIterator p)

skipEntry

private boolean skipEntry(AbstractTreeIterator minRef)
                   throws CorruptObjectException

Throws:

CorruptObjectException

combineDF

private AbstractTreeIterator combineDF(AbstractTreeIterator minRef)
                                throws CorruptObjectException

Throws:

CorruptObjectException

popEntriesEqual

void popEntriesEqual()
              throws CorruptObjectException

Overrides:

popEntriesEqual in class TreeWalk

Throws:

CorruptObjectException

skipEntriesEqual

void skipEntriesEqual()
               throws CorruptObjectException

Overrides:

skipEntriesEqual in class TreeWalk

Throws:

CorruptObjectException

stopWalk

void stopWalk()
       throws java.io.IOException

Description copied from class: TreeWalk

Notify iterators the walk is aborting.

Primarily to notify DirCacheBuildIterator the walk is aborting so that it can copy any remaining entries.

Overrides:

stopWalk in class TreeWalk

Throws:

java.io.IOException - if traversal of remaining entries throws an exception during object access. This should never occur as remaining trees should already be in memory, however the methods used to finish traversal are declared to throw IOException.

needsStopWalk

private boolean needsStopWalk()

isDirectoryFileConflict

public boolean isDirectoryFileConflict()

True if the current entry is covered by a directory/file conflict. This means that for some prefix of the current entry's path, this walk has detected a directory/file conflict. Also true if the current entry itself is a directory/file conflict. Example: If this TreeWalk points to foo/bar/a.txt and this method returns true then you know that either for path foo or for path foo/bar files and folders were detected.

Returns:

true if the current entry is covered by a directory/file conflict, false otherwise