alluxio.master.file.meta

Class LockedInodePath

java.lang.Object

alluxio.master.file.meta.LockedInodePath

All Implemented Interfaces:

Closeable, AutoCloseable

@NotThreadSafe
public class LockedInodePath
extends Object
implements Closeable

This class represents a locked path within the inode tree, starting from the root. The mUri and mPathComponents fields are immutable and contain the "target" path represented by the LockedInodePath. mLockList manages the locks held by the LockedInodePath. The mExistingInodes list holds inodes that are locked and known to exist. The inodes might not be individually locked - if one inode is write-locked, the inodes after it are implicitly write-locked and may be added to mExistingInodes. The inodes in mExistingInodes are a prefix of the inodes referenced by mPathComponents. If the full path exists, mExistingInodes will have size equal to mPathComponents.length after traversal. mExistingInodes is always at least as long as the list of inodes directly locked by mLockList. To create new inode paths from an existing path, use one of the lock*() methods. They return new locked inode paths that can be modified and closed without affecting the original path. Modifying the original inode path invalidates any subpaths that it has created. Locked inode paths are not threadsafe and should not be shared across threads.

Field Summary

Fields

Modifier and Type	Field and Description
protected InodeLockList	mLockList Lock list locking some portion of the path according to mLockPattern.
protected InodeTree.LockPattern	mLockPattern The locking pattern.
protected String[]	mPathComponents The components of mUri.
protected AlluxioURI	mUri Uri for the path represented.

Constructor Summary

Constructors

Constructor and Description
LockedInodePath(AlluxioURI uri, ReadOnlyInodeStore inodeStore, InodeLockManager inodeLockManager, InodeDirectory root, InodeTree.LockPattern lockPattern, boolean tryLock, JournalContext journalContext) Creates a new locked inode path.

Method Summary

Modifier and Type	Method and Description
void	addNextInode(Inode inode) Adds the next inode to the path.
void	close()
void	downgradeToRead() Downgrades all locks in this list to read locks.
boolean	fullPathExists()
Inode	getAncestorInode() Returns the closest ancestor of the target inode (last inode in the full path).
int	getExistingInodeCount()
Inode	getInode()
InodeFile	getInodeFile()
List<Inode>	getInodeList()
Inode	getInodeOrNull()
List<InodeView>	getInodeViewList()
Inode	getLastExistingInode()
InodeTree.LockPattern	getLockPattern()
InodeDirectory	getParentInodeDirectory()
Inode	getParentInodeOrNull()
AlluxioURI	getUri()
LockedInodePath	lockChild(Inode child, InodeTree.LockPattern lockPattern) Returns a new locked inode path composed of the current path plus the child inode.
LockedInodePath	lockChild(Inode child, InodeTree.LockPattern lockPattern, String[] childComponentsHint) Efficient version of #lockChild(Inode, LockPattern) for when the child path components are already known.
LockedInodePath	lockChildByName(String childName, InodeTree.LockPattern lockPattern, String[] childComponentsHint) Efficient version of #lockChild(Inode, LockPattern) for when the child path components are already known.
LockedInodePath	lockDescendant(AlluxioURI descendantUri, InodeTree.LockPattern lockPattern) Locks a descendant of the current path and returns a new locked inode path.
LockedInodePath	lockFinalEdgeWrite() Returns a copy of the path with the final edge write locked.
void	removeLastInode() Removes the last inode from the list.
int	size()
String	toString()
void	traverse() Traverses the inode path according to its lock pattern.

Methods inherited from class java.lang.Object

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

Field Detail

mUri

protected final AlluxioURI mUri

Uri for the path represented.

mPathComponents

protected final String[] mPathComponents

The components of mUri.

mLockList

protected final InodeLockList mLockList

Lock list locking some portion of the path according to mLockPattern.

mLockPattern

protected InodeTree.LockPattern mLockPattern

The locking pattern.

Constructor Detail

LockedInodePath

public LockedInodePath(AlluxioURI uri,
                       ReadOnlyInodeStore inodeStore,
                       InodeLockManager inodeLockManager,
                       InodeDirectory root,
                       InodeTree.LockPattern lockPattern,
                       boolean tryLock,
                       JournalContext journalContext)
                throws InvalidPathException

Creates a new locked inode path.

Parameters:

uri - the uri for the path

inodeStore - the inode store for looking up inode children

inodeLockManager - the inode lock manager

root - the root inode

lockPattern - the pattern to lock in

tryLock - whether or not use Lock.tryLock() or Lock.lock()

journalContext - the journal context to flush when the lock is released

Throws:

InvalidPathException

Method Detail

getUri

public AlluxioURI getUri()

Returns:

the full uri of the path

getInode

public Inode getInode()
               throws FileDoesNotExistException

Returns:

the target inode

Throws:

FileDoesNotExistException - if the target inode does not exist

getInodeOrNull

@Nullable
public Inode getInodeOrNull()

Returns:

the target inode, or null if it does not exist

getInodeFile

public InodeFile getInodeFile()
                       throws FileDoesNotExistException

Returns:

the target inode as an MutableInodeFile

Throws:

FileDoesNotExistException - if the target inode does not exist, or it is not a file

getParentInodeDirectory

public InodeDirectory getParentInodeDirectory()
                                       throws InvalidPathException,
                                              FileDoesNotExistException

Returns:

the parent of the target inode

Throws:

InvalidPathException - if the parent inode is not a directory

FileDoesNotExistException - if the parent of the target does not exist

getParentInodeOrNull

@Nullable
public Inode getParentInodeOrNull()

Returns:

the parent of the target inode, or null if the parent does not exist

getLastExistingInode

public Inode getLastExistingInode()

Returns:

the last existing inode on the inode path. This could be out of date if the current thread has added or deleted inodes since the last call to traverse()

getInodeList

public List<Inode> getInodeList()

Returns:

a copy of the list of existing inodes, from the root

getInodeViewList

public List<InodeView> getInodeViewList()

Returns:

a copy of the list of existing inodes, from the root

getExistingInodeCount

public int getExistingInodeCount()

Returns:

the number of existing inodes in this path. This could be out of date if the current thread has added or deleted inodes since the last call to traverse()

size

public int size()

Returns:

number of components in this locked path

fullPathExists

public boolean fullPathExists()

Returns:

true if the entire path of inodes exists, false otherwise. This could be out of date if the current thread has added or deleted inodes since the last call to traverse()

getLockPattern

public InodeTree.LockPattern getLockPattern()

Returns:

the InodeTree.LockPattern of this path

removeLastInode

public void removeLastInode()

Removes the last inode from the list. This is necessary when the last inode is deleted and we want to continue using the inodepath. This operation is only supported when the path is complete.

addNextInode

public void addNextInode(Inode inode)

Adds the next inode to the path. This tries to reduce the scope of locking by moving the write lock forward to the new final edge, downgrading the previous write lock to a read lock.

Parameters:

inode - the inode to add

downgradeToRead

public void downgradeToRead()

Downgrades all locks in this list to read locks.

getAncestorInode

public Inode getAncestorInode()
                       throws FileDoesNotExistException

Returns the closest ancestor of the target inode (last inode in the full path).

Returns:

the closest ancestor inode

Throws:

FileDoesNotExistException - if an ancestor does not exist

lockDescendant

public LockedInodePath lockDescendant(AlluxioURI descendantUri,
                                      InodeTree.LockPattern lockPattern)
                               throws InvalidPathException

Locks a descendant of the current path and returns a new locked inode path. The path is traversed according to the lock pattern. Closing the new path will have no effect on the current path. On failure, all locks taken by this method will be released.

Parameters:

descendantUri - the full descendent uri starting from the root

lockPattern - the lock pattern to lock in

Returns:

the new locked path

Throws:

InvalidPathException

lockChild

public LockedInodePath lockChild(Inode child,
                                 InodeTree.LockPattern lockPattern)
                          throws InvalidPathException

Returns a new locked inode path composed of the current path plus the child inode. The path is traversed according to the lock pattern. The original locked inode path is unaffected. childComponentsHint can be used to save the work of computing path components when the path components for the new path are already known. On failure, all locks taken by this method will be released.

Parameters:

child - the child inode

lockPattern - the lock pattern

Returns:

the new locked path

Throws:

InvalidPathException

lockChild

public LockedInodePath lockChild(Inode child,
                                 InodeTree.LockPattern lockPattern,
                                 String[] childComponentsHint)
                          throws InvalidPathException

Efficient version of #lockChild(Inode, LockPattern) for when the child path components are already known.

Parameters:

child - the child inode

lockPattern - the lock pattern

childComponentsHint - path components for the new path

Returns:

the new locked path

Throws:

InvalidPathException

lockChildByName

public LockedInodePath lockChildByName(String childName,
                                       InodeTree.LockPattern lockPattern,
                                       String[] childComponentsHint)
                                throws InvalidPathException

Efficient version of #lockChild(Inode, LockPattern) for when the child path components are already known.

Parameters:

childName - the name of the child inode

lockPattern - the lock pattern

childComponentsHint - path components for the new path

Returns:

the new locked path

Throws:

InvalidPathException

lockFinalEdgeWrite

public LockedInodePath lockFinalEdgeWrite()
                                   throws InvalidPathException

Returns a copy of the path with the final edge write locked. This requires that we haven't already locked the final edge, i.e. the path is incomplete.

Returns:

the new locked path

Throws:

InvalidPathException

traverse

public void traverse()
              throws InvalidPathException

Traverses the inode path according to its lock pattern. If the inode path is already partially traversed, this method will pick up where the previous traversal left off. On return, all existing inodes in the path are added to mExistingInodes and the inodes are locked according to InodeTree.LockPattern. Journals are not flushed in this method because: 1. When a LockedInodePath is created, it will be traversed first before any journal is written 2. The only use cases that call this method independently are in metadata sync InodeSyncStream. Where traverse() is called right before the lock is released, where the journals will be flushed anyway.

Throws:

InvalidPathException

close

public void close()

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

toString

public String toString()

Overrides:

toString in class Object