alluxio.master.file.meta

Class CompositeInodeLockList

java.lang.Object

alluxio.master.file.meta.CompositeInodeLockList

All Implemented Interfaces:

InodeLockList, AutoCloseable

@NotThreadSafe
public class CompositeInodeLockList
extends Object
implements InodeLockList

Manages the locks for a list of inodes, based off an existing lock list. This does not modify the base lock list, and when this lock list is closed, the base lock list is not closed. The purpose of this class is to allow lock lists to be temporarily extended and then restored. The base lock list can end with either an inode or edge, and can be read locked or write locked. Modification is only supported for the non-base part of the lock list.

Constructor Summary

Constructors

Constructor and Description
CompositeInodeLockList(InodeLockList baseLockList, boolean useTryLock) Constructs a new lock list, using an existing lock list as the base list.

Method Summary

Modifier and Type	Method and Description
void	close() Closes the lock list, releasing all locks.
void	downgradeLastEdge() Downgrades the last edge lock in the lock list from WRITE lock to READ lock.
void	downgradeToReadLocks() Downgrades all locks in the current lock list to read locks.
boolean	endsInInode()
Inode	get(int index)
InodeLockManager	getInodeLockManager()
List<Inode>	getLockedInodes()
LockMode	getLockMode()
boolean	isEmpty()
void	lockEdge(Inode inode, String childName, LockMode mode) Locks an edge leading out of the last inode in the list.
void	lockInode(Inode inode, LockMode mode) Locks the given inode and adds it to the lock list.
void	lockRootEdge(LockMode mode) Locks the root edge in the specified mode.
int	numInodes()
void	pushWriteLockedEdge(Inode inode, String childName) Leapfrogs the final edge write lock forward, reducing the lock list's write-locked scope.
void	unlockLastEdge() Unlocks the last locked edge.
void	unlockLastInode() Unlocks the last locked inode.

Methods inherited from class java.lang.Object

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

Methods inherited from interface alluxio.master.file.meta.InodeLockList

getLockedInodeViews

Constructor Detail

CompositeInodeLockList

public CompositeInodeLockList(InodeLockList baseLockList,
                              boolean useTryLock)

Constructs a new lock list, using an existing lock list as the base list.

Parameters:

baseLockList - the base InodeLockList to use

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

Method Detail

lockRootEdge

public void lockRootEdge(LockMode mode)

Description copied from interface: InodeLockList

Locks the root edge in the specified mode. The lock list must be empty to call this method.

Specified by:

lockRootEdge in interface InodeLockList

Parameters:

mode - the mode to lock in

lockInode

public void lockInode(Inode inode,
                      LockMode mode)

Description copied from interface: InodeLockList

Locks the given inode and adds it to the lock list. This method does *not* check that the inode is still a child of the previous inode, or that the inode still exists. This method should only be called when the edge leading to the inode is locked. Example Starting from [a, a->b] lockInode(b, LockMode.READ) results in [a, a->b, b] lockInode(b, LockMode.WRITE) results in [a, a->b, b*]

Specified by:

lockInode in interface InodeLockList

Parameters:

inode - the inode to lock

mode - the mode to lock in

lockEdge

public void lockEdge(Inode inode,
                     String childName,
                     LockMode mode)

Description copied from interface: InodeLockList

Locks an edge leading out of the last inode in the list. Example Starting from [a, a->b, b] lockEdge(b, c, LockMode.READ) results in [a, a->b, b, b->c] lockEdge(b, c, LockMode.WRITE) results in [a, a->b, b, b->c*]

Specified by:

lockEdge in interface InodeLockList

Parameters:

inode - the parent inode of the edge

childName - the child name of the edge

mode - the mode to lock in

unlockLastInode

public void unlockLastInode()

Description copied from interface: InodeLockList

Unlocks the last locked inode. Example Starting from [a, a->b, b] unlockLastInode() results in [a, a->b]

Specified by:

unlockLastInode in interface InodeLockList

unlockLastEdge

public void unlockLastEdge()

Description copied from interface: InodeLockList

Unlocks the last locked edge. Example Starting from [a, a->b] unlockLastEdge results in [a]

Specified by:

unlockLastEdge in interface InodeLockList

downgradeToReadLocks

public void downgradeToReadLocks()

Description copied from interface: InodeLockList

Downgrades all locks in the current lock list to read locks.

Specified by:

downgradeToReadLocks in interface InodeLockList

downgradeLastEdge

public void downgradeLastEdge()

Description copied from interface: InodeLockList

Downgrades the last edge lock in the lock list from WRITE lock to READ lock. Example Starting from [a, a->b*] downgradeLastEdge() results in [a, a->b]

Specified by:

downgradeLastEdge in interface InodeLockList

pushWriteLockedEdge

public void pushWriteLockedEdge(Inode inode,
                                String childName)

Description copied from interface: InodeLockList

Leapfrogs the final edge write lock forward, reducing the lock list's write-locked scope. Example Starting from [a, a->b*] pushWriteLockedEdge(b, c) results in [a, a->b, b, b->c*] The read lock on a->b is acquired before releasing the write lock. This ensures that no other thread can take the write lock before the read lock is acquired. If this is a composite lock list and the final write lock is part of the base lock list, the new locks will be acquired but no downgrade will occur.

Specified by:

pushWriteLockedEdge in interface InodeLockList

Parameters:

inode - the inode to add to the lock list

childName - the child name for the edge to add to the lock list

getLockMode

public LockMode getLockMode()

Specified by:

getLockMode in interface InodeLockList

Returns:

LockMode.WRITE if the last entry in the list is write-locked, otherwise LockMode.READ

getLockedInodes

public List<Inode> getLockedInodes()

Specified by:

getLockedInodes in interface InodeLockList

Returns:

a copy of all locked inodes

get

public Inode get(int index)

Specified by:

get in interface InodeLockList

Parameters:

index - the index of the list

Returns:

the inode at the specified index

numInodes

public int numInodes()

Specified by:

numInodes in interface InodeLockList

Returns:

the size of the list in terms of locked inodes

endsInInode

public boolean endsInInode()

Specified by:

endsInInode in interface InodeLockList

Returns:

whether this lock list ends in an inode (as opposed to an edge)

isEmpty

public boolean isEmpty()

Specified by:

isEmpty in interface InodeLockList

Returns:

true if the locklist is empty

getInodeLockManager

public InodeLockManager getInodeLockManager()

Specified by:

getInodeLockManager in interface InodeLockList

Returns:

the inode lock manager for this lock list

close

public void close()

Description copied from interface: InodeLockList

Closes the lock list, releasing all locks.

Specified by:

close in interface InodeLockList

Specified by:

close in interface AutoCloseable