alluxio.master

Class StateLockManager

java.lang.Object

alluxio.master.StateLockManager

public class StateLockManager
extends Object

Provides graceful and interruptable locking protocol for taking the state lock. lockShared() will be used by user RPCs and may throw InterruptedException based on options passed to lockExclusive(StateLockOptions). lockExclusive(StateLockOptions) will be used by metadata backups in order to guarantee paused state during critical tasks.

Constructor Summary

Constructors

Constructor and Description
StateLockManager() Creates a new state-lock manager.

Method Summary

Modifier and Type	Method and Description
Collection<String>	getSharedWaitersAndHolders()
boolean	interruptCycleTicking()
LockResource	lockExclusive(StateLockOptions lockOptions) Locks the state exclusively.
LockResource	lockExclusive(StateLockOptions lockOptions, RetryUtils.RunnableThrowsIOException beforeAttempt) Locks the state exclusively.
LockResource	lockShared() Locks the state shared.
void	mastersStartedCallback() This is called by owning process in order to signal that the state is read completely and masters are started.

Methods inherited from class java.lang.Object

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

Constructor Detail

StateLockManager

public StateLockManager()

Creates a new state-lock manager.

Method Detail

mastersStartedCallback

public void mastersStartedCallback()

This is called by owning process in order to signal that the state is read completely and masters are started. This triggers the beginning of exclusive-only maintenance mode for the state-lock. Note: Calling it multiple times does not reset the maintenance window.

lockShared

public LockResource lockShared()
                        throws InterruptedException

Locks the state shared. Calling thread might be interrupted by this manager, if it found to be waiting for the shared lock under when: - backup is exiting grace-cycle and entering the lock permanently - backup is in progress

Returns:

the lock resource

Throws:

InterruptedException

lockExclusive

public LockResource lockExclusive(StateLockOptions lockOptions)
                           throws TimeoutException,
                                  InterruptedException,
                                  IOException

Locks the state exclusively.

Parameters:

lockOptions - exclusive lock options

Returns:

the lock resource

Throws:

TimeoutException - if locking times out

InterruptedException - if interrupting during locking

IOException

lockExclusive

public LockResource lockExclusive(StateLockOptions lockOptions,
                                  RetryUtils.RunnableThrowsIOException beforeAttempt)
                           throws TimeoutException,
                                  InterruptedException,
                                  IOException

Locks the state exclusively.

Parameters:

lockOptions - exclusive lock options

beforeAttempt - a function which runs before each lock attempt and returns whether the lock should continue

Returns:

the lock resource

Throws:

TimeoutException - if locking times out

InterruptedException - if interrupting during locking

IOException - if the beforeAttempt functions fails

getSharedWaitersAndHolders

public Collection<String> getSharedWaitersAndHolders()

Returns:

the list of thread identifiers that are waiting and holding on the shared lock

interruptCycleTicking

public boolean interruptCycleTicking()

Returns:

true if the interrupt-cycle has been ticked and ticking