tp.impl
Class MyLM

java.lang.Object
  tp.impl.MyLM

All Implemented Interfaces:

LM

public class MyLM
extends Object
implements LM

Your Lock Manager By default, it supports timeout based deadlock detection. Please refer comments (TODO) in the code when implementing lock conversion and deadlock detection using wait-for graph.

Nested Class Summary

Nested classes/interfaces inherited from interface tp.LM

LM.DeadLockException, LM.LockType

Field Summary

Fields inherited from interface tp.LM

DEFAULT_DEADLOCK_TIMEOUT

Constructor Summary

MyLM()

Method Summary

void	lockForRead(Transaction context, Lockable resource) obtain a read lock for given resource
void	lockForWrite(Transaction context, Lockable resource) obtain a write lock for given resource
void	setDeadlockTimeout(long ms) Set deadlock timeout in millisecond.
void	unlockAll(Transaction context) unlock all locks held by the transaction

Methods inherited from class java.lang.Object

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

Constructor Detail

MyLM

public MyLM()

Method Detail

lockForRead

public void lockForRead(Transaction context,
                        Lockable resource)
                 throws LM.DeadLockException,
                        InterruptedException

Description copied from interface: LM

obtain a read lock for given resource

Specified by:

lockForRead in interface LM

Parameters:

context - transaction identifier

resource - lockable resource identifier

Throws:

LM.DeadLockException - deadlock detected by either timeout or explicit deadlock detection algorithm

InterruptedException - thread has been interrupted by coordination thread

lockForWrite

public void lockForWrite(Transaction context,
                         Lockable resource)
                  throws LM.DeadLockException,
                         InterruptedException

Description copied from interface: LM

obtain a write lock for given resource

Specified by:

lockForWrite in interface LM

Parameters:

context - transaction identifier

resource - lockable resource identifier

Throws:

LM.DeadLockException - deadlock detected by either timeout or explicit deadlock detection algorithm

InterruptedException - thread has been interrupted by coordination thread

unlockAll

public void unlockAll(Transaction context)

Description copied from interface: LM

unlock all locks held by the transaction

Specified by:

unlockAll in interface LM

Parameters:

context - transaction identifier

setDeadlockTimeout

public void setDeadlockTimeout(long ms)

Description copied from interface: LM

Set deadlock timeout in millisecond. The default value is 10 seconds. Use this interface for testing concurrency control.

Specified by:

setDeadlockTimeout in interface LM

Parameters:

ms - timeout value in millisecond