edu.berkeley.cs186.database.concurrency

Class LockManager

java.lang.Object

edu.berkeley.cs186.database.concurrency.LockManager

public class LockManager
extends Object

The LockManager provides a basic locking implementation that ensures that only one transaction runs at a time. We will cover locking later in the semester; for now, you don't need to change anything here.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	LockManager.LockType

Constructor Summary

Constructors

Constructor and Description
LockManager()

Method Summary

Methods

Modifier and Type	Method and Description
void	acquireLock(String tableName, long transNum, LockManager.LockType lockType) Acquires a lock on tableNum of type lockType for transaction transNum.
boolean	holdsLock(String tableName, long transNum, LockManager.LockType lockType) Returns a boolean indicating whether or not transNum holds a lock of type lockType on tableName.
void	releaseLock(String tableName, long transNum) Releases transNum's lock on tableName.

Methods inherited from class java.lang.Object

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

Constructor Detail

LockManager

public LockManager()

Method Detail

acquireLock

public void acquireLock(String tableName,
               long transNum,
               LockManager.LockType lockType)

Acquires a lock on tableNum of type lockType for transaction transNum.

Parameters:

tableName - the database to lock on

transNum - the transactions id

lockType - the type of lock

releaseLock

public void releaseLock(String tableName,
               long transNum)

Releases transNum's lock on tableName.

Parameters:

tableName - the table that was locked

transNum - the transaction that held the lock

holdsLock

public boolean holdsLock(String tableName,
                long transNum,
                LockManager.LockType lockType)

Returns a boolean indicating whether or not transNum holds a lock of type lockType on tableName.

Parameters:

tableName - the table that we're checking

transNum - the transaction that we're checking for

lockType - the lock type

Returns:

whether the lock is held or not