Package org.h2.store

Class FileLock

java.lang.Object

org.h2.store.FileLock

All Implemented Interfaces:

Runnable

public class FileLock
extends Object
implements Runnable

The file lock is used to lock a database so that only one process can write to it. It uses a cooperative locking protocol. Usually a .lock.db file is used, but locking by creating a socket is supported as well.

Constructor Summary

Constructors

Constructor	Description
FileLock(TraceSystem traceSystem, String fileName, int sleep)	Create a new file locking object.

Method Summary

Modifier and Type	Method	Description
static FileLockMethod	getFileLockMethod(String method)	Get the file locking method type given a method name.
String	getUniqueId()
Properties	load()	Load the properties file.
void	lock(FileLockMethod fileLockMethod)	Lock the file if possible.
void	run()
Properties	save()	Save the lock file.
void	setProperty(String key, String value)	Add or change a setting to the properties.
void	unlock()	Unlock the file.

Methods inherited from class java.lang.Object

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

Constructor Details

FileLock

public FileLock(TraceSystem traceSystem,
 String fileName,
 int sleep)

Create a new file locking object.

Parameters:

traceSystem - the trace system to use

fileName - the file name

sleep - the number of milliseconds to sleep

Method Details

lock

public void lock(FileLockMethod fileLockMethod)

Lock the file if possible. A file may only be locked once.

Parameters:

fileLockMethod - the file locking method to use

Throws:

DbException - if locking was not successful

unlock

public void unlock()

Unlock the file. The watchdog thread is stopped. This method does nothing if the file is already unlocked.

setProperty

public void setProperty(String key,
 String value)

Add or change a setting to the properties. This call does not save the file.

Parameters:

key - the key

value - the value

save

public Properties save()

Save the lock file.

Returns:

the saved properties

load

public Properties load()

Load the properties file.

Returns:

the properties

getFileLockMethod

public static FileLockMethod getFileLockMethod(String method)

Get the file locking method type given a method name.

Parameters:

method - the method name

Returns:

the method type

Throws:

DbException - if the method name is unknown

getUniqueId

public String getUniqueId()

run

public void run()

Specified by:

run in interface Runnable