FileLock (Narayana: ArjunaJTA narayana-jta 5.13.1.Final API)

java.lang.Object
- com.arjuna.ats.arjuna.utils.FileLock

```
public class FileLock
extends java.lang.Object
```
Sometimes it is necessary to lock a file at the disk level. Since there is no native Java way of locking a file, we have to implement our own. Unfortunately, it appears as though we can only assume that rename is atomic. We base the locking on this then: rename the lock file and update it with the lock owners. How it works: for every file we want to lock we create an _lock file. This file contains information about who is locking the file, and in what mode. (Single writer, multiple readers.) To guarantee atomicity of update, we move (rename) the actual file each time we want to lock it and update the lock file. When this is done, we move (rename) it back. Almost like a two-phase commit protocol! Currently we don't support re-entrant locking.

Since:

JTS 1.0.

Version:

$Id: FileLock.java 2342 2006-03-30 13:06:17Z $

Author:

Mark Little (mark@arjuna.com)

Field Summary

Fields
Modifier and Type Field Description

static int defaultRetry

static int defaultTimeout

static int F_RDLCK

static int F_WRLCK

Constructor Summary

Constructors
Constructor	Description
`FileLock(java.io.File name)`
`FileLock(java.io.File name, long timeout, long retry)`
`FileLock(java.lang.String name)`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`lock(int lmode)`
`boolean`	`lock(int lmode, boolean create)`
`static java.lang.String`	`modeString(int mode)`
`boolean`	`unlock()`

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail
- F_RDLCK
```
public static final int F_RDLCK
```
  See Also:
  
  Constant Field Values
- F_WRLCK
```
public static final int F_WRLCK
```
  See Also:
  
  Constant Field Values
- defaultTimeout
```
public static final int defaultTimeout
```
  See Also:
  
  Constant Field Values
- defaultRetry
```
public static final int defaultRetry
```
  See Also:
  
  Constant Field Values

Constructor Detail

FileLock

public FileLock(java.lang.String name)

FileLock
```
public FileLock(java.io.File name)
```

FileLock

public FileLock(java.io.File name,
                long timeout,
                long retry)

Method Detail

lock
```
public boolean lock(int lmode)
```
Since:

JTS 2.1.1.

lock

public boolean lock(int lmode,
                    boolean create)

unlock
```
public boolean unlock()
```

modeString

public static java.lang.String modeString(int mode)