com.toolsverse.util.concurrent

Class FileLocker<R>

Object

com.toolsverse.util.concurrent.FileLocker<R>

Type Parameters:

R - the generic type.

public final class FileLocker<R>
extends Object

The class for acquiring and releasing os level file locks. Use it only for one lock at the time.

Since:

2.0

Version:

2.0

Constructor Summary

Constructors

Constructor and Description
FileLocker() Instantiates a new file locker.

Method Summary

Modifier and Type	Method and Description
boolean	acquireLock(FileInputStream in) Locks the given file input stream.
boolean	acquireLock(FileInputStream in, int retry, int sleepTime) Locks the given file input stream.
boolean	acquireLock(FileOutputStream out) Locks the given file output stream.
boolean	acquireLock(FileOutputStream out, int retry, int sleepTime) Locks the given file output stream.
boolean	createLock(String fileName, boolean exclusive) Creates a locks file with the given name.
boolean	createLock(String fileName, int retry, int sleepTime, boolean exclusive) Creates a locks file with the given name.
R	execute(Callable<R> callable, String fileName, boolean exclusive) Executes the Callable.call() method.
R	execute(Callable<R> callable, String fileName, int retry, int sleepTime, boolean exclusive) Executes the Callable.call() method.
static String	getDefaultLockFileName(String fileName) Gets the default lock file name using given file name.
boolean	releaseLock() Releases current lock.

Methods inherited from class Object

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

Constructor Detail

FileLocker

public FileLocker()

Instantiates a new file locker.

Method Detail

getDefaultLockFileName

public static String getDefaultLockFileName(String fileName)

Gets the default lock file name using given file name.

Example: c:\abc\x.txt -> c:\abc\x.lck

Parameters:

fileName - the file name

Returns:

the default lock file name

acquireLock

public boolean acquireLock(FileInputStream in)

Locks the given file input stream. Uses DEFAULT_RETRY for the number of retries and

Parameters:

in - the the file input stream

Returns:

true, if successful DEFAULT_SLEEP_TIME for the sleep time between retries.

acquireLock

public boolean acquireLock(FileInputStream in,
                           int retry,
                           int sleepTime)

Locks the given file input stream.

Parameters:

in - the the file input stream

retry - the number of retries

sleepTime - the sleep time between retries

Returns:

true, if successful

acquireLock

public boolean acquireLock(FileOutputStream out)

Locks the given file output stream. Uses DEFAULT_RETRY for the number of retries and

Parameters:

out - the the file output stream

Returns:

true, if successful DEFAULT_SLEEP_TIME for the sleep time between retries.

acquireLock

public boolean acquireLock(FileOutputStream out,
                           int retry,
                           int sleepTime)

Locks the given file output stream.

Parameters:

out - the the file output stream

retry - the number of retries

sleepTime - the sleep time between retries

Returns:

true, if successful

createLock

public boolean createLock(String fileName,
                          boolean exclusive)

Creates a locks file with the given name. Uses DEFAULT_RETRY for the number of retries and

Parameters:

fileName - the file name

exclusive - if true try to acquire exclusive lock

Returns:

true, if successful DEFAULT_SLEEP_TIME for the sleep time between retries.

createLock

public boolean createLock(String fileName,
                          int retry,
                          int sleepTime,
                          boolean exclusive)

Creates a locks file with the given name.

Parameters:

fileName - the file name

retry - the number of retries

sleepTime - the sleep time between retries

exclusive - if true try to acquire exclusive lock

Returns:

true, if successful

execute

public R execute(Callable<R> callable,
                 String fileName,
                 boolean exclusive)
          throws Exception

Executes the Callable.call() method. If fileName != null crates a lock file with the given name before and deletes it after. Uses DEFAULT_RETRY for the number of retries and DEFAULT_SLEEP_TIME for the sleep time between retries.

Parameters:

callable - the instance of the Callable interface

fileName - the lock file name

exclusive - if true try to acquire exclusive lock

Returns:

the instance of the generic type R

Throws:

Exception - the exception in case of any error

execute

public R execute(Callable<R> callable,
                 String fileName,
                 int retry,
                 int sleepTime,
                 boolean exclusive)
          throws Exception

Executes the Callable.call() method. If fileName != null crates a lock file with the given name before and deletes it after.

Parameters:

callable - the instance of the Callable interface

fileName - the lock file name

retry - the number of retries

sleepTime - the sleep time between retries

exclusive - if true try to acquire exclusive lock

Returns:

the instance of the generic type R

Throws:

Exception - the exception in case of any error

releaseLock

public boolean releaseLock()

Releases current lock.

Returns:

true, if successful