Lock

Documentation of 'org.apache.lucene.store.Lock' Java class Lock

All Classes

Summary:
Nested |
Field |
Constr |
Method

Detail:
Field |
Constr |
Method

java.lang.Object
- org.apache.lucene.store.Lock

public abstract class Lock
extends java.lang.Object

An interprocess mutex lock.

Typical use might look like:

 new Lock.With(directory.makeLock("my.lock")) {
     public Object doBody() {
       ... code to execute while locked ...
     }
   }.run();

See Also:: Directory.makeLock(String)

Nested Class Summary

Nested Classes
Modifier and Type Class and Description

static class Lock.With
Utility class for executing code with exclusive access.

Nested Classes
Modifier and Type	Class and Description
`static class`	`Lock.With` Utility class for executing code with exclusive access.

Field Summary

Fields
Modifier and Type	Field and Description
`static long`	`LOCK_OBTAIN_WAIT_FOREVER` Pass this value to `obtain(long)` to try forever to obtain the lock.
`static long`	`LOCK_POLL_INTERVAL` How long `obtain(long)` waits, in milliseconds, in between attempts to acquire the lock.

Constructor Summary

Constructors
Constructor and Description

Lock()

Constructors
Constructor and Description
`Lock()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`abstract boolean`	`isLocked()` Returns true if the resource is currently locked.
`abstract boolean`	`obtain()` Attempts to obtain exclusive access and immediately return upon success or failure.
`boolean`	`obtain(long lockWaitTimeout)` Attempts to obtain an exclusive lock within amount of time given.
`abstract void`	`release()` Releases exclusive access.

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

- Field Detail
  - LOCK_POLL_INTERVAL
```
public static long LOCK_POLL_INTERVAL
```
    How long obtain(long) waits, in milliseconds, in between attempts to acquire the lock.
  - LOCK_OBTAIN_WAIT_FOREVER
```
public static final long LOCK_OBTAIN_WAIT_FOREVER
```
    Pass this value to obtain(long) to try forever to obtain the lock.
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - Lock
```
public Lock()
```
- Method Detail
  - obtain
```
public abstract boolean obtain()
                        throws java.io.IOException
```
    Attempts to obtain exclusive access and immediately return upon success or failure.
    
    Returns:
    
    true iff exclusive access is obtained
    
    Throws:
    
    java.io.IOException
  - obtain
```
public boolean obtain(long lockWaitTimeout)
               throws LockObtainFailedException,
                      java.io.IOException
```
    Attempts to obtain an exclusive lock within amount of time given. Polls once per LOCK_POLL_INTERVAL (currently 1000) milliseconds until lockWaitTimeout is passed.
    
    Parameters:
    
    lockWaitTimeout - length of time to wait in milliseconds or LOCK_OBTAIN_WAIT_FOREVER to retry forever
    
    Returns:
    
    true if lock was obtained
    
    Throws:
    
    LockObtainFailedException - if lock wait times out
    
    java.lang.IllegalArgumentException - if lockWaitTimeout is out of bounds
    
    java.io.IOException - if obtain() throws IOException
  - release
```
public abstract void release()
                      throws java.io.IOException
```
    Releases exclusive access.
    
    Throws:
    
    java.io.IOException
  - isLocked
```
public abstract boolean isLocked()
```
    Returns true if the resource is currently locked. Note that one must still call obtain() before using the resource.