Lock (Lucene 3.6.2 API)

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

public abstract class Lock
extends 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 Description

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

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

Field Summary

Fields
Modifier and Type	Field	Description
`protected Throwable`	`failureReason`	If a lock obtain called, this failureReason may be set with the "root cause" Exception as to why the lock was not obtained.
`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 Description

Lock()

Constructors
Constructor	Description
`Lock()`

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	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
clone, equals, finalize, 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
  - failureReason
```
protected Throwable failureReason
```
    If a lock obtain called, this failureReason may be set with the "root cause" Exception as to why the lock was not obtained.
- Constructor Detail
  - Lock
```
public Lock()
```
- Method Detail
  - obtain
```
public abstract boolean obtain()
                        throws IOException
```
    Attempts to obtain exclusive access and immediately return upon success or failure.
    
    Returns:
    
    true iff exclusive access is obtained
    
    Throws:
    
    IOException
  - obtain
```
public boolean obtain(long lockWaitTimeout)
               throws LockObtainFailedException,
                      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
    
    IllegalArgumentException - if lockWaitTimeout is out of bounds
    
    IOException - if obtain() throws IOException
  - release
```
public abstract void release()
                      throws IOException
```
    Releases exclusive access.
    
    Throws:
    
    IOException
  - isLocked
```
public abstract boolean isLocked()
                          throws IOException
```
    Returns true if the resource is currently locked. Note that one must still call obtain() before using the resource.
    
    Throws:
    
    IOException

Class Lock

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

LOCK_POLL_INTERVAL

LOCK_OBTAIN_WAIT_FOREVER

failureReason

Constructor Detail

Lock

Method Detail

obtain

obtain

release

isLocked