Lock (Apache Tomcat 9.0.0.M9 API Documentation)

java.lang.Object
- org.apache.tomcat.jni.Lock

```
public class Lock
extends Object
```
Lock

Author:

Mladen Turk

Field Summary

Fields
Modifier and Type	Field and Description
`static int`	`APR_LOCK_DEFAULT` POSIX semaphore process-based locking
`static int`	`APR_LOCK_FCNTL` Enumerated potential types for APR process locking methods Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo.
`static int`	`APR_LOCK_FLOCK` fcntl()
`static int`	`APR_LOCK_POSIXSEM` POSIX pthread process-based locking
`static int`	`APR_LOCK_PROC_PTHREAD` System V Semaphores
`static int`	`APR_LOCK_SYSVSEM` flock()

Constructor Summary

Constructors
Constructor and Description

Lock()

Constructors
Constructor and Description
`Lock()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static long`	`childInit(String fname, long pool)` Re-open a mutex in a child process.
`static long`	`create(String fname, int mech, long pool)` Create and initialize a mutex that can be used to synchronize processes.
`static String`	`defname()` Display the name of the default mutex: APR_LOCK_DEFAULT
`static int`	`destroy(long mutex)` Destroy the mutex and free the memory associated with the lock.
`static int`	`lock(long mutex)` Acquire the lock for the given mutex.
`static String`	`lockfile(long mutex)` Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock file
`static String`	`name(long mutex)` Display the name of the mutex, as it relates to the actual method used.
`static int`	`trylock(long mutex)` Attempt to acquire the lock for the given mutex.
`static int`	`unlock(long mutex)` Release the lock for the given mutex.

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

- Field Detail
  - APR_LOCK_FCNTL
```
public static final int APR_LOCK_FCNTL
```
    Enumerated potential types for APR process locking methods
    Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
    
    See Also:
    
    Constant Field Values
  - APR_LOCK_FLOCK
```
public static final int APR_LOCK_FLOCK
```
    fcntl()
    
    See Also:
    
    Constant Field Values
  - APR_LOCK_SYSVSEM
```
public static final int APR_LOCK_SYSVSEM
```
    flock()
    
    See Also:
    
    Constant Field Values
  - APR_LOCK_PROC_PTHREAD
```
public static final int APR_LOCK_PROC_PTHREAD
```
    System V Semaphores
    
    See Also:
    
    Constant Field Values
  - APR_LOCK_POSIXSEM
```
public static final int APR_LOCK_POSIXSEM
```
    POSIX pthread process-based locking
    
    See Also:
    
    Constant Field Values
  - APR_LOCK_DEFAULT
```
public static final int APR_LOCK_DEFAULT
```
    POSIX semaphore process-based locking
    
    See Also:
    
    Constant Field Values
- Constructor Detail
  - Lock
```
public Lock()
```
- Method Detail
  - create
```
public static long create(String fname,
                          int mech,
                          long pool)
                   throws Error
```
    Create and initialize a mutex that can be used to synchronize processes.
    Warning : Check APR_HAS_foo_SERIALIZE defines to see if the platform supports APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
    Parameters:
    
    fname - A file name to use if the lock mechanism requires one. This argument should always be provided. The lock code itself will determine if it should be used.
    mech - The mechanism to use for the interprocess lock, if any; one of
    APR_LOCK_FCNTL APR_LOCK_FLOCK APR_LOCK_SYSVSEM APR_LOCK_POSIXSEM APR_LOCK_PROC_PTHREAD APR_LOCK_DEFAULT pick the default mechanism for the platform
    pool - the pool from which to allocate the mutex.
    
    Returns:
    
    Newly created mutex.
    
    Throws:
    
    Error - An error occurred
  - childInit
```
public static long childInit(String fname,
                             long pool)
                      throws Error
```
    Re-open a mutex in a child process. This function must be called to maintain portability, even if the underlying lock mechanism does not require it.
    
    Parameters:
    
    fname - A file name to use if the mutex mechanism requires one. This argument should always be provided. The mutex code itself will determine if it should be used. This filename should be the same one that was passed to apr_proc_mutex_create().
    
    pool - The pool to operate on.
    
    Returns:
    
    Newly opened mutex.
    
    Throws:
    
    Error - An error occurred
  - lock
```
public static int lock(long mutex)
```
    Acquire the lock for the given mutex. If the mutex is already locked, the current thread will be put to sleep until the lock becomes available.
    
    Parameters:
    
    mutex - the mutex on which to acquire the lock.
    
    Returns:
    
    the operation status
  - trylock
```
public static int trylock(long mutex)
```
    Attempt to acquire the lock for the given mutex. If the mutex has already been acquired, the call returns immediately with APR_EBUSY. Note: it is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine if the return value was APR_EBUSY, for portability reasons.
    
    Parameters:
    
    mutex - the mutex on which to attempt the lock acquiring.
    
    Returns:
    
    the operation status
  - unlock
```
public static int unlock(long mutex)
```
    Release the lock for the given mutex.
    
    Parameters:
    
    mutex - the mutex from which to release the lock.
    
    Returns:
    
    the operation status
  - destroy
```
public static int destroy(long mutex)
```
    Destroy the mutex and free the memory associated with the lock.
    
    Parameters:
    
    mutex - the mutex to destroy.
    
    Returns:
    
    the operation status
  - lockfile
```
public static String lockfile(long mutex)
```
    Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock file
    
    Parameters:
    
    mutex - the name of the mutex
    
    Returns:
    
    the name of the lock file
  - name
```
public static String name(long mutex)
```
    Display the name of the mutex, as it relates to the actual method used. This matches the valid options for Apache's AcceptMutex directive
    
    Parameters:
    
    mutex - the name of the mutex
    
    Returns:
    
    the name of the mutex
  - defname
```
public static String defname()
```
    Display the name of the default mutex: APR_LOCK_DEFAULT
    
    Returns:
    
    the default name

Class Lock

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

APR_LOCK_FCNTL

APR_LOCK_FLOCK

APR_LOCK_SYSVSEM

APR_LOCK_PROC_PTHREAD

APR_LOCK_POSIXSEM

APR_LOCK_DEFAULT

Constructor Detail

Lock

Method Detail

create

childInit

lock

trylock

unlock

destroy

lockfile

name

defname