org.apache.tomcat.jni

Class Lock

public class Lock extends Object

Lock

Version: $Revision: 467222 $, $Date: 2006-10-24 05:17:11 +0200 (Tue, 24 Oct 2006) $

Author: Mladen Turk

Field Summary
static intAPR_LOCK_DEFAULT
POSIX semaphore process-based locking
static intAPR_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 intAPR_LOCK_FLOCK
fcntl()
static intAPR_LOCK_POSIXSEM
POSIX pthread process-based locking
static intAPR_LOCK_PROC_PTHREAD
System V Semaphores
static intAPR_LOCK_SYSVSEM
flock()
Method Summary
static longchildInit(String fname, long pool)
Re-open a mutex in a child process.
static longcreate(String fname, int mech, long pool)
Create and initialize a mutex that can be used to synchronize processes.
static Stringdefname()
Display the name of the default mutex: APR_LOCK_DEFAULT
static intdestroy(long mutex)
Destroy the mutex and free the memory associated with the lock.
static intlock(long mutex)
Acquire the lock for the given mutex.
static Stringlockfile(long mutex)
Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock file
static Stringname(long mutex)
Display the name of the mutex, as it relates to the actual method used.
static inttrylock(long mutex)
Attempt to acquire the lock for the given mutex.
static intunlock(long mutex)
Release the lock for the given mutex.

Field Detail

APR_LOCK_DEFAULT

public static final int APR_LOCK_DEFAULT
POSIX semaphore process-based locking

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.

APR_LOCK_FLOCK

public static final int APR_LOCK_FLOCK
fcntl()

APR_LOCK_POSIXSEM

public static final int APR_LOCK_POSIXSEM
POSIX pthread process-based locking

APR_LOCK_PROC_PTHREAD

public static final int APR_LOCK_PROC_PTHREAD
System V Semaphores

APR_LOCK_SYSVSEM

public static final int APR_LOCK_SYSVSEM
flock()

Method Detail

childInit

public static long childInit(String fname, long pool)
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.

create

public static long create(String fname, int mech, long pool)
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.

defname

public static String defname()
Display the name of the default mutex: APR_LOCK_DEFAULT

destroy

public static int destroy(long mutex)
Destroy the mutex and free the memory associated with the lock.

Parameters: mutex the mutex to destroy.

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.

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

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

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.

unlock

public static int unlock(long mutex)
Release the lock for the given mutex.

Parameters: mutex the mutex from which to release the lock.

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