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  /*
   *  Licensed to the Apache Software Foundation (ASF) under one or more
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   *  this work for additional information regarding copyright ownership.
   *  The ASF licenses this file to You under the Apache License, Version 2.0
   *  (the "License"); you may not use this file except in compliance with
   *  the License.  You may obtain a copy of the License at
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   *      http://www.apache.org/licenses/LICENSE-2.0
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  *  Unless required by applicable law or agreed to in writing, software
  *  distributed under the License is distributed on an "AS IS" BASIS,
  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  *  See the License for the specific language governing permissions and
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 package org.apache.tomcat.jni;

Lock

Author(s):
Mladen Turk
Version:
$Revision: 515 $, $Date: 2008-03-17 22:02:23 +0100 (Mon, 17 Mar 2008) $
 
 
 public class Lock {

    
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.
 
 
     public static final int APR_LOCK_FCNTL        = 0; 
fcntl()
 
     public static final int APR_LOCK_FLOCK        = 1; 
flock()
 
     public static final int APR_LOCK_SYSVSEM      = 2; 
System V Semaphores
 
     public static final int APR_LOCK_PROC_PTHREAD = 3; 
POSIX pthread process-based locking
 
     public static final int APR_LOCK_POSIXSEM     = 4; 
POSIX semaphore process-based locking
 
     public static final int APR_LOCK_DEFAULT      = 5; 
Use the default process lock
 

    
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.
 
     public static native long create(String fnameint mechlong 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.
 
     public static native long childInit(String fnamelong pool)
         throws Error;

    
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.
 
     public static native int lock(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.
 
     public static native int trylock(long mutex);

    
Release the lock for the given mutex.

Parameters:
mutex the mutex from which to release the lock.
 
     public static native int unlock(long mutex);

    
Destroy the mutex and free the memory associated with the lock.

Parameters:
mutex the mutex to destroy.
    public static native int destroy(long mutex);

    
Return the name of the lockfile for the mutex, or NULL if the mutex doesn't use a lock file
    public static native String lockfile(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
    public static native String name(long mutex);

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