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1 /*
2  * Licensed to the Apache Software Foundation (ASF) under one or more
3  * contributor license agreements. See the NOTICE file distributed with
4  * this work for additional information regarding copyright ownership.
5  * The ASF licenses this file to You under the Apache License, Version 2.0
6  * (the "License"); you may not use this file except in compliance with
7  * the License. You may obtain a copy of the License at
8  *
9  * http://www.apache.org/licenses/LICENSE-2.0
10  *
11  * Unless required by applicable law or agreed to in writing, software
12  * distributed under the License is distributed on an "AS IS" BASIS,
13  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  * See the License for the specific language governing permissions and
15  * limitations under the License.
16  */
17
18 package org.apache.tomcat.jni;
19
20 /** Global
21  *
22  * @author Mladen Turk
23  * @version $Revision: 467222 $, $Date: 2006-10-24 05:17:11 +0200 (mar., 24 oct. 2006) $
24  */
25
26 public class Global {
27
28     /**
29      * Create and initialize a mutex that can be used to synchronize both
30      * processes and threads. Note: There is considerable overhead in using
31      * this API if only cross-process or cross-thread mutual exclusion is
32      * required. See apr_proc_mutex.h and apr_thread_mutex.h for more
33      * specialized lock routines.
34      * <br /><b>Warning :</b> Check APR_HAS_foo_SERIALIZE defines to see if the platform supports
35      * APR_LOCK_foo. Only APR_LOCK_DEFAULT is portable.
36      * @param fname A file name to use if the lock mechanism requires one. This
37      * argument should always be provided. The lock code itself will
38      * determine if it should be used.
39      * @param mech The mechanism to use for the interprocess lock, if any; one of
40      * <PRE>
41      * APR_LOCK_FCNTL
42      * APR_LOCK_FLOCK
43      * APR_LOCK_SYSVSEM
44      * APR_LOCK_POSIXSEM
45      * APR_LOCK_PROC_PTHREAD
46      * APR_LOCK_DEFAULT pick the default mechanism for the platform
47      * </PRE>
48      * @param pool the pool from which to allocate the mutex.
49      * @return Newly created mutex.
50      */
51     public static native long create(String JavaDoc fname, int mech, long pool)
52         throws Error JavaDoc;
53
54     /**
55      * Re-open a mutex in a child process.
56      * @param fname A file name to use if the mutex mechanism requires one. This
57      * argument should always be provided. The mutex code itself will
58      * determine if it should be used. This filename should be the
59      * same one that was passed to apr_proc_mutex_create().
60      * @param pool The pool to operate on.
61      * This function must be called to maintain portability, even
62      * if the underlying lock mechanism does not require it.
63      * @return Newly opened mutex.
64      */
65     public static native long childInit(String JavaDoc fname, long pool)
66         throws Error JavaDoc;
67
68     /**
69      * Acquire the lock for the given mutex. If the mutex is already locked,
70      * the current thread will be put to sleep until the lock becomes available.
71      * @param mutex the mutex on which to acquire the lock.
72      */
73     public static native int lock(long mutex);
74
75     /**
76      * Attempt to acquire the lock for the given mutex. If the mutex has already
77      * been acquired, the call returns immediately with APR_EBUSY. Note: it
78      * is important that the APR_STATUS_IS_EBUSY(s) macro be used to determine
79      * if the return value was APR_EBUSY, for portability reasons.
80      * @param mutex the mutex on which to attempt the lock acquiring.
81      */
82     public static native int trylock(long mutex);
83
84     /**
85      * Release the lock for the given mutex.
86      * @param mutex the mutex from which to release the lock.
87      */
88     public static native int unlock(long mutex);
89
90     /**
91      * Destroy the mutex and free the memory associated with the lock.
92      * @param mutex the mutex to destroy.
93      */
94     public static native int destroy(long mutex);
95
96 }
97
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