1PTHREAD_MUTEXATTR_GETTYPE(3PP)OSIX Programmer's ManuPaTlHREAD_MUTEXATTR_GETTYPE(3P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 pthread_mutexattr_gettype, pthread_mutexattr_settype - get and set the
13 mutex type attribute
14
16 #include <pthread.h>
17 int pthread_mutexattr_gettype(const pthread_mutexattr_t *restrict attr,
19 int *restrict type);
20 int pthread_mutexattr_settype(pthread_mutexattr_t *attr, int type);
21
24 The pthread_mutexattr_gettype() and pthread_mutexattr_settype() func‐
25 tions, respectively, shall get and set the mutex type attribute. This
26 attribute is set in the type parameter to these functions. The default
27 value of the type attribute is PTHREAD_MUTEX_DEFAULT.
28 The type of mutex is contained in the type attribute of the mutex
30 attributes. Valid mutex types include:
31 PTHREAD_MUTEX_NORMAL
33 This type of mutex does not detect deadlock. A thread attempting
35 to relock this mutex without first unlocking it shall deadlock.
36 Attempting to unlock a mutex locked by a different thread
37 results in undefined behavior. Attempting to unlock an unlocked
38 mutex results in undefined behavior.
39 PTHREAD_MUTEX_ERRORCHECK
41 This type of mutex provides error checking. A thread attempting
43 to relock this mutex without first unlocking it shall return
44 with an error. A thread attempting to unlock a mutex which
45 another thread has locked shall return with an error. A thread
46 attempting to unlock an unlocked mutex shall return with an
47 error.
48 PTHREAD_MUTEX_RECURSIVE
50 A thread attempting to relock this mutex without first unlocking
52 it shall succeed in locking the mutex. The relocking deadlock
53 which can occur with mutexes of type PTHREAD_MUTEX_NORMAL cannot
54 occur with this type of mutex. Multiple locks of this mutex
55 shall require the same number of unlocks to release the mutex
56 before another thread can acquire the mutex. A thread attempting
57 to unlock a mutex which another thread has locked shall return
58 with an error. A thread attempting to unlock an unlocked mutex
59 shall return with an error.
60 PTHREAD_MUTEX_DEFAULT
62 Attempting to recursively lock a mutex of this type results in
64 undefined behavior. Attempting to unlock a mutex of this type
65 which was not locked by the calling thread results in undefined
66 behavior. Attempting to unlock a mutex of this type which is
67 not locked results in undefined behavior. An implementation may
68 map this mutex to one of the other mutex types.
69
72 Upon successful completion, the pthread_mutexattr_gettype() function
73 shall return zero and store the value of the type attribute of attr
74 into the object referenced by the type parameter. Otherwise, an error
75 shall be returned to indicate the error.
76 If successful, the pthread_mutexattr_settype() function shall return
78 zero; otherwise, an error number shall be returned to indicate the
79 error.
80
82 The pthread_mutexattr_settype() function shall fail if:
83 EINVAL The value type is invalid.
85 The pthread_mutexattr_gettype() and pthread_mutexattr_settype() func‐
88 tions may fail if:
89 EINVAL The value specified by attr is invalid.
91 These functions shall not return an error code of [EINTR].
94 The following sections are informative.
96
98 None.
99
101 It is advised that an application should not use a PTHREAD_MUTEX_RECUR‐
102 SIVE mutex with condition variables because the implicit unlock per‐
103 formed for a pthread_cond_timedwait() or pthread_cond_wait() may not
104 actually release the mutex (if it had been locked multiple times). If
105 this happens, no other thread can satisfy the condition of the predi‐
106 cate.
107
109 None.
110
112 None.
113
115 pthread_cond_timedwait(), the Base Definitions volume of
116 IEEE Std 1003.1-2001, <pthread.h>
117
119 Portions of this text are reprinted and reproduced in electronic form
120 from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
121 -- Portable Operating System Interface (POSIX), The Open Group Base
122 Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
123 Electrical and Electronics Engineers, Inc and The Open Group. In the
124 event of any discrepancy between this version and the original IEEE and
125 The Open Group Standard, the original IEEE and The Open Group Standard
126 is the referee document. The original Standard can be obtained online
127 at http://www.opengroup.org/unix/online.html .
128IEEE/The Open Group 2003 PTHREAD_MUTEXATTR_GETTYPE(3P)