1PTHREAD_RWLOCK_DESTROY(3P) POSIX Programmer's ManualPTHREAD_RWLOCK_DESTROY(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_rwlock_destroy, pthread_rwlock_init — destroy and initialize a
13 read-write lock object
14
16 #include <pthread.h>
17 int pthread_rwlock_destroy(pthread_rwlock_t *rwlock);
19 int pthread_rwlock_init(pthread_rwlock_t *restrict rwlock,
20 const pthread_rwlockattr_t *restrict attr);
21 pthread_rwlock_t rwlock = PTHREAD_RWLOCK_INITIALIZER;
22
24 The pthread_rwlock_destroy() function shall destroy the read-write lock
25 object referenced by rwlock and release any resources used by the lock.
26 The effect of subsequent use of the lock is undefined until the lock is
27 reinitialized by another call to pthread_rwlock_init(). An implementa‐
28 tion may cause pthread_rwlock_destroy() to set the object referenced by
29 rwlock to an invalid value. Results are undefined if
30 pthread_rwlock_destroy() is called when any thread holds rwlock.
31 Attempting to destroy an uninitialized read-write lock results in unde‐
32 fined behavior.
33 The pthread_rwlock_init() function shall allocate any resources
35 required to use the read-write lock referenced by rwlock and initial‐
36 izes the lock to an unlocked state with attributes referenced by attr.
37 If attr is NULL, the default read-write lock attributes shall be used;
38 the effect is the same as passing the address of a default read-write
39 lock attributes object. Once initialized, the lock can be used any num‐
40 ber of times without being reinitialized. Results are undefined if
41 pthread_rwlock_init() is called specifying an already initialized read-
42 write lock. Results are undefined if a read-write lock is used without
43 first being initialized.
44 If the pthread_rwlock_init() function fails, rwlock shall not be ini‐
46 tialized and the contents of rwlock are undefined.
47 See Section 2.9.9, Synchronization Object Copies and Alternative Map‐
49 pings for further requirements.
50 In cases where default read-write lock attributes are appropriate, the
52 macro PTHREAD_RWLOCK_INITIALIZER can be used to initialize read-write
53 locks. The effect shall be equivalent to dynamic initialization by a
54 call to pthread_rwlock_init() with the attr parameter specified as
55 NULL, except that no error checks are performed.
56 The behavior is undefined if the value specified by the attr argument
58 to pthread_rwlock_init() does not refer to an initialized read-write
59 lock attributes object.
60
62 If successful, the pthread_rwlock_destroy() and pthread_rwlock_init()
63 functions shall return zero; otherwise, an error number shall be
64 returned to indicate the error.
65
67 The pthread_rwlock_init() function shall fail if:
68 EAGAIN The system lacked the necessary resources (other than memory) to
70 initialize another read-write lock.
71 ENOMEM Insufficient memory exists to initialize the read-write lock.
73 EPERM The caller does not have the privilege to perform the operation.
75 These functions shall not return an error code of [EINTR].
77 The following sections are informative.
79
81 None.
82
84 Applications using these and related read-write lock functions may be
85 subject to priority inversion, as discussed in the Base Definitions
86 volume of POSIX.1‐2017, Section 3.291, Priority Inversion.
87
89 If an implementation detects that the value specified by the rwlock
90 argument to pthread_rwlock_destroy() does not refer to an initialized
91 read-write lock object, it is recommended that the function should fail
92 and report an [EINVAL] error.
93 If an implementation detects that the value specified by the attr argu‐
95 ment to pthread_rwlock_init() does not refer to an initialized read-
96 write lock attributes object, it is recommended that the function
97 should fail and report an [EINVAL] error.
98 If an implementation detects that the value specified by the rwlock
100 argument to pthread_rwlock_destroy() or pthread_rwlock_init() refers to
101 a locked read-write lock object, or detects that the value specified by
102 the rwlock argument to pthread_rwlock_init() refers to an already ini‐
103 tialized read-write lock object, it is recommended that the function
104 should fail and report an [EBUSY] error.
105
107 None.
108
110 pthread_rwlock_rdlock(), pthread_rwlock_timedrdlock(),
111 pthread_rwlock_timedwrlock(), pthread_rwlock_trywrlock(),
112 pthread_rwlock_unlock()
113 The Base Definitions volume of POSIX.1‐2017, Section 3.291, Priority
115 Inversion, <pthread.h>
116
118 Portions of this text are reprinted and reproduced in electronic form
119 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
120 table Operating System Interface (POSIX), The Open Group Base Specifi‐
121 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
122 Electrical and Electronics Engineers, Inc and The Open Group. In the
123 event of any discrepancy between this version and the original IEEE and
124 The Open Group Standard, the original IEEE and The Open Group Standard
125 is the referee document. The original Standard can be obtained online
126 at http://www.opengroup.org/unix/online.html .
127 Any typographical or formatting errors that appear in this page are
129 most likely to have been introduced during the conversion of the source
130 files to man page format. To report such errors, see https://www.ker‐
131 nel.org/doc/man-pages/reporting_bugs.html .
132IEEE/The Open Group 2017 PTHREAD_RWLOCK_DESTROY(3P)