1PTHREAD_SETCANCELSTATE(3P) POSIX Programmer's ManualPTHREAD_SETCANCELSTATE(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
13 pthread_setcancelstate, pthread_setcanceltype, pthread_testcancel — set
14 cancelability state
15
17 #include <pthread.h>
18 int pthread_setcancelstate(int state, int *oldstate);
20 int pthread_setcanceltype(int type, int *oldtype);
21 void pthread_testcancel(void);
22
24 The pthread_setcancelstate() function shall atomically both set the
25 calling thread's cancelability state to the indicated state and return
26 the previous cancelability state at the location referenced by old‐
27 state. Legal values for state are PTHREAD_CANCEL_ENABLE and
28 PTHREAD_CANCEL_DISABLE.
29 The pthread_setcanceltype() function shall atomically both set the
31 calling thread's cancelability type to the indicated type and return
32 the previous cancelability type at the location referenced by oldtype.
33 Legal values for type are PTHREAD_CANCEL_DEFERRED and PTHREAD_CAN‐
34 CEL_ASYNCHRONOUS.
35 The cancelability state and type of any newly created threads, includ‐
37 ing the thread in which main() was first invoked, shall be PTHREAD_CAN‐
38 CEL_ENABLE and PTHREAD_CANCEL_DEFERRED respectively.
39 The pthread_testcancel() function shall create a cancellation point in
41 the calling thread. The pthread_testcancel() function shall have no
42 effect if cancelability is disabled.
43
45 If successful, the pthread_setcancelstate() and pthread_setcanceltype()
46 functions shall return zero; otherwise, an error number shall be
47 returned to indicate the error.
48
50 The pthread_setcancelstate() function may fail if:
51 EINVAL The specified state is not PTHREAD_CANCEL_ENABLE or PTHREAD_CAN‐
53 CEL_DISABLE.
54 The pthread_setcanceltype() function may fail if:
56 EINVAL The specified type is not PTHREAD_CANCEL_DEFERRED or
58 PTHREAD_CANCEL_ASYNCHRONOUS.
59 These functions shall not return an error code of [EINTR].
61 The following sections are informative.
63
65 None.
66
68 None.
69
71 The pthread_setcancelstate() and pthread_setcanceltype() functions con‐
72 trol the points at which a thread may be asynchronously canceled. For
73 cancellation control to be usable in modular fashion, some rules need
74 to be followed.
75 An object can be considered to be a generalization of a procedure. It
77 is a set of procedures and global variables written as a unit and
78 called by clients not known by the object. Objects may depend on other
79 objects.
80 First, cancelability should only be disabled on entry to an object,
82 never explicitly enabled. On exit from an object, the cancelability
83 state should always be restored to its value on entry to the object.
84 This follows from a modularity argument: if the client of an object (or
86 the client of an object that uses that object) has disabled cancelabil‐
87 ity, it is because the client does not want to be concerned about
88 cleaning up if the thread is canceled while executing some sequence of
89 actions. If an object is called in such a state and it enables cancela‐
90 bility and a cancellation request is pending for that thread, then the
91 thread is canceled, contrary to the wish of the client that disabled.
92 Second, the cancelability type may be explicitly set to either deferred
94 or asynchronous upon entry to an object. But as with the cancelability
95 state, on exit from an object the cancelability type should always be
96 restored to its value on entry to the object.
97 Finally, only functions that are cancel-safe may be called from a
99 thread that is asynchronously cancelable.
100
102 None.
103
105 pthread_cancel()
106 The Base Definitions volume of POSIX.1‐2008, <pthread.h>
108
110 Portions of this text are reprinted and reproduced in electronic form
111 from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
112 -- Portable Operating System Interface (POSIX), The Open Group Base
113 Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
114 cal and Electronics Engineers, Inc and The Open Group. (This is
115 POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the
116 event of any discrepancy between this version and the original IEEE and
117 The Open Group Standard, the original IEEE and The Open Group Standard
118 is the referee document. The original Standard can be obtained online
119 at http://www.unix.org/online.html .
120 Any typographical or formatting errors that appear in this page are
122 most likely to have been introduced during the conversion of the source
123 files to man page format. To report such errors, see https://www.ker‐
124 nel.org/doc/man-pages/reporting_bugs.html .
125IEEE/The Open Group 2013 PTHREAD_SETCANCELSTATE(3P)