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25.\" $FreeBSD: src/share/man/man3/pthread_switch_add_np.3,v 1.5 2007/10/22 10:08:01 ru Exp $
26.\"
27.Dd July 10, 2009
28.Dt PTHREAD_SWITCH_ADD_NP 3
29.Os
30.Sh NAME
31.Nm pthread_switch_add_np ,
32.Nm pthread_switch_delete_np
33.Nd thread context switches debugging primitives
34.Sh LIBRARY
35.Lb libpthread
36.Sh SYNOPSIS
37.In pthread.h
38.In pthread_np.h
39.Ft int
40.Fn pthread_switch_add_np "pthread_switch_routine_t routine"
41.Ft int
42.Fn pthread_switch_delete_np "pthread_switch_routine_t routine"
43.Sh DESCRIPTION
44An application is allowed to monitor the thread context switches inside
45the threading library.
46An application can install a routine that gets called every time a thread
47(explicitly created by an application with the
48.Xr pthread_create 3
49function) gets the context switched.
50The routine is passed the thread IDs of the threads that are
51being switched in and out.
52Installation and removal of these hooks may be done using the
53.Fn pthread_switch_add_np
54and
55.Fn pthread_switch_delete_np
56functions respectively.
57.Sh RETURN VALUES
58If successful,
59these functions return 0.
60Otherwise, an error number is returned to indicate the error.
61.Sh ERRORS
62The
63.Fn pthread_switch_add_np
64may fail if:
65.Bl -tag -width Er
66.It Bq Er EINVAL
67.Dv NULL
68pointer was passed in the
69.Fa routine
70argument.
71.El
72.Pp
73The
74.Fn pthread_switch_delete_np
75may fail if:
76.Bl -tag -width Er
77.It Bq Er EINVAL
78The
79.Fa routine
80argument is different from the argument previously passed to the
81.Fn pthread_switch_add_np
82function.
83.El
84.Sh SEE ALSO
85.Xr pthread_create 3
86.Sh AUTHORS
87This manual page was written by
88.An Alexey Zelkin Aq Mt phantom@FreeBSD.org .
89