1*062c5bc4SJason Schmidlapp /*
2*062c5bc4SJason Schmidlapp * pthread_timechange_handler_np.c
3*062c5bc4SJason Schmidlapp *
4*062c5bc4SJason Schmidlapp * Description:
5*062c5bc4SJason Schmidlapp * This translation unit implements miscellaneous thread functions.
6*062c5bc4SJason Schmidlapp *
7*062c5bc4SJason Schmidlapp * --------------------------------------------------------------------------
8*062c5bc4SJason Schmidlapp *
9*062c5bc4SJason Schmidlapp * Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems
10*062c5bc4SJason Schmidlapp * Copyright(C) 2008 Jason Schmidlapp
11*062c5bc4SJason Schmidlapp *
12*062c5bc4SJason Schmidlapp * Contact Email: jschmidlapp@users.sourceforge.net
13*062c5bc4SJason Schmidlapp *
14*062c5bc4SJason Schmidlapp *
15*062c5bc4SJason Schmidlapp * Based upon Pthreads-win32 - POSIX Threads Library for Win32
16*062c5bc4SJason Schmidlapp * Copyright(C) 1998 John E. Bossom
17*062c5bc4SJason Schmidlapp * Copyright(C) 1999,2005 Pthreads-win32 contributors
18*062c5bc4SJason Schmidlapp *
19*062c5bc4SJason Schmidlapp * Contact Email: rpj@callisto.canberra.edu.au
20*062c5bc4SJason Schmidlapp *
21*062c5bc4SJason Schmidlapp * The original list of contributors to the Pthreads-win32 project
22*062c5bc4SJason Schmidlapp * is contained in the file CONTRIBUTORS.ptw32 included with the
23*062c5bc4SJason Schmidlapp * source code distribution. The list can also be seen at the
24*062c5bc4SJason Schmidlapp * following World Wide Web location:
25*062c5bc4SJason Schmidlapp * http://sources.redhat.com/pthreads-win32/contributors.html
26*062c5bc4SJason Schmidlapp *
27*062c5bc4SJason Schmidlapp * This library is free software; you can redistribute it and/or
28*062c5bc4SJason Schmidlapp * modify it under the terms of the GNU Lesser General Public
29*062c5bc4SJason Schmidlapp * License as published by the Free Software Foundation; either
30*062c5bc4SJason Schmidlapp * version 2 of the License, or (at your option) any later version.
31*062c5bc4SJason Schmidlapp *
32*062c5bc4SJason Schmidlapp * This library is distributed in the hope that it will be useful,
33*062c5bc4SJason Schmidlapp * but WITHOUT ANY WARRANTY; without even the implied warranty of
34*062c5bc4SJason Schmidlapp * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
35*062c5bc4SJason Schmidlapp * Lesser General Public License for more details.
36*062c5bc4SJason Schmidlapp *
37*062c5bc4SJason Schmidlapp * You should have received a copy of the GNU Lesser General Public
38*062c5bc4SJason Schmidlapp * License along with this library in the file COPYING.LIB;
39*062c5bc4SJason Schmidlapp * if not, write to the Free Software Foundation, Inc.,
40*062c5bc4SJason Schmidlapp * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
41*062c5bc4SJason Schmidlapp */
42*062c5bc4SJason Schmidlapp
43*062c5bc4SJason Schmidlapp #include "pthread.h"
44*062c5bc4SJason Schmidlapp #include "implement.h"
45*062c5bc4SJason Schmidlapp
46*062c5bc4SJason Schmidlapp /*
47*062c5bc4SJason Schmidlapp * Notes on handling system time adjustments (especially negative ones).
48*062c5bc4SJason Schmidlapp * ---------------------------------------------------------------------
49*062c5bc4SJason Schmidlapp *
50*062c5bc4SJason Schmidlapp * This solution was suggested by Alexander Terekhov, but any errors
51*062c5bc4SJason Schmidlapp * in the implementation are mine - [Ross Johnson]
52*062c5bc4SJason Schmidlapp *
53*062c5bc4SJason Schmidlapp * 1) The problem: threads doing a timedwait on a CV may expect to timeout
54*062c5bc4SJason Schmidlapp * at a specific absolute time according to a system timer. If the
55*062c5bc4SJason Schmidlapp * system clock is adjusted backwards then those threads sleep longer than
56*062c5bc4SJason Schmidlapp * expected. Also, pthreads-embedded converts absolute times to intervals in
57*062c5bc4SJason Schmidlapp * order to make use of the underlying OS, and so waiting threads may
58*062c5bc4SJason Schmidlapp * awake before their proper abstimes.
59*062c5bc4SJason Schmidlapp *
60*062c5bc4SJason Schmidlapp * 2) We aren't able to distinquish between threads on timed or untimed waits,
61*062c5bc4SJason Schmidlapp * so we wake them all at the time of the adjustment so that they can
62*062c5bc4SJason Schmidlapp * re-evaluate their conditions and re-compute their timeouts.
63*062c5bc4SJason Schmidlapp *
64*062c5bc4SJason Schmidlapp * 3) We rely on correctly written applications for this to work. Specifically,
65*062c5bc4SJason Schmidlapp * they must be able to deal properly with spurious wakeups. That is,
66*062c5bc4SJason Schmidlapp * they must re-test their condition upon wakeup and wait again if
67*062c5bc4SJason Schmidlapp * the condition is not satisfied.
68*062c5bc4SJason Schmidlapp */
69*062c5bc4SJason Schmidlapp
70*062c5bc4SJason Schmidlapp void *
pthread_timechange_handler_np(void * arg)71*062c5bc4SJason Schmidlapp pthread_timechange_handler_np (void *arg)
72*062c5bc4SJason Schmidlapp /*
73*062c5bc4SJason Schmidlapp * ------------------------------------------------------
74*062c5bc4SJason Schmidlapp * DOCPUBLIC
75*062c5bc4SJason Schmidlapp * Broadcasts all CVs to force re-evaluation and
76*062c5bc4SJason Schmidlapp * new timeouts if required.
77*062c5bc4SJason Schmidlapp *
78*062c5bc4SJason Schmidlapp * PARAMETERS
79*062c5bc4SJason Schmidlapp * NONE
80*062c5bc4SJason Schmidlapp *
81*062c5bc4SJason Schmidlapp *
82*062c5bc4SJason Schmidlapp * DESCRIPTION
83*062c5bc4SJason Schmidlapp * Broadcasts all CVs to force re-evaluation and
84*062c5bc4SJason Schmidlapp * new timeouts if required.
85*062c5bc4SJason Schmidlapp *
86*062c5bc4SJason Schmidlapp * This routine may be passed directly to pthread_create()
87*062c5bc4SJason Schmidlapp * as a new thread in order to run asynchronously.
88*062c5bc4SJason Schmidlapp *
89*062c5bc4SJason Schmidlapp *
90*062c5bc4SJason Schmidlapp * RESULTS
91*062c5bc4SJason Schmidlapp * 0 successfully broadcast all CVs
92*062c5bc4SJason Schmidlapp * EAGAIN Not all CVs were broadcast
93*062c5bc4SJason Schmidlapp *
94*062c5bc4SJason Schmidlapp * ------------------------------------------------------
95*062c5bc4SJason Schmidlapp */
96*062c5bc4SJason Schmidlapp {
97*062c5bc4SJason Schmidlapp int result = 0;
98*062c5bc4SJason Schmidlapp pthread_cond_t cv;
99*062c5bc4SJason Schmidlapp
100*062c5bc4SJason Schmidlapp
101*062c5bc4SJason Schmidlapp pte_osMutexLock (pte_cond_list_lock);
102*062c5bc4SJason Schmidlapp
103*062c5bc4SJason Schmidlapp cv = pte_cond_list_head;
104*062c5bc4SJason Schmidlapp
105*062c5bc4SJason Schmidlapp while (cv != NULL && 0 == result)
106*062c5bc4SJason Schmidlapp {
107*062c5bc4SJason Schmidlapp result = pthread_cond_broadcast (&cv);
108*062c5bc4SJason Schmidlapp cv = cv->next;
109*062c5bc4SJason Schmidlapp }
110*062c5bc4SJason Schmidlapp
111*062c5bc4SJason Schmidlapp pte_osMutexUnlock(pte_cond_list_lock);
112*062c5bc4SJason Schmidlapp
113*062c5bc4SJason Schmidlapp return (void *) (result != 0 ? EAGAIN : 0);
114*062c5bc4SJason Schmidlapp }
115