1*062c5bc4SJason Schmidlapp /*
2*062c5bc4SJason Schmidlapp * pthread_once.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 "pte_osal.h"
44*062c5bc4SJason Schmidlapp #include "pthread.h"
45*062c5bc4SJason Schmidlapp #include "implement.h"
46*062c5bc4SJason Schmidlapp
47*062c5bc4SJason Schmidlapp #define PTE_ONCE_STARTED 1
48*062c5bc4SJason Schmidlapp #define PTE_ONCE_INIT 0
49*062c5bc4SJason Schmidlapp #define PTE_ONCE_DONE 2
50*062c5bc4SJason Schmidlapp
51*062c5bc4SJason Schmidlapp static void
pte_once_init_routine_cleanup(void * arg)52*062c5bc4SJason Schmidlapp pte_once_init_routine_cleanup(void * arg)
53*062c5bc4SJason Schmidlapp {
54*062c5bc4SJason Schmidlapp pthread_once_t * once_control = (pthread_once_t *) arg;
55*062c5bc4SJason Schmidlapp
56*062c5bc4SJason Schmidlapp (void) PTE_ATOMIC_EXCHANGE(&once_control->state,PTE_ONCE_INIT);
57*062c5bc4SJason Schmidlapp
58*062c5bc4SJason Schmidlapp if (PTE_ATOMIC_EXCHANGE_ADD((int*)&once_control->semaphore, 0L)) /* MBR fence */
59*062c5bc4SJason Schmidlapp {
60*062c5bc4SJason Schmidlapp pte_osSemaphorePost((pte_osSemaphoreHandle) once_control->semaphore, 1);
61*062c5bc4SJason Schmidlapp }
62*062c5bc4SJason Schmidlapp }
63*062c5bc4SJason Schmidlapp
64*062c5bc4SJason Schmidlapp int
pthread_once(pthread_once_t * once_control,void (* init_routine)(void))65*062c5bc4SJason Schmidlapp pthread_once (pthread_once_t * once_control, void (*init_routine) (void))
66*062c5bc4SJason Schmidlapp /*
67*062c5bc4SJason Schmidlapp * ------------------------------------------------------
68*062c5bc4SJason Schmidlapp * DOCPUBLIC
69*062c5bc4SJason Schmidlapp * If any thread in a process with a once_control parameter
70*062c5bc4SJason Schmidlapp * makes a call to pthread_once(), the first call will summon
71*062c5bc4SJason Schmidlapp * the init_routine(), but subsequent calls will not. The
72*062c5bc4SJason Schmidlapp * once_control parameter determines whether the associated
73*062c5bc4SJason Schmidlapp * initialization routine has been called. The init_routine()
74*062c5bc4SJason Schmidlapp * is complete upon return of pthread_once().
75*062c5bc4SJason Schmidlapp * This function guarantees that one and only one thread
76*062c5bc4SJason Schmidlapp * executes the initialization routine, init_routine when
77*062c5bc4SJason Schmidlapp * access is controlled by the pthread_once_t control
78*062c5bc4SJason Schmidlapp * key.
79*062c5bc4SJason Schmidlapp *
80*062c5bc4SJason Schmidlapp * pthread_once() is not a cancelation point, but the init_routine
81*062c5bc4SJason Schmidlapp * can be. If it's cancelled then the effect on the once_control is
82*062c5bc4SJason Schmidlapp * as if pthread_once had never been entered.
83*062c5bc4SJason Schmidlapp *
84*062c5bc4SJason Schmidlapp *
85*062c5bc4SJason Schmidlapp * PARAMETERS
86*062c5bc4SJason Schmidlapp * once_control
87*062c5bc4SJason Schmidlapp * pointer to an instance of pthread_once_t
88*062c5bc4SJason Schmidlapp *
89*062c5bc4SJason Schmidlapp * init_routine
90*062c5bc4SJason Schmidlapp * pointer to an initialization routine
91*062c5bc4SJason Schmidlapp *
92*062c5bc4SJason Schmidlapp *
93*062c5bc4SJason Schmidlapp * DESCRIPTION
94*062c5bc4SJason Schmidlapp * See above.
95*062c5bc4SJason Schmidlapp *
96*062c5bc4SJason Schmidlapp * RESULTS
97*062c5bc4SJason Schmidlapp * 0 success,
98*062c5bc4SJason Schmidlapp * EINVAL once_control or init_routine is NULL
99*062c5bc4SJason Schmidlapp *
100*062c5bc4SJason Schmidlapp * ------------------------------------------------------
101*062c5bc4SJason Schmidlapp */
102*062c5bc4SJason Schmidlapp {
103*062c5bc4SJason Schmidlapp int result;
104*062c5bc4SJason Schmidlapp int state;
105*062c5bc4SJason Schmidlapp pte_osSemaphoreHandle sema;
106*062c5bc4SJason Schmidlapp
107*062c5bc4SJason Schmidlapp if (once_control == NULL || init_routine == NULL)
108*062c5bc4SJason Schmidlapp {
109*062c5bc4SJason Schmidlapp result = EINVAL;
110*062c5bc4SJason Schmidlapp goto FAIL0;
111*062c5bc4SJason Schmidlapp }
112*062c5bc4SJason Schmidlapp else
113*062c5bc4SJason Schmidlapp {
114*062c5bc4SJason Schmidlapp result = 0;
115*062c5bc4SJason Schmidlapp }
116*062c5bc4SJason Schmidlapp
117*062c5bc4SJason Schmidlapp while ((state =
118*062c5bc4SJason Schmidlapp PTE_ATOMIC_COMPARE_EXCHANGE(&once_control->state,
119*062c5bc4SJason Schmidlapp PTE_ONCE_STARTED,
120*062c5bc4SJason Schmidlapp PTE_ONCE_INIT))
121*062c5bc4SJason Schmidlapp != PTE_ONCE_DONE)
122*062c5bc4SJason Schmidlapp {
123*062c5bc4SJason Schmidlapp if (PTE_ONCE_INIT == state)
124*062c5bc4SJason Schmidlapp {
125*062c5bc4SJason Schmidlapp
126*062c5bc4SJason Schmidlapp
127*062c5bc4SJason Schmidlapp pthread_cleanup_push(pte_once_init_routine_cleanup, (void *) once_control);
128*062c5bc4SJason Schmidlapp (*init_routine)();
129*062c5bc4SJason Schmidlapp pthread_cleanup_pop(0);
130*062c5bc4SJason Schmidlapp
131*062c5bc4SJason Schmidlapp (void) PTE_ATOMIC_EXCHANGE(&once_control->state,PTE_ONCE_DONE);
132*062c5bc4SJason Schmidlapp
133*062c5bc4SJason Schmidlapp /*
134*062c5bc4SJason Schmidlapp * we didn't create the semaphore.
135*062c5bc4SJason Schmidlapp * it is only there if there is someone waiting.
136*062c5bc4SJason Schmidlapp */
137*062c5bc4SJason Schmidlapp if (PTE_ATOMIC_EXCHANGE_ADD((int*)&once_control->semaphore, 0L)) /* MBR fence */
138*062c5bc4SJason Schmidlapp {
139*062c5bc4SJason Schmidlapp pte_osSemaphorePost((pte_osSemaphoreHandle) once_control->semaphore,once_control->numSemaphoreUsers);
140*062c5bc4SJason Schmidlapp }
141*062c5bc4SJason Schmidlapp }
142*062c5bc4SJason Schmidlapp else
143*062c5bc4SJason Schmidlapp {
144*062c5bc4SJason Schmidlapp PTE_ATOMIC_INCREMENT(&once_control->numSemaphoreUsers);
145*062c5bc4SJason Schmidlapp
146*062c5bc4SJason Schmidlapp if (!PTE_ATOMIC_EXCHANGE_ADD((int*)&once_control->semaphore, 0L)) /* MBR fence */
147*062c5bc4SJason Schmidlapp {
148*062c5bc4SJason Schmidlapp pte_osSemaphoreCreate(0, (pte_osSemaphoreHandle*) &sema);
149*062c5bc4SJason Schmidlapp
150*062c5bc4SJason Schmidlapp if (PTE_ATOMIC_COMPARE_EXCHANGE((int *) &once_control->semaphore,
151*062c5bc4SJason Schmidlapp (int) sema,
152*062c5bc4SJason Schmidlapp 0))
153*062c5bc4SJason Schmidlapp {
154*062c5bc4SJason Schmidlapp pte_osSemaphoreDelete((pte_osSemaphoreHandle)sema);
155*062c5bc4SJason Schmidlapp }
156*062c5bc4SJason Schmidlapp }
157*062c5bc4SJason Schmidlapp
158*062c5bc4SJason Schmidlapp /*
159*062c5bc4SJason Schmidlapp * Check 'state' again in case the initting thread has finished or
160*062c5bc4SJason Schmidlapp * cancelled and left before seeing that there was a semaphore.
161*062c5bc4SJason Schmidlapp */
162*062c5bc4SJason Schmidlapp if (PTE_ATOMIC_EXCHANGE_ADD(&once_control->state, 0L) == PTE_ONCE_STARTED)
163*062c5bc4SJason Schmidlapp {
164*062c5bc4SJason Schmidlapp pte_osSemaphorePend((pte_osSemaphoreHandle) once_control->semaphore,NULL);
165*062c5bc4SJason Schmidlapp }
166*062c5bc4SJason Schmidlapp
167*062c5bc4SJason Schmidlapp if (0 == PTE_ATOMIC_DECREMENT(&once_control->numSemaphoreUsers))
168*062c5bc4SJason Schmidlapp {
169*062c5bc4SJason Schmidlapp /* we were last */
170*062c5bc4SJason Schmidlapp if ((sema =
171*062c5bc4SJason Schmidlapp (pte_osSemaphoreHandle) PTE_ATOMIC_EXCHANGE((int *) &once_control->semaphore,0)))
172*062c5bc4SJason Schmidlapp {
173*062c5bc4SJason Schmidlapp pte_osSemaphoreDelete(sema);
174*062c5bc4SJason Schmidlapp }
175*062c5bc4SJason Schmidlapp }
176*062c5bc4SJason Schmidlapp }
177*062c5bc4SJason Schmidlapp }
178*062c5bc4SJason Schmidlapp
179*062c5bc4SJason Schmidlapp /*
180*062c5bc4SJason Schmidlapp * ------------
181*062c5bc4SJason Schmidlapp * Failure Code
182*062c5bc4SJason Schmidlapp * ------------
183*062c5bc4SJason Schmidlapp */
184*062c5bc4SJason Schmidlapp FAIL0:
185*062c5bc4SJason Schmidlapp return (result);
186*062c5bc4SJason Schmidlapp } /* pthread_once */
187