1 | /* POSIX barrier implementation for LinuxThreads. |
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2 | Copyright (C) 2000 Free Software Foundation, Inc. |
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3 | This file is part of the GNU C Library. |
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4 | Contributed by Kaz Kylheku <kaz@ashi.footprints.net>, 2000. |
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5 | |
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6 | The GNU C Library is free software; you can redistribute it and/or |
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7 | modify it under the terms of the GNU Library General Public License as |
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8 | published by the Free Software Foundation; either version 2 of the |
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9 | License, or (at your option) any later version. |
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10 | |
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11 | The GNU C Library is distributed in the hope that it will be useful, |
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12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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14 | Library General Public License for more details. |
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15 | |
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16 | You should have received a copy of the GNU Library General Public |
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17 | License along with the GNU C Library; see the file COPYING.LIB. If not, |
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18 | write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, |
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19 | Boston, MA 02111-1307, USA. */ |
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20 | |
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21 | #include <errno.h> |
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22 | #include "pthread.h" |
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23 | #include "internals.h" |
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24 | #include "spinlock.h" |
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25 | #include "queue.h" |
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26 | #include "restart.h" |
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27 | |
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28 | int |
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29 | pthread_barrier_wait(pthread_barrier_t *barrier) |
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30 | { |
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31 | pthread_descr self = thread_self(); |
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32 | pthread_descr temp_wake_queue, th; |
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33 | int result = 0; |
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34 | |
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35 | __pthread_lock(&barrier->__ba_lock, self); |
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36 | |
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37 | /* If the required number of threads have achieved rendezvous... */ |
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38 | if (barrier->__ba_present >= barrier->__ba_required - 1) |
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39 | { |
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40 | /* ... then this last caller shall be the serial thread */ |
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41 | result = PTHREAD_BARRIER_SERIAL_THREAD; |
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42 | /* Copy and clear wait queue and reset barrier. */ |
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43 | temp_wake_queue = barrier->__ba_waiting; |
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44 | barrier->__ba_waiting = NULL; |
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45 | barrier->__ba_present = 0; |
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46 | } |
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47 | else |
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48 | { |
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49 | result = 0; |
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50 | barrier->__ba_present++; |
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51 | enqueue(&barrier->__ba_waiting, self); |
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52 | } |
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53 | |
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54 | __pthread_unlock(&barrier->__ba_lock); |
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55 | |
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56 | if (result == 0) |
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57 | { |
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58 | /* Non-serial threads have to suspend */ |
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59 | suspend(self); |
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60 | /* We don't bother dealing with cancellation because the POSIX |
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61 | spec for barriers doesn't mention that pthread_barrier_wait |
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62 | is a cancellation point. */ |
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63 | } |
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64 | else |
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65 | { |
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66 | /* Serial thread wakes up all others. */ |
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67 | while ((th = dequeue(&temp_wake_queue)) != NULL) |
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68 | restart(th); |
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69 | } |
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70 | |
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71 | return result; |
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72 | } |
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73 | |
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74 | int |
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75 | pthread_barrier_init(pthread_barrier_t *barrier, |
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76 | const pthread_barrierattr_t *attr, |
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77 | unsigned int count) |
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78 | { |
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79 | if (count == 0) |
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80 | return EINVAL; |
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81 | |
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82 | __pthread_init_lock(&barrier->__ba_lock); |
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83 | barrier->__ba_required = count; |
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84 | barrier->__ba_present = 0; |
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85 | barrier->__ba_waiting = NULL; |
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86 | return 0; |
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87 | } |
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88 | |
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89 | int |
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90 | pthread_barrier_destroy(pthread_barrier_t *barrier) |
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91 | { |
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92 | if (barrier->__ba_waiting != NULL) return EBUSY; |
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93 | return 0; |
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94 | } |
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95 | |
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96 | int |
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97 | pthread_barrierattr_init(pthread_barrierattr_t *attr) |
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98 | { |
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99 | attr->__pshared = PTHREAD_PROCESS_PRIVATE; |
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100 | return 0; |
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101 | } |
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102 | |
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103 | int |
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104 | pthread_barrierattr_destroy(pthread_barrierattr_t *attr) |
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105 | { |
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106 | return 0; |
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107 | } |
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108 | |
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109 | int |
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110 | __pthread_barrierattr_getpshared(const pthread_barrierattr_t *attr, |
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111 | int *pshared) |
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112 | { |
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113 | *pshared = attr->__pshared; |
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114 | return 0; |
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115 | } |
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116 | |
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117 | int |
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118 | pthread_barrierattr_setpshared(pthread_barrierattr_t *attr, int pshared) |
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119 | { |
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120 | if (pshared != PTHREAD_PROCESS_PRIVATE && pshared != PTHREAD_PROCESS_SHARED) |
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121 | return EINVAL; |
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122 | |
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123 | attr->__pshared = pshared; |
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124 | return 0; |
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125 | } |
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