1 | #if 0 |
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2 | INDI |
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3 | Copyright (C) 2003 Elwood C. Downey |
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4 | |
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5 | This library is free software; you can redistribute it and/or |
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6 | modify it under the terms of the GNU Lesser General Public |
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7 | License as published by the Free Software Foundation; either |
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8 | version 2.1 of the License, or (at your option) any later version. |
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9 | |
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10 | This library is distributed in the hope that it will be useful, |
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11 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 | Lesser General Public License for more details. |
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14 | |
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15 | You should have received a copy of the GNU Lesser General Public |
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16 | License along with this library; if not, write to the Free Software |
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17 | Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
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18 | |
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19 | #endif |
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20 | |
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21 | /* suite of functions to implement an event driven program. |
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22 | * |
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23 | * callbacks may be registered that are triggered when a file descriptor |
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24 | * will not block when read; |
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25 | * |
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26 | * timers may be registered that will run no sooner than a specified delay from |
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27 | * the moment they were registered; |
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28 | * |
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29 | * work procedures may be registered that are called when there is nothing |
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30 | * else to do; |
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31 | * |
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32 | #define MAIN_TEST for a stand-alone test program. |
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33 | */ |
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34 | |
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35 | #include <stdio.h> |
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36 | #include <stdlib.h> |
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37 | #include <math.h> |
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38 | #include <string.h> |
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39 | #include <time.h> |
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40 | #include <sys/types.h> |
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41 | #include <sys/time.h> |
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42 | #include <unistd.h> |
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43 | |
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44 | #include "eventloop.h" |
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45 | |
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46 | /* info about one registered callback. |
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47 | * the malloced array cback is never shrunk, entries are reused. new id's are |
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48 | * the index of first unused slot in array (and thus reused like unix' open(2)). |
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49 | */ |
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50 | typedef struct { |
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51 | int in_use; /* flag to mark this record is active */ |
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52 | int fd; /* fd descriptor to watch for read */ |
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53 | void *ud; /* user's data handle */ |
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54 | CBF *fp; /* callback function */ |
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55 | } CB; |
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56 | static CB *cback; /* malloced list of callbacks */ |
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57 | static int ncback; /* n entries in cback[] */ |
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58 | static int ncbinuse; /* n entries in cback[] marked in_use */ |
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59 | static int lastcb; /* cback index of last cb called */ |
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60 | |
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61 | /* info about one registered timer function. |
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62 | * the entries are kept sorted by decreasing time from epoch, ie, |
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63 | * the next entry to fire is at the end of the array. |
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64 | */ |
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65 | typedef struct { |
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66 | double tgo; /* trigger time, ms from epoch */ |
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67 | void *ud; /* user's data handle */ |
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68 | TCF *fp; /* timer function */ |
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69 | int tid; /* unique id for this timer */ |
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70 | } TF; |
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71 | static TF *timef; /* malloced list of timer functions */ |
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72 | static int ntimef; /* n entries in ntimef[] */ |
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73 | static int tid; /* source of unique timer ids */ |
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74 | #define EPOCHDT(tp) /* ms from epoch to timeval *tp */ \ |
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75 | (((tp)->tv_usec)/1000.0 + ((tp)->tv_sec)*1000.0) |
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76 | |
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77 | /* info about one registered work procedure. |
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78 | * the malloced array wproc is never shrunk, entries are reused. new id's are |
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79 | * the index of first unused slot in array (and thus reused like unix' open(2)). |
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80 | */ |
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81 | typedef struct { |
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82 | int in_use; /* flag to mark this record is active */ |
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83 | void *ud; /* user's data handle */ |
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84 | WPF *fp; /* work proc function function */ |
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85 | } WP; |
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86 | static WP *wproc; /* malloced list of work procedures */ |
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87 | static int nwproc; /* n entries in wproc[] */ |
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88 | static int nwpinuse; /* n entries in wproc[] marked in-use */ |
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89 | static int lastwp; /* wproc index of last workproc called*/ |
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90 | |
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91 | static void runWorkProc (void); |
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92 | static void callCallback(fd_set *rfdp); |
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93 | static void checkTimer(); |
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94 | static void oneLoop(void); |
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95 | static void deferTO (void *p); |
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96 | |
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97 | /* inf loop to dispatch callbacks, work procs and timers as necessary. |
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98 | * never returns. |
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99 | */ |
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100 | void |
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101 | eventLoop() |
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102 | { |
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103 | /* run loop forever */ |
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104 | while (1) |
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105 | oneLoop(); |
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106 | } |
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107 | |
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108 | /* allow other timers/callbacks/workprocs to run until time out in maxms |
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109 | * or *flagp becomes non-0. wait forever if maxms is 0. |
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110 | * return 0 if flag did flip, else -1 if never changed and we timed out. |
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111 | * the expected usage for this is for the caller to arrange for a T/C/W to set |
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112 | * a flag, then give caller an in-line way to wait for the flag to change. |
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113 | */ |
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114 | int |
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115 | deferLoop (int maxms, int *flagp) |
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116 | { |
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117 | int toflag = 0; |
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118 | int totid = maxms ? addTimer (maxms, deferTO, &toflag) : 0; |
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119 | |
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120 | while (!*flagp) { |
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121 | oneLoop(); |
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122 | if (toflag) |
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123 | return (-1); /* totid already dead */ |
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124 | } |
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125 | |
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126 | if (totid) |
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127 | rmTimer (totid); |
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128 | return (0); |
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129 | } |
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130 | |
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131 | /* allow other timers/callbacks/workprocs to run until time out in maxms |
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132 | * or *flagp becomes 0. wait forever if maxms is 0. |
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133 | * return 0 if flag did flip, else -1 if never changed and we timed out. |
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134 | * the expected usage for this is for the caller to arrange for a T/C/W to set |
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135 | * a flag, then give caller an in-line way to wait for the flag to change. |
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136 | */ |
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137 | int |
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138 | deferLoop0 (int maxms, int *flagp) |
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139 | { |
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140 | int toflag = 0; |
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141 | int totid = maxms ? addTimer (maxms, deferTO, &toflag) : 0; |
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142 | |
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143 | while (*flagp) { |
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144 | oneLoop(); |
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145 | if (toflag) |
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146 | return (-1); /* totid already dead */ |
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147 | } |
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148 | |
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149 | if (totid) |
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150 | rmTimer (totid); |
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151 | return (0); |
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152 | } |
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153 | |
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154 | /* register a new callback, fp, to be called with ud as arg when fd is ready. |
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155 | * return a unique callback id for use with rmCallback(). |
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156 | */ |
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157 | int |
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158 | addCallback (int fd, CBF *fp, void *ud) |
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159 | { |
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160 | CB *cp; |
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161 | |
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162 | /* reuse first unused slot or grow */ |
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163 | for (cp = cback; cp < &cback[ncback]; cp++) |
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164 | if (!cp->in_use) |
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165 | break; |
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166 | if (cp == &cback[ncback]) { |
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167 | cback = cback ? (CB *) realloc (cback, (ncback+1)*sizeof(CB)) |
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168 | : (CB *) malloc (sizeof(CB)); |
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169 | cp = &cback[ncback++]; |
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170 | } |
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171 | |
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172 | /* init new entry */ |
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173 | cp->in_use = 1; |
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174 | cp->fp = fp; |
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175 | cp->ud = ud; |
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176 | cp->fd = fd; |
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177 | ncbinuse++; |
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178 | |
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179 | /* id is index into array */ |
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180 | return (cp - cback); |
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181 | } |
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182 | |
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183 | /* remove the callback with the given id, as returned from addCallback(). |
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184 | * silently ignore if id not valid. |
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185 | */ |
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186 | void |
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187 | rmCallback (int cid) |
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188 | { |
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189 | CB *cp; |
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190 | |
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191 | /* validate id */ |
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192 | if (cid < 0 || cid >= ncback) |
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193 | return; |
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194 | cp = &cback[cid]; |
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195 | if (!cp->in_use) |
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196 | return; |
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197 | |
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198 | /* mark for reuse */ |
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199 | cp->in_use = 0; |
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200 | ncbinuse--; |
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201 | } |
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202 | |
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203 | /* register a new timer function, fp, to be called with ud as arg after ms |
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204 | * milliseconds. add to list in order of decreasing time from epoch, ie, |
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205 | * last entry runs soonest. return id for use with rmTimer(). |
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206 | */ |
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207 | int |
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208 | addTimer (int ms, TCF *fp, void *ud) |
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209 | { |
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210 | struct timeval t; |
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211 | TF *tp; |
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212 | |
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213 | /* get time now */ |
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214 | gettimeofday (&t, NULL); |
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215 | |
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216 | /* add one entry */ |
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217 | timef = timef ? (TF *) realloc (timef, (ntimef+1)*sizeof(TF)) |
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218 | : (TF *) malloc (sizeof(TF)); |
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219 | tp = &timef[ntimef++]; |
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220 | |
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221 | /* init new entry */ |
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222 | tp->ud = ud; |
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223 | tp->fp = fp; |
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224 | tp->tgo = EPOCHDT(&t) + ms; |
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225 | |
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226 | /* insert maintaining sort */ |
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227 | for ( ; tp > timef && tp[0].tgo > tp[-1].tgo; tp--) { |
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228 | TF tmptf = tp[-1]; |
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229 | tp[-1] = tp[0]; |
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230 | tp[0] = tmptf; |
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231 | } |
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232 | |
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233 | /* store and return new unique id */ |
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234 | return (tp->tid = ++tid); |
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235 | } |
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236 | |
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237 | /* remove the timer with the given id, as returned from addTimer(). |
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238 | * silently ignore if id not found. |
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239 | */ |
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240 | void |
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241 | rmTimer (int timer_id) |
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242 | { |
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243 | TF *tp; |
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244 | |
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245 | /* find it */ |
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246 | for (tp = timef; tp < &timef[ntimef]; tp++) |
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247 | if (tp->tid == timer_id) |
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248 | break; |
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249 | if (tp == &timef[ntimef]) |
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250 | return; |
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251 | |
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252 | /* bubble it out */ |
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253 | for (++tp; tp < &timef[ntimef]; tp++) |
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254 | tp[-1] = tp[0]; |
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255 | |
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256 | /* shrink list */ |
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257 | timef = (TF *) realloc (timef, (--ntimef)*sizeof(TF)); |
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258 | } |
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259 | |
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260 | /* add a new work procedure, fp, to be called with ud when nothing else to do. |
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261 | * return unique id for use with rmWorkProc(). |
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262 | */ |
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263 | int |
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264 | addWorkProc (WPF *fp, void *ud) |
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265 | { |
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266 | WP *wp; |
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267 | |
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268 | /* reuse first unused slot or grow */ |
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269 | for (wp = wproc; wp < &wproc[nwproc]; wp++) |
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270 | if (!wp->in_use) |
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271 | break; |
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272 | if (wp == &wproc[nwproc]) { |
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273 | wproc = wproc ? (WP *) realloc (wproc, (nwproc+1)*sizeof(WP)) |
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274 | : (WP *) malloc (sizeof(WP)); |
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275 | wp = &wproc[nwproc++]; |
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276 | } |
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277 | |
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278 | /* init new entry */ |
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279 | wp->in_use = 1; |
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280 | wp->fp = fp; |
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281 | wp->ud = ud; |
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282 | nwpinuse++; |
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283 | |
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284 | /* id is index into array */ |
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285 | return (wp - wproc); |
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286 | } |
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287 | |
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288 | |
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289 | /* remove the work proc with the given id, as returned from addWorkProc(). |
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290 | * silently ignore if id not found. |
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291 | */ |
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292 | void |
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293 | rmWorkProc (int wid) |
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294 | { |
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295 | WP *wp; |
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296 | |
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297 | /* validate id */ |
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298 | if (wid < 0 || wid >= nwproc) |
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299 | return; |
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300 | wp = &wproc[wid]; |
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301 | if (!wp->in_use) |
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302 | return; |
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303 | |
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304 | /* mark for reuse */ |
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305 | wp->in_use = 0; |
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306 | nwpinuse--; |
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307 | } |
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308 | |
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309 | /* run next work procedure */ |
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310 | static void |
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311 | runWorkProc () |
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312 | { |
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313 | WP *wp; |
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314 | |
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315 | /* skip if list is empty */ |
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316 | if (!nwpinuse) |
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317 | return; |
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318 | |
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319 | /* find next */ |
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320 | do { |
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321 | lastwp = (lastwp+1) % nwproc; |
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322 | wp = &wproc[lastwp]; |
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323 | } while (!wp->in_use); |
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324 | |
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325 | /* run */ |
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326 | (*wp->fp) (wp->ud); |
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327 | } |
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328 | |
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329 | /* run next callback whose fd is listed as ready to go in rfdp */ |
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330 | static void |
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331 | callCallback(fd_set *rfdp) |
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332 | { |
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333 | CB *cp; |
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334 | |
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335 | /* skip if list is empty */ |
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336 | if (!ncbinuse) |
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337 | return; |
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338 | |
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339 | /* find next */ |
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340 | do { |
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341 | lastcb = (lastcb+1) % ncback; |
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342 | cp = &cback[lastcb]; |
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343 | } while (!cp->in_use || !FD_ISSET (cp->fd, rfdp)); |
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344 | |
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345 | /* run */ |
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346 | (*cp->fp) (cp->fd, cp->ud); |
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347 | } |
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348 | |
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349 | /* run the next timer callback whose time has come, if any. all we have to do |
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350 | * is is check the last entry in timef[] because it is sorted in decreasing |
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351 | * order of time from epoch to run, ie, last entry runs soonest. |
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352 | */ |
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353 | static void |
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354 | checkTimer() |
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355 | { |
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356 | struct timeval now; |
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357 | double tgonow; |
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358 | TF *tp; |
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359 | |
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360 | /* skip if list is empty */ |
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361 | if (!ntimef) |
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362 | return; |
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363 | |
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364 | gettimeofday (&now, NULL); |
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365 | tgonow = EPOCHDT (&now); |
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366 | tp = &timef[ntimef-1]; |
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367 | if (tp->tgo <= tgonow) { |
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368 | ntimef--; /* pop then call */ |
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369 | (*tp->fp) (tp->ud); |
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370 | } |
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371 | } |
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372 | |
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373 | /* check fd's from each active callback. |
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374 | * if any ready, call their callbacks else call each registered work procedure. |
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375 | */ |
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376 | static void |
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377 | oneLoop() |
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378 | { |
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379 | struct timeval tv, *tvp; |
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380 | fd_set rfd; |
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381 | CB *cp; |
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382 | int maxfd, ns; |
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383 | |
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384 | /* build list of callback file descriptors to check */ |
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385 | FD_ZERO (&rfd); |
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386 | maxfd = -1; |
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387 | for (cp = cback; cp < &cback[ncback]; cp++) { |
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388 | if (cp->in_use) { |
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389 | FD_SET (cp->fd, &rfd); |
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390 | if (cp->fd > maxfd) |
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391 | maxfd = cp->fd; |
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392 | } |
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393 | } |
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394 | |
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395 | /* determine timeout: |
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396 | * if there are work procs |
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397 | * set delay = 0 |
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398 | * else if there is at least one timer func |
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399 | * set delay = time until soonest timer func expires |
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400 | * else |
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401 | * set delay = forever |
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402 | */ |
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403 | if (nwpinuse > 0) { |
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404 | tvp = &tv; |
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405 | tvp->tv_sec = tvp->tv_usec = 0; |
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406 | } else if (ntimef > 0) { |
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407 | struct timeval now; |
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408 | double late; |
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409 | gettimeofday (&now, NULL); |
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410 | late = timef[ntimef-1].tgo - EPOCHDT (&now); /* ms late */ |
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411 | if (late < 0) |
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412 | late = 0; |
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413 | late /= 1000.0; /* secs late */ |
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414 | tvp = &tv; |
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415 | tvp->tv_sec = (long)floor(late); |
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416 | tvp->tv_usec = (long)floor((late - tvp->tv_sec)*1000000.0); |
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417 | } else |
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418 | tvp = NULL; |
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419 | |
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420 | /* check file descriptors, timeout depending on pending work */ |
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421 | ns = select (maxfd+1, &rfd, NULL, NULL, tvp); |
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422 | if (ns < 0) { |
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423 | perror ("select"); |
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424 | exit(1); |
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425 | } |
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426 | |
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427 | /* dispatch */ |
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428 | checkTimer(); |
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429 | if (ns == 0) |
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430 | runWorkProc(); |
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431 | else |
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432 | callCallback(&rfd); |
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433 | } |
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434 | |
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435 | /* timer callback used to implement deferLoop(). |
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436 | * arg is pointer to int which we set to 1 |
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437 | */ |
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438 | static void |
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439 | deferTO (void *p) |
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440 | { |
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441 | *(int*)p = 1; |
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442 | } |
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443 | |
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444 | #if defined(MAIN_TEST) |
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445 | /* make a small stand-alone test program. |
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446 | */ |
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447 | |
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448 | #include <unistd.h> |
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449 | #include <sys/time.h> |
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450 | |
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451 | int mycid; |
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452 | int mywid; |
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453 | int mytid; |
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454 | |
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455 | int user_a; |
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456 | int user_b; |
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457 | int counter; |
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458 | |
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459 | void |
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460 | wp (void *ud) |
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461 | { |
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462 | struct timeval tv; |
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463 | |
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464 | gettimeofday (&tv, NULL); |
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465 | printf ("workproc @ %ld.%03ld %d %d\n", |
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466 | (long)tv.tv_sec, (long)tv.tv_usec/1000, counter, ++(*(int*)ud)); |
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467 | } |
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468 | |
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469 | void |
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470 | to (void *ud) |
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471 | { |
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472 | printf ("timeout %d\n", (int)ud); |
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473 | } |
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474 | |
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475 | void |
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476 | stdinCB (int fd, void *ud) |
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477 | { |
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478 | char c; |
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479 | |
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480 | if (read (fd, &c, 1) != 1) { |
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481 | perror ("read"); |
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482 | exit(1); |
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483 | } |
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484 | |
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485 | switch (c) { |
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486 | case '+': counter++; break; |
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487 | case '-': counter--; break; |
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488 | |
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489 | case 'W': mywid = addWorkProc (wp, &user_b); break; |
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490 | case 'w': rmWorkProc (mywid); break; |
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491 | |
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492 | case 'c': rmCallback (mycid); break; |
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493 | |
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494 | case 't': rmTimer (mytid); break; |
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495 | case '1': mytid = addTimer (1000, to, (void *)1); break; |
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496 | case '2': mytid = addTimer (2000, to, (void *)2); break; |
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497 | case '3': mytid = addTimer (3000, to, (void *)3); break; |
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498 | case '4': mytid = addTimer (4000, to, (void *)4); break; |
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499 | case '5': mytid = addTimer (5000, to, (void *)5); break; |
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500 | default: return; /* silently absorb other chars like \n */ |
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501 | } |
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502 | |
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503 | printf ("callback: %d\n", ++(*(int*)ud)); |
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504 | } |
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505 | |
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506 | int |
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507 | main (int ac, char *av[]) |
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508 | { |
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509 | (void) addCallback (0, stdinCB, &user_a); |
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510 | eventLoop(); |
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511 | exit(0); |
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512 | } |
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513 | |
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514 | #endif |
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515 | |
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