parallel.c

   1 /*
   2  *  parallel.c - run commands in parallel until you run out of commands
   3  *
   4  *  Copyright © 2008  Tollef Fog Heen <tfheen@err.no>
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  version 2 as published by the Free Software Foundation.
   9  *
  10  *  This program is distributed in the hope that it will be useful,
  11  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  *  General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU General Public License
  16  * along with this program; if not, write to the Free Software
  17  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  18  * USA
  19  *
  20  */
  21
  22 #define _GNU_SOURCE
  23 #include <unistd.h>
  24 #include <string.h>
  25 #include <stdio.h>
  26 #include <sys/time.h>
  27 #include <time.h>
  28 #include <stdlib.h>
  29 #include <errno.h>
  30 #include <sys/select.h>
  31 #include <sys/types.h>
  32 #include <sys/wait.h>
  33 #include <unistd.h>
  34
  35 void usage() {
  36         printf("parallel [OPTIONS] command -- arguments: for each argument, "
  37                "run command with argument\n");
  38         exit(1);
  39 }
  40
  41 void exec_child(char **command, char **arguments, int replace_cb, int nargs) {
  42         char **argv;
  43         int argc = 0;
  44         int i;
  45
  46         while (command[argc] != 0) {
  47                 argc++;
  48         }
  49         if (replace_cb == 0)
  50                 argc++;
  51         argv = calloc(sizeof(char*), argc + nargs);
  52         for (i = 0; i < argc; i++) {
  53                 argv[i] = command[i];
  54                 if (replace_cb && (strcmp(argv[i], "{}") == 0))
  55                         argv[i] = arguments[0];
  56         }
  57         if (replace_cb == 0)
  58                 memcpy(argv + i - 1, arguments, nargs * sizeof(char *));
  59         if (fork() == 0) {
  60                 /* Child */
  61                 execvp(argv[0], argv);
  62                 exit(1);
  63         }
  64         return;
  65 }
  66
  67 int wait_for_child(int options) {
  68         id_t id_ignored = 0;
  69         siginfo_t infop;
  70
  71         infop.si_pid = 0;
  72         waitid(P_ALL, id_ignored, &infop, WEXITED | options);
  73         if (infop.si_pid == 0)
  74                 return -1; /* Nothing to wait for */
  75         if (infop.si_code == CLD_EXITED)
  76                 return infop.si_status;
  77         return 1;
  78 }
  79
  80 int main(int argc, char **argv) {
  81         int maxjobs = -1;
  82         int curjobs = 0;
  83         int maxload = -1;
  84         int argsatonce = 1;
  85         int opt;
  86         char **command = calloc(sizeof(char*), argc);
  87         char **arguments = NULL;
  88         int argidx = 0;
  89         int arglen = 0;
  90         int cidx = 0;
  91         int returncode = 0;
  92         int replace_cb = 0;
  93         char *t;
  94
  95         while ((opt = getopt(argc, argv, "+hij:l:n:")) != -1) {
  96                 switch (opt) {
  97                 case 'h':
  98                         usage();
  99                         break;
 100                 case 'i':
 101                         replace_cb = 1;
 102                         break;
 103                 case 'j':
 104                         errno = 0;
 105                         maxjobs = strtoul(optarg, &t, 0);
 106                         if (errno != 0 || (t-optarg) != strlen(optarg)) {
 107                                 fprintf(stderr, "option '%s' is not a number\n",
 108                                         optarg);
 109                                 exit(2);
 110                         }
 111                         break;
 112                 case 'l':
 113                         errno = 0;
 114                         maxload = strtoul(optarg, &t, 0);
 115                         if (errno != 0 || (t-optarg) != strlen(optarg)) {
 116                                 fprintf(stderr, "option '%s' is not a number\n",
 117                                         optarg);
 118                                 exit(2);
 119                         }
 120                         break;
 121                 case 'n':
 122                         errno = 0;
 123                         argsatonce = strtoul(optarg, &t, 0);
 124                         if (errno != 0 || argsatonce < 1 || (t-optarg) != strlen(optarg)) {
 125                                 fprintf(stderr, "option '%s' is not a positive number\n",
 126                                         optarg);
 127                                 exit(2);
 128                         }
 129                         break;
 130                 default: /* ’?’ */
 131                         usage();
 132                         break;
 133                 }
 134         }
 135
 136         if (replace_cb && argsatonce > 1) {
 137                 fprintf(stderr, "options -i and -n are incomaptible\n");
 138                 exit(2);
 139         }
 140
 141         if (maxjobs < 0) {
 142 #ifdef _SC_NPROCESSORS_ONLN
 143                 maxjobs = sysconf(_SC_NPROCESSORS_ONLN);
 144 #else
 145 #warning Cannot autodetect number of CPUS on this system: _SC_NPROCESSORS_ONLN not defined.
 146                 maxjobs = 1;
 147 #endif
 148         }
 149
 150         while (optind < argc) {
 151                 if (strcmp(argv[optind], "--") == 0) {
 152                         int i;
 153
 154                         optind++;
 155                         arglen = argc - optind;
 156                         arguments = calloc(sizeof(char *), arglen);
 157                         if (! arguments) {
 158                                 exit(1);
 159                         }
 160
 161                         for (i = 0; i < arglen; i++) {
 162                                 arguments[i] = strdup(argv[optind + i]);
 163                         }
 164                         optind += i;
 165                 }
 166                 else {
 167                         command[cidx] = strdup(argv[optind]);
 168                         cidx++;
 169                 }
 170                 optind++;
 171         }
 172
 173         while (argidx < arglen) {
 174                 double load;
 175
 176                 getloadavg(&load, 1);
 177
 178                 if ((maxjobs > 0 && curjobs < maxjobs) ||
 179                     (maxload > 0 && load < maxload)) {
 180                         if (argsatonce > arglen - argidx)
 181                                 argsatonce = arglen - argidx;
 182                         exec_child(command, arguments + argidx,
 183                                    replace_cb, argsatonce);
 184                         argidx += argsatonce;
 185                         curjobs++;
 186                 }
 187
 188                 if (maxjobs > 0 && curjobs == maxjobs) {
 189                         returncode |= wait_for_child(0);
 190                         curjobs--;
 191                 }
 192
 193                 if (maxload > 0 && load > maxload) {
 194                         int r;
 195                         sleep(1); /* XXX We should have a better
 196                                    * heurestic than this */
 197                         r = wait_for_child(WNOHANG);
 198                         if (r > 0) {
 199                                 returncode |= r;
 200                                 curjobs--;
 201                         }
 202                 }
 203         }
 204         while (curjobs > 0) {
 205                 returncode |= wait_for_child(0);
 206                 curjobs--;
 207         }
 208
 209         return returncode;
 210 }
 211