prep

[moreutils.git] / parallel.c

/*
 *  parallel.c - run commands in parallel until you run out of commands
 *
 *  Copyright © 2008  Tollef Fog Heen <tfheen@err.no>
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  version 2 as published by the Free Software Foundation.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 *  General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 *
 */

#define _GNU_SOURCE
#include <unistd.h>
#include <string.h>
#include <stdio.h>
#include <sys/time.h>
#include <time.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/select.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#ifdef __sun
# include <sys/loadavg.h> /* getloadavg() */
#endif

#if !defined(WEXITED)
#define WEXITED 0
#endif

void usage() {
        printf("parallel [OPTIONS] command -- arguments\n\tfor each argument, "
               "run command with argument, in parallel\n");
        printf("parallel [OPTIONS] -- commands\n\trun specified commands in parallel\n");
        exit(1);
}

void exec_child(char **command, char **arguments, int replace_cb, int nargs) {
        if (fork() != 0) {
                return;
        }

        if (command[0]) {
                char **argv;
                int argc = 0;
                int i;
                char *s;

                while (command[argc] != 0) {
                        argc++;
                }
                if (! replace_cb)
                        argc++;
                argv = calloc(sizeof(char*), argc + nargs);

                for (i = 0; i < argc; i++) {
                        while (replace_cb && (s=strstr(command[i], "{}"))) {
                                char *buf=malloc(strlen(command[i]) + strlen(arguments[0]));
                                s[0]='\0';
                                sprintf(buf, "%s%s%s", command[i], arguments[0], s+2);
                                command[i]=buf;
                        }
                        argv[i] = command[i];
                }
                if (! replace_cb)
                        memcpy(argv + i - 1, arguments, nargs * sizeof(char *));
                execvp(argv[0], argv);
                exit(1);
        }
        else {
                int ret=system(arguments[0]);
                if (WIFEXITED(ret)) {
                        exit(WEXITSTATUS(ret));
                }
                else {
                        exit(1);
                }
        }
        return;
}

int wait_for_child(int options) {
        id_t id_ignored = 0;
        siginfo_t infop;

        infop.si_pid = 0;
        waitid(P_ALL, id_ignored, &infop, WEXITED | options);
        if (infop.si_pid == 0) {
                return -1; /* Nothing to wait for */
        }
        if (infop.si_code == CLD_EXITED) {
                return infop.si_status;
        }
        return 1;
}

int main(int argc, char **argv) {
        int maxjobs = -1;
        int curjobs = 0;
        double maxload = -1;
        int argsatonce = 1;
        int opt;
        char **command = calloc(sizeof(char*), argc);
        char **arguments = NULL;
        int argidx = 0;
        int arglen = 0;
        int cidx = 0;
        int returncode = 0;
        int replace_cb = 0;
        char *t;

        while ((argv[optind] && strcmp(argv[optind], "--") != 0) &&
               (opt = getopt(argc, argv, "+hij:l:n:")) != -1) {
                switch (opt) {
                case 'h':
                        usage();
                        break;
                case 'i':
                        replace_cb = 1;
                        break;
                case 'j':
                        errno = 0;
                        maxjobs = strtoul(optarg, &t, 0);
                        if (errno != 0 || (t-optarg) != strlen(optarg)) {
                                fprintf(stderr, "option '%s' is not a number\n",
                                        optarg);
                                exit(2);
                        }
                        break;
                case 'l':
                        errno = 0;
                        maxload = strtod(optarg, &t);
                        if (errno != 0 || (t-optarg) != strlen(optarg)) {
                                fprintf(stderr, "option '%s' is not a number\n",
                                        optarg);
                                exit(2);
                        }
                        break;
                case 'n':
                        errno = 0;
                        argsatonce = strtoul(optarg, &t, 0);
                        if (errno != 0 || argsatonce < 1 || (t-optarg) != strlen(optarg)) {
                                fprintf(stderr, "option '%s' is not a positive number\n",
                                        optarg);
                                exit(2);
                        }
                        break;
                default: /* ’?’ */
                        usage();
                        break;
                }
        }
        
        if (replace_cb && argsatonce > 1) {
                fprintf(stderr, "options -i and -n are incomaptible\n");
                exit(2);
        }

        if (maxjobs < 0) {
#ifdef _SC_NPROCESSORS_ONLN
                maxjobs = sysconf(_SC_NPROCESSORS_ONLN);
#else
#warning Cannot autodetect number of CPUS on this system: _SC_NPROCESSORS_ONLN not defined.
                maxjobs = 1;
#endif
        }
        
        while (optind < argc) {
                if (strcmp(argv[optind], "--") == 0) {
                        int i;

                        optind++;
                        arglen = argc - optind;
                        arguments = calloc(sizeof(char *), arglen);
                        if (! arguments) {
                                exit(1);
                        }

                        for (i = 0; i < arglen; i++) {
                                arguments[i] = strdup(argv[optind + i]);
                        }
                        optind += i;
                }
                else {
                        command[cidx] = strdup(argv[optind]);
                        cidx++;
                }
                optind++;
        }

        if (argsatonce > 1 && ! command[0]) {
                fprintf(stderr, "option -n cannot be used without a command\n");
                exit(2);
        }

        while (argidx < arglen) {
                double load;

                getloadavg(&load, 1);

                if ((maxjobs == 0 || curjobs < maxjobs) &&
                    (maxload < 0 || load < maxload)) {

                        if (argsatonce > arglen - argidx)
                                argsatonce = arglen - argidx;
                        exec_child(command, arguments + argidx,
                                   replace_cb, argsatonce);
                        argidx += argsatonce;
                        curjobs++;
                }
                
                if (maxjobs == 0 || curjobs == maxjobs) {
                        returncode |= wait_for_child(0);
                        curjobs--;
                }

                if (maxload > 0 && load >= maxload) {
                        int r;
                        sleep(1); /* XXX We should have a better
                                   * heurestic than this */
                        r = wait_for_child(WNOHANG);
                        if (r > 0)
                                returncode |= r;
                        if (r != -1)
                                curjobs--;
                }
        }
        while (curjobs > 0) {
                returncode |= wait_for_child(0);
                curjobs--;
        }

        return returncode;
}