mdw@git.distorted.org.uk Git - secnet/blob - hackypar.c

   1 /* Hacky parallelism */
   2 /*
   3  * This file is part of secnet.
   4  * See README for full list of copyright holders.
   5  *
   6  * secnet is free software; you can redistribute it and/or modify it
   7  * under the terms of the GNU General Public License as published by
   8  * the Free Software Foundation; either version 3 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * secnet is distributed in the hope that it will be useful, but
  12  * WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14  * General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * version 3 along with secnet; if not, see
  18  * https://www.gnu.org/licenses/gpl.html.
  19  */
  20
  21 #define _GNU_SOURCE
  22
  23 #include "secnet.h"
  24 #include "util.h"
  25 #include "hackypar.h"
  26
  27 #ifdef HACKY_PARALLEL
  28
  29 #include <stdio.h>
  30 #include <unistd.h>
  31 #include <errno.h>
  32 #include <string.h>
  33 #include <signal.h>
  34 #include <assert.h>
  35 #include <sys/wait.h>
  36
  37 #define HASHSIZE 16
  38 #define CACHESIZE 16
  39
  40 typedef enum { hp_idle, hp_compute, hp_deferring, hp_fail } HPState;
  41
  42 static HPState state;
  43 static pid_t child;
  44
  45 static void checkchild(void)
  46 {
  47     int r, status;
  48
  49     if (!child) return;
  50
  51     r= waitpid(child,&status,WNOHANG); if (!r) return;
  52     if (r==-1) {
  53         Message(M_ERR,"hacky_par: waitpid: %s\n",strerror(errno));
  54         return;
  55     }
  56     child= 0;
  57
  58     if (WIFSIGNALED(status)) {
  59         Message(M_ERR,"hacky_par: signaled! %s\n",strsignal(WTERMSIG(status)));
  60     } else if (!WIFEXITED(status)) {
  61         Message(M_ERR,"hacky_par: unexpected status! %d\n", r);
  62     }
  63 }
  64
  65 static HPState start(void)
  66 {
  67     assert(!child);
  68
  69     child= fork();
  70     if (child == -1) {
  71         Message(M_ERR,"hacky_par: fork failed: %s\n",strerror(errno));
  72         return hp_fail;
  73     }
  74
  75     if (!child) { /* we are the child */
  76         afterfork();
  77         return hp_compute;
  78     }
  79
  80     Message(M_INFO,"hacky_par: started, punting\n");
  81     return hp_deferring;
  82 }
  83
  84 int hacky_par_start_failnow(void)
  85 {
  86     state= hp_idle;
  87     checkchild();
  88     if (child) {
  89         state= hp_deferring;
  90         Message(M_INFO,"hacky_par: busy, punting\n");
  91         return 1;
  92     }
  93     return 0;
  94 }
  95
  96 int hacky_par_mid_failnow(void)
  97 {
  98     state= start();
  99     return state != hp_compute;
 100 }
 101
 102 bool_t (*packy_par_gen)(struct site *st);
 103
 104 void hacky_par_end(int *ok,
 105                    int32_t retries, int32_t timeout,
 106                    bool_t (*send_msg)(struct site *st), struct site *st)
 107 {
 108     int i;
 109
 110     switch (state) {
 111     case hp_deferring:
 112         assert(!*ok);
 113         *ok= 1;
 114         return;
 115     case hp_fail:
 116         assert(!*ok);
 117         return;
 118     case hp_idle:
 119         return;
 120     case hp_compute:
 121         if (!ok) {
 122             Message(M_ERR,"hacky_par: compute failed\n");
 123             _exit(2);
 124         }
 125         Message(M_INFO,"hacky_par: got result, sending\n");
 126         for (i=1; i<retries; i++) {
 127             sleep((timeout + 999)/1000);
 128             if (!send_msg(st)) {
 129                 Message(M_ERR,"hacky_par: retry failed\n");
 130                 _exit(1);
 131             }
 132         }
 133         _exit(0);
 134     }
 135 }
 136
 137 #else /*!HACKY_PARALLEL*/
 138
 139 int hacky_par_start_failnow(void) { return 0; }
 140 int hacky_par_mid_failnow(void) { return 0; }
 141 void hacky_par_end(int *ok,
 142                    int32_t retries, int32_t timeout,
 143                    bool_t (*send_msg)(struct site *st), struct site *st) { }
 144
 145 #endif /*HACKY_PARALLEL...else*/