git.pond.sub.org Git - empserver/blob - src/lib/lwp/sel.c

   1 /*
   2  *  Empire - A multi-player, client/server Internet based war game.
   3  *  Copyright (C) 1986-2000, Dave Pare, Jeff Bailey, Thomas Ruschak,
   4  *                           Ken Stevens, Steve McClure
   5  *
   6  *  This program is free software; you can redistribute it and/or modify
   7  *  it under the terms of the GNU General Public License as published by
   8  *  the Free Software Foundation; either version 2 of the License, or
   9  *  (at your option) any later version.
  10  *
  11  *  This program is distributed in the hope that it will be useful,
  12  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *  GNU General Public License for more details.
  15  *
  16  *  You should have received a copy of the GNU General Public License
  17  *  along with this program; if not, write to the Free Software
  18  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  *
  20  *  ---
  21  *
  22  *  See the "LEGAL", "LICENSE", "CREDITS" and "README" files for all the
  23  *  related information and legal notices. It is expected that any future
  24  *  projects/authors will amend these files as needed.
  25  *
  26  *  ---
  27  *
  28  *  sel.c: arrange to block on read/write file descriptors using lwp
  29  *
  30  *  Known contributors to this file:
  31  *     Dave Pare, 1994
  32  */
  33
  34 #include <stdlib.h>
  35 #include <errno.h>
  36 #include <sys/types.h>
  37 #include <sys/uio.h>
  38 #include <sys/file.h>
  39 #include <sys/time.h>
  40
  41 #ifdef hpux
  42 #include <stdio.h>
  43 #endif
  44
  45 #include "bit.h"
  46 #include "lwp.h"
  47 #include "lwpint.h"
  48 #include "prototypes.h"
  49
  50 #if defined(_EMPTH_LWP)
  51
  52 struct lwpSelect {
  53         int     maxfd;
  54         int     nfds;
  55         int     nfile;
  56         fd_set  readmask;
  57         fd_set  writemask;
  58         struct lwpProc **wait;
  59         struct lwpQueue delayq;
  60         struct lwpProc *proc;
  61 };
  62
  63 struct lwpSelect LwpSelect;
  64
  65 void lwpInitSelect(proc)
  66         struct lwpProc *proc;
  67 {
  68         LwpSelect.maxfd = 0;
  69         LwpSelect.nfds = 0;
  70 #ifdef hpux
  71         LwpSelect.nfile = _NFILE;
  72 #else
  73         LwpSelect.nfile = getdtablesize();
  74 #endif
  75         FD_ZERO(&LwpSelect.readmask);
  76         FD_ZERO(&LwpSelect.writemask);
  77         LwpSelect.wait = (struct lwpProc **)
  78                 calloc(LwpSelect.nfile, sizeof(char *));
  79         LwpSelect.delayq.head = 0;
  80         LwpSelect.delayq.tail = 0;
  81         LwpSelect.proc = proc;
  82 }
  83
  84 void lwpSleepFd(fd, mask)
  85         int     fd;
  86         int     mask;
  87 {
  88         extern struct lwpProc *LwpCurrent;
  89
  90         lwpStatus(LwpCurrent, "sleeping on fd %d", fd);
  91
  92         if (LwpSelect.wait[fd] != 0) {
  93                 lwpStatus(LwpCurrent,
  94                          "multiple sleeps attempted on file descriptor %d", fd);
  95                 return;
  96         }
  97         if (mask & LWP_FD_READ)
  98                 FD_SET(fd, &LwpSelect.readmask);
  99         if (mask & LWP_FD_WRITE)
 100                 FD_SET(fd, &LwpSelect.writemask);
 101
 102         LwpSelect.nfds++;
 103
 104         if (LwpSelect.maxfd == 0 && LwpSelect.delayq.head == 0) {
 105                 /* select process is sleeping until first waiter arrives */
 106                 lwpStatus(LwpCurrent, "going to resched fd %d", fd);
 107                 lwpReady(LwpSelect.proc);
 108         }
 109         lwpStatus(LwpCurrent, "going to wait on fd %d", fd);
 110         if (fd > LwpSelect.maxfd)
 111                 LwpSelect.maxfd = fd;
 112         LwpSelect.wait[fd] = LwpCurrent;
 113         LwpCurrent->fd = fd;
 114         lwpReschedule();
 115 }
 116
 117 void lwpWakeupFd(proc)
 118         struct lwpProc *proc;
 119 {
 120         if (proc->fd < 0)
 121                 return;
 122
 123         lwpStatus(proc, "awakening; was sleeping on fd %d", proc->fd);
 124         FD_CLR(proc->fd, &LwpSelect.readmask);
 125         FD_CLR(proc->fd, &LwpSelect.writemask);
 126         LwpSelect.nfds--;
 127         LwpSelect.wait[proc->fd] = 0;
 128         proc->fd = -1;
 129         lwpReady(proc);
 130 }
 131
 132 void lwpSleepUntil(until)
 133         long    until;
 134 {
 135         extern struct lwpProc *LwpCurrent;
 136
 137         lwpStatus(LwpCurrent, "sleeping for %d sec", until - time(0));
 138         LwpCurrent->runtime = until;
 139         if (LwpSelect.maxfd == 0 && LwpSelect.delayq.head == 0) {
 140                 /* select process is sleeping until first waiter arrives */
 141                 lwpReady(LwpSelect.proc);
 142         }
 143         lwpAddTail(&LwpSelect.delayq, LwpCurrent);
 144         lwpReschedule();
 145 }
 146
 147 /*ARGSUSED*/
 148 void
 149 lwpSelect(argc, argv)
 150         int     argc;
 151         char    **argv;
 152 {
 153         extern struct lwpProc *LwpCurrent;
 154         struct lwpProc *us = LwpCurrent;
 155         fd_set readmask;
 156         fd_set writemask;
 157         int     n;
 158         int     fd;
 159         time_t  now;
 160         time_t  delta;
 161         struct lwpProc *proc;
 162         struct timeval tv;
 163         struct lwpQueue save;
 164
 165         lwpStatus(us, "starting select loop");
 166         FD_ZERO(&readmask);
 167         FD_ZERO(&writemask);
 168         while (1) {
 169                 while (1) {
 170                         if (LwpSelect.nfds)
 171                                 break;
 172                         if (LwpSelect.delayq.head)
 173                                 break;
 174                         /* wait for someone to lwpSleepFd or lwpSleepUntil */
 175                         LwpSelect.maxfd = 0;
 176                         lwpStatus(us, "no fds or sleepers, waiting");
 177                         lwpReschedule();
 178                 }
 179                 tv.tv_sec = 1000000;
 180                 tv.tv_usec = 0;
 181                 if (LwpSelect.delayq.head) {
 182                         time(&now);
 183                         proc = LwpSelect.delayq.head;
 184                         for ( ; proc != 0; proc = proc->next) {
 185                                 delta = proc->runtime - now;
 186                                 if (delta < tv.tv_sec)
 187                                         tv.tv_sec = delta;
 188                         }
 189                         if (tv.tv_sec < 0)
 190                                 tv.tv_sec = 0;
 191                 }
 192                 lwpStatus(us, "selecting; sleep %ld secs", (long)delta);
 193
 194                 bcopy((s_char *)&LwpSelect.readmask, (s_char *)&readmask, sizeof(fd_set));
 195                 bcopy((s_char *)&LwpSelect.writemask, (s_char *)&writemask, sizeof(fd_set));
 196                 n = select(LwpSelect.maxfd + 1, &readmask, &writemask,
 197                            (fd_set *)0, &tv);
 198
 199                 if (n < 0) {
 200                         if (errno == EINTR) {
 201                                 /* go handle the signal */
 202                                 lwpReady(us);
 203                                 lwpReschedule();
 204                                 continue;
 205                         }
 206                         lwpStatus(us,
 207                                   "select failed (bad file descriptor?)");
 208                         exit(-1);
 209                 }
 210
 211                 if (LwpSelect.delayq.head) {
 212                         /* sleeping proecss activity */
 213                         time(&now);
 214                         save.tail = save.head = 0;
 215                         while (NULL != (proc = lwpGetFirst(&LwpSelect.delayq))) {
 216                                 if (now >= proc->runtime) {
 217                                         lwpStatus(proc, "sleep done");
 218                                         lwpReady(proc);
 219                                 } else {
 220                                         lwpAddTail(&save, proc);
 221                                 }
 222                         }
 223                         LwpSelect.delayq = save;
 224                 }
 225                 if (n > 0) {
 226                         /* file descriptor activity */
 227                         for(fd = 0; fd <= LwpSelect.maxfd; fd++) {
 228                                 if (LwpSelect.wait[fd] == 0)
 229                                         continue;
 230                                 if (FD_ISSET(fd, &readmask)) {
 231                                         lwpStatus(LwpSelect.wait[fd],
 232                                                   "input ready");
 233                                         lwpWakeupFd(LwpSelect.wait[fd]);
 234                                         continue;
 235                                 }
 236                                 if (FD_ISSET(fd, &writemask)) {
 237                                         lwpStatus(LwpSelect.wait[fd],
 238                                                   "output ready");
 239                                         lwpWakeupFd(LwpSelect.wait[fd]);
 240                                         continue;
 241                                 }
 242                         }
 243                 }
 244                 lwpStatus(us, "fd dispatch completed");
 245                 lwpReady(LwpCurrent);
 246                 lwpReschedule();
 247         }
 248         /*NOTREACHED*/
 249 }
 250 #endif