listen: add process limit option

[plan9front.git] / sys / src / cmd / aux / listen.c

diff --git a/sys/src/cmd/aux/listen.c b/sys/src/cmd/aux/listen.c
index b396c7d06defabd731e21d3ab1c0e782341a3dbd..fd236c6d63c564abd08040eb269a3c5f3fc8afaf 100644 (file)
--- a/sys/src/cmd/aux/listen.c
+++ b/sys/src/cmd/aux/listen.c
@@ -22,7 +22,7 @@ struct Announce
 };
 
 int    readstr(char*, char*, char*, int);
-void   dolisten(char*, char*, int, char*, char*);
+void   dolisten(char*, char*, int, char*, char*, long*);
 void   newcall(int, char*, char*, Service*);
 int    findserv(char*, char*, Service*, char*);
 int    getserv(char*, char*, Service*);
@@ -33,6 +33,8 @@ void  listendir(char*, char*, int);
 
 char   listenlog[] = "listen";
 
+long   procs;
+long   maxprocs;
 int    quiet;
 int    immutable;
 char   *cpu;
@@ -45,7 +47,7 @@ char *namespace;
 void
 usage(void)
 {
-       error("usage: aux/listen [-q] [-n namespace] [-d servdir] [-t trustdir]"
+       error("usage: aux/listen [-q] [-n namespace] [-d servdir] [-t trustdir] [-p maxprocs]"
                " [proto]");
 }
 
@@ -88,6 +90,7 @@ main(int argc, char *argv[])
        quiet = 0;
        immutable = 0;
        argv0 = argv[0];
+       maxprocs = 0;
        cpu = getenv("cputype");
        if(cpu == 0)
                error("can't get cputype");
@@ -105,6 +108,9 @@ main(int argc, char *argv[])
        case 'n':
                namespace = EARGF(usage());
                break;
+       case 'p':
+               maxprocs = atoi(EARGF(usage()));
+               break;
        case 'i':
                /*
                 * fixed configuration, no periodic
@@ -161,9 +167,11 @@ void
 listendir(char *protodir, char *srvdir, int trusted)
 {
        int ctl, pid, start;
-       char dir[40], err[128];
+       char dir[40], err[128], ds[128];
+       long childs;
        Announce *a;
        Waitmsg *wm;
+       int whined;
 
        if (srvdir == 0)
                return;
@@ -201,27 +209,32 @@ listendir(char *protodir, char *srvdir, int trusted)
 
                        sleep((pid*10)%200);
 
+                       /* copy to stack */
+                       strncpy(ds, a->a, sizeof(ds));
+                       whined = a->whined;
+
                        /* a process per service */
-                       switch(pid = rfork(RFFDG|RFPROC)){
+                       switch(pid = rfork(RFFDG|RFPROC|RFMEM)){
                        case -1:
-                               syslog(1, listenlog, "couldn't fork for %s", a->a);
+                               syslog(1, listenlog, "couldn't fork for %s", ds);
                                break;
                        case 0:
+                               childs = 0;
                                for(;;){
-                                       ctl = announce(a->a, dir);
+                                       ctl = announce(ds, dir);
                                        if(ctl < 0) {
                                                errstr(err, sizeof err);
-                                               if (!a->whined)
+                                               if (!whined)
                                                        syslog(1, listenlog,
                                                           "giving up on %s: %r",
-                                                       a->a);
+                                                       ds);
                                                if(strstr(err, "address in use")
                                                    != nil)
                                                        exits("addr-in-use");
                                                else
                                                        exits("ctl");
                                        }
-                                       dolisten(proto, dir, ctl, srvdir, a->a);
+                                       dolisten(proto, dir, ctl, srvdir, ds, &childs);
                                        close(ctl);
                                }
                        default:
@@ -377,14 +390,57 @@ becomenone(void)
 }
 
 void
-dolisten(char *proto, char *dir, int ctl, char *srvdir, char *dialstr)
+dolisten(char *proto, char *dir, int ctl, char *srvdir, char *dialstr, long *pchilds)
 {
        Service s;
-       char ndir[40];
-       int nctl, data;
+       char ndir[40], wbuf[64];
+       int nctl, data, wfd, nowait;
 
        procsetname("%s %s", dir, dialstr);
+
+       wfd = -1;
+       nowait = RFNOWAIT;
+       if(pchilds && maxprocs > 0){
+               snprint(wbuf, sizeof(wbuf), "/proc/%d/wait", getpid());
+               if((wfd = open(wbuf, OREAD)) >= 0)
+                       nowait = 0;
+       }
+
        for(;;){
+               if(!nowait){
+                       static int hit = 0;
+                       Dir *d;
+
+                       /*
+                        *  check for exited subprocesses
+                        */
+                       if(procs >= maxprocs || (*pchilds % 8) == 0)
+                               while(*pchilds > 0){
+                                       d = dirfstat(wfd);
+                                       if(d == nil || d->length == 0){
+                                               free(d);
+                                               break;
+                                       }
+                                       free(d);
+                                       if(read(wfd, wbuf, sizeof(wbuf)) > 0){
+                                               adec(&procs);
+                                               pchilds[0]--;
+                                       }
+                               }
+
+                       if(procs >= maxprocs){
+                               if(!quiet && !hit)
+                                       syslog(1, listenlog, "%s: process limit of %ld reached",
+                                               proto, maxprocs);
+                               if(hit < 8)
+                                       hit++;
+                               sleep(10<<hit);
+                               continue;
+                       } 
+                       if(hit > 0)
+                               hit--;
+               }
+
                /*
                 *  wait for a call (or an error)
                 */
@@ -392,13 +448,15 @@ dolisten(char *proto, char *dir, int ctl, char *srvdir, char *dialstr)
                if(nctl < 0){
                        if(!quiet)
                                syslog(1, listenlog, "listen: %r");
+                       if(wfd >= 0)
+                               close(wfd);
                        return;
                }
 
                /*
                 *  start a subprocess for the connection
                 */
-               switch(rfork(RFFDG|RFPROC|RFNOWAIT|RFENVG|RFNAMEG|RFNOTEG)){
+               switch(rfork(RFFDG|RFPROC|RFMEM|RFENVG|RFNAMEG|RFNOTEG|nowait)){
                case -1:
                        reject(nctl, ndir, "host overloaded");
                        close(nctl);
@@ -423,10 +481,16 @@ dolisten(char *proto, char *dir, int ctl, char *srvdir, char *dialstr)
                        fprint(nctl, "keepalive");
                        close(ctl);
                        close(nctl);
+                       if(wfd >= 0)
+                               close(wfd);
                        newcall(data, proto, ndir, &s);
                        exits(0);
                default:
                        close(nctl);
+                       if(nowait)
+                               break;
+                       ainc(&procs);
+                       pchilds[0]++;
                        break;
                }
        }