Correct bug in SIwait causing excessive CPU use

[ric-plt/lib/rmr.git] / src / rmr / si / src / si95 / siwait.c

diff --git a/src/rmr/si/src/si95/siwait.c b/src/rmr/si/src/si95/siwait.c
index d45efa6..75de117 100644 (file)
--- a/src/rmr/si/src/si95/siwait.c
+++ b/src/rmr/si/src/si95/siwait.c
@@ -49,6 +49,12 @@
 #include "sitransport.h"
 #include       <sys/wait.h>
 
+/*
+       The select timeout is about 300 mu-sec. This is fast enough to add a new
+       outbound connection to the poll list before the other side responds,
+       but slow enough so as not to consume excess CPU when idle.
+*/
+#define SI_SELECT_TIMEOUT 300000
 
 extern int SIwait( struct ginfo_blk *gptr ) {
        int fd;                                                 //  file descriptor for use in this routine 
@@ -68,23 +74,21 @@ extern int SIwait( struct ginfo_blk *gptr ) {
        gptr->sierr = SI_ERR_SHUTD;
 
        if( gptr->flags & GIF_SHUTDOWN ) {                              //  cannot do if we should shutdown 
-               fprintf( stderr, ">>> wait: shutdown on entry????\n" );
                return SI_ERROR;                                                        //  so just get out 
        }
 
        gptr->sierr = SI_ERR_HANDLE;
 
        if( gptr->magicnum != MAGICNUM ) {                              //  if not a valid ginfo block 
-               fprintf( stderr, ">>> wait: bad magic on entry????\n" );
+               fprintf( stderr, "[CRI] SI95: wait: bad global info struct magic number is wrong\n" );
                return SI_ERROR;
        }
 
-       timeout.tv_sec = 0;
-       timeout.tv_usec = 500000;                               // pop every 500ms to ensure we pick up new outbound connections in list
-
-       do {                                                                    // main wait/process loop 
+       do {                                                                    // spin until a callback says to stop (likely never)
+               timeout.tv_sec = 0;                                     // must be reset on every call!
+               timeout.tv_usec = SI_SELECT_TIMEOUT;
 
-               SIbldpoll( gptr );                                      // build the fdlist for poll 
+               SIbldpoll( gptr );                                      // poll list is trashed on each pop; must rebuild
                pstat = select( gptr->fdcount, &gptr->readfds, &gptr->writefds, &gptr->execpfds, &timeout );
 
                if( (pstat < 0 && errno != EINTR)  ) {
@@ -113,7 +117,6 @@ extern int SIwait( struct ginfo_blk *gptr ) {
                                                                status = SInewsession( gptr, tpptr );                   // accept connection
                                                        } else  {                                                                                       //  data received on a regular port (we support just tcp now
                                                                status = RECV( fd, gptr->rbuf, MAX_RBUF, 0 );   //  read data 
-                                                               //fprintf( stderr, ">>>>> wait popped status =%d\n", status );
                                                                if( status > 0  &&  ! (tpptr->flags & TPF_DRAIN) ) {
                                                                        if( (cbptr = gptr->cbtab[SI_CB_CDATA].cbrtn) != NULL ) {
                                                                                status = (*cbptr)( gptr->cbtab[SI_CB_CDATA].cbdata, fd, gptr->rbuf, status );