avoid scanning loops in comm_select(); from Jeff Mogul patches

diff --git a/src/comm.cc b/src/comm.cc
index 04020b1fb9e25ed393ed2159309661d50b97af39..ca9440e433ce88a8c9d05c207e8b8b1cb100fe41 100644 (file)
--- a/src/comm.cc
+++ b/src/comm.cc
@@ -1,7 +1,7 @@
 
 
 /*
- * $Id: comm.cc,v 1.286 1998/09/14 23:35:24 wessels Exp $
+ * $Id: comm.cc,v 1.287 1998/10/01 22:28:26 wessels Exp $
  *
  * DEBUG: section 5     Socket Functions
  * AUTHOR: Harvest Derived
@@ -626,10 +626,12 @@ commSetSelect(int fd, unsigned int type, PF * handler, void *client_data, time_t
     if (type & COMM_SELECT_READ) {
        F->read_handler = handler;
        F->read_data = client_data;
+       commUpdateReadBits(fd, handler);
     }
     if (type & COMM_SELECT_WRITE) {
        F->write_handler = handler;
        F->write_data = client_data;
+       commUpdateWriteBits(fd, handler);
     }
     if (timeout)
        F->timeout = squid_curtime + timeout;

diff --git a/src/comm_select.cc b/src/comm_select.cc
index 7c4bc148167ba455a7b21f930b914a2685b3410a..6e763c52b97a60064acdb8b6f8be251fb7582d52 100644 (file)
--- a/src/comm_select.cc
+++ b/src/comm_select.cc
@@ -1,7 +1,6 @@
 
-
 /*
- * $Id: comm_select.cc,v 1.12 1998/09/30 04:34:06 wessels Exp $
+ * $Id: comm_select.cc,v 1.13 1998/10/01 22:28:27 wessels Exp $
  *
  * DEBUG: section 5     Socket Functions
  *
@@ -57,6 +56,10 @@ static int comm_check_incoming_select_handlers(int nfds, int *fds);
 #endif
 
 static struct timeval zero_tv;
+static fd_set global_readfds;
+static fd_set global_writefds;
+static int nreadfds;
+static int nwritefds;
 
 /*
  * Automatic tuning for incoming requests:
@@ -523,9 +526,13 @@ comm_select(int msec)
     int fd;
     int i;
     int maxfd;
-    int nfds;
     int num;
     int callicp = 0, callhttp = 0;
+    int maxindex;
+    int k;
+    int j;
+    int *fdsp;
+    int tmask;
     static time_t last_timeout = 0;
     struct timeval poll_time;
     double timeout = current_dtime + (msec / 1000.0);
@@ -536,27 +543,33 @@ comm_select(int msec)
 #if USE_ASYNC_IO
        aioCheckCallbacks();
 #endif
-       FD_ZERO(&readfds);
-       FD_ZERO(&writefds);
        if (commCheckICPIncoming)
            comm_select_icp_incoming();
        if (commCheckHTTPIncoming)
            comm_select_http_incoming();
        callicp = callhttp = 0;
-       nfds = 0;
        maxfd = Biggest_FD + 1;
+       /* copy whole integers. XXX breaks if fd_mask is long */
+       xmemcpy(&readfds, &global_readfds, ((maxfd + 31) / 32) * 4);
+       xmemcpy(&writefds, &global_writefds, ((maxfd + 31) / 32) * 4);
+       /* remove stalled FDs */
+       for (i = 0; i < maxfd; i++) {
+           if (FD_ISSET(i, &readfds))
+               if (commDeferRead(i))
+                   FD_CLR(i, &readfds);
+       }
+#if DEBUG_FDBITS
        for (i = 0; i < maxfd; i++) {
            /* Check each open socket for a handler. */
            if (fd_table[i].read_handler && !commDeferRead(i)) {
-               nfds++;
-               FD_SET(i, &readfds);
+               assert(FD_ISSET(i, &readfds));
            }
            if (fd_table[i].write_handler) {
-               nfds++;
-               FD_SET(i, &writefds);
+               assert(FD_ISSET(i, &writefds));
            }
        }
-       if (nfds == 0) {
+#endif
+       if (nreadfds + nwritefds == 0) {
            assert(shutting_down);
            return COMM_SHUTDOWN;
        }
@@ -591,12 +604,26 @@ comm_select(int msec)
        }
        if (num == 0)
            continue;
-       /* scan each socket but the accept socket. Poll this 
-        * more frequently to minimize losses due to the 5 connect 
-        * limit in SunOS */
-       for (fd = 0; fd < maxfd; fd++) {
-           if (!FD_ISSET(fd, &readfds) && !FD_ISSET(fd, &writefds))
+       /* Scan return fd masks for ready descriptors */
+#ifndef        howmany
+#define howmany(x, y)   (((x)+((y)-1))/(y))
+#endif
+#ifndef        NBBY
+#define        NBBY    8
+#endif
+       maxindex = howmany(maxfd, (sizeof(int) * NBBY));
+       fdsp = (int *) &readfds;
+       for (j = 0; j < maxindex; j++) {
+           if ((tmask = fdsp[j]) == 0)
+               continue;       /* no bits here */
+           for (k = 0; k < (sizeof(int) * NBBY); k++) {
+               if ((tmask & (1 << k)) == 0)
                continue;
+               /* Found a set bit */
+               fd = (j * (sizeof(int) * NBBY)) + k;
+#if DEBUG_FDBITS
+               assert(FD_ISSET(fd, &readfds));
+#endif
            if (fdIsIcp(fd)) {
                callicp = 1;
                continue;
@@ -605,11 +632,11 @@ comm_select(int msec)
                callhttp = 1;
                continue;
            }
-           if (FD_ISSET(fd, &readfds)) {
                debug(5, 6) ("comm_select: FD %d ready for reading\n", fd);
                if (fd_table[fd].read_handler) {
                    hdl = fd_table[fd].read_handler;
                    fd_table[fd].read_handler = NULL;
+                   commUpdateReadBits(fd, NULL);
                    hdl(fd, fd_table[fd].read_data);
                    Counter.select_fds++;
                }
@@ -617,12 +644,36 @@ comm_select(int msec)
                    comm_select_icp_incoming();
                if (commCheckHTTPIncoming)
                    comm_select_http_incoming();
+               tmask = tmask - (1 << k);       /* this bit is done */
+               if (tmask == 0)
+                   break;      /* and no more bits left */
+           }
+       }
+       fdsp = (int *) &writefds;
+       for (j = 0; j < maxindex; j++) {
+           if ((tmask = fdsp[j]) == 0)
+               continue;       /* no bits here */
+           for (k = 0; k < (sizeof(int) * NBBY); k++) {
+               if ((tmask & (1 << k)) == 0)
+                   continue;
+               /* Found a set bit */
+               fd = (j * (sizeof(int) * NBBY)) + k;
+#if DEBUG_FDBITS
+               assert(FD_ISSET(fd, &writefds));
+#endif
+               if (fdIsIcp(fd)) {
+                   callicp = 1;
+                   continue;
+               }
+               if (fdIsHttp(fd)) {
+                   callhttp = 1;
+                   continue;
            }
-           if (FD_ISSET(fd, &writefds)) {
                debug(5, 5) ("comm_select: FD %d ready for writing\n", fd);
                if (fd_table[fd].write_handler) {
                    hdl = fd_table[fd].write_handler;
                    fd_table[fd].write_handler = NULL;
+                   commUpdateWriteBits(fd, NULL);
                    hdl(fd, fd_table[fd].write_data);
                    Counter.select_fds++;
                }
@@ -630,6 +681,9 @@ comm_select(int msec)
                    comm_select_icp_incoming();
                if (commCheckHTTPIncoming)
                    comm_select_http_incoming();
+               tmask = tmask - (1 << k);       /* this bit is done */
+               if (tmask == 0)
+                   break;      /* and no more bits left */
            }
        }
        if (callicp)
@@ -651,6 +705,9 @@ comm_select_init(void)
     cachemgrRegister("comm_incoming",
        "comm_incoming() stats",
        commIncomingStats, 0, 1);
+    FD_ZERO(&global_readfds);
+    FD_ZERO(&global_writefds);
+    nreadfds = nwritefds = 0;
 }
 
 #if !HAVE_POLL
@@ -771,3 +828,27 @@ commIncomingStats(StoreEntry * sentry)
 #endif
     statHistDump(&f->comm_http_incoming, sentry, statHistIntDumper);
 }
+
+void
+commUpdateReadBits(int fd, PF *handler)
+{
+       if (handler && !FD_ISSET(fd, &global_readfds)) {
+           FD_SET(fd, &global_readfds);
+           nreadfds++;
+       } else if (!handler && FD_ISSET(fd, &global_readfds)) {
+           FD_CLR(fd, &global_readfds);
+           nreadfds--;
+       }
+}
+
+void
+commUpdateWriteBits(int fd, PF *handler)
+{
+       if (handler && !FD_ISSET(fd, &global_writefds)) {
+           FD_SET(fd, &global_writefds);
+           nwritefds++;
+       } else if (!handler && FD_ISSET(fd, &global_writefds)) {
+           FD_CLR(fd, &global_writefds);
+           nwritefds--;
+       }
+}

diff --git a/src/fd.cc b/src/fd.cc
index a1088d2ad48a93c2c928353fc06eabbe5aeb7b6f..b0e6fb7e721ded23f1ef2597c824a1368cf012cb 100644 (file)
--- a/src/fd.cc
+++ b/src/fd.cc
@@ -1,6 +1,6 @@
 
 /*
- * $Id: fd.cc,v 1.27 1998/09/09 20:05:49 wessels Exp $
+ * $Id: fd.cc,v 1.28 1998/10/01 22:28:28 wessels Exp $
  *
  * DEBUG: section 51    Filedescriptor Functions
  * AUTHOR: Duane Wessels
@@ -79,6 +79,8 @@ fd_close(int fd)
     Number_FD--;
     if (F->type == FD_FILE)
        open_disk_fd--;
+    commUpdateReadBits(fd, NULL);
+    commUpdateWriteBits(fd, NULL);
     memset(F, '\0', sizeof(fde));
     F->timeout = 0;
 }

diff --git a/src/protos.h b/src/protos.h
index 76d640112248f3efb44f066d0a98854ffef660a9..ac9889ca46d09a0f109411f22b9de95e53008c85 100644 (file)
--- a/src/protos.h
+++ b/src/protos.h
@@ -1,6 +1,6 @@
 
 /*
- * $Id: protos.h,v 1.274 1998/09/30 04:34:08 wessels Exp $
+ * $Id: protos.h,v 1.275 1998/10/01 22:28:29 wessels Exp $
  *
  *
  * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
@@ -153,6 +153,7 @@ extern void commSetDefer(int fd, DEFER * func, void *);
 extern int ignoreErrno(int);
 extern void commCloseAllSockets(void);
 
+
 /*
  * comm_select.c
  */
@@ -162,6 +163,8 @@ extern int comm_poll(int);
 #else
 extern int comm_select(int);
 #endif
+extern void commUpdateReadBits(int, PF *);
+extern void commUpdateWriteBits(int, PF *);
 
 extern void packerToStoreInit(Packer * p, StoreEntry * e);
 extern void packerToMemInit(Packer * p, MemBuf * mb);