ModDevPoll.cc cleanup as discussed in squid-cache#1551

Also partially addresses https://bugs.squid-cache.org/show_bug.cgi?id=5314
by replacing the devpoll_state array (that was sized to SQUID_MAXFD) with
use of the epoll_state member of the fde structure, to match ModEpoll, but
doesn't solve the problem of devpoll_fd not being opened in that path.

src/comm/ModDevPoll.cc

@@ -17,10 +17,8 @@
  *
  * Ported by Peter Payne from Squid 2.7.STABLE9 comm_devpoll.c
  * on August 11, 2010 at 3pm (GMT+0100 Europe/London).
- *
- * Last modified 2010-10-08
  */
-
+re
 /*
  * There are several poll types in Squid, ALL of which are compiled and linked
  * in. Thus conditional compile-time flags are used to prevent the different
@@ -48,18 +46,15 @@
 
 #define DEBUG_DEVPOLL 0
 
-#define DEVPOLL_UPDATESIZE  Squid_MaxFD
-#define DEVPOLL_QUERYSIZE   Squid_MaxFD
+// Maximum number of fd's to buffer requests to change polling state
+#define DEVPOLL_UPDATESIZE  256
+// Maximum number of fd's to receive polling updates for in a single syscall
+#define DEVPOLL_QUERYSIZE   1024
 
 /* TYPEDEFS */
 typedef short pollfd_events_t; /* type of pollfd.events from sys/poll.h */
 
 /* STRUCTURES */
-/** \brief Current state */
-struct _devpoll_state {
-    pollfd_events_t state; /**< current known state of file handle */
-};
-
 /** \brief Update list
  *
  * This structure contains an array of settings to send to the /dev/poll
@@ -78,7 +73,6 @@ static struct {
 static int devpoll_fd; /**< handle to /dev/poll device */
 static int max_poll_time = 1000; /**< maximum milliseconds to spend in poll */
 
-static struct _devpoll_state *devpoll_state; /**< array of socket states */
 static struct dvpoll do_poll; /**< data struct for storing poll results */
 static int dpoll_nfds; /**< maximum number of poll results */
 
@@ -127,7 +121,7 @@ comm_flush_updates(void)
  * @param events events to register (usually POLLIN, POLLOUT, or POLLREMOVE)
  */
 static void
-comm_update_fd(int fd, int events)
+comm_update_fd(int fd, pollfd_events_t events)
 {
     debugs(
         5,
@@ -175,22 +169,24 @@ void
 Comm::SelectLoopInit(void)
 {
     /* allocate memory first before attempting to open poll device */
-    /* This tracks the FD devpoll offset+state */
-    devpoll_state = (struct _devpoll_state *)xcalloc(
-                        SQUID_MAXFD, sizeof(struct _devpoll_state)
-                    );
-
-    /* And this is the stuff we use to read events */
+    /* This is the stuff we use to read events.  If it's larger than
+       the current RLIMIT_NOFILE, the Solaris kernel returns EINVAL. */
+    dpoll_nfds = DEVPOLL_QUERYSIZE;
+    if (dpoll_nfds > Squid_MaxFD)
+        dpoll_nfds = Squid_MaxFD;
     do_poll.dp_fds = (struct pollfd *)xcalloc(
-                         DEVPOLL_QUERYSIZE, sizeof(struct pollfd)
+                         dpoll_nfds, sizeof(struct pollfd)
                      );
-    dpoll_nfds = DEVPOLL_QUERYSIZE;
 
-    devpoll_update.pfds = (struct pollfd *)xcalloc(
-                              DEVPOLL_UPDATESIZE, sizeof(struct pollfd)
-                          );
+    /* This is the stuff we use to write requests to change tracking state.
+       It's also limited to the current RLIMIT_NOFILE by the Solaris kernel. */
     devpoll_update.cur = -1;
     devpoll_update.size = DEVPOLL_UPDATESIZE;
+    if (devpoll_update.size > Squid_MaxFD)
+        devpoll_update.size = Squid_MaxFD;
+    devpoll_update.pfds = (struct pollfd *)xcalloc(
+                              devpoll_update.size, sizeof(struct pollfd)
+                          );
 
     /* attempt to open /dev/poll device */
     devpoll_fd = open("/dev/poll", O_RDWR);
@@ -231,11 +227,11 @@ Comm::SetSelect(int fd, unsigned int type, PF * handler, void *client_data, time
     if (!F->flags.open) {
         /* remove from poll set */
         comm_update_fd( fd, POLLREMOVE );
-        devpoll_state[fd].state = 0;
+        F->epoll_state = 0;
         return;
     }
 
-    pollfd_events_t state_old = devpoll_state[fd].state;
+    pollfd_events_t state_old = (pollfd_events_t) F->epoll_state;
     pollfd_events_t state_new = 0; /* new state (derive from old state) */
 
     if ( type & COMM_SELECT_READ ) {
@@ -286,7 +282,7 @@ Comm::SetSelect(int fd, unsigned int type, PF * handler, void *client_data, time
                 comm_update_fd( fd, newly_set_only );
         }
 
-        devpoll_state[fd].state = state_new;
+        F->epoll_state = state_new;
     }
 
     if (timeout)
@@ -351,7 +347,7 @@ Comm::DoSelect(int msec)
             DEBUG_DEVPOLL ? 0 : 8,
             "got FD " << fd
             << ",events=" << std::hex << do_poll.dp_fds[i].revents
-            << ",monitoring=" << devpoll_state[fd].state
+            << ",monitoring=" << F->epoll_state
             << ",F->read_handler=" << F->read_handler
             << ",F->write_handler=" << F->write_handler
         );