Revu la construction des listes resultats, plus efficace si FD_SETSIZE est grand (PR#738)

git-svn-id: http://caml.inria.fr/svn/ocaml/trunk@4774 f963ae5c-01c2-4b8c-9fe0-0dff7051ff02

1 files changed, 30 insertions, 24 deletions

diff --git a/otherlibs/unix/select.c b/otherlibs/unix/select.c
index 8923e130f..e512b3043 100644
--- a/otherlibs/unix/select.c
+++ b/otherlibs/unix/select.c
@@ -31,25 +31,28 @@
 
 typedef fd_set file_descr_set;
 
-static void fdlist_to_fdset(value fdlist, file_descr_set *fdset)
+static void fdlist_to_fdset(value fdlist, fd_set *fdset, int *maxfd)
 {
   value l;
   FD_ZERO(fdset);
   for (l = fdlist; l != Val_int(0); l = Field(l, 1)) {
-    FD_SET(Int_val(Field(l, 0)), fdset);
+    int fd = Int_val(Field(l, 0));
+    FD_SET(fd, fdset);
+    if (fd > *maxfd) *maxfd = fd;
   }
 }
 
-static value fdset_to_fdlist(file_descr_set *fdset)
+static value fdset_to_fdlist(value fdlist, fd_set *fdset)
 {
-  int i;
+  value l;
   value res = Val_int(0);
 
-  Begin_root(res);
-    for (i = FD_SETSIZE - 1; i >= 0; i--) {
-      if (FD_ISSET(i, fdset)) {
+  Begin_roots2(l, res);
+    for (l = fdlist; l != Val_int(0); l = Field(l, 1)) {
+      int fd = Int_val(Field(l, 0));
+      if (FD_ISSET(fd, fdset)) {
         value newres = alloc_small(2, 0);
-        Field(newres, 0) = Val_int(i);
+        Field(newres, 0) = Val_int(fd);
         Field(newres, 1) = res;
         res = newres;
       }
@@ -58,46 +61,49 @@ static value fdset_to_fdlist(file_descr_set *fdset)
   return res;
 }
 
-CAMLprim value unix_select(value readfds, value writefds, value exceptfds, value timeout)
+CAMLprim value unix_select(value readfds, value writefds, value exceptfds, 
+                           value timeout)
 {
-  file_descr_set read, write, except;
+  fd_set read, write, except;
+  int maxfd;
   double tm;
   struct timeval tv;
   struct timeval * tvp;
   int retcode;
   value res;
-  value read_list = Val_unit, write_list = Val_unit, except_list = Val_unit;
 
-  Begin_roots3 (read_list, write_list, except_list);
-    fdlist_to_fdset(readfds, &read);
-    fdlist_to_fdset(writefds, &write);
-    fdlist_to_fdset(exceptfds, &except);
+  Begin_roots3 (readfds, writefds, exceptfds);
+    maxfd = 0;
+    fdlist_to_fdset(readfds, &read, &maxfd);
+    fdlist_to_fdset(writefds, &write, &maxfd);
+    fdlist_to_fdset(exceptfds, &except, &maxfd);
     tm = Double_val(timeout);
     if (tm < 0.0)
       tvp = (struct timeval *) NULL;
     else {
       tv.tv_sec = (int) tm;
-      tv.tv_usec = (int) (1e6 * (tm - (int) tm));
+      tv.tv_usec = (int) (1e6 * (tm - tv.tv_sec));
       tvp = &tv;
     }
     enter_blocking_section();
-    retcode = select(FD_SETSIZE, &read, &write, &except, tvp);
+    retcode = select(maxfd, &read, &write, &except, tvp);
     leave_blocking_section();
     if (retcode == -1) uerror("select", Nothing);
-    read_list = fdset_to_fdlist(&read);
-    write_list = fdset_to_fdlist(&write);
-    except_list = fdset_to_fdlist(&except);
+    readfds = fdset_to_fdlist(readfds, &read);
+    writefds = fdset_to_fdlist(writefds, &write);
+    exceptfds = fdset_to_fdlist(exceptfds, &except);
     res = alloc_small(3, 0);
-    Field(res, 0) = read_list;
-    Field(res, 1) = write_list;
-    Field(res, 2) = except_list;
+    Field(res, 0) = readfds;
+    Field(res, 1) = writefds;
+    Field(res, 2) = exceptfds;
   End_roots();
   return res;
 }
 
 #else
 
-CAMLprim value unix_select(value readfds, value writefds, value exceptfds, value timeout)
+CAMLprim value unix_select(value readfds, value writefds, value exceptfds,
+                           value timeout)
 { invalid_argument("select not implemented"); }
 
 #endif