Fix mc_select_children warning about non-existent children to wait for.

git-svn-id: https://svn.r-project.org/R/trunk@75467 00db46b3-68df-0310-9c12-caf00c1e9a41

src/library/parallel/src/fork.c

@@ -23,7 +23,7 @@
    
    Derived from multicore version 0.1-8 by Simon Urbanek
 */
-//#define MC_DEBUG
+/* #define MC_DEBUG */
 
 #ifdef HAVE_CONFIG_H
 # include <config.h> /* for affinity function checks and sigaction */
@@ -766,21 +766,17 @@ SEXP mc_select_children(SEXP sTimeout, SEXP sWhich)
 	    /* attached children have ci->pfd > 0 */
 	    if (which) { /* check for the FD only if it's on the list */
 		unsigned int k = 0;
-		int found = 0;
-		while (k < wlen) 
+		while (k < wlen) {
 		    if (which[k++] == ci->pid) { 
 			FD_SET(ci->pfd, &fs);
 			if (ci->pfd > maxfd) maxfd = ci->pfd;
 #ifdef MC_DEBUG
 			Dprintf("select_children: added child %d (%d)\n", ci->pid, ci->pfd);
 #endif
 			wcount++;
-			found = 1;
 			break; 
 		    }
-		if (!found)
-		    /* FIXME: probably should be an error */
-		    warning(_("cannot wait for child %d as it does not exist"), ci->pid);
+		}
 	    } else {
 		/* not sure if this should be allowed */
 		FD_SET(ci->pfd, &fs);
@@ -793,6 +789,31 @@ SEXP mc_select_children(SEXP sTimeout, SEXP sWhich)
 	ci = ci->next;
     }
 
+    if (which && wcount < wlen) {
+	/* children specified multiple times or not found */
+	for(unsigned int k = 0; k < wlen; k++) {
+	    ci = children;
+	    int found = 0;
+	    while(ci) {
+		if (!ci->detached && ci->ppid == ppid &&
+		    ci->pid == which[k] && FD_ISSET(ci->pfd, &fs)) {
+
+		    found = 1;
+		    break;
+		}
+		ci = ci->next;
+	    }
+	    if (!found) {
+#ifdef MC_DEBUG
+		Dprintf("select_children: cannot wait for child %d (idx %d) as it does not exist\n",
+		        which[k], k);
+#endif
+		/* FIXME: probably should be an error */
+		warning(_("cannot wait for child %d as it does not exist"), which[k]);
+	    }
+	}
+    }
+
 #ifdef MC_DEBUG
     Dprintf("select_children: maxfd=%d, wlen=%d, wcount=%d, timeout=%f\n", maxfd, wlen, wcount, timeout);
 #endif