From 40cafb32414e203e227def29dc1fd8b4b5688d1f Mon Sep 17 00:00:00 2001
From: John Denker <jsd@av8n.com>
Date: Sun, 15 Jul 2012 01:37:10 -0700
Subject: still not reliable!

---
 tools/hi-q.c | 39 +++++++++++++++++++++++++++++++--------
 1 file changed, 31 insertions(+), 8 deletions(-)

(limited to 'tools')

diff --git a/tools/hi-q.c b/tools/hi-q.c
index 1e71ef4..3de9f1c 100644
--- a/tools/hi-q.c
+++ b/tools/hi-q.c
@@ -209,6 +209,11 @@ int main(int argc, char** argv, char const * const * env) {
 
   vector<pid_t> kidpid(nkids);  // indexed by kid number
 
+  const int rEnd(0);  // end of a pipe for reading
+  const int wEnd(1);  // end of a pipe for writing
+  int sync[2];
+  if (pipe(sync) != 0) cerr << "sync pipe failed" << endl;
+
 // At this point, there are some loop invariants;
 // (a) fd0 is open (standard input) and has the email msg, 
 //     ready for the next child to read, and
@@ -247,10 +252,11 @@ int main(int argc, char** argv, char const * const * env) {
 //    It will be written by this kid and read by the next kid.
 // For the last kid, the loose end connects to hi-q.
 //    It will be written by hi-q and read by the last kid.
+
     int lastkid = (ii == nkids-1);
 #define flip(a,b) (lastkid ? b : a)
-    loose_end = datapipe[flip(0,1)];
-    kid_end   = datapipe[flip(1,0)];
+    loose_end = datapipe[flip(rEnd, wEnd)];
+    kid_end   = datapipe[flip(wEnd, rEnd)];
 
     kidpid[ii] = fork();
     if (!kidpid[ii]) {  /*** child code ***/
@@ -262,9 +268,17 @@ int main(int argc, char** argv, char const * const * env) {
         cerr << "setpgid failed! " << errno << " ... ";
         perror(0);
       }
-      cerr << "kid [" << ii << "] starts: " << getpid() 
+      if (ii == 0) {
+        int junk(1);
+        write(sync[wEnd], &junk, 1);
+        //cerr << "sync sent" << endl;
+      }
+
+#if 1
+      cerr << "kid [" << ii << "] " << getpid() 
         << "  kidpid[0] " << kidpid[0]
-        << endl;
+        << " starts" << endl;
+#endif
 // Now that we are through creating pipes, we don't
 // need to continue blocking fd1:
       close(1);
@@ -308,15 +322,24 @@ int main(int argc, char** argv, char const * const * env) {
 // otherwise it won't fully exist when the other kids start,
 // and depending race conditions, the setpgid could fail
 ////////???    if (1) usleep(0);
-  if (ii == 0) usleep(1);
-#if 1
-    cerr << "forked kid #" << ii 
+///////???  if (ii == 0) usleep(1);
+
+    if (ii==0) {
+      int junk;
+      //cerr << "about to read sync" << endl;
+      ssize_t rslt = read(sync[rEnd], &junk, 1);
+      //cerr << "back from read sync: " << rslt << endl;
+      if (rslt) {}
+    }
+
+#if 0
+    cerr << "apparent kid #" << ii 
             << " (" << kidpid[ii] << ") "
             << endl;
 #endif
   } /* end loop starting all kids */
 
-// here with the whole pipeline of kids running
+// here with the whole pipeline of kids launched
 
   close(0);             // the reading end of stdin was
                         // delegated to the first child
-- 
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