# HG changeset patch
# User Nina Engelhardt <nengel@mailbox.tu-berlin.de>
# Date 1362576835 -3600
# Node ID c54f7e0a9d112f31a4417efb2c6dabc5998b3150
# Parent  8fcbe46de60a68d2c0a8bef5e7f8ef20a584d246
fix peek + debug code

diff -r 8fcbe46de60a -r c54f7e0a9d11 PrivateQueue.c
--- a/PrivateQueue.c	Wed Dec 19 15:38:08 2012 +0100
+++ b/PrivateQueue.c	Wed Mar 06 14:33:55 2013 +0100
@@ -149,11 +149,17 @@
    void **extractPos = Q->extractPos;
 
       //if not empty -- (extract is just below insert when empty)
-   if( insertPos - extractPos != 1 &&
-       !(extractPos == endOfData && insertPos == startOfData))
-    { 
-      out = *(Q->extractPos + 1);
-      return out;
+       if (insertPos - extractPos != 1 &&
+            !(extractPos == endOfData && insertPos == startOfData)) { //move before read
+        if (extractPos == endOfData) //write new pos exactly once, correctly
+        {
+            out = *(startOfData); //can't overrun then fix it 'cause
+        }// other thread might read bad pos
+        else {
+            out = *(Q->extractPos + 1);
+        }
+        
+        return out;
     }
       //Q is empty
    return NULL;
@@ -162,9 +168,6 @@
 /*Returns NULL when queue is empty
  */
 void* readPrivQ(PrivQueueStruc* Q) {
-#ifdef DEBUG_PRIVATE_Q
-    Q->numReads++;
-#endif
     
     void *out = 0;
     void **startOfData = Q->startOfData;
@@ -184,6 +187,10 @@
             Q->extractPos++;
         }
         out = *(Q->extractPos);
+        //*(Q->extractPos) = NULL;
+#ifdef DEBUG_PRIVATE_Q
+        Q->numReads++;
+#endif
         return out;
     }
     //Q is empty