--- trunk/OOPSE/libmdtools/DumpWriter.cpp	2004/01/13 20:04:28	934
+++ trunk/OOPSE/libmdtools/DumpWriter.cpp	2004/01/15 14:22:16	947
@@ -40,15 +40,6 @@ DumpWriter::DumpWriter( SimInfo* the_entry_plug ){
       simError();
     }
 
-    finalOut.open( entry_plug->finalName, ios::out | ios::trunc );
-    if( !finalOut ){
-      sprintf( painCave.errMsg,
-	       "Could not open \"%s\" for final dump output.\n",
-	       entry_plug->finalName );
-      painCave.isFatal = 1;
-      simError();
-    }
-
 #ifdef IS_MPI
   }
 
@@ -68,7 +59,6 @@ DumpWriter::~DumpWriter( ){
 #endif // is_mpi
 
     dumpFile.close();
-    finalOut.close();
 
 #ifdef IS_MPI
   }
@@ -111,11 +101,20 @@ void DumpWriter::writeDump(double currentTime){
 
 void DumpWriter::writeDump(double currentTime){
 
+  ofstream finalOut;
   vector<ofstream*> fileStreams;
 
 #ifdef IS_MPI
   if(worldRank == 0 ){
-    finalOut.seekp(0);
+    
+    finalOut.open( entry_plug->finalName, ios::out | ios::trunc );
+    if( !finalOut ){
+      sprintf( painCave.errMsg,
+	       "Could not open \"%s\" for final dump output.\n",
+	       entry_plug->finalName );
+      painCave.isFatal = 1;
+      simError();
+    }
   }
 #endif // is_mpi
 
@@ -123,21 +122,40 @@ void DumpWriter::writeDump(double currentTime){
   fileStreams.push_back(&dumpFile);
 
   writeFrame(fileStreams, currentTime);
+
+#ifdef IS_MPI
+  finalOut.close();
+#endif
   	
 }
 
 void DumpWriter::writeFinal(double currentTime){
 
+  ofstream finalOut;
   vector<ofstream*> fileStreams;
 
 #ifdef IS_MPI
   if(worldRank == 0 ){
-    finalOut.seekp(0);
+
+    finalOut.open( entry_plug->finalName, ios::out | ios::trunc );
+
+    if( !finalOut ){
+      sprintf( painCave.errMsg,
+	       "Could not open \"%s\" for final dump output.\n",
+	       entry_plug->finalName );
+      painCave.isFatal = 1;
+      simError();
+    }
+
   }
 #endif // is_mpi
   
   fileStreams.push_back(&finalOut);  
   writeFrame(fileStreams, currentTime);
+
+#ifdef IS_MPI
+  finalOut.close();
+#endif
   
 }
 
@@ -146,13 +164,50 @@ void DumpWriter::writeFrame( vector<ofstream*>& outFil
   const int BUFFERSIZE = 2000;
   const int MINIBUFFERSIZE = 100;
 
-  char tempBuffer[BUFFERSIZE];
+  char tempBuffer[BUFFERSIZE];  
   char writeLine[BUFFERSIZE];
 
   int i, k;
 
 #ifdef IS_MPI
   
+  /*********************************************************************
+   * Documentation?  You want DOCUMENTATION?
+   * 
+   * Why all the potatoes below?  
+   *
+   * To make a long story short, the original version of DumpWriter
+   * worked in the most inefficient way possible.  Node 0 would 
+   * poke each of the node for an individual atom's formatted data 
+   * as node 0 worked its way down the global index. This was particularly 
+   * inefficient since the method blocked all processors at every atom 
+   * (and did it twice!).
+   *
+   * An intermediate version of DumpWriter could be described from Node
+   * zero's perspective as follows:
+   * 
+   *  1) Have 100 of your friends stand in a circle.
+   *  2) When you say go, have all of them start tossing potatoes at
+   *     you (one at a time).
+   *  3) Catch the potatoes.
+   *
+   * It was an improvement, but MPI has buffers and caches that could 
+   * best be described in this analogy as "potato nets", so there's no 
+   * need to block the processors atom-by-atom.
+   * 
+   * This new and improved DumpWriter works in an even more efficient 
+   * way:
+   * 
+   *  1) Have 100 of your friend stand in a circle.
+   *  2) When you say go, have them start tossing 5-pound bags of 
+   *     potatoes at you.
+   *  3) Once you've caught a friend's bag of potatoes,
+   *     toss them a spud to let them know they can toss another bag.
+   *
+   * How's THAT for documentation?
+   *
+   *********************************************************************/
+
   int *potatoes;
   int myPotato;