fix for "negative seek offset" error during extension of heap files.

This would have always happend when a heap file exceeds 2GB.
should fix https://github.com/yacy/yacy_search_server/issues/372

source/net/yacy/kelondro/blob/Heap.java

@@ -117,7 +117,6 @@ public final class Heap extends HeapModifier implements BLOB {
         return super.size() + ((this.buffer == null) ? 0 : this.buffer.size());
     }
 
-    
     /**
      * test if a key is in the heap file. This does not need any IO, because it uses only the ram index
      * @param key
@@ -147,7 +146,7 @@ public final class Heap extends HeapModifier implements BLOB {
     private void add(byte[] key, final byte[] blob) throws IOException {
         assert blob.length > 0;
         if ((blob == null) || (blob.length == 0)) return;
-        final int pos = (int) this.file.length();
+        final long pos = this.file.length();
         try {
             this.index.put(key, pos);
             this.file.seek(pos);
@@ -283,7 +282,7 @@ public final class Heap extends HeapModifier implements BLOB {
         ConcurrentLog.info("Heap", "clearing heap " + this.name());
         assert this.buffer != null;
         if (this.buffer == null) this.buffer = new TreeMap<byte[], byte[]>(this.ordering);
-    	this.buffer.clear();
+        this.buffer.clear();
         this.buffersize = 0;
         super.clear();
     }
@@ -294,16 +293,16 @@ public final class Heap extends HeapModifier implements BLOB {
     @Override
     public synchronized void close(final boolean writeIDX) {
         ConcurrentLog.info("Heap", "closing heap " + this.name());
-    	if (this.file != null && this.buffer != null) {
+        if (this.file != null && this.buffer != null) {
             try {
                 flushBuffer();
             } catch (final IOException e) {
                 ConcurrentLog.logException(e);
             }
         }
-    	this.buffer = null;
-    	super.close(writeIDX);
-    	assert this.file == null;
+        this.buffer = null;
+        super.close(writeIDX);
+        assert this.file == null;
     }
 
     @Override