prevent opening of new files as that could be a cause for the latest

too-many-open-files exception. The old file is just truncated if the
table is cleaned.

source/net/yacy/kelondro/io/BufferedRecords.java

@@ -52,6 +52,11 @@ public final class BufferedRecords {
         this.maxEntries = maxEntries;
         this.buffer = new TreeMap<Long, byte[]>();
     }
+    
+    public synchronized void clear() {
+        this.efs.clear();
+        this.buffer.clear();
+    }
 
     /**
      * flush the buffer: this shall be called before any file-based iterations

source/net/yacy/kelondro/io/Records.java

@@ -116,6 +116,17 @@ public final class Records {
         this.buffer = new byte[buffersize];
         this.buffercount = 0;
     }
+    
+    public void clear() {
+        try {
+            this.raf.setLength(0);
+            int buffersize = Math.max(1, (maxWriteBuffer / recordsize)) * recordsize;
+            this.buffer = new byte[buffersize];
+            this.buffercount = 0;
+        } catch (IOException e) {
+            ConcurrentLog.logException(e);
+        }
+    }
 
     /**
      * @param tablefile

source/net/yacy/kelondro/table/Table.java

@@ -876,24 +876,7 @@ public class Table implements Index, Iterable<Row.Entry> {
 
     @Override
     public synchronized void clear() throws IOException {
-        final File f = this.file.filename();
-        this.file.close();
-        this.file = null;
-        FileUtils.deletedelete(f);
-        tableTracker.remove(f.getName());
-
-        // make new file
-        FileOutputStream fos = null;
-        try {
-            fos = new FileOutputStream(f);
-        } catch (final FileNotFoundException e) {
-            // should not happen
-            ConcurrentLog.severe("Table", "", e);
-        }
-        if (fos != null) try { fos.close(); } catch (final IOException e) {}
-
-        this.file = new BufferedRecords(new Records(f, this.rowdef.objectsize), this.buffersize);
-
+        this.file.clear();
         // initialize index and copy table
         this.table = (this.table == null) ? null : new RowSet(this.taildef);
         this.index.clear();