Extended HexPrinter to handle multiple header style, grouping style.

Now we standardize the format to print multiple hex strings:
 - The line numbers are always coded in hex.
 - Each byte is presented in two hex digits and bytes are separated with one space.

However one could freely choose how many digits to use for line numbers, what suffix or prefix around line number digits, how many bytes in each line and each group, and what group separator to use.

community/kernel/src/main/java/org/neo4j/helpers/Strings.java

@@ -190,4 +190,30 @@ public static void escape( Appendable output, String arg ) throws IOException
             }
         }
     }
+
+    /**
+     * Use this to standardize the width of some text output to all be left-justified and space-padded
+     * on the right side to fill up the given column width.
+     *
+     * @param str
+     * @param columnWidth
+     * @return
+     */
+    public static String ljust( String str, int columnWidth )
+    {
+        return String.format( "%-" + columnWidth + "s", str );
+    }
+
+    /**
+     * Use this to standardize the width of some text output to all be right-justified and space-padded
+     * on the left side to fill up the given column width.
+     *
+     * @param str
+     * @param columnWidth
+     * @return
+     */
+    public static String rjust( String str, int columnWidth )
+    {
+        return String.format( "%" + columnWidth + "s", str );
+    }
 }

community/kernel/src/main/java/org/neo4j/kernel/impl/store/DumpStore.java

@@ -35,6 +35,7 @@
 import org.neo4j.kernel.impl.store.record.RelationshipGroupRecord;
 import org.neo4j.kernel.impl.store.record.RelationshipRecord;
 import org.neo4j.kernel.impl.store.record.TokenRecord;
+import org.neo4j.kernel.impl.util.HexPrinter;
 import org.neo4j.logging.FormattedLogProvider;
 import org.neo4j.logging.LogProvider;
 import org.neo4j.logging.NullLogProvider;
@@ -226,10 +227,12 @@ protected Object transform( NodeRecord record ) throws Exception
     }
 
     private final PrintStream out;
+    private final HexPrinter printer;
 
     protected DumpStore( PrintStream out )
     {
         this.out = out;
+        this.printer = new HexPrinter( out ).withBytesGroupingFormat( 16, 4, "  " ).withLineNumberDigits( 8 );
     }
 
     public final void dump( STORE store, long[] ids ) throws Exception
@@ -291,64 +294,44 @@ private boolean dumpRecord( STORE store, int size, StoreChannel fileChannel, Byt
             out.print( record );
             buffer.clear();
             fileChannel.read( buffer, id * size );
-            buffer.flip();
-            if ( record.inUse() )
-            {
-                dumpHex( buffer, id * size );
-            }
-            else if ( allZero( buffer ) )
-            {
-                out.printf( ": all zeros @ 0x%x - 0x%x%n", id * size, (id + 1) * size );
-            }
-            else
-            {
-                dumpHex( buffer, id * size );
-            }
+            dumpHex( record, buffer, id, size );
         }
 
         return record.inUse();
     }
 
-    private boolean allZero( ByteBuffer buffer )
+    void dumpHex( RECORD record, ByteBuffer buffer, long id, int size )
     {
-        int pos = buffer.position();
-        try
+        printer.withLineNumberOffset( id * size );
+        if ( record.inUse() )
         {
-            while ( buffer.remaining() > 0 )
-            {
-                if ( buffer.get() != 0 )
-                {
-                    return false;
-                }
-            }
+            printer.append( buffer );
         }
-        finally
+        else if ( allZero( buffer ) )
         {
-            buffer.position( pos );
+            out.printf( ": all zeros @ 0x%x - 0x%x", id * size, (id + 1) * size );
         }
-        return true;
-    }
-
-    protected Object transform( RECORD record ) throws Exception
-    {
-        return record.inUse() ? record : null;
+        else
+        {
+            printer.append( buffer );
+        }
+        out.printf( "%n" );
     }
 
-    private void dumpHex( ByteBuffer buffer, long offset )
+    private boolean allZero( ByteBuffer buffer )
     {
-        for ( int count = 0; buffer.remaining() > 0; count++, offset++ )
+        for ( int i = 0; i < buffer.position(); i++ )
         {
-            int b = buffer.get();
-            if ( count % 16 == 0 )
+            if ( buffer.get( i ) != 0 )
             {
-                out.printf( "%n    @ 0x%08x: ", offset );
+                return false;
             }
-            else if ( count % 4 == 0 )
-            {
-                out.print( " " );
-            }
-            out.printf( " %x%x", 0xF & (b >> 4), 0xF & b );
         }
-        out.println();
+        return true;
+    }
+
+    protected Object transform( RECORD record ) throws Exception
+    {
+        return record.inUse() ? record : null;
     }
 }