Memory mapped files: There was a bug in version 1.2.139 so that memory mapped…

Memory mapped files: There was a bug in version 1.2.139 so that memory mapped files could only be used together with split

h2/src/main/org/h2/store/fs/FileObjectDiskMapped.java

@@ -47,29 +47,29 @@ public class FileObjectDiskMapped implements FileObject {
     }
 
     private void unMap() throws IOException {
-        if (mapped != null) {
+        if (mapped == null) {
+            return;
+        }
         // first write all data
         mapped.force();
 
         // need to dispose old direct buffer, see bug
         // http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=4724038
 
-            boolean useSystemGc;
+        boolean useSystemGc = true;
         if (SysProperties.NIO_CLEANER_HACK) {
             try {
-                    useSystemGc = false;
                 Method cleanerMethod = mapped.getClass().getMethod("cleaner");
                 cleanerMethod.setAccessible(true);
                 Object cleaner = cleanerMethod.invoke(mapped);
                 Method clearMethod = cleaner.getClass().getMethod("clear");
                 clearMethod.invoke(cleaner);
+                useSystemGc = false;
             } catch (Throwable e) {
-                    useSystemGc = true;
+                // useSystemGc is already true
             } finally {
                 mapped = null;
             }
-            } else {
-                useSystemGc = true;
         }
         if (useSystemGc) {
             WeakReference<MappedByteBuffer> bufferWeakRef = new WeakReference<MappedByteBuffer>(mapped);
@@ -85,7 +85,6 @@ public class FileObjectDiskMapped implements FileObject {
             }
         }
     }
-    }
 
     /**
      * Re-map byte buffer into memory, called when file size has changed or file
@@ -95,7 +94,6 @@ public class FileObjectDiskMapped implements FileObject {
         int oldPos = 0;
         if (mapped != null) {
             oldPos = pos;
-            mapped.force();
             unMap();
         }
         long length = file.length();
@@ -141,6 +139,7 @@ public class FileObjectDiskMapped implements FileObject {
         try {
             mapped.position(pos);
             mapped.get(b, off, len);
+            pos += len;
         } catch (IllegalArgumentException e) {
             EOFException e2 = new EOFException("EOF");
             e2.initCause(e);
@@ -159,8 +158,11 @@ public class FileObjectDiskMapped implements FileObject {
 
     public void setFileLength(long newLength) throws IOException {
         checkFileSizeLimit(newLength);
+        int oldPos = pos;
+        unMap();
         IOUtils.setLength(file, newLength);
         reMap();
+        pos = (int) Math.min(newLength, oldPos);
     }
 
     public void sync() throws IOException {
@@ -175,6 +177,7 @@ public class FileObjectDiskMapped implements FileObject {
         }
         mapped.position(pos);
         mapped.put(b, off, len);
+        pos += len;
     }
 
 }