add size in bytes to bb dir

src/main/java/org/apache/lucene/store/bytebuffer/ByteBufferDirectory.java

@@ -28,6 +28,7 @@ import java.nio.ByteBuffer;
 import java.util.Collection;
 import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.atomic.AtomicLong;
 
 /**
  * A memory based directory that uses {@link java.nio.ByteBuffer} in order to store the directory content.
@@ -48,6 +49,8 @@ public class ByteBufferDirectory extends Directory {
 
     private final boolean internalAllocator;
 
+    final AtomicLong sizeInBytes = new AtomicLong();
+
     /**
      * Constructs a new directory using {@link PlainByteBufferAllocator}.
      */
@@ -74,6 +77,13 @@ public class ByteBufferDirectory extends Directory {
         }
     }
 
+    /**
+     * Returns the size in bytes of the directory, chunk by buffer size.
+     */
+    public long sizeInBytes() {
+        return sizeInBytes.get();
+    }
+
     public void sync(Collection<String> names) throws IOException {
         // nothing to do here
     }
@@ -123,6 +133,7 @@ public class ByteBufferDirectory extends Directory {
         ByteBufferFile file = files.remove(name);
         if (file == null)
             throw new FileNotFoundException(name);
+        sizeInBytes.addAndGet(-file.sizeInBytes.get());
         file.delete();
     }
 
@@ -143,6 +154,7 @@ public class ByteBufferDirectory extends Directory {
         ByteBufferFile file = new ByteBufferFile(this, allocator.sizeInBytes(allocatorType));
         ByteBufferFile existing = files.put(name, file);
         if (existing != null) {
+            sizeInBytes.addAndGet(-existing.sizeInBytes.get());
             existing.delete();
         }
         return new ByteBufferIndexOutput(name, allocator, allocatorType, file);

src/main/java/org/apache/lucene/store/bytebuffer/ByteBufferFile.java

@@ -20,6 +20,7 @@ package org.apache.lucene.store.bytebuffer;
 import java.nio.ByteBuffer;
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicLong;
 
 /**
  */
@@ -35,6 +36,8 @@ public class ByteBufferFile {
 
     private final AtomicInteger refCount = new AtomicInteger(1);
 
+    final AtomicLong sizeInBytes = new AtomicLong();
+
     public ByteBufferFile(ByteBufferDirectory dir, int bufferSize) {
         this.dir = dir;
         this.bufferSize = bufferSize;
@@ -60,6 +63,8 @@ public class ByteBufferFile {
 
     protected final void addBuffer(ByteBuffer buffer) {
         buffers.add(buffer);
+        sizeInBytes.addAndGet(buffer.remaining());
+        dir.sizeInBytes.addAndGet(buffer.remaining());
     }
 
     protected final ByteBuffer getBuffer(int index) {