Added methods to Buffer and InMemoryBuffer for batch fetching

Signed-off-by: Marcos Gonzalez Mayedo <[email protected]>

data-prepper-plugins/cloudwatch-logs/src/main/java/org/opensearch/dataprepper/plugins/sink/buffer/Buffer.java

@@ -5,6 +5,8 @@
 
 package org.opensearch.dataprepper.plugins.sink.buffer;
 
+import java.util.ArrayList;
+
 /**
  * Buffer that handles the temporary storage of
  * events. It isolates the implementation of system storage.
@@ -28,4 +30,8 @@ public interface Buffer {
     void writeEvent(byte[] event);
 
     byte[] popEvent();
+
+    ArrayList<byte[]> getBufferedData();
+
+    void clearBuffer();
 }

data-prepper-plugins/cloudwatch-logs/src/main/java/org/opensearch/dataprepper/plugins/sink/buffer/InMemoryBuffer.java

@@ -36,4 +36,15 @@ public byte[] popEvent() {
         bufferSize -= eventsBuffered.get(0).length;
         return eventsBuffered.remove(0);
     }
+
+    @Override
+    public ArrayList<byte[]> getBufferedData() {
+        return eventsBuffered;
+    }
+
+    @Override
+    public void clearBuffer() {
+        bufferSize = 0;
+        eventsBuffered.clear();
+    }
 }