Index: lucene/CHANGES.txt
===================================================================
--- lucene/CHANGES.txt	(revision 1098529)
+++ lucene/CHANGES.txt	(working copy)
@@ -9,6 +9,11 @@
   a method getHeapArray() was added to retrieve the internal heap array as a
   non-generic Object[].  (Uwe Schindler, Yonik Seeley)
 
+API Changes
+
+* LUCENE-3061: IndexWriter's getNextMerge() and merge(OneMerge) are now public, 
+  allowing for custom MergeScheduler implementations. (Shai Erera)
+
 Optimizations
 
 * LUCENE-2990: ArrayUtil/CollectionUtil.*Sort() methods now exit early
Index: lucene/src/test/org/apache/lucene/TestMergeSchedulerExternal.java
===================================================================
--- lucene/src/test/org/apache/lucene/TestMergeSchedulerExternal.java	(revision 1098529)
+++ lucene/src/test/org/apache/lucene/TestMergeSchedulerExternal.java	(working copy)
@@ -19,17 +19,20 @@
 import java.io.IOException;
 
 import org.apache.lucene.util.LuceneTestCase;
+import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.MockDirectoryWrapper;
+import org.apache.lucene.store.RAMDirectory;
+import org.apache.lucene.index.CorruptIndexException;
 import org.apache.lucene.index.IndexWriter;
 import org.apache.lucene.index.IndexWriterConfig;
 import org.apache.lucene.index.LogMergePolicy;
 import org.apache.lucene.index.MergePolicy;
 import org.apache.lucene.index.ConcurrentMergeScheduler;
+import org.apache.lucene.index.MergeScheduler;
 import org.apache.lucene.analysis.MockAnalyzer;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.Field;
 
-
 /**
  * Holds tests cases to verify external APIs are accessible
  * while not being in org.apache.lucene.index package.
@@ -106,4 +109,42 @@
     assertTrue(excCalled);
     dir.close();
   }
+  
+  private static class ReportingMergeScheduler extends MergeScheduler {
+
+    @Override
+    public void merge(IndexWriter writer) throws CorruptIndexException, IOException {
+      while(true) {
+        MergePolicy.OneMerge merge = writer.getNextMerge();
+        if (merge == null)
+          break;
+        if (VERBOSE) {
+          System.out.println("executing merge " + merge.segString(writer.getDirectory()));
+        }
+        writer.merge(merge);
+      }
+    }
+
+    @Override
+    public void close() throws CorruptIndexException, IOException {}
+    
+  }
+
+  public void testCustomMergeScheduler() throws Exception {
+    // we don't really need to execute anything, just to make sure the custom MS
+    // compiles. But ensure that it can be used as well, e.g., no other hidden
+    // dependencies or something. Therefore, don't use any random API !
+    Directory dir = new RAMDirectory();
+    IndexWriterConfig conf = new IndexWriterConfig(TEST_VERSION_CURRENT, null);
+    conf.setMergeScheduler(new ReportingMergeScheduler());
+    IndexWriter writer = new IndexWriter(dir, conf);
+    writer.addDocument(new Document());
+    writer.commit(); // trigger flush
+    writer.addDocument(new Document());
+    writer.commit(); // trigger flush
+    writer.optimize();
+    writer.close();
+    dir.close();
+  }
+  
 }
Index: lucene/src/java/org/apache/lucene/index/IndexWriter.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/IndexWriter.java	(revision 1098529)
+++ lucene/src/java/org/apache/lucene/index/IndexWriter.java	(working copy)
@@ -2621,7 +2621,7 @@
   /** Expert: the {@link MergeScheduler} calls this method
    *  to retrieve the next merge requested by the
    *  MergePolicy */
-  synchronized MergePolicy.OneMerge getNextMerge() {
+  public synchronized MergePolicy.OneMerge getNextMerge() {
     if (pendingMerges.size() == 0)
       return null;
     else {
@@ -3599,8 +3599,7 @@
    * Merges the indicated segments, replacing them in the stack with a
    * single segment.
    */
-
-  final void merge(MergePolicy.OneMerge merge)
+  public final void merge(MergePolicy.OneMerge merge)
     throws CorruptIndexException, IOException {
 
     boolean success = false;