Lucene.Net.Index.IndexWriter.AddIndexes C# (CSharp) Method

		public virtual void  AddIndexes(params IndexReader[] readers)
		{
			
			EnsureOpen();
			
			// Do not allow add docs or deletes while we are running:
			docWriter.PauseAllThreads();
			
			// We must pre-acquire a read lock here (and upgrade to
			// write lock in startTransaction below) so that no
			// other addIndexes is allowed to start up after we have
			// flushed & optimized but before we then start our
			// transaction.  This is because the merging below
			// requires that only one segment is present in the
			// index:
			AcquireRead();
			
			try
			{
				
				SegmentInfo info = null;
				System.String mergedName = null;
				SegmentMerger merger = null;
				
				bool success = false;
				
				try
				{
					Flush(true, false, true);
					Optimize(); // start with zero or 1 seg
					success = true;
				}
				finally
				{
					// Take care to release the read lock if we hit an
					// exception before starting the transaction
					if (!success)
						ReleaseRead();
				}
				
				// true means we already have a read lock; if this
				// call hits an exception it will release the write
				// lock:
				StartTransaction(true);
				
				try
				{
					mergedName = NewSegmentName();
					merger = new SegmentMerger(this, mergedName, null);
					
					SegmentReader sReader = null;
					lock (this)
					{
						if (segmentInfos.Count == 1)
						{
							// add existing index, if any
							sReader = readerPool.Get(segmentInfos.Info(0), true, BufferedIndexInput.BUFFER_SIZE, - 1);
						}
					}
					
					success = false;
					
					try
					{
						if (sReader != null)
							merger.Add(sReader);
						
						for (int i = 0; i < readers.Length; i++)
						// add new indexes
							merger.Add(readers[i]);
						
						int docCount = merger.Merge(); // merge 'em
						
						lock (this)
						{
							segmentInfos.Clear(); // pop old infos & add new
							info = new SegmentInfo(mergedName, docCount, directory, false, true, - 1, null, false, merger.HasProx());
							SetDiagnostics(info, "addIndexes(params IndexReader[])");
							segmentInfos.Add(info);
						}
						
						// Notify DocumentsWriter that the flushed count just increased
						docWriter.UpdateFlushedDocCount(docCount);
						
						success = true;
					}
					finally
					{
						if (sReader != null)
						{
							readerPool.Release(sReader);
						}
					}
				}
				finally
				{
					if (!success)
					{
						if (infoStream != null)
							Message("hit exception in addIndexes during merge");
						RollbackTransaction();
					}
					else
					{
						CommitTransaction();
					}
				}
				
				if (mergePolicy is LogMergePolicy && UseCompoundFile)
				{
					
					IList<string> files = null;
					
					lock (this)
					{
						// Must incRef our files so that if another thread
						// is running merge/optimize, it doesn't delete our
						// segment's files before we have a change to
						// finish making the compound file.
						if (segmentInfos.Contains(info))
						{
							files = info.Files();
							deleter.IncRef(files);
						}
					}
					
					if (files != null)
					{
						
						success = false;
						
						StartTransaction(false);
						
						try
						{
							merger.CreateCompoundFile(mergedName + ".cfs");
							lock (this)
							{
								info.SetUseCompoundFile(true);
							}
							
							success = true;
						}
						finally
						{
                            lock (this)
                            {
                                deleter.DecRef(files);
                            }
														
							if (!success)
							{
								if (infoStream != null)
									Message("hit exception building compound file in addIndexes during merge");
								
								RollbackTransaction();
							}
							else
							{
								CommitTransaction();
							}
						}
					}
				}
			}
			catch (System.OutOfMemoryException oom)
			{
				HandleOOM(oom, "addIndexes(params IndexReader[])");
			}
			finally
			{
				if (docWriter != null)
				{
					docWriter.ResumeAllThreads();
				}
			}
		}

        public virtual void TestTypeChangeViaAddIndexesIR2()
        {
            Directory         dir    = NewDirectory();
            IndexWriterConfig conf   = NewIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(Random));
            IndexWriter       writer = new IndexWriter(dir, (IndexWriterConfig)conf.Clone());
            Document          doc    = new Document();

            doc.Add(new NumericDocValuesField("dv", 0L));
            writer.AddDocument(doc);
            writer.Dispose();

            Directory dir2 = NewDirectory();

            writer = new IndexWriter(dir2, (IndexWriterConfig)conf.Clone());
            IndexReader[] readers = new IndexReader[] { DirectoryReader.Open(dir) };
            writer.AddIndexes(readers);
            readers[0].Dispose();
            doc = new Document();
            doc.Add(new SortedDocValuesField("dv", new BytesRef("foo")));
            try
            {
                writer.AddDocument(doc);
                Assert.Fail("did not hit exception");
            }
#pragma warning disable 168
            catch (ArgumentException iae)
#pragma warning restore 168
            {
                // expected
            }
            writer.Dispose();
            dir2.Dispose();
            dir.Dispose();
        }