docs/attachments/LUCENE-3092/LUCENE-3092.patch

Index: lucene/src/java/org/apache/lucene/index/MergePolicy.java
===================================================================
--- lucene/src/java/org/apache/lucene/index/MergePolicy.java	(revision 1104081)
+++ lucene/src/java/org/apache/lucene/index/MergePolicy.java	(working copy)
@@ -72,7 +72,7 @@
     long mergeGen;                  // used by IndexWriter
     boolean isExternal;             // used by IndexWriter
     int maxNumSegmentsOptimize;     // used by IndexWriter
-    long estimatedMergeBytes;       // used by IndexWriter
+    public long estimatedMergeBytes;       // used by IndexWriter
     List<SegmentReader> readers;        // used by IndexWriter
     List<SegmentReader> readerClones;   // used by IndexWriter
     public final List<SegmentInfo> segments;
Index: lucene/contrib/CHANGES.txt
===================================================================
--- lucene/contrib/CHANGES.txt	(revision 1104081)
+++ lucene/contrib/CHANGES.txt	(working copy)
@@ -85,6 +85,11 @@
    it cannot group by function queries nor arbitrary queries.  (Mike
    McCandless)
 
+ * LUCENE-3092: Added NRTCachingDirectory in contrib/misc, which
+   caches small segments in RAM.  This is useful, in near-real-time
+   case where the indexing rate is lowish but the reopen rate is
+   highish, to take load off the IO system.  (Mike McCandless)
+
 Optimizations
 
  * LUCENE-3040: Switch all analysis consumers (highlighter, morelikethis, memory, ...)
Index: lucene/contrib/misc/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java
===================================================================
--- lucene/contrib/misc/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java	(revision 0)
+++ lucene/contrib/misc/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java	(revision 0)
@@ -0,0 +1,120 @@
+package org.apache.lucene.store;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.io.File;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+
+import org.apache.lucene.analysis.Analyzer;
+import org.apache.lucene.analysis.MockAnalyzer;
+import org.apache.lucene.document.Document;
+import org.apache.lucene.index.CorruptIndexException;
+import org.apache.lucene.index.IndexReader;
+import org.apache.lucene.index.IndexWriter;
+import org.apache.lucene.index.IndexWriterConfig;
+import org.apache.lucene.index.MergePolicy;
+import org.apache.lucene.index.RandomIndexWriter;
+import org.apache.lucene.index.SegmentInfo;
+import org.apache.lucene.index.SegmentInfos;
+import org.apache.lucene.index.Term;
+import org.apache.lucene.search.IndexSearcher;
+import org.apache.lucene.search.TermQuery;
+import org.apache.lucene.search.TopDocs;
+import org.apache.lucene.util.BytesRef;
+import org.apache.lucene.util.LineFileDocs;
+import org.apache.lucene.util.LuceneTestCase;
+import org.apache.lucene.util.Version;
+import org.apache.lucene.util._TestUtil;
+
+public class TestNRTCachingDirectory extends LuceneTestCase {
+
+  public void testNRTAndCommit() throws Exception {
+    Directory dir = newDirectory();
+    NRTCachingDirectory cachedDir = new NRTCachingDirectory(dir, 2.0, 25.0);
+    IndexWriterConfig conf = newIndexWriterConfig(TEST_VERSION_CURRENT, new MockAnalyzer(random));
+    conf.setMergeScheduler(cachedDir.getMergeScheduler());
+    RandomIndexWriter w = new RandomIndexWriter(random, cachedDir, conf);
+    w.w.setInfoStream(VERBOSE ? System.out : null);
+    final LineFileDocs docs = new LineFileDocs(random);    
+    final int numDocs = _TestUtil.nextInt(random, 100, 400);
+
+    if (VERBOSE) {
+      System.out.println("TEST: numDocs=" + numDocs);
+    }
+
+    final List<BytesRef> ids = new ArrayList<BytesRef>();
+    IndexReader r = null;
+    for(int docCount=0;docCount<numDocs;docCount++) {
+      final Document doc = docs.nextDoc();
+      ids.add(new BytesRef(doc.get("docid")));
+      w.addDocument(doc);
+      if (random.nextInt(20) == 17) {
+        if (r == null) {
+          r = IndexReader.open(w.w, false);
+        } else {
+          final IndexReader r2 = r.reopen();
+          if (r2 != r) {
+            r.close();
+            r = r2;
+          }
+        }
+        assertEquals(1+docCount, r.numDocs());
+        final IndexSearcher s = new IndexSearcher(r);
+        // Just make sure search can run; we can't assert
+        // totHits since it could be 0
+        TopDocs hits = s.search(new TermQuery(new Term("body", "the")), 10);
+        // System.out.println("tot hits " + hits.totalHits);
+      }
+    }
+
+    if (r != null) {
+      r.close();
+    }
+
+    // Close should force cache to clear since all files are sync'd
+    w.close();
+
+    final String[] cachedFiles = cachedDir.listCachedFiles();
+    for(String file : cachedFiles) {
+      System.out.println("FAIL: cached file " + file + " remains after sync");
+    }
+    assertEquals(0, cachedFiles.length);
+    
+    r = IndexReader.open(dir);
+    for(BytesRef id : ids) {
+      assertEquals(1, r.docFreq("docid", id));
+    }
+    r.close();
+    cachedDir.close();
+  }
+
+  // NOTE: not a test; just here to make sure the code frag
+  // in the javadocs is correct!
+  public void verifyCompiles() throws Exception {
+    Analyzer analyzer = null;
+
+    Directory fsDir = FSDirectory.open(new File("/path/to/index"));
+    NRTCachingDirectory cachedFSDir = new NRTCachingDirectory(fsDir, 2.0, 25.0);
+    IndexWriterConfig conf = new IndexWriterConfig(Version.LUCENE_32, analyzer);
+    conf.setMergeScheduler(cachedFSDir.getMergeScheduler());
+    IndexWriter writer = new IndexWriter(cachedFSDir, conf);
+  }
+}

Property changes on: lucene/contrib/misc/src/test/org/apache/lucene/store/TestNRTCachingDirectory.java
___________________________________________________________________
Added: svn:eol-style
   + native

Index: lucene/contrib/misc/src/java/org/apache/lucene/store/NRTCachingDirectory.java
===================================================================
--- lucene/contrib/misc/src/java/org/apache/lucene/store/NRTCachingDirectory.java	(revision 0)
+++ lucene/contrib/misc/src/java/org/apache/lucene/store/NRTCachingDirectory.java	(revision 0)
@@ -0,0 +1,288 @@
+package org.apache.lucene.store;
+
+/**
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+
+import org.apache.lucene.index.ConcurrentMergeScheduler;
+import org.apache.lucene.index.IndexFileNames;
+import org.apache.lucene.index.IndexWriter;       // javadocs
+import org.apache.lucene.index.MergePolicy;
+import org.apache.lucene.index.MergeScheduler;
+import org.apache.lucene.util.IOUtils;
+
+// TODO
+//   - let subclass dictate policy...?
+//   - rename to MergeCacheingDir?  NRTCachingDir
+
+/**
+ * Wraps a {@link RAMDirectory}
+ * around any provided delegate directory, to
+ * be used during NRT search.  Make sure you pull the merge
+ * scheduler using {@link #getMergeScheduler} and pass that to your
+ * {@link IndexWriter}; this class uses that to keep track of which
+ * merges are being done by which threads, to decide when to
+ * cache each written file.
+ *
+ * <p>This class is likely only useful in a near-real-time
+ * context, where indexing rate is lowish but reopen
+ * rate is highish, resulting in many tiny files being
+ * written.  This directory keeps such segments (as well as
+ * the segments produced by merging them, as long as they
+ * are small enough), in RAM.</p>
+ *
+ * <p>This is safe to use: when your app calls {IndexWriter#commit},
+ * all cached files will be flushed from the cached and sync'd.</p>
+ *
+ * <p><b>NOTE</b>: this class is somewhat sneaky in its
+ * approach for spying on merges to determine the size of a
+ * merge: it records which threads are running which merges
+ * by watching ConcurrentMergeScheduler's doMerge method.
+ * While this works correctly, likely future versions of
+ * this class will take a more general approach.
+ *
+ * <p>Here's a simple example usage:
+ *
+ * <pre>
+ *   Directory fsDir = FSDirectory.open(new File("/path/to/index"));
+ *   NRTCachingDirectory cachedFSDir = new NRTCachingDirectory(fsDir, 5.0, 60.0);
+ *   IndexWriterConfig conf = new IndexWriterConfig(Version.LUCENE_32, analyzer);
+ *   conf.setMergeScheduler(cachedFSDir.getMergeScheduler());
+ *   IndexWriter writer = new IndexWriter(cachedFSDir, conf);
+ * </pre>
+ *
+ * <p>This will cache all newly flushed segments, all merges
+ * whose expected segment size is <= 5 MB, unless the net
+ * cached bytes exceeds 60 MB at which point all writes will
+ * not be cached (until the net bytes falls below 60 MB).</p>
+ *
+ * @lucene.experimental
+ */
+
+public class NRTCachingDirectory extends Directory {
+
+  private final RAMDirectory cache = new RAMDirectory();
+
+  private final Directory delegate;
+
+  private final long maxMergeSizeBytes;
+  private final long maxCachedBytes;
+
+  private static final boolean VERBOSE = false;
+  
+  /**
+   *  We will cache a newly created output if 1) it's a
+   *  flush or a merge and the estimated size of the merged segmnt is <=
+   *  maxMergeSizeMB, and 2) the total cached bytes is <=
+   *  maxCachedMB */
+  public NRTCachingDirectory(Directory delegate, double maxMergeSizeMB, double maxCachedMB) {
+    this.delegate = delegate;
+    maxMergeSizeBytes = (long) (maxMergeSizeMB*1024*1024);
+    maxCachedBytes = (long) (maxCachedMB*1024*1024);
+  }
+
+  @Override
+  public synchronized String[] listAll() throws IOException {
+    final Set<String> files = new HashSet<String>();
+    for(String f : cache.listAll()) {
+      files.add(f);
+    }
+    for(String f : delegate.listAll()) {
+      assert !files.contains(f);
+      files.add(f);
+    }
+    return files.toArray(new String[files.size()]);
+  }
+
+  /** Returns how many bytes are being used by the
+   *  RAMDirectory cache */
+  public long sizeInBytes()  {
+    return cache.sizeInBytes();
+  }
+
+  @Override
+  public synchronized boolean fileExists(String name) throws IOException {
+    return cache.fileExists(name) || delegate.fileExists(name);
+  }
+
+  @Override
+  public synchronized long fileModified(String name) throws IOException {
+    if (cache.fileExists(name)) {
+      return cache.fileModified(name);
+    } else {
+      return delegate.fileModified(name);
+    }
+  }
+
+  @Override
+  public synchronized void touchFile(String name) throws IOException {
+    if (cache.fileExists(name)) {
+      cache.touchFile(name);
+    } else {
+      delegate.touchFile(name);
+    }
+  }
+
+  @Override
+  public synchronized void deleteFile(String name) throws IOException {
+    // Delete from both, in case we are currently uncaching:
+    if (VERBOSE) {
+      System.out.println("nrtdir.deleteFile name=" + name);
+    }
+    cache.deleteFile(name);
+    delegate.deleteFile(name);
+  }
+
+  @Override
+  public synchronized long fileLength(String name) throws IOException {
+    if (cache.fileExists(name)) {
+      return cache.fileLength(name);
+    } else {
+      return delegate.fileLength(name);
+    }
+  }
+
+  public String[] listCachedFiles() {
+    return cache.listAll();
+  }
+
+  @Override
+  public IndexOutput createOutput(String name) throws IOException {
+    if (VERBOSE) {
+      System.out.println("nrtdir.createOutput name=" + name);
+    }
+    if (doCacheWrite(name)) {
+      if (VERBOSE) {
+        System.out.println("  to cache");
+      }
+      return cache.createOutput(name);
+    } else {
+      return delegate.createOutput(name);
+    }
+  }
+
+  @Override
+  public void sync(Collection<String> fileNames) throws IOException {
+    if (VERBOSE) {
+      System.out.println("nrtdir.sync files=" + fileNames);
+    }
+    for(String fileName : fileNames) {
+      unCache(fileName);
+    }
+    delegate.sync(fileNames);
+  }
+
+  @Override
+  public synchronized IndexInput openInput(String name) throws IOException {
+    if (VERBOSE) {
+      System.out.println("nrtdir.openInput name=" + name);
+    }
+    if (cache.fileExists(name)) {
+      if (VERBOSE) {
+        System.out.println("  from cache");
+      }
+      return cache.openInput(name);
+    } else {
+      return delegate.openInput(name);
+    }
+  }
+
+  @Override
+  public synchronized IndexInput openInput(String name, int bufferSize) throws IOException {
+    if (cache.fileExists(name)) {
+      return cache.openInput(name, bufferSize);
+    } else {
+      return delegate.openInput(name, bufferSize);
+    }
+  }
+
+  @Override
+  public Lock makeLock(String name) {
+    return delegate.makeLock(name);
+  }
+
+  @Override
+  public void clearLock(String name) throws IOException {
+    delegate.clearLock(name);
+  }
+
+  /** Close thius directory, which flushes any cached files
+   *  to the delegate and then closes the delegate. */
+  @Override
+  public void close() throws IOException {
+    for(String fileName : cache.listAll()) {
+      unCache(fileName);
+    }
+    cache.close();
+    delegate.close();
+  }
+
+  private final ConcurrentHashMap<Thread,MergePolicy.OneMerge> merges = new ConcurrentHashMap<Thread,MergePolicy.OneMerge>();
+
+  public MergeScheduler getMergeScheduler() {
+    return new ConcurrentMergeScheduler() {
+      @Override
+      protected void doMerge(MergePolicy.OneMerge merge) throws IOException {
+        try {
+          merges.put(Thread.currentThread(), merge);
+          super.doMerge(merge);
+        } finally {
+          merges.remove(Thread.currentThread());
+        }
+      }
+    };
+  }
+
+  /** Subclass can override this to customize logic; return
+   *  true if this file should be written to the RAMDirectory. */
+  protected boolean doCacheWrite(String name) {
+    final MergePolicy.OneMerge merge = merges.get(Thread.currentThread());
+    //System.out.println(Thread.currentThread().getName() + ": CACHE check merge=" + merge + " size=" + (merge==null ? 0 : merge.estimatedMergeBytes));
+    return !name.equals(IndexFileNames.SEGMENTS_GEN) && (merge == null || merge.estimatedMergeBytes <= maxMergeSizeBytes) && cache.sizeInBytes() <= maxCachedBytes;
+  }
+
+  private void unCache(String fileName) throws IOException {
+    final IndexOutput out;
+    synchronized(this) {
+      if (!delegate.fileExists(fileName)) {
+        assert cache.fileExists(fileName);
+        out = delegate.createOutput(fileName);
+      } else {
+        out = null;
+      }
+    }
+
+    if (out != null) {
+      IndexInput in = null;
+      try {
+        in = cache.openInput(fileName);
+        in.copyBytes(out, in.length());
+      } finally {
+        IOUtils.closeSafely(in, out);
+      }
+      synchronized(this) {
+        cache.deleteFile(fileName);
+      }
+    }
+  }
+}
+

Property changes on: lucene/contrib/misc/src/java/org/apache/lucene/store/NRTCachingDirectory.java
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Added: svn:eol-style
   + native