Lucene: allow configuring writer flush options

Use index.changes_{open,closed}.{ramBufferSize,maxBufferedDocs} in the
server config to set the corresponding parameters on the
IndexWriterConfigs.

Change-Id: Idaa3ac3c541c330ceee052e8de23a63aea0dcf30

gerrit-lucene/src/main/java/com/google/gerrit/lucene/LuceneChangeIndex.java

@@ -43,11 +43,14 @@ import com.google.gerrit.server.query.change.IndexRewriteImpl;
 import com.google.gwtorm.server.OrmException;
 import com.google.gwtorm.server.ResultSet;
 
+import org.apache.lucene.analysis.standard.StandardAnalyzer;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.document.Field;
 import org.apache.lucene.document.IntField;
 import org.apache.lucene.document.StringField;
 import org.apache.lucene.index.IndexWriter;
+import org.apache.lucene.index.IndexWriterConfig;
+import org.apache.lucene.index.IndexWriterConfig.OpenMode;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.search.BooleanClause;
 import org.apache.lucene.search.BooleanQuery;
@@ -60,6 +63,7 @@ import org.apache.lucene.search.TopDocs;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.NumericUtils;
 import org.apache.lucene.util.Version;
+import org.eclipse.jgit.lib.Config;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -86,19 +90,33 @@ public class LuceneChangeIndex implements ChangeIndex, LifecycleListener {
   public static final String CHANGES_OPEN = "changes_open";
   public static final String CHANGES_CLOSED = "changes_closed";
 
+  private static IndexWriterConfig getIndexWriterConfig(Config cfg, String name) {
+    IndexWriterConfig writerConfig = new IndexWriterConfig(LUCENE_VERSION,
+        new StandardAnalyzer(LUCENE_VERSION));
+    writerConfig.setOpenMode(OpenMode.CREATE_OR_APPEND);
+    double m = 1 << 20;
+    writerConfig.setRAMBufferSizeMB(cfg.getLong("index", name, "ramBufferSize",
+          (long) (IndexWriterConfig.DEFAULT_RAM_BUFFER_SIZE_MB * m)) / m);
+    writerConfig.setMaxBufferedDocs(cfg.getInt("index", name, "maxBufferedDocs",
+          IndexWriterConfig.DEFAULT_MAX_BUFFERED_DOCS));
+    return writerConfig;
+  }
+
   private final RefreshThread refreshThread;
   private final FillArgs fillArgs;
   private final boolean readOnly;
   private final SubIndex openIndex;
   private final SubIndex closedIndex;
 
-  LuceneChangeIndex(SitePaths sitePaths, FillArgs fillArgs, boolean readOnly)
-      throws IOException {
+  LuceneChangeIndex(Config cfg, SitePaths sitePaths, FillArgs fillArgs,
+      boolean readOnly) throws IOException {
     this.refreshThread = new RefreshThread();
     this.fillArgs = fillArgs;
     this.readOnly = readOnly;
-    openIndex = new SubIndex(new File(sitePaths.index_dir, CHANGES_OPEN));
-    closedIndex = new SubIndex(new File(sitePaths.index_dir, CHANGES_CLOSED));
+    openIndex = new SubIndex(new File(sitePaths.index_dir, CHANGES_OPEN),
+        getIndexWriterConfig(cfg, "changes_open"));
+    closedIndex = new SubIndex(new File(sitePaths.index_dir, CHANGES_CLOSED),
+          getIndexWriterConfig(cfg, "changes_closed"));
   }
 
   @Override

gerrit-lucene/src/main/java/com/google/gerrit/lucene/LuceneIndexModule.java

@@ -15,6 +15,7 @@
 package com.google.gerrit.lucene;
 
 import com.google.gerrit.lifecycle.LifecycleModule;
+import com.google.gerrit.server.config.GerritServerConfig;
 import com.google.gerrit.server.config.SitePaths;
 import com.google.gerrit.server.index.ChangeIndex;
 import com.google.gerrit.server.index.FieldDef.FillArgs;
@@ -22,6 +23,8 @@ import com.google.gerrit.server.index.IndexModule;
 import com.google.inject.Provides;
 import com.google.inject.Singleton;
 
+import org.eclipse.jgit.lib.Config;
+
 import java.io.IOException;
 
 public class LuceneIndexModule extends LifecycleModule {
@@ -52,8 +55,8 @@ public class LuceneIndexModule extends LifecycleModule {
 
   @Provides
   @Singleton
-  public LuceneChangeIndex getChangeIndex(SitePaths sitePaths,
-      FillArgs fillArgs) throws IOException {
-    return new LuceneChangeIndex(sitePaths, fillArgs, readOnly);
+  public LuceneChangeIndex getChangeIndex(@GerritServerConfig Config cfg,
+      SitePaths sitePaths, FillArgs fillArgs) throws IOException {
+    return new LuceneChangeIndex(cfg, sitePaths, fillArgs, readOnly);
   }
 }

gerrit-lucene/src/main/java/com/google/gerrit/lucene/SubIndex.java

@@ -14,13 +14,9 @@
 
 package com.google.gerrit.lucene;
 
-import static com.google.gerrit.lucene.LuceneChangeIndex.LUCENE_VERSION;
-
-import org.apache.lucene.analysis.standard.StandardAnalyzer;
 import org.apache.lucene.document.Document;
 import org.apache.lucene.index.IndexWriter;
 import org.apache.lucene.index.IndexWriterConfig;
-import org.apache.lucene.index.IndexWriterConfig.OpenMode;
 import org.apache.lucene.index.Term;
 import org.apache.lucene.search.IndexSearcher;
 import org.apache.lucene.search.SearcherManager;
@@ -40,11 +36,8 @@ class SubIndex {
   private final IndexWriter writer;
   private final SearcherManager searcherManager;
 
-  SubIndex(File file) throws IOException {
+  SubIndex(File file, IndexWriterConfig writerConfig) throws IOException {
     dir = FSDirectory.open(file);
-    IndexWriterConfig writerConfig =
-        new IndexWriterConfig(LUCENE_VERSION, new StandardAnalyzer(LUCENE_VERSION));
-    writerConfig.setOpenMode(OpenMode.CREATE_OR_APPEND);
     writer = new IndexWriter(dir, writerConfig);
     searcherManager = new SearcherManager(writer, true, null);
   }