Scan index directory to determine Lucene versions

Mark index versions as "ready" when they are fully indexed and the
server is not running (i.e. from Reindex). By default, search from the
most recent ready index version, and write to both the most recent
ready version and (if different) the most recent known version.

At server startup, mark all versions except those we are about to
start writing to as not ready.

Change-Id: Icf42a3eb27b0445899300d60941cd701a8072d41

gerrit-pgm/src/main/java/com/google/gerrit/pgm/Reindex.java

@@ -43,6 +43,8 @@ import com.google.gerrit.server.git.MultiProgressMonitor;
 import com.google.gerrit.server.git.MultiProgressMonitor.Task;
 import com.google.gerrit.server.index.ChangeIndex;
 import com.google.gerrit.server.index.ChangeIndexer;
+import com.google.gerrit.server.index.ChangeSchemas;
+import com.google.gerrit.server.index.IndexCollection;
 import com.google.gerrit.server.index.IndexExecutor;
 import com.google.gerrit.server.index.IndexModule;
 import com.google.gerrit.server.index.IndexModule.IndexType;
@@ -63,7 +65,6 @@ import com.google.inject.TypeLiteral;
 
 import org.eclipse.jgit.diff.DiffEntry;
 import org.eclipse.jgit.diff.DiffFormatter;
-import org.eclipse.jgit.errors.ConfigInvalidException;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.ObjectInserter;
@@ -98,14 +99,22 @@ public class Reindex extends SiteProgram {
   @Option(name = "--threads", usage = "Number of threads to use for indexing")
   private int threads = Runtime.getRuntime().availableProcessors();
 
+  @Option(name = "--schema-version",
+      usage = "Schema version to reindex; default is most recent version")
+  private Integer version;
+
   @Option(name = "--output", usage = "Prefix for output; path for local disk index, or prefix for remote index")
   private String outputBase;
 
   @Option(name = "--verbose", usage = "Output debug information for each change")
   private boolean verbose;
 
+  @Option(name = "--dry-run", usage = "Dry run: don't write anything to index")
+  private boolean dryRun;
+
   private Injector dbInjector;
   private Injector sysInjector;
+  private ChangeIndex index;
 
   @Override
   public int run() throws Exception {
@@ -114,22 +123,22 @@ public class Reindex extends SiteProgram {
     if (IndexModule.getIndexType(dbInjector) == IndexType.SQL) {
       throw die("index.type must be configured (or not SQL)");
     }
-
+    if (version == null) {
+      version = ChangeSchemas.getLatest().getVersion();
+    }
     LifecycleManager dbManager = new LifecycleManager();
     dbManager.add(dbInjector);
     dbManager.start();
 
     sysInjector = createSysInjector();
-
-    // Delete before any index may be created depending on this data.
-    deleteAll();
-
     LifecycleManager sysManager = new LifecycleManager();
     sysManager.add(sysInjector);
     sysManager.start();
 
+    index = sysInjector.getInstance(IndexCollection.class).getSearchIndex();
+    index.deleteAll();
     int result = indexAll();
-    writeVersion();
+    index.markReady();
 
     sysManager.stop();
     dbManager.stop();
@@ -142,7 +151,7 @@ public class Reindex extends SiteProgram {
     AbstractModule changeIndexModule;
     switch (IndexModule.getIndexType(dbInjector)) {
       case LUCENE:
-        changeIndexModule = new LuceneIndexModule(false, threads, outputBase);
+        changeIndexModule = new LuceneIndexModule(version, threads, outputBase);
         break;
       case SOLR:
         changeIndexModule = new SolrIndexModule(false, threads, outputBase);
@@ -207,11 +216,6 @@ public class Reindex extends SiteProgram {
     }
   }
 
-  private void deleteAll() throws IOException {
-    ChangeIndex index = sysInjector.getInstance(ChangeIndex.class);
-    index.deleteAll();
-  }
-
   private int indexAll() throws Exception {
     ReviewDb db = sysInjector.getInstance(ReviewDb.class);
     ListeningScheduledExecutorService executor = sysInjector.getInstance(
@@ -464,10 +468,4 @@ public class Reindex extends SiteProgram {
       }
     }
   }
-
-  private void writeVersion() throws IOException,
-      ConfigInvalidException {
-    ChangeIndex index = sysInjector.getInstance(ChangeIndex.class);
-    index.finishIndex();
-  }
 }