Rewrite schema versioning in preparation for multiple versions

Store indexes in versioned directories, and don't consider open/closed
to have separate versions.

Extract a simple base Schema class with a version and a list of
fields, which is analogous to the DB's SchemaVersion. Construct
indexes using specific versions.

Change-Id: I11e8e3a78cd62b1a01aa122bfd747ed5295fe057

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

@@ -15,13 +15,12 @@
 package com.google.gerrit.lucene;
 
 import static com.google.gerrit.lucene.LuceneChangeIndex.LUCENE_VERSION;
-
 import static org.apache.lucene.util.Version.LUCENE_CURRENT;
 
 import com.google.common.collect.ImmutableMap;
 import com.google.gerrit.extensions.events.LifecycleListener;
 import com.google.gerrit.server.config.SitePaths;
-import com.google.gerrit.server.index.ChangeField;
+import com.google.gerrit.server.index.ChangeSchemas;
 import com.google.inject.Inject;
 import com.google.inject.ProvisionException;
 
@@ -36,8 +35,8 @@ import java.util.Map;
 
 public class IndexVersionCheck implements LifecycleListener {
   public static final Map<String, Integer> SCHEMA_VERSIONS = ImmutableMap.of(
-      LuceneChangeIndex.CHANGES_OPEN, ChangeField.SCHEMA_VERSION,
-      LuceneChangeIndex.CHANGES_CLOSED, ChangeField.SCHEMA_VERSION);
+      LuceneChangeIndex.CHANGES_OPEN, ChangeSchemas.getLatestRelease().getVersion(),
+      LuceneChangeIndex.CHANGES_CLOSED, ChangeSchemas.getLatestRelease().getVersion());
 
   public static File gerritIndexConfig(SitePaths sitePaths) {
     return new File(sitePaths.index_dir, "gerrit_index.config");

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

@@ -35,6 +35,7 @@ import com.google.gerrit.server.index.FieldDef;
 import com.google.gerrit.server.index.FieldDef.FillArgs;
 import com.google.gerrit.server.index.FieldType;
 import com.google.gerrit.server.index.IndexRewriteImpl;
+import com.google.gerrit.server.index.Schema;
 import com.google.gerrit.server.query.Predicate;
 import com.google.gerrit.server.query.QueryParseException;
 import com.google.gerrit.server.query.change.ChangeData;
@@ -93,8 +94,8 @@ public class LuceneChangeIndex implements ChangeIndex, LifecycleListener {
       LoggerFactory.getLogger(LuceneChangeIndex.class);
 
   public static final Version LUCENE_VERSION = Version.LUCENE_43;
-  public static final String CHANGES_OPEN = "changes_open";
-  public static final String CHANGES_CLOSED = "changes_closed";
+  public static final String CHANGES_OPEN = "open";
+  public static final String CHANGES_CLOSED = "closed";
   private static final String ID_FIELD = ChangeField.LEGACY_ID.getName();
 
   private static IndexWriterConfig getIndexWriterConfig(Config cfg, String name) {
@@ -113,19 +114,23 @@ public class LuceneChangeIndex implements ChangeIndex, LifecycleListener {
   private final FillArgs fillArgs;
   private final ExecutorService executor;
   private final boolean readOnly;
+  private final Schema<ChangeData> fields;
   private final SubIndex openIndex;
   private final SubIndex closedIndex;
 
   LuceneChangeIndex(Config cfg, SitePaths sitePaths,
       ListeningScheduledExecutorService executor, FillArgs fillArgs,
-      boolean readOnly) throws IOException {
+      Schema<ChangeData> fields, boolean readOnly) throws IOException {
     this.sitePaths = sitePaths;
     this.fillArgs = fillArgs;
     this.executor = executor;
     this.readOnly = readOnly;
-    openIndex = new SubIndex(new File(sitePaths.index_dir, CHANGES_OPEN),
+    this.fields = fields;
+
+    File dir = new File(sitePaths.index_dir, "changes_" + fields.getVersion());
+    openIndex = new SubIndex(new File(dir, CHANGES_OPEN),
         getIndexWriterConfig(cfg, "changes_open"));
-    closedIndex = new SubIndex(new File(sitePaths.index_dir, CHANGES_CLOSED),
+    closedIndex = new SubIndex(new File(dir, CHANGES_CLOSED),
           getIndexWriterConfig(cfg, "changes_closed"));
   }
 
@@ -323,7 +328,7 @@ public class LuceneChangeIndex implements ChangeIndex, LifecycleListener {
   private Document toDocument(ChangeData cd) throws IOException {
     try {
       Document result = new Document();
-      for (FieldDef<ChangeData, ?> f : ChangeField.ALL.values()) {
+      for (FieldDef<ChangeData, ?> f : fields.getFields().values()) {
         if (f.isRepeatable()) {
           add(result, f, (Iterable<?>) f.get(cd, fillArgs));
         } else {

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

@@ -19,6 +19,7 @@ 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.ChangeSchemas;
 import com.google.gerrit.server.index.FieldDef.FillArgs;
 import com.google.gerrit.server.index.IndexExecutor;
 import com.google.gerrit.server.index.IndexModule;
@@ -61,6 +62,7 @@ public class LuceneIndexModule extends LifecycleModule {
       SitePaths sitePaths,
       @IndexExecutor ListeningScheduledExecutorService executor,
       FillArgs fillArgs) throws IOException {
-    return new LuceneChangeIndex(cfg, sitePaths, executor, fillArgs, readOnly);
+    return new LuceneChangeIndex(cfg, sitePaths, executor, fillArgs,
+        ChangeSchemas.getLatestRelease(), readOnly);
   }
 }