refactor cache creation to avoid instanceOf

Author: Vladimir Kotal

opengrok-indexer/src/main/java/org/opengrok/indexer/history/Repository.java

@@ -349,6 +349,10 @@ protected String getRevisionForAnnotate(String history_revision) {
         return history_revision;
     }
 
+    protected void doCreateCache(HistoryCache cache, String sinceRevision, File directory) throws HistoryException {
+        finishCreateCache(cache, getHistory(directory, sinceRevision), null);
+    }
+
     /**
      * Create a history log cache for all files in this repository.
      * {@code getHistory()} is used to fetch the history for the entire
@@ -380,34 +384,10 @@ final void createCache(HistoryCache cache, String sinceRevision) throws HistoryE
 
         File directory = new File(getDirectoryName());
 
-        History history;
-        if (!(this instanceof RepositoryWithPerPartesHistory)) {
-            history = getHistory(directory, sinceRevision);
-            finishCreateCache(cache, history, null);
-            return;
-        }
-
-        // For repositories that supports this, avoid storing complete History in memory
-        // (which can be sizeable, at least for the initial indexing, esp. if merge changeset support is enabled),
-        // by splitting the work into multiple chunks.
-        RepositoryWithPerPartesHistory repo = (RepositoryWithPerPartesHistory) this;
-        BoundaryChangesets boundaryChangesets = new BoundaryChangesets(repo);
-        List<String> boundaryChangesetList = boundaryChangesets.getBoundaryChangesetIDs(sinceRevision);
-        LOGGER.log(Level.FINE, "boundary changesets: {0}", boundaryChangesetList);
-        int cnt = 0;
-        for (String tillRevision: boundaryChangesetList) {
-            Statistics stat = new Statistics();
-            LOGGER.log(Level.FINEST, "getting history for ({0}, {1})", new Object[]{sinceRevision, tillRevision});
-            history = repo.getHistory(directory, sinceRevision, tillRevision);
-            finishCreateCache(cache, history, tillRevision);
-            sinceRevision = tillRevision;
-
-            stat.report(LOGGER, Level.FINE, String.format("finished chunk %d/%d of history cache for repository ''%s''",
-                    ++cnt, boundaryChangesetList.size(), this.getDirectoryName()));
-        }
+        doCreateCache(cache, sinceRevision, directory);
     }
 
-    private void finishCreateCache(HistoryCache cache, History history, String tillRevision) throws HistoryException {
+    void finishCreateCache(HistoryCache cache, History history, String tillRevision) throws HistoryException {
         // We need to refresh list of tags for incremental reindex.
         RuntimeEnvironment env = RuntimeEnvironment.getInstance();
         if (env.isTagsEnabled() && this.hasFileBasedTags()) {

opengrok-indexer/src/main/java/org/opengrok/indexer/history/RepositoryWithPerPartesHistory.java

@@ -22,8 +22,14 @@
  */
 package org.opengrok.indexer.history;
 
+import org.opengrok.indexer.logger.LoggerFactory;
+import org.opengrok.indexer.util.Statistics;
+
 import java.io.File;
+import java.util.List;
 import java.util.function.Consumer;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 
 /**
  * Repositories extending this class will benefit from per partes history
@@ -33,6 +39,8 @@ public abstract class RepositoryWithPerPartesHistory extends Repository {
     private static final long serialVersionUID = -3433255821312805064L;
     public static final int MAX_CHANGESETS = 128;
 
+    private static final Logger LOGGER = LoggerFactory.getLogger(RepositoryWithPerPartesHistory.class);
+
     /**
      * Just like for {@link Repository#getHistory(File)} it is expected that the lists of (renamed) files
      * individual files (i.e. not directory) are empty.
@@ -58,4 +66,24 @@ public int getPerPartesCount() {
      * @throws HistoryException on error during history retrieval
      */
     public abstract void accept(String sinceRevision, Consumer<String> visitor) throws HistoryException;
+
+    @Override
+    protected void doCreateCache(HistoryCache cache, String sinceRevision, File directory) throws HistoryException {
+        // For repositories that supports this, avoid storing complete History in memory
+        // (which can be sizeable, at least for the initial indexing, esp. if merge changeset support is enabled),
+        // by splitting the work into multiple chunks.
+        BoundaryChangesets boundaryChangesets = new BoundaryChangesets(this);
+        List<String> boundaryChangesetList = boundaryChangesets.getBoundaryChangesetIDs(sinceRevision);
+        LOGGER.log(Level.FINE, "boundary changesets: {0}", boundaryChangesetList);
+        int cnt = 0;
+        for (String tillRevision: boundaryChangesetList) {
+            Statistics stat = new Statistics();
+            LOGGER.log(Level.FINEST, "getting history for ({0}, {1})", new Object[]{sinceRevision, tillRevision});
+            finishCreateCache(cache, getHistory(directory, sinceRevision, tillRevision), tillRevision);
+            sinceRevision = tillRevision;
+
+            stat.report(LOGGER, Level.FINE, String.format("finished chunk %d/%d of history cache for repository ''%s''",
+                    ++cnt, boundaryChangesetList.size(), this.getDirectoryName()));
+        }
+    }
 }