Automatically delete corrupt indexes upon detection

src/main/java/com/cloudant/search3/FDBDirectorySearchHandlerFactory.java

@@ -59,6 +59,14 @@ public SearchHandler open(final Database db, final Subspace index, final Analyze
         return new FDBDirectorySearchHandler(dir, writer, manager, analyzer);
     }
 
+    @Override
+    public void delete(final Database db, final Subspace index) {
+        db.run(txn -> {
+           txn.clear(index.range());
+           return null;
+        });
+    }
+
     /**
      * The current holder of the lock will know they lost the lock on their next
      * attempt at a destructive operation and will crash cleanly.

src/main/java/com/cloudant/search3/Search.java

@@ -29,6 +29,7 @@
 import org.apache.lucene.analysis.Analyzer;
 import org.apache.lucene.analysis.TokenStream;
 import org.apache.lucene.analysis.tokenattributes.TermToBytesRefAttribute;
+import org.apache.lucene.index.CorruptIndexException;
 import org.apache.lucene.queryparser.classic.ParseException;
 import org.apache.lucene.store.AlreadyClosedException;
 import org.apache.lucene.util.BytesRef;
@@ -294,6 +295,10 @@ private <T> void execute(
         try {
             final SearchHandler handler = getOrOpen(index);
             f.accept(handler);
+        } catch (final CorruptIndexException e) {
+            searchHandlerFactory.delete(db, toSubspace(index));
+            failedHandler(index, e);
+            responseObserver.onError(fromThrowable(e));
         } catch (final IOException | AlreadyClosedException e) {
             failedHandler(index, e);
             responseObserver.onError(fromThrowable(e));

src/main/java/com/cloudant/search3/SearchHandlerFactory.java

@@ -25,4 +25,6 @@ public interface SearchHandlerFactory {
 
     SearchHandler open(final Database db, final Subspace index, final Analyzer analyzer) throws IOException;
 
+    void delete(final Database db, final Subspace index);
+
 }