notebookAuthorization as singleton

zeppelin-server/src/main/java/org/apache/zeppelin/server/ZeppelinServer.java

@@ -92,7 +92,7 @@ public class ZeppelinServer extends Application {
         notebookWsServer, heliumApplicationFactory, depResolver);
     this.notebookRepo = new NotebookRepoSync(conf);
     this.notebookIndex = new LuceneSearch();
-    this.notebookAuthorization = new NotebookAuthorization(conf);
+    this.notebookAuthorization = NotebookAuthorization.init(conf);
     this.credentials = new Credentials(conf.credentialsPersist(), conf.getCredentialsPath());
     notebook = new Notebook(conf,
         notebookRepo, schedulerFactory, replFactory, notebookWsServer,

zeppelin-zengine/src/main/java/org/apache/zeppelin/notebook/NotebookAuthorization.java

@@ -31,17 +31,22 @@ import java.util.*;
  */
 public class NotebookAuthorization {
   private static final Logger LOG = LoggerFactory.getLogger(NotebookAuthorization.class);
-
+  private static NotebookAuthorization instance = null;
   /*
    * { "note1": { "owners": ["u1"], "readers": ["u1", "u2"], "writers": ["u1"] },  "note2": ... } }
    */
-  private Map<String, Map<String, Set<String>>> authInfo = new HashMap<>();
-  private ZeppelinConfiguration conf;
-  private Gson gson;
-  private String filePath;
+  private static Map<String, Map<String, Set<String>>> authInfo = new HashMap<>();
+  private static ZeppelinConfiguration conf;
+  private static Gson gson;
+  private static String filePath;
 
-  public NotebookAuthorization(ZeppelinConfiguration conf) {
-    this.conf = conf;
+  private NotebookAuthorization() {}
+
+  public static NotebookAuthorization init(ZeppelinConfiguration config) {
+    if (instance == null) {
+      instance = new NotebookAuthorization();
+    }
+    conf = config;
     filePath = conf.getNotebookAuthorizationPath();
     GsonBuilder builder = new GsonBuilder();
     builder.setPrettyPrinting();
@@ -51,9 +56,19 @@ public class NotebookAuthorization {
     } catch (IOException e) {
       LOG.error("Error loading NotebookAuthorization", e);
     }
+    return instance;
   }
 
-  private void loadFromFile() throws IOException {
+  public static NotebookAuthorization getInstance() {
+    if (instance == null) {
+      LOG.warn("Notebook authorization module was called without initialization,"
+          + " initializing with default configuration");
+      init(ZeppelinConfiguration.create());
+    }
+    return instance;
+  }
+
+  private static void loadFromFile() throws IOException {
     File settingFile = new File(filePath);
     LOG.info(settingFile.getAbsolutePath());
     if (!settingFile.exists()) {
@@ -74,7 +89,7 @@ public class NotebookAuthorization {
     String json = sb.toString();
     NotebookAuthorizationInfoSaving info = gson.fromJson(json,
             NotebookAuthorizationInfoSaving.class);
-    this.authInfo = info.authInfo;
+    authInfo = info.authInfo;
   }
 
   private void saveToFile() {

zeppelin-zengine/src/test/java/org/apache/zeppelin/helium/HeliumApplicationFactoryTest.java

@@ -89,7 +89,7 @@ public class HeliumApplicationFactoryTest implements JobListenerFactory {
 
     SearchService search = mock(SearchService.class);
     notebookRepo = new VFSNotebookRepo(conf);
-    NotebookAuthorization notebookAuthorization = new NotebookAuthorization(conf);
+    NotebookAuthorization notebookAuthorization = NotebookAuthorization.init(conf);
     notebook = new Notebook(
         conf,
         notebookRepo,

zeppelin-zengine/src/test/java/org/apache/zeppelin/notebook/NotebookTest.java

@@ -91,7 +91,7 @@ public class NotebookTest implements JobListenerFactory{
 
     SearchService search = mock(SearchService.class);
     notebookRepo = new VFSNotebookRepo(conf);
-    notebookAuthorization = new NotebookAuthorization(conf);
+    notebookAuthorization = NotebookAuthorization.init(conf);
     credentials = new Credentials(conf.credentialsPersist(), conf.getCredentialsPath());
 
     notebook = new Notebook(conf, notebookRepo, schedulerFactory, factory, this, search,

zeppelin-zengine/src/test/java/org/apache/zeppelin/notebook/repo/NotebookRepoSyncTest.java

@@ -99,7 +99,7 @@ public class NotebookRepoSyncTest implements JobListenerFactory {
     
     search = mock(SearchService.class);
     notebookRepoSync = new NotebookRepoSync(conf);
-    notebookAuthorization = new NotebookAuthorization(conf);
+    notebookAuthorization = NotebookAuthorization.init(conf);
     credentials = new Credentials(conf.credentialsPersist(), conf.getCredentialsPath());
     notebookSync = new Notebook(conf, notebookRepoSync, schedulerFactory, factory, this, search,
             notebookAuthorization, credentials);