Merge pull request #10307 from vespa-engine/hmusum/cleanup-zk-application

Hmusum/cleanup zk application

7 files changed, 69 insertions, 164 deletions

diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClient.java b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClient.java
index a99a2a2917d..401b6974596 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClient.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/deploy/ZooKeeperClient.java
@@ -42,12 +42,7 @@ public class ZooKeeperClient {
     /* This is the generation that will be used for reading and writing application data. (1 more than last deployed application) */
     private final Path rootPath;
 
-    static final ApplicationFile.PathFilter xmlFilter = new ApplicationFile.PathFilter() {
-        @Override
-        public boolean accept(Path path) {
-            return path.getName().endsWith(".xml");
-        }
-    };
+    private static final ApplicationFile.PathFilter xmlFilter = path -> path.getName().endsWith(".xml");
 
     public ZooKeeperClient(ConfigCurator configCurator, DeployLogger logger, boolean logFine, Path rootPath) {
         this.configCurator = configCurator;
@@ -116,23 +111,15 @@ public class ZooKeeperClient {
         logFine("Feeding application config into ZooKeeper");
         // gives lots and lots of debug output: // BasicConfigurator.configure();
         try {
-            logFine("zk operations: " + configCurator.getNumberOfOperations());
             logFine("Feeding user def files into ZooKeeper");
             writeUserDefs(app);
-            logFine("zk operations: " + configCurator.getNumberOfOperations());
             logFine("Feeding application package into ZooKeeper");
-            // TODO 1200 zk operations done in the below method
             writeSomeOf(app);
             writeSearchDefinitions(app);
             writeUserIncludeDirs(app, app.getUserIncludeDirs());
-            logFine("zk operations: " + configCurator.getNumberOfOperations());
-            logFine("zk read operations: " + configCurator.getNumberOfReadOperations());
-            logFine("zk write operations: " + configCurator.getNumberOfWriteOperations());
             logFine("Feeding sd from docproc bundle into ZooKeeper");
-            logFine("zk operations: " + configCurator.getNumberOfOperations());
             logFine("Write application metadata into ZooKeeper");
             write(app.getMetaData());
-            logFine("zk operations: " + configCurator.getNumberOfOperations());
         } catch (Exception e) {
             throw new IllegalStateException("Unable to write vespa model to config server(s) " + System.getProperty("configsources") + "\n" +
                     "Please ensure that cloudconfig_server is started on the config server node(s), " +
@@ -164,7 +151,7 @@ public class ZooKeeperClient {
      * @param app The application package to use as input.
      * @throws java.io.IOException  if not able to write to Zookeeper
      */
-    void writeSomeOf(ApplicationPackage app) throws IOException {
+    private void writeSomeOf(ApplicationPackage app) throws IOException {
         ApplicationFile.PathFilter srFilter = new ApplicationFile.PathFilter() {
             @Override
             public boolean accept(Path path) {
@@ -342,7 +329,7 @@ public class ZooKeeperClient {
      * @param trailingPath trailing part of path to be appended to ZK app path
      * @return a String with the full ZK application path including trailing path, if set
      */
-    Path getZooKeeperAppPath(String trailingPath) {
+    private Path getZooKeeperAppPath(String trailingPath) {
         if (trailingPath != null) {
             return rootPath.append(trailingPath);
         } else {
@@ -350,7 +337,7 @@ public class ZooKeeperClient {
         }
     }
 
-    void logFine(String msg) {
+    private void logFine(String msg) {
         if (logFine) {
             logger.log(LogLevel.FINE, msg);
         }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ConfigCurator.java b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ConfigCurator.java
index 56709225c1d..30754b7bc04 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ConfigCurator.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ConfigCurator.java
@@ -13,7 +13,6 @@ import java.io.FilenameFilter;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.concurrent.atomic.AtomicInteger;
 
 /**
  * A (stateful) curator wrapper for the config server. This simplifies Curator method calls used by the config server
@@ -23,17 +22,12 @@ import java.util.concurrent.atomic.AtomicInteger;
  * Config ids are stored as foo#bar#c0 instead of foo/bar/c0, for simplicity.
  * Keep the amount of domain-specific logic here to a minimum.
  * Data for one application x is stored on this form:
- * /vespa/config/apps/x/defconfigs
- * /vespa/config/apps/x/userapp
- * The different types of configs are stored on this form (ie. names of the ZK nodes under their respective
- * paths):
+ * /config/v2/tenants/x/sessions/y/defconfigs
+ * /config/v2/tenants/x/sessions/y/userapp
  * <p>
- * Def configs are stored on the form        name,version
  * The user application structure is exactly the same as in the user's app dir during deploy.
- * The current live app id (for example x) is stored in the node /vespa/config/liveapp
- * It is updated outside this class, typically in config server during reload-config.
- * Some methods have retries and/or reconnect. This is necessary because ZK will throw on certain scenarios,
- * even though it will recover from it itself, @see http://wiki.apache.org/hadoop/ZooKeeper/ErrorHandling
+ * The current live app id (for example y) is stored in the node //config/v2/tenants/x/applications/&lt;application-id&gt;
+ * It is updated outside this class, typically in config server when activating config
  *
  * @author Vegard Havdal
  * @author bratseth
@@ -55,33 +49,15 @@ public class ConfigCurator {
     /** Path for session state */
     public static final String SESSIONSTATE_ZK_SUBPATH = "/sessionState";
 
-    protected static final FilenameFilter acceptsAllFileNameFilter = (dir, name) -> true;
+    private static final FilenameFilter acceptsAllFileNameFilter = (dir, name) -> true;
 
     private final Curator curator;
 
     public static final java.util.logging.Logger log = java.util.logging.Logger.getLogger(ConfigCurator.class.getName());
 
-    /** The number of zookeeper operations done with this ZKFacade instance */
-    private final AtomicInteger operations = new AtomicInteger();
-
-    /** The number of zookeeper read operations done with this ZKFacade instance */
-    private final AtomicInteger readOperations = new AtomicInteger();
-
-    /** The number of zookeeper write operations done with this ZKFacade instance */
-    private final AtomicInteger writeOperations = new AtomicInteger();
-
     /** The maximum size of a ZooKeeper node */
     private final int maxNodeSize;
 
-    /**
-     * Sets up thread local zk access if not done before and returns a facade object
-     *
-     * @return a ZKFacade object
-     */
-    public static ConfigCurator create(Curator curator, int juteMaxBuffer) {
-        return new ConfigCurator(curator, juteMaxBuffer);
-    }
-
     public static ConfigCurator create(Curator curator) {
         return new ConfigCurator(curator, 1024*1024*10);
     }
@@ -102,10 +78,8 @@ public class ConfigCurator {
     public Curator curator() { return curator; }
 
     /** Cleans and creates a zookeeper completely */
-    public void initAndClear(String path) {
+    void initAndClear(String path) {
         try {
-            operations.incrementAndGet();
-            readOperations.incrementAndGet();
             if (exists(path))
                 deleteRecurse(path);
             createRecurse(path);
@@ -151,8 +125,6 @@ public class ConfigCurator {
     public byte[] getBytes(String path) {
         try {
             if ( ! exists(path)) return null; // TODO: Ugh
-            operations.incrementAndGet();
-            readOperations.incrementAndGet();
             return curator.framework().getData().forPath(path);
         }
         catch (Exception e) {
@@ -179,8 +151,6 @@ public class ConfigCurator {
     public void createNode(String path) {
         if ( ! exists(path))
             createRecurse(path);
-        operations.incrementAndGet();
-        writeOperations.incrementAndGet();
     }
 
     /** Creates a Zookeeper node synchronously. Replaces / by # in node names. */
@@ -210,7 +180,7 @@ public class ConfigCurator {
     }
 
     /** Sets data at a given path and name. Replaces / by # in node names. Creates the node if it doesn't exist */
-    public void putData(String path, String node, byte[] data) {
+    private void putData(String path, String node, byte[] data) {
         putData(createFullPath(path, node), data);
     }
 
@@ -218,8 +188,6 @@ public class ConfigCurator {
     public void putData(String path, byte[] data) {
         try {
             ensureDataIsNotTooLarge(data, path);
-            operations.incrementAndGet();
-            writeOperations.incrementAndGet();
             if (exists(path))
                 curator.framework().setData().forPath(path, data);
             else
@@ -230,36 +198,13 @@ public class ConfigCurator {
         }
     }
 
-    /** Sets data at an existing node. Replaces / by # in node names. */
-    public void setData(String path, String node, String data) {
-        setData(path, node, Utf8.toBytes(data));
-    }
-
-    /** Sets data at an existing node. Replaces / by # in node names. */
-    public void setData(String path, String node, byte[] data) {
-        setData(createFullPath(path, node), data);
-    }
-
-    /** Sets data at an existing node. Replaces / by # in node names. */
-    public void setData(String path, byte[] data) {
-        try {
-            ensureDataIsNotTooLarge(data, path);
-            operations.incrementAndGet();
-            writeOperations.incrementAndGet();
-            curator.framework().setData().forPath(path, data);
-        }
-        catch (Exception e) {
-            throw new RuntimeException("Exception writing to path " + path + " in ZooKeeper", e);
-        }
-    }
-
     /**
      * Replaces / with # in the given node.
      *
      * @param node a zookeeper node name
      * @return a config server node name
      */
-    protected String toConfigserverName(String node) {
+    private String toConfigserverName(String node) {
         if (node.startsWith("/")) node = node.substring(1);
         return node.replaceAll("/", "#");
     }
@@ -271,8 +216,6 @@ public class ConfigCurator {
      */
     public List<String> getChildren(String path) {
         try {
-            operations.incrementAndGet();
-            readOperations.incrementAndGet();
             return curator.framework().getChildren().forPath(path);
         }
         catch (Exception e) {
@@ -300,7 +243,7 @@ public class ConfigCurator {
      * @param filenameFilter A FilenameFilter which decides which files in dir are fed to zookeeper
      * @param recurse        recurse subdirectories
      */
-    public void feedZooKeeper(File dir, String path, FilenameFilter filenameFilter, boolean recurse) {
+    void feedZooKeeper(File dir, String path, FilenameFilter filenameFilter, boolean recurse) {
         try {
             if (filenameFilter == null) {
                 filenameFilter = acceptsAllFileNameFilter;
@@ -347,7 +290,7 @@ public class ConfigCurator {
                 }
             }
         }
-        return ret.toArray(new File[ret.size()]);
+        return ret.toArray(new File[0]);
     }
 
     /** Deletes the node at the given path, and any children it may have. If the node does not exist this does nothing */
@@ -361,17 +304,6 @@ public class ConfigCurator {
         }
     }
 
-    public Integer getNumberOfOperations() { return operations.intValue(); }
-
-    public Integer getNumberOfReadOperations() {
-        return readOperations.intValue();
-    }
-
-    public Integer getNumberOfWriteOperations() {
-        return writeOperations.intValue();
-    }
-
-
     private void testZkConnection() { // This is not necessary, but allows us to give a useful error message
         if (curator.connectionSpec().isEmpty()) return;
         try {
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/InitializedCounter.java b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/InitializedCounter.java
index dc93886e0c0..773888a8a03 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/InitializedCounter.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/InitializedCounter.java
@@ -17,10 +17,10 @@ import java.util.List;
 public class InitializedCounter {
 
     private static final java.util.logging.Logger log = java.util.logging.Logger.getLogger(InitializedCounter.class.getName());
-    protected final CuratorCounter counter;
+    final CuratorCounter counter;
     private final String sessionsDirPath;
 
-    public InitializedCounter(ConfigCurator configCurator, String counterPath, String sessionsDirPath) {
+    InitializedCounter(ConfigCurator configCurator, String counterPath, String sessionsDirPath) {
         this.sessionsDirPath = sessionsDirPath;
         this.counter = new CuratorCounter(configCurator.curator(), counterPath);
         initializeCounterValue(getLatestSessionId(configCurator, sessionsDirPath));
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKLiveApp.java b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplication.java
index 383672b3639..3ae678969eb 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKLiveApp.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplication.java
@@ -9,25 +9,22 @@ import java.io.StringReader;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.List;
-import java.util.logging.Logger;
 
 /**
- * Responsible for providing data from the currently live application subtree in zookeeper.
- * (i.e. /vespa/config/apps/&lt;id of currently active app&gt;/).
+ * Responsible for providing data from an application subtree in zookeeper.
+ * (i.e. /config/v2/tenants/x/session/&lt;session id for an application&gt;/).
+ *
+ * Takes care of
  *
- * Note: The application revision ("session") stored in this tree is not necessarily live, just complete,
- * preparable, prepared or active.
  *
  * @author Tony Vaagenes
  */
-public class ZKLiveApp {
-
-    private static final Logger log = Logger.getLogger(ZKLiveApp.class.getName());
+public class ZKApplication {
 
     private final ConfigCurator zk;
     private final Path appPath;
 
-    public ZKLiveApp(ConfigCurator zk, Path appPath) {
+    ZKApplication(ConfigCurator zk, Path appPath) {
         this.zk = zk;
         this.appPath = appPath;
     }
@@ -36,14 +33,14 @@ public class ZKLiveApp {
      * Returns a list of the files (as readers) in the given path. The readers <b>must</b>
      * be closed by the caller.
      *
-     * @param path           a path relative to the currently active application
-     *                       (i.e. /vespa/config/apps/&lt;id of currently active app&gt;/).
+     * @param path           a path relative to the session
+     *                       (i.e. /config/v2/tenants/x/sessions/&lt;session id&gt;/).
      * @param fileNameSuffix the suffix of files to return, or null to return all
      * @param recursive      if true, all files from all subdirectories of this will also be returned
-     * @return the files in the given path, or an empty list (never null) if the directory does not exist or is empty.
+     * @return the files in the given path, or an empty list if the directory does not exist or is empty.
      *         The list gets owned by the caller and can be modified freely.
      */
-    public List<NamedReader> getAllDataFromDirectory(String path, String fileNameSuffix, boolean recursive) {
+    List<NamedReader> getAllDataFromDirectory(String path, String fileNameSuffix, boolean recursive) {
         return getAllDataFromDirectory(path, "", fileNameSuffix, recursive);
     }
 
@@ -73,14 +70,13 @@ public class ZKLiveApp {
     }
 
     /**
-     * Retrieves a node relative to the node of the live application,
-     * e.g. /vespa/config/apps/$lt;app_id&gt;/&lt;path&gt;/&lt;node&gt;
+     * Retrieves a node relative to the node of the live application
      *
      * @param path a path relative to the currently active application
      * @param node a path relative to the path above
      * @return a Reader that can be used to get the data
      */
-    public Reader getDataReader(String path, String node) {
+    Reader getDataReader(String path, String node) {
         String data = getData(path, node);
         if (data == null) {
             throw new IllegalArgumentException("No node for " + getFullPath(path) + "/" + node + " exists");
@@ -113,7 +109,7 @@ public class ZKLiveApp {
         }
     }
 
-    public void putData(String path, String data) {
+    void putData(String path, String data) {
         try {
             zk.putData(getFullPath(path), data);
         } catch (RuntimeException e) {
@@ -121,15 +117,6 @@ public class ZKLiveApp {
         }
     }
 
-    public void create(String path, String node) {
-        if (path != null && !path.startsWith("/")) path = "/" + path;
-        try {
-            zk.createNode(getFullPath(path), node);
-        } catch (RuntimeException e) {
-            throw new IllegalArgumentException(e);
-        }
-    }
-
     /**
      * Checks if the given node exists under path under this live app
      *
@@ -164,7 +151,7 @@ public class ZKLiveApp {
      *
      * @param path path to delete
      */
-    public void deleteRecurse(String path) {
+    void deleteRecurse(String path) {
         zk.deleteRecurse(getFullPath(path));
     }
 
@@ -193,7 +180,7 @@ public class ZKLiveApp {
         }
     }
 
-    public Reader getDataReader(String path) {
+    Reader getDataReader(String path) {
         final String data = getData(path);
         if (data == null) {
             throw new IllegalArgumentException("No node for " + getFullPath(path) + " exists");
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationFile.java b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationFile.java
index c2d59844fde..ad0d4a2e540 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationFile.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationFile.java
@@ -15,16 +15,15 @@ import java.util.logging.Logger;
 
 /**
  * @author Ulf Lilleengen
- * @author vegardh
- * @since 5.1
+ * @author Vegard Havdal
  */
 class ZKApplicationFile extends ApplicationFile {
 
     private static final Logger log = Logger.getLogger("ZKApplicationFile");
-    private final ZKLiveApp zkApp;
+    private final ZKApplication zkApp;
     private final ObjectMapper mapper = new ObjectMapper();
 
-    public ZKApplicationFile(Path path, ZKLiveApp app) {
+    public ZKApplicationFile(Path path, ZKApplication app) {
         super(path);
         this.zkApp = app;
     }
diff --git a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java
index e013244c80c..786b26318a3 100644
--- a/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java
+++ b/configserver/src/main/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationPackage.java
@@ -31,6 +31,7 @@ import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.Optional;
 
 /**
@@ -40,7 +41,7 @@ import java.util.Optional;
  */
 public class ZKApplicationPackage implements ApplicationPackage {
 
-    private ZKLiveApp liveApp;
+    private ZKApplication zkApplication;
 
     private final Map<Version, PreGeneratedFileRegistry> fileRegistryMap = new HashMap<>();
     private final Optional<AllocatedHosts> allocatedHosts;
@@ -50,17 +51,17 @@ public class ZKApplicationPackage implements ApplicationPackage {
     public static final String allocatedHostsNode = "allocatedHosts";
     private final ApplicationMetaData metaData;
 
-    public ZKApplicationPackage(ConfigCurator zk, Path appPath, Optional<NodeFlavors> nodeFlavors) {
-        verifyAppPath(zk, appPath);
-        liveApp = new ZKLiveApp(zk, appPath);
-        metaData = readMetaDataFromLiveApp(liveApp);
-        importFileRegistries(fileRegistryNode);
-        allocatedHosts = importAllocatedHosts(allocatedHostsNode, nodeFlavors);
+    public ZKApplicationPackage(ConfigCurator zk, Path sessionPath, Optional<NodeFlavors> nodeFlavors) {
+        verifyAppPath(zk, sessionPath);
+        zkApplication = new ZKApplication(zk, sessionPath);
+        metaData = readMetaDataFromLiveApp(zkApplication);
+        importFileRegistries();
+        allocatedHosts = importAllocatedHosts(nodeFlavors);
     }
 
-    private Optional<AllocatedHosts> importAllocatedHosts(String allocatedHostsPath, Optional<NodeFlavors> nodeFlavors) {
-        if ( ! liveApp.exists(allocatedHostsPath)) return Optional.empty();
-        return Optional.of(readAllocatedHosts(allocatedHostsPath, nodeFlavors));
+    private Optional<AllocatedHosts> importAllocatedHosts(Optional<NodeFlavors> nodeFlavors) {
+        if ( ! zkApplication.exists(ZKApplicationPackage.allocatedHostsNode)) return Optional.empty();
+        return Optional.of(readAllocatedHosts(nodeFlavors));
     }
 
     /**
@@ -68,35 +69,35 @@ public class ZKApplicationPackage implements ApplicationPackage {
      *
      * @return the allocated hosts at this node or empty if there is no data at this path
      */
-    private AllocatedHosts readAllocatedHosts(String allocatedHostsPath, Optional<NodeFlavors> nodeFlavors) {
+    private AllocatedHosts readAllocatedHosts(Optional<NodeFlavors> nodeFlavors) {
         try {
-            return AllocatedHostsSerializer.fromJson(liveApp.getBytes(allocatedHostsPath), nodeFlavors);
+            return AllocatedHostsSerializer.fromJson(zkApplication.getBytes(ZKApplicationPackage.allocatedHostsNode), nodeFlavors);
         } catch (Exception e) {
             throw new RuntimeException("Unable to read allocated hosts", e);
         }
     }
 
-    private void importFileRegistries(String fileRegistryNode) {
-        List<String> fileRegistryNodes = liveApp.getChildren(fileRegistryNode);
+    private void importFileRegistries() {
+        List<String> fileRegistryNodes = zkApplication.getChildren(ZKApplicationPackage.fileRegistryNode);
         if (fileRegistryNodes.isEmpty()) {
-            fileRegistryMap.put(legacyVersion, importFileRegistry(fileRegistryNode));
+            fileRegistryMap.put(legacyVersion, importFileRegistry(ZKApplicationPackage.fileRegistryNode));
         } else {
             fileRegistryNodes.forEach(version ->
                         fileRegistryMap.put(Version.fromString(version),
-                                            importFileRegistry(Joiner.on("/").join(fileRegistryNode, version))));
+                                            importFileRegistry(Joiner.on("/").join(ZKApplicationPackage.fileRegistryNode, version))));
         }
     }
 
     private PreGeneratedFileRegistry importFileRegistry(String fileRegistryNode) {
         try {
-            return PreGeneratedFileRegistry.importRegistry(liveApp.getDataReader(fileRegistryNode));
+            return PreGeneratedFileRegistry.importRegistry(zkApplication.getDataReader(fileRegistryNode));
         } catch (Exception e) {
             throw new RuntimeException("Could not determine which files to distribute. " +
                                        "Please try redeploying the application", e);
         }
     }
 
-    private ApplicationMetaData readMetaDataFromLiveApp(ZKLiveApp liveApp) {
+    private ApplicationMetaData readMetaDataFromLiveApp(ZKApplication liveApp) {
         String metaDataString = liveApp.getData(ConfigCurator.META_ZK_PATH);
         if (metaDataString == null || metaDataString.isEmpty()) {
             return null;
@@ -126,7 +127,7 @@ public class ZKApplicationPackage implements ApplicationPackage {
 
     @Override
     public Reader getHosts() {
-        if (liveApp.exists(ConfigCurator.USERAPP_ZK_SUBPATH,HOSTS))
+        if (zkApplication.exists(ConfigCurator.USERAPP_ZK_SUBPATH, HOSTS))
         	return getUserAppData(HOSTS);
         return null;
     }
@@ -134,9 +135,9 @@ public class ZKApplicationPackage implements ApplicationPackage {
     @Override
     public List<NamedReader> searchDefinitionContents() {
         List<NamedReader> ret = new ArrayList<>();
-        for (String sd : liveApp.getChildren(ConfigCurator.USERAPP_ZK_SUBPATH+"/"+SEARCH_DEFINITIONS_DIR)) {
+        for (String sd : zkApplication.getChildren(ConfigCurator.USERAPP_ZK_SUBPATH+"/"+SEARCH_DEFINITIONS_DIR)) {
             if (sd.endsWith(ApplicationPackage.SD_NAME_SUFFIX)) {
-                ret.add(new NamedReader(sd, new StringReader(liveApp.getData(ConfigCurator.USERAPP_ZK_SUBPATH+"/"+SEARCH_DEFINITIONS_DIR, sd))));
+                ret.add(new NamedReader(sd, new StringReader(zkApplication.getData(ConfigCurator.USERAPP_ZK_SUBPATH+"/"+SEARCH_DEFINITIONS_DIR, sd))));
             }
         }
         return ret;
@@ -155,7 +156,7 @@ public class ZKApplicationPackage implements ApplicationPackage {
     private Optional<PreGeneratedFileRegistry> getPreGeneratedFileRegistry(Version vespaVersion) {
         // Assumes at least one file registry, which we always have.
         Optional<PreGeneratedFileRegistry> fileRegistry = Optional.ofNullable(fileRegistryMap.get(vespaVersion));
-        if ( ! fileRegistry.isPresent()) {
+        if (fileRegistry.isEmpty()) {
             fileRegistry = Optional.of(fileRegistryMap.values().iterator().next());
         }
         return fileRegistry;
@@ -168,7 +169,7 @@ public class ZKApplicationPackage implements ApplicationPackage {
 
     private Reader retrieveConfigDefReader(String def) {
         try {
-            return liveApp.getDataReader(ConfigCurator.DEFCONFIGS_ZK_SUBPATH, def);
+            return zkApplication.getDataReader(ConfigCurator.DEFCONFIGS_ZK_SUBPATH, def);
         } catch (IllegalArgumentException e) {
             throw new IllegalArgumentException("Could not retrieve config definition " + def + ".", e);
         }
@@ -178,7 +179,7 @@ public class ZKApplicationPackage implements ApplicationPackage {
     public Map<ConfigDefinitionKey, UnparsedConfigDefinition> getAllExistingConfigDefs() {
         Map<ConfigDefinitionKey, UnparsedConfigDefinition> ret = new LinkedHashMap<>();
 
-        List<String> allDefs = liveApp.getChildren(ConfigCurator.DEFCONFIGS_ZK_SUBPATH);
+        List<String> allDefs = zkApplication.getChildren(ConfigCurator.DEFCONFIGS_ZK_SUBPATH);
 
         for (String nodeName : allDefs) {
             ConfigDefinitionKey key = ConfigUtils.createConfigDefinitionKeyFromZKString(nodeName);
@@ -208,12 +209,12 @@ public class ZKApplicationPackage implements ApplicationPackage {
      */
     @Override
     public List<NamedReader> getFiles(Path relativePath, String suffix, boolean recurse) {
-        return liveApp.getAllDataFromDirectory(ConfigCurator.USERAPP_ZK_SUBPATH + '/' + relativePath.getRelative(), suffix, recurse);
+        return zkApplication.getAllDataFromDirectory(ConfigCurator.USERAPP_ZK_SUBPATH + '/' + relativePath.getRelative(), suffix, recurse);
     }
 
     @Override
     public ApplicationFile getFile(Path file) {
-        return new ZKApplicationFile(file, liveApp);
+        return new ZKApplicationFile(file, zkApplication);
     }
 
     @Override
@@ -233,7 +234,7 @@ public class ZKApplicationPackage implements ApplicationPackage {
     public Optional<Reader> getValidationOverrides() { return optionalFile(VALIDATION_OVERRIDES.getName()); }
 
     private Optional<Reader> optionalFile(String file) {
-        if (liveApp.exists(ConfigCurator.USERAPP_ZK_SUBPATH, file))
+        if (zkApplication.exists(ConfigCurator.USERAPP_ZK_SUBPATH, file))
             return Optional.of(getUserAppData(file));
         else
             return Optional.empty();
@@ -253,26 +254,25 @@ public class ZKApplicationPackage implements ApplicationPackage {
     }
 
     private Reader getUserAppData(String node) {
-        return liveApp.getDataReader(ConfigCurator.USERAPP_ZK_SUBPATH, node);
+        return zkApplication.getDataReader(ConfigCurator.USERAPP_ZK_SUBPATH, node);
     }
 
     @Override
     public Reader getRankingExpression(String name) {
-        return liveApp.getDataReader(ConfigCurator.USERAPP_ZK_SUBPATH+"/"+SEARCH_DEFINITIONS_DIR, name);
+        return zkApplication.getDataReader(ConfigCurator.USERAPP_ZK_SUBPATH+"/"+SEARCH_DEFINITIONS_DIR, name);
     }
 
     @Override
     public File getFileReference(Path pathRelativeToAppDir) {
-        String fileName = liveApp.getData(ConfigCurator.USERAPP_ZK_SUBPATH + "/" + pathRelativeToAppDir.getRelative());
-        if (fileName == null)
-            return new File(pathRelativeToAppDir.getRelative()); // File does not exist: Manufacture a non-existing file
-        return new File(fileName);
+        String fileName = zkApplication.getData(ConfigCurator.USERAPP_ZK_SUBPATH + "/" + pathRelativeToAppDir.getRelative());
+        // File does not exist: Manufacture a non-existing file
+        return new File(Objects.requireNonNullElseGet(fileName, pathRelativeToAppDir::getRelative));
     }
 
     @Override
     public void validateIncludeDir(String dirName) {
         String fullPath = ConfigCurator.USERAPP_ZK_SUBPATH + "/" + dirName;
-        if (!liveApp.exists(fullPath)) {
+        if ( ! zkApplication.exists(fullPath)) {
             throw new IllegalArgumentException("Cannot include directory '" + dirName +
                                                "', as it does not exist in ZooKeeper!");
         }
diff --git a/configserver/src/test/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationFileTest.java b/configserver/src/test/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationFileTest.java
index 0bea19adaf1..0b028b96eab 100644
--- a/configserver/src/test/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationFileTest.java
+++ b/configserver/src/test/java/com/yahoo/vespa/config/server/zookeeper/ZKApplicationFileTest.java
@@ -31,7 +31,7 @@ public class ZKApplicationFileTest extends ApplicationFileTest {
         File tmp = Files.createTempDir();
         writeAppTo(tmp);
         feed(configCurator, tmp);
-        return new ZKApplicationFile(path, new ZKLiveApp(configCurator, Path.fromString("/0")));
+        return new ZKApplicationFile(path, new ZKApplication(configCurator, Path.fromString("/0")));
     }
 
 }