Pulled handling of initial settings into ComponentContext interface and

simplified its usage

java/com.sap.sse.gwt/src/com/sap/sse/gwt/client/shared/perspective/ComponentContext.java

@@ -58,4 +58,6 @@ public interface ComponentContext<L extends ComponentLifecycle<S, ?>, S extends
     boolean hasMakeCustomDefaultSettingsSupport(Component<?> component);
 
     void initInitialSettings(OnSettingsLoadedCallback<S> onInitialSettingsLoaded);
+
+    void initInitialSettings();
 }

java/com.sap.sse.gwt/src/com/sap/sse/gwt/client/shared/perspective/ComponentContextWithSettingsStorage.java

@@ -1,9 +1,7 @@
 package com.sap.sse.gwt.client.shared.perspective;
 
 import java.util.ArrayList;
-import java.util.LinkedList;
 import java.util.List;
-import java.util.Queue;
 
 import com.google.gwt.core.client.GWT;
 import com.google.gwt.json.client.JSONObject;
@@ -48,18 +46,6 @@ public class ComponentContextWithSettingsStorage<L extends ComponentLifecycle<S,
      */
     private final SettingsStorageManager<S> settingsStorageManager;
 
-    /**
-     * Contains {@link SettingsReceiverCallback}s which are waiting to receive the initial settings of the root
-     * component.
-     */
-    private Queue<SettingsReceiverCallback<S>> settingsReceiverCallbacks = new LinkedList<>();
-
-    /**
-     * Current initial/default settings for the whole settings tree which corresponds to the root component and its
-     * subcomponents.
-     */
-    private S currentDefaultSettings = null;
-
     /**
      * 
      * @param rootLifecycle
@@ -72,73 +58,11 @@ public class ComponentContextWithSettingsStorage<L extends ComponentLifecycle<S,
         super(rootLifecycle);
         this.settingsStorageManager = settingsStorageManager;
     }
-
-    /**
-     * Initialises the instance with initial settings. This method may be called only once during the whole lifecycle of
-     * this instance. The call of this method is mandatory, otherwise it will not be possible to obtain initial
-     * settings.
-     * 
-     * @see #initInitialSettings(OnSettingsLoadedCallback)
-     */
-    public void initInitialSettings() {
-        initInitialSettings(null);
-    }
-
-    /**
-     * Initializes the instance with initial settings. This method may be called only once during the whole lifecycle of
-     * this instance. The call of this method is mandatory, otherwise it will not be possible to obtain initial
-     * settings.
-     * 
-     * @param onInitialSettingsLoaded
-     *            Callback to be called when the settings initialisation finishes
-     * @see #initInitialSettings()
-     */
+    
     @Override
-    public void initInitialSettings(final OnSettingsLoadedCallback<S> onInitialSettingsLoaded) {
-        if (currentDefaultSettings != null) {
-            throw new IllegalStateException(
-                    "Settings have been already initialized. You may only call this method once.");
-        }
+    protected void loadDefaultSettings(OnSettingsLoadedCallback<S> callback) {
         S systemDefaultSettings = rootLifecycle.createDefaultSettings();
-        settingsStorageManager.retrieveDefaultSettings(systemDefaultSettings, new OnSettingsLoadedCallback<S>() {
-
-            @Override
-            public void onError(Throwable caught, S fallbackDefaultSettings) {
-                if (onInitialSettingsLoaded != null) {
-                    onInitialSettingsLoaded.onError(caught, fallbackDefaultSettings);
-                }
-            }
-
-            @Override
-            public void onSuccess(S result) {
-                currentDefaultSettings = result;
-                if (onInitialSettingsLoaded != null) {
-                    onInitialSettingsLoaded.onSuccess(result);
-                }
-                SettingsReceiverCallback<S> callback;
-                while ((callback = settingsReceiverCallbacks.poll()) != null) {
-                    callback.receiveSettings(result);
-                }
-            }
-        });
-    }
-
-    /**
-     * Retrieve settings for the root component managed by this context. The provided callback gets called when
-     * initial/default settings are available. That means if the initialisation of this instance is finished, the
-     * provided callback is called immediately. If initialisation is not done yet, then the callback gets called when
-     * the initialisation gets finished and thus, initial settings are available. Make sure to call
-     * {@link #initInitialSettings()} when using this method, otherwise the provided callback will be never called.
-     * 
-     * @param settingsReceiverCallback
-     *            The callback which supplies the caller with initial settings
-     */
-    public void receiveInitialSettings(SettingsReceiverCallback<S> settingsReceiverCallback) {
-        if (currentDefaultSettings == null) {
-            settingsReceiverCallbacks.add(settingsReceiverCallback);
-        } else {
-            settingsReceiverCallback.receiveSettings(currentDefaultSettings);
-        }
+        settingsStorageManager.retrieveDefaultSettings(systemDefaultSettings, callback);
     }
 
     /**
@@ -150,23 +74,6 @@ public class ComponentContextWithSettingsStorage<L extends ComponentLifecycle<S,
         return settingsStorageManager.getLastError();
     }
 
-    /**
-     * Gets the current default {@link Settings} of the root component managed by this {@link ComponentContext}. The
-     * returned {@link Settings} should contain all settings for the root component and its subcomponents.
-     * 
-     * @return The {@link Settings} of the root component
-     * @throws IllegalStateException
-     *             When the instance has not been initialised yet
-     * @see #initInitialSettings()
-     */
-    @Override
-    public S getDefaultSettings() {
-        if (currentDefaultSettings == null) {
-            throw new IllegalStateException("Settings have not been initialized yet.");
-        }
-        return currentDefaultSettings;
-    }
-
     /**
      * {@inheritDoc}
      */

java/com.sap.sse.gwt/src/com/sap/sse/gwt/client/shared/perspective/DefaultOnSettingsLoadedCallback.java

@@ -0,0 +1,11 @@
+package com.sap.sse.gwt.client.shared.perspective;
+
+import com.sap.sse.common.settings.Settings;
+
+public abstract class DefaultOnSettingsLoadedCallback<S extends Settings> implements OnSettingsLoadedCallback<S> {
+    @Override
+    public void onError(Throwable caught, S fallbackDefaultSettings) {
+        onSuccess(fallbackDefaultSettings);
+    }
+
+}

java/com.sap.sse.gwt/src/com/sap/sse/gwt/client/shared/perspective/SettingsReceiverCallback.java

@@ -1,15 +0,0 @@
-package com.sap.sse.gwt.client.shared.perspective;
-
-import com.sap.sse.common.settings.Settings;
-
-/**
- * Receives initial/default settings when {@link ComponentContextWithSettingsStorage} have been initialised.
- * 
- * @author Vladislav Chumak
- *
- * @param <S> The {@link Settings} type of the settings of the root component/perspective containing all the settings for itself and its subcomponents
- * @see ComponentContextWithSettingsStorage
- */
-public interface SettingsReceiverCallback<S extends Settings> {
-    void receiveSettings(S initialSettings);
-}

java/com.sap.sse.gwt/src/com/sap/sse/gwt/client/shared/perspective/SimpleComponentContext.java

@@ -1,5 +1,8 @@
 package com.sap.sse.gwt.client.shared.perspective;
 
+import java.util.LinkedList;
+import java.util.Queue;
+
 import com.sap.sse.common.settings.Settings;
 import com.sap.sse.gwt.client.shared.components.Component;
 import com.sap.sse.gwt.client.shared.components.ComponentLifecycle;
@@ -25,6 +28,20 @@ public class SimpleComponentContext<L extends ComponentLifecycle<S, ?>, S extend
 
     protected final L rootLifecycle;
 
+    /**
+     * Contains {@link SettingsReceiverCallback}s which are waiting to receive the initial settings of the root
+     * component.
+     */
+    private Queue<OnSettingsLoadedCallback<S>> settingsReceiverCallbacks = new LinkedList<>();
+
+    /**
+     * Current initial/default settings for the whole settings tree which corresponds to the root component and its
+     * subcomponents.
+     */
+    private S currentDefaultSettings = null;
+    
+    private boolean loadingDefaultSettings = false;
+
     /**
      * 
      * @param rootLifecycle
@@ -68,8 +85,68 @@ public class SimpleComponentContext<L extends ComponentLifecycle<S, ?>, S extend
         return false;
     }
     
+
+    /**
+     * Initializes the instance with initial settings. This method may be called only once during the whole lifecycle of
+     * this instance. The call of this method is mandatory, otherwise it will not be possible to obtain initial
+     * settings.
+     * 
+     * @see #initInitialSettings(OnSettingsLoadedCallback)
+     */
+    public void initInitialSettings() {
+        loadDefaultSettingsIfNecessary();
+    }
+
+    /**
+     * Initializes the instance with initial settings. This method may be called only once during the whole lifecycle of
+     * this instance. The call of this method is mandatory, otherwise it will not be possible to obtain initial
+     * settings.
+     * 
+     * @param onInitialSettingsLoaded
+     *            Callback to be called when the settings initialization finishes
+     * @see #initInitialSettings()
+     */
     @Override
-    public void initInitialSettings(OnSettingsLoadedCallback<S> onInitialSettingsLoaded) {
-        onInitialSettingsLoaded.onSuccess(getDefaultSettings());
+    public void initInitialSettings(final OnSettingsLoadedCallback<S> onInitialSettingsLoaded) {
+        settingsReceiverCallbacks.add(onInitialSettingsLoaded);
+        loadDefaultSettingsIfNecessary();
+    }
+    
+    private void loadDefaultSettingsIfNecessary() {
+        if (loadingDefaultSettings) {
+            return;
+        }
+        if (currentDefaultSettings == null) {
+            loadingDefaultSettings = true;
+            loadDefaultSettings(new OnSettingsLoadedCallback<S>() {
+                @Override
+                public void onError(Throwable caught, S fallbackDefaultSettings) {
+                    S fallbackSettings = getDefaultSettings();
+                    OnSettingsLoadedCallback<S> callback;
+                    while ((callback = settingsReceiverCallbacks.poll()) != null) {
+                        callback.onError(caught, fallbackSettings);
+                    }
+                }
+
+                @Override
+                public void onSuccess(S result) {
+                    currentDefaultSettings = result;
+                    OnSettingsLoadedCallback<S> callback;
+                    while ((callback = settingsReceiverCallbacks.poll()) != null) {
+                        callback.onSuccess(result);
+                    }
+                }
+
+            });
+        } else {
+            OnSettingsLoadedCallback<S> callback;
+            while ((callback = settingsReceiverCallbacks.poll()) != null) {
+                callback.onSuccess(currentDefaultSettings);
+            }
+        }
+    }
+    
+    protected void loadDefaultSettings(OnSettingsLoadedCallback<S> callback) {
+        callback.onSuccess(getDefaultSettings());
     }
 }