Added possibility to set context renewal

src/main/java/org/gcube/informationsystem/resourceregistry/api/contexts/ContextCache.java

@@ -1,4 +1,4 @@
-package org.gcube.informationsystem.resourceregistry.api.utils;
+package org.gcube.informationsystem.resourceregistry.api.contexts;
 
 import java.util.ArrayList;
 import java.util.Calendar;
@@ -12,6 +12,7 @@ import org.gcube.informationsystem.context.impl.entities.ContextImpl;
 import org.gcube.informationsystem.context.impl.relations.IsParentOfImpl;
 import org.gcube.informationsystem.context.reference.entities.Context;
 import org.gcube.informationsystem.context.reference.relations.IsParentOf;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -35,25 +36,30 @@ public class ContextCache {
 	protected static ContextCache singleton;
 	
 	public synchronized static ContextCache getInstance() {
-		Calendar now = Calendar.getInstance();
-		
-		if(singleton!=null && now.after(singleton.expiringTime)) {
-			logger.debug("Context Cache has been expired. It must be renewed.");
-			singleton = null;
-		}
-		
 		if(singleton==null) {
 			singleton = new ContextCache();
-			singleton.creationTime = Calendar.getInstance();
-			singleton.creationTime.setTimeInMillis(now.getTimeInMillis());
-			singleton.expiringTime = Calendar.getInstance();
-			singleton.expiringTime.setTimeInMillis(now.getTimeInMillis());
-			singleton.expiringTime.add(Calendar.MILLISECOND, expiringTimeout);
 		}
-		
 		return singleton;
 	}
 	
+	public void cleanCache() {
+		cleanCache(Calendar.getInstance());
+	}
+	
+	private void cleanCache(Calendar now) {
+		this.contexts = null;
+		this.uuidToContext = null;
+		this.uuidToContextFullName = null;
+		this.contextFullNameToUUID = null;
+		this.creationTime = Calendar.getInstance();
+		this.creationTime.setTimeInMillis(now.getTimeInMillis());
+		this.expiringTime = Calendar.getInstance();
+		this.expiringTime.setTimeInMillis(now.getTimeInMillis());
+		this.expiringTime.add(Calendar.MILLISECOND, expiringTimeout);
+	}
+	
+	protected ContextCacheRenewal contextCacheRenewal;
+	
 	// in millisec used for logging purposes only
 	protected Calendar creationTime;
 	// in millisec
@@ -65,17 +71,41 @@ public class ContextCache {
 	protected Map<String, UUID> contextFullNameToUUID;
 	
 	public ContextCache() {
-		contexts = null;
-		uuidToContext = null;
-		uuidToContextFullName = null;
-		contextFullNameToUUID = null;
+		Calendar now = Calendar.getInstance();
+		cleanCache(now);
 	}
 	
-	public synchronized List<Context> getContexts() {
+	public void setContextCacheRenewal(ContextCacheRenewal contextCacheRenewal) {
+		if(this.contextCacheRenewal==null) {
+			this.contextCacheRenewal = contextCacheRenewal;
+		}
+	}
+	
+	public void refreshContextsIfNeeded() throws ResourceRegistryException {
+		Calendar now = Calendar.getInstance();
+		
+		if(now.after(expiringTime) || (contexts==null && contextCacheRenewal!=null)) {
+			try {
+				
+				List<Context> contexts = contextCacheRenewal.renew();
+				singleton.cleanCache(now);
+				setContexts(contexts);
+			} catch (ResourceRegistryException  e) {
+				logger.error("Unable to refresh Cache", e);
+				if(contexts==null) {
+					throw e;
+				}
+			}
+			
+		}
+	}
+	
+	public synchronized List<Context> getContexts() throws ResourceRegistryException {
+		refreshContextsIfNeeded();
 		return contexts;
 	}
 
-	public synchronized void setContexts(List<Context> contexts) {
+	private void setContexts(List<Context> contexts) {
 		this.contexts = new ArrayList<>();
 		this.uuidToContext = new HashMap<>();
 		
@@ -128,29 +158,39 @@ public class ContextCache {
 	}
 	
 	
-	public String getContextFullNameByUUID(UUID uuid) {
-		return uuidToContextFullName.get(uuid);
+	public synchronized String getContextFullNameByUUID(UUID uuid) throws ResourceRegistryException {
+		refreshContextsIfNeeded();
+		return uuidToContextFullName.get(uuid);		
 	}
 	
-	public UUID getUUIDByFullName(String fullName) {
-		return contextFullNameToUUID.get(fullName);
+	public synchronized UUID getUUIDByFullName(String contextFullName) throws ResourceRegistryException {
+		refreshContextsIfNeeded();
+		return contextFullNameToUUID.get(contextFullName);
 	}
 	
-	public Context getContextByUUID(UUID uuid) {
+	public synchronized Context getContextByUUID(UUID uuid) throws ResourceRegistryException {
+		refreshContextsIfNeeded();
+		return uuidToContext.get(uuid);
+	}
+	
+	public synchronized Context getContextByFullName(String contextFullName) throws ResourceRegistryException {
+		UUID uuid = getUUIDByFullName(contextFullName);
 		return uuidToContext.get(uuid);
 	}
 	
 	/**
 	 * @return an Map containing UUID to Context FullName association
 	 */
-	public Map<UUID, String> getUUIDToContextFullNameAssociation() {
+	public synchronized Map<UUID, String> getUUIDToContextFullNameAssociation() throws ResourceRegistryException {
+		refreshContextsIfNeeded();
 		return new HashMap<>(uuidToContextFullName);
 	}
 	
 	/**
 	 * @return an Map containing Context FullName to UUID association
 	 */
-	public Map<String, UUID> getContextFullNameToUUIDAssociation() {
+	public synchronized Map<String, UUID> getContextFullNameToUUIDAssociation() throws ResourceRegistryException {
+		refreshContextsIfNeeded();
 		return new HashMap<>(contextFullNameToUUID);
 	}
 	

src/main/java/org/gcube/informationsystem/resourceregistry/api/contexts/ContextCacheRenewal.java

@@ -0,0 +1,12 @@
+package org.gcube.informationsystem.resourceregistry.api.contexts;
+
+import java.util.List;
+
+import org.gcube.informationsystem.context.reference.entities.Context;
+import org.gcube.informationsystem.resourceregistry.api.exceptions.ResourceRegistryException;
+
+public interface ContextCacheRenewal {
+
+	public List<Context> renew() throws ResourceRegistryException;
+	
+}