Added ContextCache

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

@@ -0,0 +1,157 @@
+package org.gcube.informationsystem.resourceregistry.api.utils;
+
+import java.util.ArrayList;
+import java.util.Calendar;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.UUID;
+import java.util.concurrent.TimeUnit;
+
+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.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class ContextCache {
+
+	private static Logger logger = LoggerFactory.getLogger(ContextCache.class);
+	
+	// in millisec
+	public static final long DEFAULT_EXPIRING_TIMEOUT;
+	public static int expiringTimeout;
+	
+	static {
+		DEFAULT_EXPIRING_TIMEOUT = TimeUnit.HOURS.toMillis(6);
+		expiringTimeout = (int) DEFAULT_EXPIRING_TIMEOUT;
+	}
+	
+	public static void setExpiringTimeout(int expiringTimeout) {
+		ContextCache.expiringTimeout = expiringTimeout;
+	}
+
+	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;
+	}
+	
+	// in millisec used for logging purposes only
+	protected Calendar creationTime;
+	// in millisec
+	protected Calendar expiringTime;
+	
+	protected List<Context> contexts;
+	protected Map<UUID, Context> uuidToContext;
+	protected Map<UUID, String> uuidToContextFullName;
+	protected Map<String, UUID> contextFullNameToUUID;
+	
+	public ContextCache() {
+		contexts = null;
+		uuidToContext = null;
+		uuidToContextFullName = null;
+		contextFullNameToUUID = null;
+	}
+	
+	public synchronized List<Context> getContexts() {
+		return contexts;
+	}
+
+	public synchronized void setContexts(List<Context> contexts) {
+		this.contexts = new ArrayList<>();
+		this.uuidToContext = new HashMap<>();
+		
+		for(Context c : contexts) {
+			UUID uuid = c.getHeader().getUUID();
+			Context context = new ContextImpl(c.getName());
+			context.setHeader(c.getHeader());
+			this.contexts.add(context);
+			this.uuidToContext.put(uuid, context);
+		}
+		
+		for(Context c : contexts) {
+			UUID uuid = c.getHeader().getUUID();
+			Context context = this.uuidToContext.get(uuid);
+			if(c.getParent()!=null) {
+				IsParentOf ipo = c.getParent();
+				UUID parentUUID = ipo.getSource().getHeader().getUUID();
+				Context parent = this.uuidToContext.get(parentUUID);
+				IsParentOf isParentOf = new IsParentOfImpl(parent, context);
+				isParentOf.setHeader(ipo.getHeader());
+				parent.addChild(isParentOf);
+				context.setParent(isParentOf);
+			}
+		}
+		
+		this.uuidToContextFullName = new HashMap<>();
+		this.contextFullNameToUUID = new HashMap<>();
+		
+		for(Context context : contexts) {
+			UUID uuid = context.getHeader().getUUID();
+			String fullName = getContextFullName(context);
+			this.uuidToContextFullName.put(uuid, fullName);
+			this.contextFullNameToUUID.put(fullName, uuid);
+		}
+		
+	}
+
+	private String getContextFullName(Context context) {
+		StringBuilder stringBuilder = new StringBuilder();
+		IsParentOf ipo = context.getParent();
+		if(ipo!=null) {
+			Context c = ipo.getSource();
+			c = uuidToContext.get(c.getHeader().getUUID());
+			String parentFullName = getContextFullName(c);
+			stringBuilder.append(parentFullName);
+		}
+		stringBuilder.append("/");
+		stringBuilder.append(context.getName());
+		return stringBuilder.toString();
+	}
+	
+	
+	public String getContextFullNameByUUID(UUID uuid) {
+		return uuidToContextFullName.get(uuid);
+	}
+	
+	public UUID getUUIDByFullName(String fullName) {
+		return contextFullNameToUUID.get(fullName);
+	}
+	
+	public Context getContextByUUID(UUID uuid) {
+		return uuidToContext.get(uuid);
+	}
+	
+	/**
+	 * @return an Map containing UUID to Context FullName association
+	 */
+	public Map<UUID, String> getUUIDToContextFullNameAssociation() {
+		return new HashMap<>(uuidToContextFullName);
+	}
+	
+	/**
+	 * @return an Map containing Context FullName to UUID association
+	 */
+	public Map<String, UUID> getContextFullNameToUUIDAssociation() {
+		return new HashMap<>(contextFullNameToUUID);
+	}
+	
+}