[server] Add script field to lecture table; implement getImageDetails method to get detailed information about an image from the database

1 files changed, 43 insertions, 0 deletions

diff --git a/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/thrift/cache/CacheBase.java b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/thrift/cache/CacheBase.java
new file mode 100644
index 00000000..e42ee9fe
--- /dev/null
+++ b/dozentenmodulserver/src/main/java/org/openslx/bwlp/sat/thrift/cache/CacheBase.java
@@ -0,0 +1,43 @@
+package org.openslx.bwlp.sat.thrift.cache;
+
+import java.util.List;
+
+import org.apache.log4j.Logger;
+import org.apache.thrift.TException;
+
+/**
+ * Class that caches an instance of a given class for 10 minutes.
+ * If the cache expired and a fresh instance cannot be acquired,
+ * the old instance will be returned.
+ * 
+ * @param <T> The class to cache
+ */
+public abstract class CacheBase<T> {
+
+	private static final Logger LOGGER = Logger.getLogger(CacheBase.class);
+
+	private static final int TIMEOUT = 10 * 60 * 1000;
+
+	private T cachedInstance = null;
+
+	private long cacheTimeout = 0;
+
+	protected abstract T getCallback() throws TException;
+
+	protected synchronized T getInternal() {
+		final long now = System.currentTimeMillis();
+		if (cachedInstance == null || now > cacheTimeout) {
+			try {
+				T freshInstance = getCallback();
+				if (freshInstance != null) {
+					cachedInstance = freshInstance;
+					cacheTimeout = now + TIMEOUT;
+				}
+			} catch (TException e) {
+				LOGGER.warn("Could not retrieve fresh instance of " + getClass().getSimpleName(), e);
+			}
+		}
+		return cachedInstance;
+	}
+
+}