Added a simple ResourceMgr for collecting a set of objects that need …

…to be cleaned up

aksw-commons-utils-parent/aksw-commons-utils/src/main/java/org/aksw/commons/util/exception/FinallyRunAll.java

@@ -1,11 +1,11 @@
 package org.aksw.commons.util.exception;
 
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.List;
 import java.util.concurrent.Callable;
-import java.util.function.Consumer;
 import java.util.stream.Collectors;
 
 import org.aksw.commons.util.function.ThrowingRunnable;
@@ -39,6 +39,13 @@
 public class FinallyRunAll
     implements Runnable
 {
+    // TODO Consolidate with the identical interface from the lambda module
+    @FunctionalInterface
+    public interface ThrowingConsumer<T> extends Serializable {
+        void accept(T t) throws Exception;
+    }
+
+    // XXX Could change to an Iterator or Stream of actions.
     protected List<ThrowingRunnable> actions;
 
     public static FinallyRunAll create() {
@@ -87,47 +94,47 @@ protected void runAction(int index) {
     public static void run(ThrowingRunnable ... actions) {
         new FinallyRunAll(Arrays.asList(actions)).run();
     }
-    
-	public static <T> void runAll(Collection<T> actions, Consumer<T> runner, ThrowingRunnable finallyAction) {
-		ThrowingRunnable[] runnables = actions.stream().map(action -> {
-			ThrowingRunnable r = () -> {
-				runner.accept(action);
-			};
-			return r;
-		}).collect(Collectors.toList()).toArray(new ThrowingRunnable[0]);
-		
-		try {
-			run(runnables);
-		} finally {
-			if (finallyAction != null) {
-				try {
-					finallyAction.run();
-				} catch (Exception e) {
-					throw new RuntimeException(e);
-				}
-			}
-		}
-		
-		// Alternative approach using a loop
-		if (false) {
-			List<Exception> exceptions = null;
-			for (T action : actions) {
-				try {
-					runner.accept(action);
-				} catch (Exception e) {
-					if (exceptions == null) {
-						exceptions = new ArrayList<>();
-					}
-					exceptions.add(e);
-				}
-			}
-			
-			if (exceptions != null) {
-				RuntimeException e = new RuntimeException();
-				exceptions.forEach(e::addSuppressed);
-				throw e;
-			}
-		}
-	}
+
+    public static <T> void runAll(Collection<T> actions, ThrowingConsumer<T> runner, ThrowingRunnable finallyAction) {
+        ThrowingRunnable[] runnables = actions.stream().map(action -> {
+            ThrowingRunnable r = () -> {
+                runner.accept(action);
+            };
+            return r;
+        }).collect(Collectors.toList()).toArray(new ThrowingRunnable[0]);
+
+        try {
+            run(runnables);
+        } finally {
+            if (finallyAction != null) {
+                try {
+                    finallyAction.run();
+                } catch (Exception e) {
+                    throw new RuntimeException(e);
+                }
+            }
+        }
+
+        // Alternative approach using a loop
+        if (false) {
+            List<Exception> exceptions = null;
+            for (T action : actions) {
+                try {
+                    runner.accept(action);
+                } catch (Exception e) {
+                    if (exceptions == null) {
+                        exceptions = new ArrayList<>();
+                    }
+                    exceptions.add(e);
+                }
+            }
+
+            if (exceptions != null) {
+                RuntimeException e = new RuntimeException();
+                exceptions.forEach(e::addSuppressed);
+                throw e;
+            }
+        }
+    }
 
 }

aksw-commons-utils-parent/aksw-commons-utils/src/main/java/org/aksw/commons/util/lifecycle/ResourceMgr.java

@@ -0,0 +1,45 @@
+package org.aksw.commons.util.lifecycle;
+
+import java.util.Collections;
+import java.util.IdentityHashMap;
+import java.util.Map;
+
+import org.aksw.commons.util.exception.FinallyRunAll;
+import org.aksw.commons.util.exception.FinallyRunAll.ThrowingConsumer;
+import org.aksw.commons.util.function.ThrowingRunnable;
+
+/**
+ * A class where resources can be added.
+ * Upon closing the resource manager, all registered resources will be freed.
+ *
+ * @implNote
+ *   This implementation closes resources sequentially.
+ */
+public class ResourceMgr
+    implements AutoCloseable
+{
+    private final Map<Object, ThrowingRunnable> resourceToCloser =
+            Collections.synchronizedMap(new IdentityHashMap<>());
+
+    public ResourceMgr() {
+        super();
+    }
+
+    public <T extends AutoCloseable> T register(T closable) {
+        return register(closable, AutoCloseable::close);
+    }
+
+    public <T> T register(T obj, ThrowingConsumer<? super T> closer) {
+        return register(obj, () -> closer.accept(obj));
+    }
+
+    public <T> T register(T obj, ThrowingRunnable closeAction) {
+        resourceToCloser.put(obj, closeAction);
+        return obj;
+    }
+
+    @Override
+    public void close() {
+        FinallyRunAll.runAll(resourceToCloser.entrySet(), e -> e.getValue().run(), null);
+    }
+}