improve: use AutoCloseableIterator

computer-core/src/main/java/org/apache/hugegraph/computer/core/common/AutoCloseableIterator.java

@@ -0,0 +1,28 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with this
+ * work for additional information regarding copyright ownership. The ASF
+ * licenses this file to You under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ */
+
+package org.apache.hugegraph.computer.core.common;
+
+import java.util.Iterator;
+
+public interface AutoCloseableIterator<E> extends AutoCloseable, Iterator<E> {
+
+    @Override
+    default void close() {
+
+    }
+}

computer-core/src/main/java/org/apache/hugegraph/computer/core/input/WorkerInputManager.java

@@ -18,13 +18,13 @@
 package org.apache.hugegraph.computer.core.input;
 
 import java.util.ArrayList;
-import java.util.Iterator;
 import java.util.List;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutorService;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 
+import org.apache.hugegraph.computer.core.common.AutoCloseableIterator;
 import org.apache.hugegraph.computer.core.common.ComputerContext;
 import org.apache.hugegraph.computer.core.common.exception.ComputerException;
 import org.apache.hugegraph.computer.core.config.ComputerOptions;
@@ -131,17 +131,13 @@ public void loadGraph() {
     }
 
     private CompletableFuture<?> send(Consumer<Vertex> sendConsumer,
-                                      Supplier<Iterator<Vertex>> iteratorSupplier) {
+                                      Supplier<AutoCloseableIterator<Vertex>> iteratorSupplier) {
         return CompletableFuture.runAsync(() -> {
-            Iterator<Vertex> iterator = iteratorSupplier.get();
-            while (iterator.hasNext()) {
-                Vertex vertex = iterator.next();
-                sendConsumer.accept(vertex);
-            }
-            try {
-                ((AutoCloseable) iterator).close();
-            } catch (Exception e) {
-                throw new ComputerException("Failed to close iterator", e);
+            try (AutoCloseableIterator<Vertex> iterator = iteratorSupplier.get()) {
+                while (iterator.hasNext()) {
+                    Vertex vertex = iterator.next();
+                    sendConsumer.accept(vertex);
+                }
             }
         }, this.sendExecutor);
     }

computer-core/src/main/java/org/apache/hugegraph/computer/core/worker/load/LoadService.java

@@ -17,10 +17,8 @@
 
 package org.apache.hugegraph.computer.core.worker.load;
 
-import java.io.IOException;
-import java.util.Iterator;
 import java.util.NoSuchElementException;
-
+import org.apache.hugegraph.computer.core.common.AutoCloseableIterator;
 import org.apache.hugegraph.computer.core.common.ComputerContext;
 import org.apache.hugegraph.computer.core.config.ComputerOptions;
 import org.apache.hugegraph.computer.core.config.Config;
@@ -66,17 +64,17 @@ public void rpcService(InputSplitRpcService rpcService) {
         this.rpcService = rpcService;
     }
 
-    public Iterator<Vertex> createIteratorFromVertex() {
+    public AutoCloseableIterator<Vertex> createIteratorFromVertex() {
         GraphFetcher fetcher = InputSourceFactory.createGraphFetcher(this.config, this.rpcService);
         return new IteratorFromVertex(fetcher);
     }
 
-    public Iterator<Vertex> createIteratorFromEdge() {
+    public AutoCloseableIterator<Vertex> createIteratorFromEdge() {
         GraphFetcher fetcher = InputSourceFactory.createGraphFetcher(this.config, this.rpcService);
         return new IteratorFromEdge(fetcher);
     }
 
-    private class IteratorFromVertex implements Iterator<Vertex>, AutoCloseable {
+    private class IteratorFromVertex implements AutoCloseableIterator<Vertex> {
 
         private InputSplit currentSplit;
 
@@ -128,12 +126,12 @@ private Vertex convert(org.apache.hugegraph.structure.graph.Vertex
         }
 
         @Override
-        public void close() throws IOException {
+        public void close() {
             this.fetcher.close();
         }
     }
 
-    private class IteratorFromEdge implements Iterator<Vertex>, AutoCloseable {
+    private class IteratorFromEdge implements AutoCloseableIterator<Vertex> {
 
         /*
          * TODO: If it is an in edge, we should get the data from the in shard;
@@ -233,7 +231,7 @@ private Edge convert(org.apache.hugegraph.structure.graph.Edge edge) {
         }
 
         @Override
-        public void close() throws Exception {
+        public void close() {
             this.fetcher.close();
         }
     }