| /* |
| * Copyright 2017 HugeGraph Authors |
| * |
| * 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 com.baidu.hugegraph.computer.core.compute.input; |
| |
| import java.io.IOException; |
| import java.util.Collections; |
| import java.util.Iterator; |
| import java.util.NoSuchElementException; |
| |
| import com.baidu.hugegraph.computer.core.common.ComputerContext; |
| import com.baidu.hugegraph.computer.core.common.exception.ComputerException; |
| import com.baidu.hugegraph.computer.core.config.ComputerOptions; |
| import com.baidu.hugegraph.computer.core.config.Config; |
| import com.baidu.hugegraph.computer.core.graph.value.Value; |
| import com.baidu.hugegraph.computer.core.io.BytesInput; |
| import com.baidu.hugegraph.computer.core.io.IOFactory; |
| import com.baidu.hugegraph.computer.core.sort.flusher.PeekableIterator; |
| import com.baidu.hugegraph.computer.core.store.hgkvfile.entry.KvEntry; |
| import com.baidu.hugegraph.computer.core.store.hgkvfile.entry.Pointer; |
| |
| public class MessageInput<T extends Value> { |
| |
| private final Config config; |
| private final PeekableIterator<KvEntry> messages; |
| private final T value; |
| |
| public MessageInput(ComputerContext context, |
| PeekableIterator<KvEntry> messages) { |
| if (messages == null) { |
| this.messages = PeekableIterator.emptyIterator(); |
| } else { |
| this.messages = messages; |
| } |
| this.config = context.config(); |
| |
| this.value = this.config.createObject( |
| ComputerOptions.ALGORITHM_MESSAGE_CLASS); |
| } |
| |
| public Iterator<T> iterator(ReusablePointer vidPointer) { |
| while (this.messages.hasNext()) { |
| KvEntry entry = this.messages.peek(); |
| Pointer key = entry.key(); |
| int status = vidPointer.compareTo(key); |
| if (status < 0) { |
| return Collections.emptyIterator(); |
| } else if (status == 0) { |
| break; |
| } else { |
| this.messages.next(); |
| } |
| } |
| |
| return new MessageIterator(vidPointer); |
| } |
| |
| public void close() throws Exception { |
| this.messages.close(); |
| } |
| |
| private class MessageIterator implements Iterator<T> { |
| |
| // It indicates whether the value can be returned to client. |
| private boolean valueValid; |
| private ReusablePointer vidPointer; |
| |
| private MessageIterator(ReusablePointer vidPointer) { |
| this.vidPointer = vidPointer; |
| this.valueValid = false; |
| } |
| |
| @Override |
| public boolean hasNext() { |
| if (this.valueValid) { |
| return true; |
| } |
| if (MessageInput.this.messages.hasNext()) { |
| KvEntry entry = MessageInput.this.messages.peek(); |
| Pointer key = entry.key(); |
| int status = this.vidPointer.compareTo(key); |
| if (status == 0) { |
| MessageInput.this.messages.next(); |
| this.valueValid = true; |
| try { |
| BytesInput in = IOFactory.createBytesInput( |
| entry.value().bytes()); |
| MessageInput.this.value.read(in); |
| } catch (IOException e) { |
| throw new ComputerException("Can't read value", e); |
| } |
| return true; |
| } else { |
| return false; |
| } |
| } else { |
| return false; |
| } |
| } |
| |
| @Override |
| public T next() { |
| if (this.valueValid) { |
| this.valueValid = false; |
| return MessageInput.this.value; |
| } else { |
| throw new NoSuchElementException(); |
| } |
| } |
| } |
| } |