001/* 002 * (C) Copyright 2017 Nuxeo SA (http://nuxeo.com/) and others. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 * 016 * Contributors: 017 * bdelbosc 018 */ 019package org.nuxeo.lib.stream.log; 020 021import java.io.Externalizable; 022import java.time.Duration; 023import java.util.Objects; 024 025import org.nuxeo.lib.stream.codec.Codec; 026 027/** 028 * An appender is used to append message into a Log. Implementations must be thread safe. 029 * 030 * @since 9.3 031 */ 032public interface LogAppender<M extends Externalizable> { 033 034 /** 035 * Returns the Log's name. 036 */ 037 Name name(); 038 039 /** 040 * Returns the number of partitions in the Log. 041 */ 042 int size(); 043 044 /** 045 * Append a message into a partition, returns {@link LogOffset} position of the message. This method is thread safe, 046 * a queue can be shared by multiple producers. 047 * 048 * @param partition index lower than {@link #size()} 049 */ 050 LogOffset append(int partition, M message); 051 052 /** 053 * Same as {@link #append(int, Externalizable)}, the queue is chosen using a hash of parameters "key". 054 */ 055 default LogOffset append(String key, M message) { 056 Objects.requireNonNull(key); 057 // Provide a basic partitioning that works because: 058 // 1. String.hashCode is known to be constant even with different JVM (this is not the case for all objects) 059 // 2. the modulo operator is not optimal when rebalancing on partitions resizing but this should not happen. 060 // and yes hashCode can be negative. 061 int partition = (key.hashCode() & 0x7fffffff) % size(); 062 return append(partition, message); 063 } 064 065 /** 066 * Wait for consumer to process a message up to the offset. The message is processed if a consumer of the group 067 * commits a greater or equals offset. Return {@code true} if the message has been consumed, {@code false} in case 068 * of timeout. 069 */ 070 boolean waitFor(LogOffset offset, Name group, Duration timeout) throws InterruptedException; 071 072 /** 073 * Returns {@code true} if the appender has been closed by the manager. 074 */ 075 boolean closed(); 076 077 /** 078 * Returns the codec used to write record. A null codec is the default legacy encoding. 079 * 080 * @since 10.2 081 */ 082 Codec<M> getCodec(); 083}