Flink 1.12.2 源码浅析 : AbstractRichFunction

╰+攻爆jí腚メ 2022-11-18 15:58 260阅读 0赞

### . ###

*  一 .前言
 *  二 .代码相关
 *   *  2.1. RichFunction
     *   *  2.1.1 void open(Configuration parameters) throws Exception;
         *  2.1.2 void close() throws Exception;
         *  2.1.3 RuntimeContext getRuntimeContext();
         *  2.1.4 IterationRuntimeContext getIterationRuntimeContext();
         *  2.1.5 void setRuntimeContext(RuntimeContext t);
         *  2.1.6 官方自带demo
     *  2.2. AbstractRichFunction
 *  三 .案例
 *   *  3.1. RichSourceFunction 类型的数据源
     *  3.3. KafkaSourceFunction 类型的数据源
     *  3.3. RichSinkFunction 类型的Sink

# 一 .前言 #

Flink代码里面好多地方用到了AbstractRichFunction,所以瞄一眼这个抽象类干了啥…

![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3poYW5nbG9uZ180NDQ0_size_16_color_FFFFFF_t_70]

# 二 .代码相关 #

## 2.1. RichFunction ##

RichFunction 接口是AbstractRichFunction 的父类, 所以先看他.  
RichFunction 是为用户自定义functions 的基类 . 实现了Function接口(接口啥都没有),  
这个类定义函数生命周期的方法，以及访问执行函数的上下文的方法。

### 2.1.1 void open(Configuration parameters) throws Exception; ###

function的初始化方法  
在调用实际请求的方法之前调用. (比如 map , join ) . 因此适合一次性的设置操作.  
对于作为迭代一部分的函数，此方法将在每个迭代步骤的开始处调用  
传递给函数的配置对象可用于配置和初始化。  
configuration包含在 program composition 中的函数上配置的所有参数。

/** * 默认这个方法不做任何事情. * * Initialization method for the function. * * It is called before the actual working methods (like * map or join) and thus suitable for one time setup work. * * For functions that are part of an iteration, this method will be invoked at the beginning of each iteration superstep. * * The configuration object passed to the function can be used for configuration and initialization. * * The configuration contains all parameters that were configured on the function in the program composition. * * <pre>{@code * public class MyFilter extends RichFilterFunction<String> { * * private String searchString; * * public void open(Configuration parameters) { * this.searchString = parameters.getString("foo"); * } * * public boolean filter(String value) { * return value.equals(searchString); * } * } * }</pre> * * By default, this method does nothing. * * @param parameters The configuration containing the parameters attached to the contract. * @throws Exception Implementations may forward exceptions, which are caught by the runtime. * When the runtime catches an exception, it aborts the task and lets the fail-over logic * decide whether to retry the task execution. * @see org.apache.flink.configuration.Configuration */
 void open(Configuration parameters) throws Exception;

### 2.1.2 void close() throws Exception; ###

用户代码的 Tear-down 方法。  
主方法执行完之后调用.  
对于作为迭代一部分的函数，此方法将在每次迭代后调用。  
这个方法可以用于清理之后的work .

/** * * Tear-down method for the user code. * It is called after the last call to the main working methods (e.g. map or join). * For functions that are part of an iteration, this method will be invoked after each iteration superstep. * This method can be used for clean up work. * * @throws Exception Implementations may forward exceptions, which are caught by the runtime. * When the runtime catches an exception, it aborts the task and lets the fail-over logic * decide whether to retry the task execution. */
 void close() throws Exception;

### 2.1.3 RuntimeContext getRuntimeContext(); ###

获取包含有关UDF运行时的信息的context，例如函数的并行读、函数的子任务索引或执行函数的任务的名称。

/** * 获取包含有关UDF运行时的信息的context，例如函数的并行读、函数的子任务索引或执行函数的任务的名称。 * Gets the context that contains information about the UDF's runtime, such as the parallelism * of the function, the subtask index of the function, or the name of the task that executes the * function. * * The RuntimeContext also gives access to the {@link * org.apache.flink.api.common.accumulators.Accumulator}s and the {@link * org.apache.flink.api.common.cache.DistributedCache}. * * @return The UDF's runtime context. */
 RuntimeContext getRuntimeContext();

### 2.1.4 IterationRuntimeContext getIterationRuntimeContext(); ###

/** * * 获取{@link RuntimeContext}的指定版本，其中包含有关在其中执行函数的迭代的附加信息。 * 仅当函数是迭代的一部分时，此IterationRuntimeContext才可用。否则，此方法将引发异常。 * * Gets a specialized version of the {@link RuntimeContext}, which has additional information about the iteration in which the function is executed. * * This IterationRuntimeContext is only available if the function is part of an iteration. Otherwise, this method throws an exception. * * @return The IterationRuntimeContext. * @throws java.lang.IllegalStateException Thrown, if the function is not executed as part of an * iteration. */
        IterationRuntimeContext getIterationRuntimeContext();

### 2.1.5 void setRuntimeContext(RuntimeContext t); ###

/** * Sets the function's runtime context. Called by the framework when creating a parallel instance of the function. * * @param t The runtime context. */
        void setRuntimeContext(RuntimeContext t);

### 2.1.6 官方自带demo ###

public class MyFilter extends RichFilterFunction<String> { 
 
 private String searchString;
 
 public void open(Configuration parameters) { 
 this.searchString = parameters.getString("foo");
 }
 
 public boolean filter(String value) { 
 return value.equals(searchString);
 }
 }

## 2.2. AbstractRichFunction ##

AbstractRichFunction 是RichFunction接口的抽象实现.  
Rich functions 有额外的初始化方法 (\{@link \#open(Configuration)\}) 和 拆解方法 (\{@link \#close()\})  
以及通过\{@link \#getRuntimeContext()\}访问它们的 runtime context

AbstractRichFunction 抽象类 新增了一个 `private transient RuntimeContext runtimeContext;` 属性. 以及重写了`setRuntimeContext` 和 `getRuntimeContext` 方法.

@Override
        public void setRuntimeContext(RuntimeContext t) { 
            this.runtimeContext = t;
        }
    
        @Override
        public RuntimeContext getRuntimeContext() { 
            if (this.runtimeContext != null) { 
                return this.runtimeContext;
            } else { 
                throw new IllegalStateException("The runtime context has not been initialized.");
            }
        }
    
        @Override
        public IterationRuntimeContext getIterationRuntimeContext() { 
            if (this.runtimeContext == null) { 
                throw new IllegalStateException("The runtime context has not been initialized.");
            } else if (this.runtimeContext instanceof IterationRuntimeContext) { 
                return (IterationRuntimeContext) this.runtimeContext;
            } else { 
                throw new IllegalStateException("This stub is not part of an iteration step function.");
            }
        }

# 三 .案例 #

在这里我找个案例去看看如何应用.

## 3.1. RichSourceFunction 类型的数据源 ##

*  构建mysql数据源, 从mysql数据库中读取数据.

package org.apache.flink.table.examples.java.basics;
 
 import org.apache.flink.api.java.tuple.Tuple3;
 import org.apache.flink.configuration.Configuration;
 import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
 
 import java.sql.DriverManager;
 import java.sql.ResultSet;
 import com.mysql.jdbc.Connection;
 import com.mysql.jdbc.PreparedStatement;
 
 
 public class MysqlSource extends RichSourceFunction<Tuple3<String,String,String>> { 
 
 private static final long serialVersionUID = 3334654984018091675L;
 
 private Connection connect = null;
 private PreparedStatement ps = null;
 
 @Override
 public void open(Configuration parameters) throws Exception { 
 super.open(parameters);
 Class.forName("com.mysql.jdbc.Driver");
 connect = (Connection) DriverManager.getConnection("jdbc:mysql://192.168.xx.xx:3306", "root", "xxxxx");
 ps = (PreparedStatement) connect.prepareStatement("select id,name,age from user ");
 }
 
 @Override
 public void run(SourceContext<Tuple3<String, String, String>> ctx) throws Exception { 
 ResultSet resultSet = ps.executeQuery();
 while (resultSet.next()) { 
 Tuple3<String, String, String> tuple = new Tuple3<String, String, String>();
 tuple.setFields(resultSet.getString(1), resultSet.getString(2), resultSet.getString(3));
 ctx.collect(tuple);
 }
 
 }
 
 @Override
 public void cancel() { 
 try { 
 super.close();
 if (connect != null) { 
 connect.close();
 }
 if (ps != null) { 
 ps.close();
 }
 } catch (Exception e) { 
 e.printStackTrace();
 }
 }
 }

*  Socket 类型的数据源

/* * 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.flink.table.examples.java.connectors;
 
 import org.apache.flink.api.common.serialization.DeserializationSchema;
 import org.apache.flink.api.common.serialization.RuntimeContextInitializationContextAdapters;
 import org.apache.flink.api.common.typeinfo.TypeInformation;
 import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
 import org.apache.flink.configuration.Configuration;
 import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
 import org.apache.flink.table.data.RowData;
 
 import java.io.ByteArrayOutputStream;
 import java.io.InputStream;
 import java.net.InetSocketAddress;
 import java.net.Socket;
 
 /** * The {@link SocketSourceFunction} opens a socket and consumes bytes. * * It splits records by the given byte delimiter (`\n` by default) and delegates the decoding to a * pluggable {@link DeserializationSchema}. * * Note: This is only an example and should not be used in production. The source function is not * fault-tolerant and can only work with a parallelism of 1. */
 public final class SocketSourceFunction extends RichSourceFunction<RowData> implements ResultTypeQueryable<RowData> { 
 
 	private final String hostname;
 	private final int port;
 	private final byte byteDelimiter;
 	private final DeserializationSchema<RowData> deserializer;
 
 	private volatile boolean isRunning = true;
 	private Socket currentSocket;
 
 	public SocketSourceFunction(String hostname, int port, byte byteDelimiter, DeserializationSchema<RowData> deserializer) { 
 		this.hostname = hostname;
 		this.port = port;
 		this.byteDelimiter = byteDelimiter;
 		this.deserializer = deserializer;
 	}
 
 	@Override
 	public TypeInformation<RowData> getProducedType() { 
 		return deserializer.getProducedType();
 	}
 
 	@Override
 	public void open(Configuration parameters) throws Exception { 
 		deserializer.open(
 				RuntimeContextInitializationContextAdapters.deserializationAdapter(getRuntimeContext())
 		);
 	}
 
 	@Override
 	public void run(SourceContext<RowData> ctx) throws Exception { 
 		while (isRunning) { 
 			// open and consume from socket
 			try (final Socket socket = new Socket()) { 
 				currentSocket = socket;
 				socket.connect(new InetSocketAddress(hostname, port), 0);
 				try (InputStream stream = socket.getInputStream()) { 
 					ByteArrayOutputStream buffer = new ByteArrayOutputStream();
 					int b;
 					while ((b = stream.read()) >= 0) { 
 						// buffer until delimiter
 						if (b != byteDelimiter) { 
 							buffer.write(b);
 						}
 						// decode and emit record
 						else { 
 							ctx.collect(deserializer.deserialize(buffer.toByteArray()));
 							buffer.reset();
 						}
 					}
 				}
 			} catch (Throwable t) { 
 				t.printStackTrace(); // print and continue
 			}
 			Thread.sleep(1000);
 		}
 	}
 
 	@Override
 	public void cancel() { 
 		isRunning = false;
 		try { 
 			currentSocket.close();
 		} catch (Throwable t) { 
 			// ignore
 		}
 	}
 }

## 3.3. KafkaSourceFunction 类型的数据源 ##

static class KafkaSourceFunction extends RichParallelSourceFunction<Tuple3<Integer, Long, Integer>> { 
 		private volatile boolean running = true;
 		private final int numElementsPerProducer;
 		private final boolean unBounded;
 
 		KafkaSourceFunction(int numElementsPerProducer) { 
 			this.numElementsPerProducer = numElementsPerProducer;
 			this.unBounded = true;
 		}
 
 		KafkaSourceFunction(int numElementsPerProducer, boolean unBounded) { 
 			this.numElementsPerProducer = numElementsPerProducer;
 			this.unBounded = unBounded;
 		}
 
 		@Override
 		public void run(SourceContext<Tuple3<Integer, Long, Integer>> ctx) throws Exception{ 
 			long timestamp = INIT_TIMESTAMP;
 			int sourceInstanceId = getRuntimeContext().getIndexOfThisSubtask();
 			for (int i = 0; i < numElementsPerProducer && running; i++) { 
 				ctx.collect(new Tuple3<>(i, timestamp++, sourceInstanceId));
 			}
 
 			while (running && unBounded) { 
 				Thread.sleep(100);
 			}
 		}
 
 		@Override
 		public void cancel() { 
 			running = false;
 		}
 	}

## 3.3. RichSinkFunction 类型的Sink ##

package org.apache.flink.table.examples.java.basics;
 
 
 import org.apache.flink.api.java.tuple.Tuple3;
 import org.apache.flink.configuration.Configuration;
 import org.apache.flink.streaming.api.functions.sink.RichSinkFunction;
 import org.apache.flink.streaming.api.functions.source.RichSourceFunction;
 
 import java.sql.DriverManager;
 import java.sql.ResultSet;
 import com.mysql.jdbc.Connection;
 import com.mysql.jdbc.PreparedStatement;
 
 
 
 public class MysqlSink extends RichSinkFunction<Tuple3<String,String,String>> { 
 
 private static final long serialVersionUID = -8930276689109741501L;
 
 private Connection connect = null;
 private PreparedStatement ps = null;
 
 @Override
 public void open(Configuration parameters) throws Exception { 
 super.open(parameters);
 super.open(parameters);
 Class.forName("com.mysql.jdbc.Driver");
 connect = (Connection) DriverManager.getConnection("jdbc:mysql://192.168.xxx.xxx:3306", "root", "xxxxx");
 ps = (PreparedStatement) connect.prepareStatement("insert into user (id,name,sex) values (?,?,?)");
 }
 
 @Override
 public void invoke(Tuple3<String, String, String> value, Context context) throws Exception { 
 ps.setString(1, value.f0);
 ps.setString(2, value.f1);
 ps.setString(3, value.f2);
 ps.executeUpdate();
 }
 
 @Override
 public void close() throws Exception { 
 try { 
 super.close();
 if (connect != null) { 
 connect.close();
 }
 if (ps != null) { 
 ps.close();
 }
 } catch (Exception e) { 
 e.printStackTrace();
 }
 }
 }

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