org.apache.flink.streaming.api.functions.source

类 SocketTextStreamFunction

java.lang.Object

org.apache.flink.streaming.api.functions.source.SocketTextStreamFunction

所有已实现的接口:

Serializable, org.apache.flink.api.common.functions.Function, SourceFunction<String>

@PublicEvolving
public class SocketTextStreamFunction
extends Object
implements SourceFunction<String>

A source function that reads strings from a socket. The source will read bytes from the socket stream and convert them to characters, each byte individually. When the delimiter character is received, the function will output the current string, and begin a new string.

The function strips trailing carriage return characters (\r) when the delimiter is the newline character (\n).

The function can be set to reconnect to the server socket in case that the stream is closed on the server side.

另请参阅:

序列化表格

嵌套类概要

从接口继承的嵌套类/接口 org.apache.flink.streaming.api.functions.source.SourceFunction

SourceFunction.SourceContext<T>

构造器概要

构造器

构造器和说明
SocketTextStreamFunction(String hostname, int port, String delimiter, long maxNumRetries)
SocketTextStreamFunction(String hostname, int port, String delimiter, long maxNumRetries, long delayBetweenRetries)

方法概要

限定符和类型	方法和说明
void	cancel() Cancels the source.
void	run(SourceFunction.SourceContext<String> ctx) Starts the source.

从类继承的方法 java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

构造器详细资料

SocketTextStreamFunction

public SocketTextStreamFunction(String hostname,
                                int port,
                                String delimiter,
                                long maxNumRetries)

SocketTextStreamFunction

public SocketTextStreamFunction(String hostname,
                                int port,
                                String delimiter,
                                long maxNumRetries,
                                long delayBetweenRetries)

方法详细资料

run

public void run(SourceFunction.SourceContext<String> ctx)
         throws Exception

从接口复制的说明: SourceFunction

Starts the source. Implementations can use the SourceFunction.SourceContext emit elements.

Sources that implement CheckpointedFunction must lock on the checkpoint lock (using a synchronized block) before updating internal state and emitting elements, to make both an atomic operation:

  public class ExampleCountSource implements SourceFunction<Long>, CheckpointedFunction {
      private long count = 0L;
      private volatile boolean isRunning = true;

      private transient ListState<Long> checkpointedCount;

      public void run(SourceContext<T> ctx) {
          while (isRunning && count < 1000) {
              // this synchronized block ensures that state checkpointing,
              // internal state updates and emission of elements are an atomic operation
              synchronized (ctx.getCheckpointLock()) {
                  ctx.collect(count);
                  count++;
              }
          }
      }

      public void cancel() {
          isRunning = false;
      }

      public void initializeState(FunctionInitializationContext context) {
          this.checkpointedCount = context
              .getOperatorStateStore()
              .getListState(new ListStateDescriptor<>("count", Long.class));

          if (context.isRestored()) {
              for (Long count : this.checkpointedCount.get()) {
                  this.count = count;
              }
          }
      }

      public void snapshotState(FunctionSnapshotContext context) {
          this.checkpointedCount.clear();
          this.checkpointedCount.add(count);
      }
 }
 

指定者:

run 在接口中 SourceFunction<String>

参数:

ctx - The context to emit elements to and for accessing locks.

抛出:

Exception

cancel

public void cancel()

从接口复制的说明: SourceFunction

Cancels the source. Most sources will have a while loop inside the SourceFunction.run(SourceContext) method. The implementation needs to ensure that the source will break out of that loop after this method is called.

A typical pattern is to have an "volatile boolean isRunning" flag that is set to false in this method. That flag is checked in the loop condition.

When a source is canceled, the executing thread will also be interrupted (via Thread.interrupt()). The interruption happens strictly after this method has been called, so any interruption handler can rely on the fact that this method has completed. It is good practice to make any flags altered by this method "volatile", in order to guarantee the visibility of the effects of this method to any interruption handler.

指定者:

cancel 在接口中 SourceFunction<String>