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

类 ContinuousFileMonitoringFunction<OUT>

java.lang.Object

org.apache.flink.api.common.functions.AbstractRichFunction

org.apache.flink.streaming.api.functions.source.RichSourceFunction<TimestampedFileInputSplit>

org.apache.flink.streaming.api.functions.source.ContinuousFileMonitoringFunction<OUT>

所有已实现的接口:

Serializable, org.apache.flink.api.common.functions.Function, org.apache.flink.api.common.functions.RichFunction, CheckpointedFunction, SourceFunction<TimestampedFileInputSplit>

@Internal
public class ContinuousFileMonitoringFunction<OUT>
extends RichSourceFunction<TimestampedFileInputSplit>
implements CheckpointedFunction

This is the single (non-parallel) monitoring task which takes a FileInputFormat and, depending on the FileProcessingMode and the FilePathFilter, it is responsible for:

1. Monitoring a user-provided path.
2. Deciding which files should be further read and processed.
3. Creating the splits corresponding to those files.
4. Assigning them to downstream tasks for further processing.

The splits to be read are forwarded to the downstream ContinuousFileReaderOperator which can have parallelism greater than one.

IMPORTANT NOTE: Splits are forwarded downstream for reading in ascending modification time order, based on the modification time of the files they belong to.

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>

字段概要

字段

限定符和类型	字段和说明
static long	MIN_MONITORING_INTERVAL The minimum interval allowed between consecutive path scans.

构造器概要

构造器

构造器和说明
ContinuousFileMonitoringFunction(org.apache.flink.api.common.io.FileInputFormat<OUT> format, FileProcessingMode watchType, int readerParallelism, long interval)
ContinuousFileMonitoringFunction(org.apache.flink.api.common.io.FileInputFormat<OUT> format, FileProcessingMode watchType, int readerParallelism, long interval, long globalModificationTime)

方法概要

限定符和类型	方法和说明
void	cancel() Cancels the source.
void	close()
long	getGlobalModificationTime()
void	initializeState(org.apache.flink.runtime.state.FunctionInitializationContext context) This method is called when the parallel function instance is created during distributed execution.
void	open(org.apache.flink.configuration.Configuration parameters)
void	run(SourceFunction.SourceContext<TimestampedFileInputSplit> context) Starts the source.
void	snapshotState(org.apache.flink.runtime.state.FunctionSnapshotContext context) This method is called when a snapshot for a checkpoint is requested.

从类继承的方法 org.apache.flink.api.common.functions.AbstractRichFunction

getIterationRuntimeContext, getRuntimeContext, setRuntimeContext

从类继承的方法 java.lang.Object

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

字段详细资料

MIN_MONITORING_INTERVAL

public static final long MIN_MONITORING_INTERVAL

The minimum interval allowed between consecutive path scans.

NOTE: Only applicable to the PROCESS_CONTINUOUSLY mode.

另请参阅:

常量字段值

构造器详细资料

ContinuousFileMonitoringFunction

public ContinuousFileMonitoringFunction(org.apache.flink.api.common.io.FileInputFormat<OUT> format,
                                        FileProcessingMode watchType,
                                        int readerParallelism,
                                        long interval)

ContinuousFileMonitoringFunction

public ContinuousFileMonitoringFunction(org.apache.flink.api.common.io.FileInputFormat<OUT> format,
                                        FileProcessingMode watchType,
                                        int readerParallelism,
                                        long interval,
                                        long globalModificationTime)

方法详细资料

getGlobalModificationTime

@VisibleForTesting
public long getGlobalModificationTime()

initializeState

public void initializeState(org.apache.flink.runtime.state.FunctionInitializationContext context)
                     throws Exception

从接口复制的说明: CheckpointedFunction

This method is called when the parallel function instance is created during distributed execution. Functions typically set up their state storing data structures in this method.

指定者:

initializeState 在接口中 CheckpointedFunction

参数:

context - the context for initializing the operator

抛出:

Exception - Thrown, if state could not be created ot restored.

open

public void open(org.apache.flink.configuration.Configuration parameters)
          throws Exception

指定者:

open 在接口中 org.apache.flink.api.common.functions.RichFunction

覆盖:

open 在类中 org.apache.flink.api.common.functions.AbstractRichFunction

抛出:

Exception

run

public void run(SourceFunction.SourceContext<TimestampedFileInputSplit> context)
         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<TimestampedFileInputSplit>

参数:

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

抛出:

Exception

close

public void close()
           throws Exception

指定者:

close 在接口中 org.apache.flink.api.common.functions.RichFunction

覆盖:

close 在类中 org.apache.flink.api.common.functions.AbstractRichFunction

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<TimestampedFileInputSplit>

snapshotState

public void snapshotState(org.apache.flink.runtime.state.FunctionSnapshotContext context)
                   throws Exception

从接口复制的说明: CheckpointedFunction

This method is called when a snapshot for a checkpoint is requested. This acts as a hook to the function to ensure that all state is exposed by means previously offered through FunctionInitializationContext when the Function was initialized, or offered now by FunctionSnapshotContext itself.

指定者:

snapshotState 在接口中 CheckpointedFunction

参数:

context - the context for drawing a snapshot of the operator

抛出:

Exception - Thrown, if state could not be created ot restored.