public class HiveContinuousMonitoringFunction extends RichSourceFunction<TimestampedHiveInputSplit> implements CheckpointedFunction
HiveTableInputFormat
, it
is responsible for:
splits
corresponding to those partitions.
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 partition time order, based on the partition time of the partitions they belong to.
SourceFunction.SourceContext<T>
Constructor and Description |
---|
HiveContinuousMonitoringFunction(HiveShim hiveShim,
org.apache.hadoop.mapred.JobConf conf,
ObjectPath tablePath,
CatalogTable catalogTable,
int readerParallelism,
ConsumeOrder consumeOrder,
String consumeOffset,
String extractorKind,
String extractorClass,
String extractorPattern,
long interval) |
Modifier and Type | Method and Description |
---|---|
void |
cancel()
Cancels the source.
|
void |
close()
Tear-down method for the user code.
|
void |
initializeState(FunctionInitializationContext context)
This method is called when the parallel function instance is created during distributed
execution.
|
void |
run(SourceFunction.SourceContext<TimestampedHiveInputSplit> context)
Starts the source.
|
void |
snapshotState(FunctionSnapshotContext context)
This method is called when a snapshot for a checkpoint is requested.
|
getIterationRuntimeContext, getRuntimeContext, open, setRuntimeContext
public HiveContinuousMonitoringFunction(HiveShim hiveShim, org.apache.hadoop.mapred.JobConf conf, ObjectPath tablePath, CatalogTable catalogTable, int readerParallelism, ConsumeOrder consumeOrder, String consumeOffset, String extractorKind, String extractorClass, String extractorPattern, long interval)
public void initializeState(FunctionInitializationContext context) throws Exception
CheckpointedFunction
initializeState
in interface CheckpointedFunction
context
- the context for initializing the operatorException
- Thrown, if state could not be created ot restored.public void run(SourceFunction.SourceContext<TimestampedHiveInputSplit> context) throws Exception
SourceFunction
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);
}
}
run
in interface SourceFunction<TimestampedHiveInputSplit>
context
- The context to emit elements to and for accessing locks.Exception
public void snapshotState(FunctionSnapshotContext context) throws Exception
CheckpointedFunction
FunctionInitializationContext
when the Function was initialized, or offered now by FunctionSnapshotContext
itself.snapshotState
in interface CheckpointedFunction
context
- the context for drawing a snapshot of the operatorException
- Thrown, if state could not be created ot restored.public void close()
RichFunction
This method can be used for clean up work.
close
in interface RichFunction
close
in class AbstractRichFunction
public void cancel()
SourceFunction
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.
cancel
in interface SourceFunction<TimestampedHiveInputSplit>
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