@PublicEvolving public class FileMonitoringFunction extends Object implements SourceFunction<Tuple3<String,Long,Long>>
| Modifier and Type | Class and Description |
|---|---|
static class |
FileMonitoringFunction.WatchType |
SourceFunction.SourceContext<T>| Constructor and Description |
|---|
FileMonitoringFunction(String path,
long interval,
FileMonitoringFunction.WatchType watchType) |
| Modifier and Type | Method and Description |
|---|---|
void |
cancel()
Cancels the source.
|
void |
run(SourceFunction.SourceContext<Tuple3<String,Long,Long>> ctx)
Starts the source.
|
public FileMonitoringFunction(String path, long interval, FileMonitoringFunction.WatchType watchType)
public void run(SourceFunction.SourceContext<Tuple3<String,Long,Long>> ctx) throws Exception
SourceFunctionSourceFunction.SourceContext emit
elements.
Sources that implement Checkpointed
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 ExampleSource<T> implements SourceFunction<T>, Checkpointed<Long> {
private long count = 0L;
private volatile boolean isRunning = true;
public void run(SourceContext<T> ctx) {
while (isRunning && count < 1000) {
synchronized (ctx.getCheckpointLock()) {
ctx.collect(count);
count++;
}
}
}
public void cancel() {
isRunning = false;
}
public Long snapshotState(long checkpointId, long checkpointTimestamp) { return count; }
public void restoreState(Long state) { this.count = state; }
}
public void cancel()
SourceFunctionSourceFunction.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.
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