@PublicEvolving public class SocketTextStreamFunction extends Object implements SourceFunction<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.
SourceFunction.SourceContext<T>
Constructor and Description |
---|
SocketTextStreamFunction(String hostname,
int port,
char delimiter,
long maxNumRetries) |
SocketTextStreamFunction(String hostname,
int port,
char delimiter,
long maxNumRetries,
long delayBetweenRetries) |
Modifier and Type | Method and Description |
---|---|
void |
cancel()
Cancels the source.
|
void |
run(SourceFunction.SourceContext<String> ctx)
Starts the source.
|
public SocketTextStreamFunction(String hostname, int port, char delimiter, long maxNumRetries)
public SocketTextStreamFunction(String hostname, int port, char delimiter, long maxNumRetries, long delayBetweenRetries)
public void run(SourceFunction.SourceContext<String> ctx) throws Exception
SourceFunction
SourceFunction.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; }
}
run
in interface SourceFunction<String>
ctx
- The context to emit elements to and for accessing locks.Exception
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<String>
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