public class TwitterSource extends RichSourceFunction<String>
SourceFunction
specialized to emit tweets from Twitter. This is not a
parallel source because the Twitter API only allows two concurrent connections.Modifier and Type | Class and Description |
---|---|
static interface |
TwitterSource.EndpointInitializer
Implementing this interface allows users of this source to set a custom endpoint.
|
SourceFunction.SourceContext<T>
Modifier and Type | Field and Description |
---|---|
static String |
CLIENT_BUFFER_SIZE |
static String |
CLIENT_HOSTS |
static String |
CLIENT_NAME |
static String |
CONSUMER_KEY |
static String |
CONSUMER_SECRET |
static String |
TOKEN |
static String |
TOKEN_SECRET |
Constructor and Description |
---|
TwitterSource(Properties properties)
Create
TwitterSource for streaming. |
Modifier and Type | Method and Description |
---|---|
void |
cancel()
Cancels the source.
|
void |
close()
Tear-down method for the user code.
|
void |
open(Configuration parameters)
Initialization method for the function.
|
void |
run(SourceFunction.SourceContext<String> ctx)
Starts the source.
|
void |
setCustomEndpointInitializer(TwitterSource.EndpointInitializer initializer)
Set a custom endpoint initializer.
|
getIterationRuntimeContext, getRuntimeContext, setRuntimeContext
public static final String CONSUMER_KEY
public static final String CONSUMER_SECRET
public static final String TOKEN
public static final String TOKEN_SECRET
public static final String CLIENT_NAME
public static final String CLIENT_HOSTS
public static final String CLIENT_BUFFER_SIZE
public TwitterSource(Properties properties)
TwitterSource
for streaming.properties
- For the sourcepublic void setCustomEndpointInitializer(TwitterSource.EndpointInitializer initializer)
public void open(Configuration parameters) throws Exception
RichFunction
The configuration object passed to the function can be used for configuration and initialization. The configuration contains all parameters that were configured on the function in the program composition.
public class MyFilter extends RichFilterFunction<String> {
private String searchString;
public void open(Configuration parameters) {
this.searchString = parameters.getString("foo");
}
public boolean filter(String value) {
return value.equals(searchString);
}
}
By default, this method does nothing.
open
in interface RichFunction
open
in class AbstractRichFunction
parameters
- The configuration containing the parameters attached to the contract.Exception
- Implementations may forward exceptions, which are caught by the runtime.
When the runtime catches an exception, it aborts the task and lets the fail-over logic
decide whether to retry the task execution.Configuration
public void run(SourceFunction.SourceContext<String> ctx) throws Exception
SourceFunction
SourceFunction.SourceContext
to emit elements. Sources
that checkpoint their state for fault tolerance should use the SourceFunction.SourceContext.getCheckpointLock()
checkpoint lock} to ensure consistency between the
bookkeeping and emitting the elements.
Sources that implement CheckpointedFunction
must lock on the SourceFunction.SourceContext.getCheckpointLock()
checkpoint lock} checkpoint lock (using a synchronized
block) before updating internal state and emitting elements, to make both an atomic
operation.
Refer to the top-level class docs
for an example.
ctx
- The context to emit elements to and for accessing locks.Exception
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.
In case of an ungraceful shutdown (cancellation of the source operator, possibly for
failover), the thread that calls SourceFunction.run(SourceContext)
will also be interrupted
) by the Flink runtime, in order to speed up the cancellation
(to ensure threads exit blocking methods fast, like I/O, blocking queues, etc.). The
interruption happens strictly after this method has been called, so any interruption handler
can rely on the fact that this method has completed (for example to ignore exceptions that
happen after cancellation).
During graceful shutdown (for example stopping a job with a savepoint), the program must
cleanly exit the SourceFunction.run(SourceContext)
method soon after this method was called. The
Flink runtime will NOT interrupt the source thread during graceful shutdown. Source
implementors must ensure that no thread interruption happens on any thread that emits records
through the SourceContext
from the SourceFunction.run(SourceContext)
method; otherwise the
clean shutdown may fail when threads are interrupted while processing the final records.
Because the SourceFunction
cannot easily differentiate whether the shutdown should
be graceful or ungraceful, we recommend that implementors refrain from interrupting any
threads that interact with the SourceContext
at all. You can rely on the Flink
runtime to interrupt the source thread in case of ungraceful cancellation. Any additionally
spawned threads that directly emit records through the SourceContext
should use a
shutdown method that does not rely on thread interruption.
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