public class PubSubSource<OUT> extends RichSourceFunction<OUT> implements ResultTypeQueryable<OUT>, ParallelSourceFunction<OUT>, CheckpointListener, ListCheckpointed<AcknowledgeIdsForCheckpoint<String>>
Modifier and Type | Class and Description |
---|---|
static class |
PubSubSource.DeserializationSchemaBuilder
Part of
PubSubSource.PubSubSourceBuilder to set required fields. |
static interface |
PubSubSource.ProjectNameBuilder<OUT>
Part of
PubSubSource.PubSubSourceBuilder to set required fields. |
static class |
PubSubSource.PubSubSourceBuilder<OUT>
Builder to create PubSubSource.
|
static interface |
PubSubSource.SubscriptionNameBuilder<OUT>
Part of
PubSubSource.PubSubSourceBuilder to set required fields. |
SourceFunction.SourceContext<T>
Modifier and Type | Field and Description |
---|---|
protected AcknowledgeOnCheckpoint<String> |
acknowledgeOnCheckpoint |
protected org.apache.flink.streaming.connectors.gcp.pubsub.PubSubSource.AcknowledgeOnCheckpointFactory |
acknowledgeOnCheckpointFactory |
protected com.google.auth.Credentials |
credentials |
protected PubSubDeserializationSchema<OUT> |
deserializationSchema |
protected boolean |
isRunning |
protected int |
messagePerSecondRateLimit |
protected PubSubSubscriberFactory |
pubSubSubscriberFactory |
protected FlinkConnectorRateLimiter |
rateLimiter |
protected PubSubSubscriber |
subscriber |
Modifier and Type | Method and Description |
---|---|
void |
cancel()
Cancels the source.
|
void |
close()
Tear-down method for the user code.
|
TypeInformation<OUT> |
getProducedType()
Gets the data type (as a
TypeInformation ) produced by this function or input format. |
static PubSubSource.DeserializationSchemaBuilder |
newBuilder() |
void |
notifyCheckpointAborted(long checkpointId)
This method is called as a notification once a distributed checkpoint has been aborted.
|
void |
notifyCheckpointComplete(long checkpointId)
Notifies the listener that the checkpoint with the given
checkpointId completed and
was committed. |
void |
open(Configuration configuration)
Initialization method for the function.
|
void |
restoreState(List<AcknowledgeIdsForCheckpoint<String>> state)
Restores the state of the function or operator to that of a previous checkpoint.
|
void |
run(SourceFunction.SourceContext<OUT> sourceContext)
Starts the source.
|
List<AcknowledgeIdsForCheckpoint<String>> |
snapshotState(long checkpointId,
long timestamp)
Gets the current state of the function.
|
getIterationRuntimeContext, getRuntimeContext, setRuntimeContext
protected final PubSubDeserializationSchema<OUT> deserializationSchema
protected final PubSubSubscriberFactory pubSubSubscriberFactory
protected final com.google.auth.Credentials credentials
protected final org.apache.flink.streaming.connectors.gcp.pubsub.PubSubSource.AcknowledgeOnCheckpointFactory acknowledgeOnCheckpointFactory
protected final FlinkConnectorRateLimiter rateLimiter
protected final int messagePerSecondRateLimit
protected transient AcknowledgeOnCheckpoint<String> acknowledgeOnCheckpoint
protected transient PubSubSubscriber subscriber
protected transient volatile boolean isRunning
public void open(Configuration configuration) 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
configuration
- 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<OUT> sourceContext) 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.
run
in interface SourceFunction<OUT>
sourceContext
- The context to emit elements to and for accessing locks.Exception
public void close() throws Exception
RichFunction
This method can be used for clean up work.
close
in interface RichFunction
close
in class AbstractRichFunction
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.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.
cancel
in interface SourceFunction<OUT>
public TypeInformation<OUT> getProducedType()
ResultTypeQueryable
TypeInformation
) produced by this function or input format.getProducedType
in interface ResultTypeQueryable<OUT>
public static PubSubSource.DeserializationSchemaBuilder newBuilder()
public void notifyCheckpointComplete(long checkpointId) throws Exception
CheckpointListener
checkpointId
completed and
was committed.
These notifications are "best effort", meaning they can sometimes be skipped. To behave
properly, implementers need to follow the "Checkpoint Subsuming Contract". Please see the
class-level JavaDocs
for details.
Please note that checkpoints may generally overlap, so you cannot assume that the notifyCheckpointComplete()
call is always for the latest prior checkpoint (or snapshot) that
was taken on the function/operator implementing this interface. It might be for a checkpoint
that was triggered earlier. Implementing the "Checkpoint Subsuming Contract" (see above)
properly handles this situation correctly as well.
Please note that throwing exceptions from this method will not cause the completed checkpoint to be revoked. Throwing exceptions will typically cause task/job failure and trigger recovery.
notifyCheckpointComplete
in interface CheckpointListener
checkpointId
- The ID of the checkpoint that has been completed.Exception
- This method can propagate exceptions, which leads to a failure/recovery for
the task. Note that this will NOT lead to the checkpoint being revoked.public void notifyCheckpointAborted(long checkpointId)
CheckpointListener
Important: The fact that a checkpoint has been aborted does NOT mean that the data
and artifacts produced between the previous checkpoint and the aborted checkpoint are to be
discarded. The expected behavior is as if this checkpoint was never triggered in the first
place, and the next successful checkpoint simply covers a longer time span. See the
"Checkpoint Subsuming Contract" in the class-level JavaDocs
for
details.
These notifications are "best effort", meaning they can sometimes be skipped.
This method is very rarely necessary to implement. The "best effort" guarantee, together with the fact that this method should not result in discarding any data (per the "Checkpoint Subsuming Contract") means it is mainly useful for earlier cleanups of auxiliary resources. One example is to pro-actively clear a local per-checkpoint state cache upon checkpoint failure.
notifyCheckpointAborted
in interface CheckpointListener
checkpointId
- The ID of the checkpoint that has been aborted.public List<AcknowledgeIdsForCheckpoint<String>> snapshotState(long checkpointId, long timestamp) throws Exception
ListCheckpointed
The returned list should contain one entry for redistributable unit of state. See the
class docs
for an illustration how list-style state redistribution
works.
As special case, the returned list may be null or empty (if the operator has no state) or it may contain a single element (if the operator state is indivisible).
snapshotState
in interface ListCheckpointed<AcknowledgeIdsForCheckpoint<String>>
checkpointId
- The ID of the checkpoint - a unique and monotonously increasing value.timestamp
- The wall clock timestamp when the checkpoint was triggered by the master.Exception
- Thrown if the creation of the state object failed. This causes the
checkpoint to fail. The system may decide to fail the operation (and trigger recovery),
or to discard this checkpoint attempt and to continue running and to try again with the
next checkpoint attempt.public void restoreState(List<AcknowledgeIdsForCheckpoint<String>> state) throws Exception
ListCheckpointed
The given state list will contain all the sub states that this parallel instance of
the function needs to handle. Refer to the class docs
for an
illustration how list-style state redistribution works.
Important: When implementing this interface together with RichFunction
,
then the restoreState()
method is called before RichFunction.open(Configuration)
.
restoreState
in interface ListCheckpointed<AcknowledgeIdsForCheckpoint<String>>
state
- The state to be restored as a list of atomic sub-states.Exception
- Throwing an exception in this method causes the recovery to fail. The exact
consequence depends on the configured failure handling strategy, but typically the system
will re-attempt the recovery, or try recovering from a different checkpoint.Copyright © 2014–2023 The Apache Software Foundation. All rights reserved.