CommandQueue¶

CommandQueue is an abstraction of command queues that DistributingExecutor uses to execute statements.

Contract (Subset)¶

Creating Transactional Kafka Producer¶

Producer<CommandId, Command> createTransactionalProducer()

Creates a KafkaProducer (Apache Kafka)

See CommandStore

Used when:

• DistributingExecutor is requested to execute a statement

ensureConsumedPast¶

void ensureConsumedPast(
  long seqNum,
  Duration timeout)

See CommandStore

Used when:

• CommandStore is requested to waitForCommandConsumer
• DefaultCommandQueueSync is requested to waitFor
• CommandStoreUtil is requested to waitForCommandSequenceNumber

enqueueCommand¶

QueuedCommandStatus enqueueCommand(
  CommandId commandId,
  Command command,
  Producer<CommandId, Command> transactionalProducer)

Sends a command to the command topic (using a transactional KafkaProducer) for execution

See CommandStore

Used when:

• DistributingExecutor is requested to execute a statement

Fetching New Commands¶

List<QueuedCommand> getNewCommands(
  Duration timeout)

Fetches QueuedCommands (e.g., from a CommandTopic)

See CommandStore

Used when:

• CommandRunner is requested to fetchAndRunCommands

waitForCommandConsumer¶

void waitForCommandConsumer()

See CommandStore

Used when:

• DistributingExecutor is requested to execute a statement

Implementations¶

• CommandStore