Package at.aimon.session.postgres.internal

Class ListenDispatcher

java.lang.Object

at.aimon.session.postgres.internal.ListenDispatcher

All Implemented Interfaces:

AutoCloseable

public final class ListenDispatcher
extends Object
implements AutoCloseable

Owns the dedicated LISTEN connection for conversation_signal_doorbell.

The LISTEN connection lives outside HikariCP because LISTEN state is connection-bound and cannot survive being returned to a pool — see design §6.2. A second short-lived DataSource (typically the bus's signal pool) is used for the row-fetch SELECTs so the dedicated LISTEN connection only ever blocks on PGConnection.getNotifications().

Reconnect semantics (design §6.2 / §8 #2): on any SQLException the dispatcher closes the listen connection, sleeps 500 ms, opens a new one, re-issues LISTEN, runs a backlog query starting at the highest id seen so far, and resumes. No signal loss because the rows live in the table independent of NOTIFY delivery.

Backstop self-poll (design §4.2): every selfPollMillis ms the dispatcher re-runs the fetch query without waiting for a doorbell, catching any rows that arrived while a NOTIFY was dropped (e.g. backend crash, network blip).

Field Summary

Fields

Modifier and Type	Field	Description
static final String	CHANNEL

Constructor Summary

Constructors

Constructor	Description
ListenDispatcher(String jdbcUrl, Properties connectionProps, DataSource fetchDataSource, ConversationSignalRowCodec codec)
ListenDispatcher(String jdbcUrl, Properties connectionProps, DataSource fetchDataSource, ConversationSignalRowCodec codec, long pollMillis, long selfPollMillis, long reconnectBackoffMillis)

Method Summary

Modifier and Type	Method	Description
void	close()
void	start()	Starts the listener thread.
void	track(at.aimon.core.agent.conversation.ConversationId id, Consumer<at.aimon.session.web.spi.ConversationSignal> handler)
void	untrack(at.aimon.core.agent.conversation.ConversationId id)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Details

CHANNEL

public static final String CHANNEL

See Also:

• Constant Field Values

Constructor Details

ListenDispatcher

public ListenDispatcher(String jdbcUrl,
 Properties connectionProps,
 DataSource fetchDataSource,
 ConversationSignalRowCodec codec)

ListenDispatcher

public ListenDispatcher(String jdbcUrl,
 Properties connectionProps,
 DataSource fetchDataSource,
 ConversationSignalRowCodec codec,
 long pollMillis,
 long selfPollMillis,
 long reconnectBackoffMillis)

Method Details

start

public void start()

Starts the listener thread. Idempotent.

track

public void track(at.aimon.core.agent.conversation.ConversationId id,
 Consumer<at.aimon.session.web.spi.ConversationSignal> handler)

untrack

public void untrack(at.aimon.core.agent.conversation.ConversationId id)

close

public void close()

Specified by:

close in interface AutoCloseable