org.tools4j.elara.route

Interface EventRouter

All Known Subinterfaces:

EventRouter.Default

All Known Implementing Classes:

DefaultEventRouter

public interface EventRouter

Facilitates routing of events when processing commands.

Event routing can be done in two ways: already coded events can be routed via one of the routeEvent(..) methods. Alternatively the event can be encoded into the event log buffer directly as follows:

     try (RoutingContext context = routingEvent()) {
         int length = context.buffer().putStringAscii(0, "Hello world");
         context.route(length);
     }
 

Note that RoutingContext implements AutoCloseable and if event routing is performed inside a try-resource block as in the example above then routing will be aborted automatically if route(..) is not called for instance due to an exception.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	EventRouter.Default Provides default methods for EventRouter.
static interface	EventRouter.RoutingContext Context object returned by routingEvent() allowing for zero copy encoding of events directly into the event log buffer.

Method Summary

Modifier and Type	Method and Description
boolean	isSkipped() If true the current command was skipped without routing any events.
short	nextEventIndex() Returns the zero based index of the next event to be routed.
void	routeEvent(DirectBuffer buffer, int offset, int length) Routes an APPLICATION event already encoded in the given buffer.
void	routeEvent(int type, DirectBuffer buffer, int offset, int length) Routes an already encoded event of the specified event type.
void	routeEventWithoutPayload(int type) Routes an event of the specified event type that carries no payload data.
EventRouter.RoutingContext	routingEvent() Starts routing of an APPLICATION event and returns the routing context with the buffer for event encoding.
EventRouter.RoutingContext	routingEvent(int type) Starts routing of an event of the given type returns the routing context with the buffer for event encoding.
boolean	skipCommand() Skip the current command if possible.

Method Detail

routingEvent

EventRouter.RoutingContext routingEvent()

Starts routing of an APPLICATION event and returns the routing context with the buffer for event encoding. Encoding and routing is completed with route(..) and is recommended to be performed inside a try-resource block; see class documentation for an example.

Returns:

the context for event encoding and routing

routingEvent

EventRouter.RoutingContext routingEvent(int type)

Starts routing of an event of the given type returns the routing context with the buffer for event encoding. Encoding and routing is completed with route(..) and is recommended to be performed inside a try-resource block; see class documentation for an example.

Parameters:

type - the event type, typically non-negative for application events (plugins use negative event types)

Returns:

the context for event encoding and routing

Throws:

IllegalArgumentException - if type is COMMIT or ROLLBACK

routeEvent

void routeEvent(DirectBuffer buffer,
                int offset,
                int length)

Routes an APPLICATION event already encoded in the given buffer.

Parameters:

buffer - the buffer containing the event data

offset - offset where the event data starts in buffer

length - the length of the event data in bytes

Throws:

IllegalStateException - if this command has been skipped

routeEvent

void routeEvent(int type,
                DirectBuffer buffer,
                int offset,
                int length)

Routes an already encoded event of the specified event type.

Parameters:

type - the event type, typically non-negative for application events (plugins use negative event types)

buffer - the buffer containing the event data

offset - offset where the event data starts in buffer

length - the length of the event data in bytes

Throws:

IllegalArgumentException - if type is COMMIT or ROLLBACK

IllegalStateException - if this command has been skipped

routeEventWithoutPayload

void routeEventWithoutPayload(int type)

Routes an event of the specified event type that carries no payload data.

Parameters:

type - the event type, typically non-negative for application events (plugins use negative event types)

Throws:

IllegalArgumentException - if type is COMMIT or ROLLBACK

IllegalStateException - if this command has been skipped

nextEventIndex

short nextEventIndex()

Returns the zero based index of the next event to be routed. If routing has started via routingEvent() then the index refers to the event currently being encoded.

Returns:

index of the next event to be routed.

skipCommand

boolean skipCommand()

Skip the current command if possible. Skipping is only possible when no events have been routed yet. Routing events after the command was skipped will result in an exception. Calling skip repeatedly has no further effect and returns the same result as for the first invocation.

Returns:

true if the command was skipped, and false if events have been routed already

isSkipped

boolean isSkipped()

If true the current command was skipped without routing any events. Routing events after the command was skipped will result in an exception.

The application state after processing the current command will be exactly the same as before the command. Note that the command will not be be marked as processed and is normally also not replayed. Replaying of the command may occur however if the application is restarted or leadership is passed to another node and commands are replayed from the command log. However replaying occurs only if no subsequent command from the same source has yet been marked as processed.

Returns:

true if this command is skipped