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Index ¶
Constants ¶
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Variables ¶
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Functions ¶
This section is empty.
Types ¶
type EventPropagator ¶
type EventPropagator struct {
// contains filtered or unexported fields
}
Event propagator that will propagate events from a source to subscribers.
The event propagator will use one dedicated goroutine to relay events to each subscriber. The propagator will use non-blocking writes and events will be discarded when the subscriber's channel is full.
The event propagator does not support multiple event sources.
func NewEventPropagator ¶
func NewEventPropagator(logger *log.Logger, tracerProvider trace.TracerProvider) *EventPropagator
Description ¶
Create a new, non-started event propagator.
Inputs ¶
logger: Logger to use to publish debug logs. If nil, a logger with a io.Discard is used.
tracerProvider: tracer provider to use to get a tracer to instrument code. If nil, global tracer provider will be used.
Return ¶
A new, not started event propagator.
func (*EventPropagator) Start ¶
func (propagator *EventPropagator) Start(ctx context.Context, sourceId string, source chan event.Event, newSubscribers chan Subscription, confirmations chan error) error
Description ¶
Start the propagator. The propagator must start and manage one or several goroutines that will listen for new subscribers and for events to propagate to subscribers.
Inputs ¶
- ctx: Context used for tracing purpose.
- sourceId: ID of the event source.
- source: Source of events to propagate to subscribers.
- newSubscribers: Channel used to listen for new subscriptions.
- confirmations: Channel used by the propagator to publish the outcome of the subscription.
Implementation requirements & hints ¶
- The propagator should be used to propagate event from only one event source.
- Do not use the provided context to receive cancellation signals as the provided context can expire a bit after Start has been called.
- Subscribers' names are not required to be unique.
- Subscriber's channel can be closed by the subscriber to unsubscribe. Propagator must handle the case when it writes to a closed channel. Once a subscriber's channel is closed, it must be removed from the list of subscribers to which events are propagated to.
- The source channel can be closed in case the event source is stopped. In this case, the propagator must close all subscriber's channel and stop all internal goroutines.
- The propagator must return an error if it has already been started.
- The propagator must return an error if it has been stopped (no restart - stale source).
- When stopping, the propagator must close the confirmations channel so the event bus can reject new subscriptions and remove the event source.
Return ¶
An error if propagator failed to start.
func (*EventPropagator) Stop ¶
func (propagator *EventPropagator) Stop(ctx context.Context) error
Description ¶
Stop the propagator. The propagator is expected to stop listening for new subscribers or events, close all its current subscribers'channels, close the newSubscriber channel and stop all its internal goroutines.
Inputs ¶
- ctx: Context used for tracing purpose.
Return ¶
An error if propatagor failed to stop.
type EventPropagatorInterface ¶
type EventPropagatorInterface interface {
// # Description
//
// Start the propagator. The propagator must start and manage one or several goroutines that
// will listen for new subscribers and for events to propagate to subscribers.
//
// # Inputs
//
// - ctx: Context used for tracing purpose.
// - sourceId: ID of the event source.
// - source: Source of events to propagate to subscribers.
// - newSubscribers: Channel used to listen for new subscriptions.
// - confirmations: Channel used by the propagator to publish the outcome of the subscription.
//
// # Implementation requirements & hints
//
// - The propagator should be used to propagate event from only one event source.
// - Do not use the provided context to receive cancellation signals as the provided context
// can expire a bit after Start has been called.
// - Subscribers' names are not required to be unique.
// - Subscriber's channel can be closed by the subscriber to unsubscribe. Propagator must
// handle the case when it writes to a closed channel. Once a subscriber's channel is
// closed, it must be removed from the list of subscribers to which events are propagated to.
// - The source channel can be closed in case the event source is stopped. In this case, the
// propagator must close all subscriber's channel and stop all internal goroutines.
// - The propagator must return an error if it has already been started.
// - The propagator must return an error if it has been stopped (no restart - stale source).
// - When stopping, the propagator must close the confirmations channel so the event bus can
// reject new subscriptions and remove the event source.
//
// # Return
//
// An error if propagator failed to start.
Start(ctx context.Context, sourceId string, source chan event.Event, newSubscribers chan Subscription, confirmations chan error) error
// # Description
//
// Stop the propagator. The propagator is expected to stop listening for new subscribers or
// events, close all its current subscribers'channels, close the newSubscriber channel and
// stop all its internal goroutines.
//
// # Inputs
//
// - ctx: Context used for tracing purpose.
//
// # Return
//
// An error if propatagor failed to stop.
Stop(ctx context.Context) error
}
Interface for a component that will propagate events from a source to subscribers.
type EventPropagatorMock ¶
Mock an EventPropagator
func (*EventPropagatorMock) Start ¶
func (mock *EventPropagatorMock) Start(ctx context.Context, sourceId string, source chan event.Event, newSubscribers chan Subscription, confirmations chan error) error
Description ¶
Start the propagator. The propagator must start and manage one or several goroutines that will listen for new subscribers and for events to propagate to subscribers.
Inputs ¶
- ctx: Context used for tracing purpose.
- sourceId: ID of the event source.
- source: Source of events to propagate to subscribers.
- newSubscribers: Channel used to listen for new subscriptions.
- confirmations: Channel used by the propagator to publish the outcome of the subscription.
Implementation requirements & hints ¶
- The propagator should be used to propagate event from only one event source.
- Do not use the provided context to receive cancellation signals as the provided context can expire a bit after Start has been called.
- Subscribers' names are not required to be unique.
- Subscriber's channel can be closed by the subscriber to unsubscribe. Propagator must handle the case when it writes to a closed channel. Once a subscriber's channel is closed, it must be removed from the list of subscribers to which events are propagated to.
- The source channel can be closed in case the event source is stopped. In this case, the propagator must close all subscriber's channel and stop all internal goroutines.
- The propagator must return an error if it has already been started.
- The propagator must return an error if it has been stopped (no restart - stale source).
- When stopping, the propagator must close the confirmations channel so the event bus can reject new subscriptions and remove the event source.
Return ¶
An error if propagator failed to start.
func (*EventPropagatorMock) Stop ¶
func (mock *EventPropagatorMock) Stop(ctx context.Context) error
Description ¶
Stop the propagator. The propagator is expected to stop listening for new subscribers or events, close all its current subscribers'channels, close the newSubscriber channel and stop all its internal goroutines.
Inputs ¶
- ctx: Context used for tracing purpose.
Return ¶
An error if propatagor failed to stop.
type Subscription ¶
type Subscription struct {
// Name provided by the subscriber to identify itself. Uniqueness must not be required.
Name string
// Channel provided by the subscriber to receive propagated events.
Subscriber chan event.Event
}
Contains everything needed to propagate events to the subscriber.
Source Files