Documentation
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Overview ¶
Package websocket is a WebSocket-backed AsyncNotifier that holds its client connections in process memory.
This provider is correct at one replica ¶
Connections live in this process, so Publish reaches only the clients connected to this instance. Run two replicas behind a load balancer and a client connected to replica A never sees an event published on replica B. It fails as a missing notification rather than an error: nothing here detects the second instance, and nothing reports the events it did not receive.
That is a constraint on the deployment, not a tuning knob. A service that scales out wants the ably or pusher provider instead, where a hosted broker holds the connections and every replica publishes through it.
Why there is no messagequeue backplane ¶
Fanning these events out over messagequeue was considered and rejected.
Such a backplane has to carry every event, including the ones bound for clients on the replica that published: delivering locally *and* over the queue would deliver twice to anyone connected here. So the broker's delivery guarantee becomes this provider's guarantee. Redis pub/sub is the only broker anyone would stand up for notification fanout, and it is at-most-once (see messagequeue's Consumer docs) — which would make the single-replica case, the one that works correctly today, less reliable than it is now. The multi-replica case it would fix already has two working answers above.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var (
ErrNilConfig = errors.New("websocket async notifier config is nil")
)
Functions ¶
This section is empty.
Types ¶
type Config ¶
type Config struct {
HeartbeatInterval time.Duration `env:"HEARTBEAT_INTERVAL" json:"heartbeatInterval,omitempty" yaml:"heartbeatInterval,omitempty"`
ReadBufferSize int `env:"READ_BUFFER_SIZE" json:"readBufferSize,omitempty" yaml:"readBufferSize,omitempty"`
WriteBufferSize int `env:"WRITE_BUFFER_SIZE" json:"writeBufferSize,omitempty" yaml:"writeBufferSize,omitempty"`
}
Config holds WebSocket async notifier configuration.
type Notifier ¶
type Notifier struct {
// contains filtered or unexported fields
}
Notifier is a WebSocket-backed AsyncNotifier that manages direct client connections.
func NewNotifier ¶
NewNotifier creates a new WebSocket-backed AsyncNotifier.
func (*Notifier) AcceptConnection ¶
func (n *Notifier) AcceptConnection(w http.ResponseWriter, r *http.Request, channel, memberID string) error
AcceptConnection upgrades the HTTP connection to a WebSocket and registers it under the given channel and memberID.
func (*Notifier) Publish ¶
Publish sends an event to all connected clients on the given channel.
One client's failure does not stop the others: every connection on the channel is attempted, and the joined per-client failures come back from here, so a non-nil error means the event reached a subset of the channel.
type Option ¶
type Option func(*options)
Option configures the Notifier this package constructs. The zero configuration works: absent observability deps are normalized downstream.
func WithTracerProvider ¶
WithTracerProvider attaches a tracer provider.
Source Files