Ilia Denisov
55 lines
2.0 KiB
Go
55 lines
2.0 KiB
Go
package push
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import "encoding/json"
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// Event is the typed contract for client events emitted onto the gRPC
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// push stream. Implementations carry their own serialiser; push.Service
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// invokes Marshal at publish time to obtain the bytes that go into
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// `pushv1.ClientEvent.Payload`.
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//
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// Notification dispatcher builds a typed FlatBuffers Event for every
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// catalog kind through `notification.buildClientPushEvent`, backed by
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// the per-kind helpers in `pkg/transcoder/notification.go`. JSONEvent
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// (below) remains the safety net for kinds that arrive without a
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// catalog schema.
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type Event interface {
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// Kind returns the catalog kind of this event (`backend/README.md`
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// §10). Empty kind is rejected at publish time.
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Kind() string
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// Marshal returns the bytes that travel inside
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// `pushv1.ClientEvent.Payload`. Implementations are expected to use
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// FlatBuffers (preferred) or any deterministic encoding the client
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// can decode; the push transport treats the result as opaque
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// payload bytes.
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Marshal() ([]byte, error)
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}
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// JSONEvent is the safety-net Event implementation for kinds that
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// arrive without a catalog FlatBuffers schema. It serialises Payload
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// via encoding/json so a misconfigured producer cannot silently drop
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// events while a new kind is being added.
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//
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// New kinds must ship with a typed FlatBuffers schema in
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// `pkg/schema/fbs/notification.fbs` and a matching case in
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// `notification.buildClientPushEvent`; JSONEvent is not a canonical
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// shape, only a fallback.
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type JSONEvent struct {
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// EventKind is the catalog kind returned by Kind().
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EventKind string
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// Payload is the JSON-serialisable map written by the producer.
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Payload map[string]any
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}
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// Kind returns EventKind verbatim.
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func (e JSONEvent) Kind() string { return e.EventKind }
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// Marshal returns Payload encoded as JSON. The result is treated as
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// opaque bytes by the push transport.
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func (e JSONEvent) Marshal() ([]byte, error) {
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return json.Marshal(e.Payload)
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}
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var _ Event = JSONEvent{}
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