Documentation
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Index ¶
Constants ¶
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Variables ¶
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Functions ¶
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Types ¶
type Deps ¶
type Deps struct {
View View
Client StreamClient
Logger hclog.Logger
Waiter *retry.Waiter
Request func(index uint64) pbsubscribe.SubscribeRequest
}
type Materializer ¶
type Materializer struct {
// contains filtered or unexported fields
}
Materializer consumes the event stream, handling any framing events, and sends the events to View as they are received.
Materializer is used as the cache.Result.State for a streaming cache type and manages the actual streaming RPC call to the servers behind the scenes until the cache result is discarded when TTL expires.
func NewMaterializer ¶
func NewMaterializer(deps Deps) *Materializer
NewMaterializer returns a new Materializer. Run must be called to start it.
func (*Materializer) Fetch ¶
func (m *Materializer) Fetch(done <-chan struct{}, opts cache.FetchOptions) (cache.FetchResult, error)
Fetch implements the logic a StreamingCacheType will need during it's Fetch call. Cache types that use streaming should just be able to proxy to this once they have a subscription object and return it's results directly.
func (*Materializer) Run ¶
func (m *Materializer) Run(ctx context.Context)
Run receives events from the StreamClient and sends them to the View. It runs until ctx is cancelled, so it is expected to be run in a goroutine.
type StreamClient ¶
type StreamClient interface {
Subscribe(ctx context.Context, in *pbsubscribe.SubscribeRequest, opts ...grpc.CallOption) (pbsubscribe.StateChangeSubscription_SubscribeClient, error)
}
StreamClient provides a subscription to state change events.
type View ¶
type View interface {
// Update is called when one or more events are received. The first call will
// include _all_ events in the initial snapshot which may be an empty set.
// Subsequent calls will contain one or more update events in the order they
// are received.
Update(events []*pbsubscribe.Event) error
// Result returns the type-specific cache result based on the state. When no
// events have been delivered yet the result should be an empty value type
// suitable to return to clients in case there is an empty result on the
// servers. The index the materialized view represents is maintained
// separately and passed in in case the return type needs an Index field
// populating. This allows implementations to not worry about maintaining
// indexes seen during Update.
Result(index uint64) (interface{}, error)
// Reset the view to the zero state, done in preparation for receiving a new
// snapshot.
Reset()
}
View receives events from, and return results to, Materializer. A view is responsible for converting the pbsubscribe.Event.Payload into the local type, and storing it so that it can be returned by Result().
Source Files