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) 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 Request ¶ added in v1.10.0
type Request interface {
cache.Request
// NewMaterializer will be called if there is no active materializer to fulfil
// the request. It should return a Materializer appropriate for streaming
// data to fulfil this request.
NewMaterializer() (*Materializer, error)
// Type should return a string which uniquely identifies this type of request.
// The returned value is used as the prefix of the key used to index
// entries in the Store.
Type() string
}
Request is used to request data from the Store. Note that cache.Request is required, but some of the fields cache.RequestInfo fields are ignored (ex: MaxAge, and MustRevalidate).
type Result ¶ added in v1.10.0
type Result struct {
Index uint64
Value interface{}
// Cached is true if the requested value was already available locally. If
// the value is false, it indicates that getFromView had to wait for an update,
Cached bool
}
Result returned from the View.
type Store ¶ added in v1.10.0
type Store struct {
// contains filtered or unexported fields
}
Store of Materializers. Store implements an interface similar to agent/cache.Cache, and allows a single Materializer to fulfil multiple requests as long as the requests are identical. Store is used in place of agent/cache.Cache because with the streaming backend there is no longer any need to run a background goroutine to refresh stored values.
func NewStore ¶ added in v1.10.0
func NewStore(logger hclog.Logger) *Store
NewStore creates and returns a Store that is ready for use. The caller must call Store.Run (likely in a separate goroutine) to start the expiration loop.
func (*Store) Get ¶ added in v1.10.0
Get a value from the store, blocking if the store has not yet seen the req.Index value. See agent/cache.Cache.Get for complete documentation.
func (*Store) Notify ¶ added in v1.10.0
func (s *Store) Notify( ctx context.Context, req Request, correlationID string, updateCh chan<- cache.UpdateEvent, ) error
Notify the updateCh when there are updates to the entry identified by req. See agent/cache.Cache.Notify for complete documentation.
Request.CacheInfo().Timeout is ignored because it is not really relevant in this case. Instead set a deadline on the context.
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{}
// 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().
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