subscription

Documentation

Index

• type BackoffSleeper
  • func NewBackoffSleeper() *BackoffSleeper
  • func (bs *BackoffSleeper) After() time.Duration
  • func (bs *BackoffSleeper) Duration() time.Duration
  • func (bs *BackoffSleeper) Reset()
  • func (bs *BackoffSleeper) Sleep()
• type HeadTrackable
• type HeadTracker
  • func NewHeadTracker(ethClient client.Client, store store.Store, config *types.Config, ...) *HeadTracker
  • func (ht *HeadTracker) Connected() bool
  • func (ht *HeadTracker) ExportedDone() chan struct{}
  • func (ht *HeadTracker) GetChainWithBackfill(ctx context.Context, head *models.Head, depth int64) (*models.Head, error)
  • func (ht *HeadTracker) HighestSeenHead() *models.Head
  • func (ht *HeadTracker) Save(h *models.Head) error
  • func (ht *HeadTracker) Start() error
  • func (ht *HeadTracker) Stop() error
• type ManagedSubscription
  • func NewManagedSubscription(logSubscriber client.Client, filter ethereum.FilterQuery, ...) (*ManagedSubscription, error)
  • func (sub ManagedSubscription) Unsubscribe()
• type Sleeper
• type Unsubscriber

Types

type BackoffSleeper

type BackoffSleeper struct {
	backoff.Backoff
	// contains filtered or unexported fields
}

BackoffSleeper is a sleeper that backs off on subsequent attempts.

func NewBackoffSleeper

func NewBackoffSleeper() *BackoffSleeper

NewBackoffSleeper returns a BackoffSleeper that is configured to sleep for 0 seconds initially, then backs off from 1 second minimum to 10 seconds maximum.

func (*BackoffSleeper) After

func (bs *BackoffSleeper) After() time.Duration

After returns the duration for the next stop, and increments the backoff.

func (*BackoffSleeper) Duration

func (bs *BackoffSleeper) Duration() time.Duration

Duration returns the current duration value.

func (*BackoffSleeper) Reset

func (bs *BackoffSleeper) Reset()

Reset resets the backoff intervals.

func (*BackoffSleeper) Sleep

func (bs *BackoffSleeper) Sleep()

Sleep waits for the given duration, incrementing the back off.

type HeadTrackable

type HeadTrackable interface {
	Connect(head *models.Head) error
	Disconnect()
	OnNewLongestChain(ctx context.Context, head *models.Head)
}

HeadTrackable represents any object that wishes to respond to ethereum events, after being attached to HeadTracker.

type HeadTracker

type HeadTracker struct {
	// contains filtered or unexported fields
}

HeadTracker holds and stores the latest block number seen in a thread safe manner. Reconstitutes the last block number from the data store on reboot.

func NewHeadTracker

func NewHeadTracker(
	ethClient client.Client,
	store store.Store,
	config *types.Config,
	callbacks []HeadTrackable,
	sleepers ...Sleeper) *HeadTracker

NewHeadTracker instantiates a new HeadTracker using the db to persist new block numbers. Can be passed in an optional sleeper object that will dictate how often it tries to reconnect.

func (*HeadTracker) Connected

func (ht *HeadTracker) Connected() bool

Connected returns whether or not this HeadTracker is connected.

func (*HeadTracker) ExportedDone

func (ht *HeadTracker) ExportedDone() chan struct{}

ExportedDone exports the done channel for testing

func (*HeadTracker) GetChainWithBackfill

func (ht *HeadTracker) GetChainWithBackfill(ctx context.Context, head *models.Head, depth int64) (*models.Head, error)

GetChainWithBackfill returns a chain of the given length, backfilling any heads that may be missing from the database

func (*HeadTracker) HighestSeenHead

func (ht *HeadTracker) HighestSeenHead() *models.Head

HighestSeenHead returns the block header with the highest number that has been seen, or nil

func (*HeadTracker) Save

func (ht *HeadTracker) Save(h *models.Head) error

Save updates the latest block number, if indeed the latest, and persists this number in case of reboot. Thread safe.

func (*HeadTracker) Start

func (ht *HeadTracker) Start() error

Start retrieves the last persisted block number from the HeadTracker, subscribes to new heads, and if successful fires Connect on the HeadTrackable argument.

func (*HeadTracker) Stop

func (ht *HeadTracker) Stop() error

Stop unsubscribes all connections and fires Disconnect.

type ManagedSubscription

type ManagedSubscription struct {
	// contains filtered or unexported fields
}

ManagedSubscription encapsulates the connecting, backfilling, and clean up of an ethereum node subscription.

func NewManagedSubscription

func NewManagedSubscription(
	logSubscriber client.Client,
	filter ethereum.FilterQuery,
	callback func(models.Log),
) (*ManagedSubscription, error)

NewManagedSubscription subscribes to the ethereum node with the passed filter and delegates incoming logs to callback.

func (ManagedSubscription) Unsubscribe

func (sub ManagedSubscription) Unsubscribe()

Unsubscribe closes channels and cleans up resources.

type Sleeper

type Sleeper interface {
	Reset()
	Sleep()
	After() time.Duration
	Duration() time.Duration
}

Sleeper interface is used for tasks that need to be done on some interval, excluding Cron, like reconnecting.

type Unsubscriber

type Unsubscriber interface {
	Unsubscribe()
}

Unsubscriber is the interface for all subscriptions, allowing one to unsubscribe.