filters

Documentation

Index

• Variables
• type Backend
• type EventSystem
  • func NewEventSystem(backend Backend) *EventSystem
  • func (es *EventSystem) SubscribeLogs(crit FilterQuery, logs chan []*types.Log) (*Subscription, error)
  • func (es *EventSystem) SubscribeNewHeads(headers chan *types.Header) *Subscription
  • func (es *EventSystem) SubscribePendingTxs(hashes chan []common.Hash) *Subscription
• type Filter
• type FilterCriteria
  • func (args *FilterCriteria) UnmarshalJSON(data []byte) error
• type FilterQuery
• type PublicFilterAPI
  • func NewPublicFilterAPI(backend Backend) *PublicFilterAPI
  • func (api *PublicFilterAPI) GetFilterChanges(id rpc.ID) (interface{}, error)
  • func (api *PublicFilterAPI) Logs(ctx context.Context, crit FilterCriteria) (*rpc.Subscription, error)
  • func (api *PublicFilterAPI) NewBlockFilter() rpc.ID
  • func (api *PublicFilterAPI) NewFilter(crit FilterCriteria) (rpc.ID, error)
  • func (api *PublicFilterAPI) NewHeads(ctx context.Context) (*rpc.Subscription, error)
  • func (api *PublicFilterAPI) NewPendingTransactionFilter() rpc.ID
  • func (api *PublicFilterAPI) NewPendingTransactions(ctx context.Context) (*rpc.Subscription, error)
  • func (api *PublicFilterAPI) UninstallFilter(id rpc.ID) bool
• type Subscription
  • func (sub *Subscription) Err() <-chan error
  • func (sub *Subscription) Unsubscribe()
• type Type

Variables

var (
	ErrInvalidSubscriptionID = errors.New("invalid id")
)

Types

type Backend

type Backend interface {
	ChainDb() fdb.Database
	HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) *types.Header
	HeaderByHash(ctx context.Context, blockHash common.Hash) *types.Header
	GetReceipts(ctx context.Context, blockHash common.Hash) ([]*types.Receipt, error)
	GetLogs(ctx context.Context, blockHash common.Hash) ([][]*types.Log, error)
}

type EventSystem

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

EventSystem creates subscriptions, processes events and broadcasts them to the subscription which match the subscription criteria.

func NewEventSystem

func NewEventSystem(backend Backend) *EventSystem

NewEventSystem creates a new manager that listens for event on the given mux, parses and filters them. It uses the all map to retrieve filter changes. The work loop holds its own index that is used to forward events to filters.

The returned manager has a loop that needs to be stopped with the Stop function or by stopping the given mux.

func (*EventSystem) SubscribeLogs

func (es *EventSystem) SubscribeLogs(crit FilterQuery, logs chan []*types.Log) (*Subscription, error)

SubscribeLogs creates a subscription that will write all logs matching the given criteria to the given logs channel. Default value for the from and to block is "latest". If the fromBlock > toBlock an error is returned.

func (*EventSystem) SubscribeNewHeads

func (es *EventSystem) SubscribeNewHeads(headers chan *types.Header) *Subscription

SubscribeNewHeads creates a subscription that writes the header of a block that is imported in the chain.

func (*EventSystem) SubscribePendingTxs

func (es *EventSystem) SubscribePendingTxs(hashes chan []common.Hash) *Subscription

SubscribePendingTxs creates a subscription that writes transaction hashes for transactions that enter the transaction pool.

type Filter

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

Filter can be used to retrieve and filter logs.

type FilterCriteria

type FilterCriteria FilterQuery

FilterCriteria represents a request to create a new filter.

func (*FilterCriteria) UnmarshalJSON

func (args *FilterCriteria) UnmarshalJSON(data []byte) error

UnmarshalJSON sets *args fields with given data.

type FilterQuery

type FilterQuery struct {
	Accounts []common.Name // restricts matches to events created by specific contracts

	// The Topic list restricts matches to particular event topics. Each event has a list
	// of topics. Topics matches a prefix of that list. An empty element slice matches any
	// topic. Non-empty elements represent an alternative that matches any of the
	// contained topics.
	//
	// Examples:
	// {} or nil          matches any topic list
	// {{A}}              matches topic A in first position
	// {{}, {B}}          matches any topic in first position, B in second position
	// {{A}, {B}}         matches topic A in first position, B in second position
	// {{A, B}}, {C, D}}  matches topic (A OR B) in first position, (C OR D) in second position
	Topics [][]common.Hash
}

type PublicFilterAPI

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

PublicFilterAPI offers support to create and manage filters. This will allow external clients to retrieve various information related to the set protocol such als blocks, transactions and logs.

func NewPublicFilterAPI

func NewPublicFilterAPI(backend Backend) *PublicFilterAPI

NewPublicFilterAPI returns a new PublicFilterAPI instance.

func (*PublicFilterAPI) GetFilterChanges

func (api *PublicFilterAPI) GetFilterChanges(id rpc.ID) (interface{}, error)

GetFilterChanges returns the logs for the filter with the given id since last time it was called. This can be used for polling.

For pending transaction and block filters the result is []common.Hash. (pending)Log filters return []Log.

func (*PublicFilterAPI) Logs

func (api *PublicFilterAPI) Logs(ctx context.Context, crit FilterCriteria) (*rpc.Subscription, error)

Logs creates a subscription that fires for all new log that match the given filter criteria.

func (*PublicFilterAPI) NewBlockFilter

func (api *PublicFilterAPI) NewBlockFilter() rpc.ID

NewBlockFilter creates a filter that fetches blocks that are imported into the chain. It is part of the filter package since polling goes with ft_getFilterChanges.

func (*PublicFilterAPI) NewFilter

func (api *PublicFilterAPI) NewFilter(crit FilterCriteria) (rpc.ID, error)

NewFilter creates a new filter and returns the filter id. It can be used to retrieve logs when the state changes. This method cannot be used to fetch logs that are already stored in the state.

func (*PublicFilterAPI) NewHeads

func (api *PublicFilterAPI) NewHeads(ctx context.Context) (*rpc.Subscription, error)

NewHeads send a notification each time a new (header) block is appended to the chain.

func (*PublicFilterAPI) NewPendingTransactionFilter

func (api *PublicFilterAPI) NewPendingTransactionFilter() rpc.ID

NewPendingTransactionFilter creates a filter that fetches pending transaction hashes as transactions enter the pending state.

It is part of the filter package because this filter can be used through the `ft_getFilterChanges` polling method that is also used for log filters.

func (*PublicFilterAPI) NewPendingTransactions

func (api *PublicFilterAPI) NewPendingTransactions(ctx context.Context) (*rpc.Subscription, error)

NewPendingTransactions creates a subscription that is triggered each time a transaction enters the transaction pool and was signed from one of the transactions this nodes manages.

func (*PublicFilterAPI) UninstallFilter

func (api *PublicFilterAPI) UninstallFilter(id rpc.ID) bool

UninstallFilter removes the filter with the given filter id.

type Subscription

type Subscription struct {
	ID rpc.ID
	// contains filtered or unexported fields
}

Subscription is created when the client registers itself for a particular event.

func (*Subscription) Err

func (sub *Subscription) Err() <-chan error

Err returns a channel that is closed when unsubscribed.

func (*Subscription) Unsubscribe

func (sub *Subscription) Unsubscribe()

Unsubscribe uninstalls the subscription from the event broadcast loop.

type Type

type Type byte

Type determines the kind of filter and is used to put the filter in to the correct bucket when added.

const (
	// UnknownSubscription indicates an unknown subscription type
	UnknownSubscription Type = iota
	// LogsSubscription queries for new or removed (chain reorg) logs
	LogsSubscription
	// transactions entering the pending state
	PendingTransactionsSubscription
	// BlocksSubscription queries hashes for blocks that are imported
	BlocksSubscription
	// LastSubscription keeps track of the last index
	LastIndexSubscription
)