filters

Documentation

Overview

Package filters implements an ethereum filtering system for block, transactions and log events.

Index

• type Backend
• type Config
• type EventSystem
  • func NewEventSystem(sys *FilterSystem) *EventSystem
  • func (es *EventSystem) SubscribeLogs(crit ethereum.FilterQuery, logs chan []*types.Log) (*Subscription, error)
  • func (es *EventSystem) SubscribeNewHeads(headers chan *types.Header) *Subscription
  • func (es *EventSystem) SubscribePendingTxs(txs chan []*types.Transaction) *Subscription
• type Filter
  • func (f *Filter) Logs(ctx context.Context) ([]*types.Log, error)
• type FilterAPI
  • func NewFilterAPI(system *FilterSystem) *FilterAPI
  • func (api *FilterAPI) GetFilterChanges(id rpc.ID) (interface{}, error)
  • func (api *FilterAPI) GetFilterLogs(ctx context.Context, id rpc.ID) ([]*types.Log, error)
  • func (api *FilterAPI) GetLogs(ctx context.Context, crit FilterCriteria) ([]*types.Log, error)
  • func (api *FilterAPI) Logs(ctx context.Context, crit FilterCriteria) (*rpc.Subscription, error)
  • func (api *FilterAPI) NewBlockFilter() rpc.ID
  • func (api *FilterAPI) NewFilter(crit FilterCriteria) (rpc.ID, error)
  • func (api *FilterAPI) NewHeads(ctx context.Context) (*rpc.Subscription, error)
  • func (api *FilterAPI) NewPendingTransactionFilter(fullTx *bool) rpc.ID
  • func (api *FilterAPI) NewPendingTransactions(ctx context.Context, fullTx *bool) (*rpc.Subscription, error)
  • func (api *FilterAPI) UninstallFilter(id rpc.ID) bool
• type FilterCriteria
  • func (args *FilterCriteria) UnmarshalJSON(data []byte) error
• type FilterSystem
  • func NewFilterSystem(backend Backend, config Config) *FilterSystem
  • func (sys *FilterSystem) NewBlockFilter(block common.Hash, addresses []common.Address, topics [][]common.Hash) *Filter
  • func (sys *FilterSystem) NewRangeFilter(begin, end int64, addresses []common.Address, topics [][]common.Hash) *Filter
• type Subscription
  • func (sub *Subscription) Err() <-chan error
  • func (sub *Subscription) Unsubscribe()
• type Type

Types

type Backend

type Backend interface {
	ChainDb() ethdb.Database
	HeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*types.Header, error)
	HeaderByHash(ctx context.Context, blockHash common.Hash) (*types.Header, error)
	GetBody(ctx context.Context, hash common.Hash, number rpc.BlockNumber) (*types.Body, error)
	GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error)
	GetLogs(ctx context.Context, blockHash common.Hash, number uint64) ([][]*types.Log, error)

	CurrentHeader() *types.Header
	ChainConfig() *params.ChainConfig
	SubscribeNewTxsEvent(chan<- core.NewTxsEvent) event.Subscription
	SubscribeChainEvent(ch chan<- core.ChainEvent) event.Subscription
	SubscribeRemovedLogsEvent(ch chan<- core.RemovedLogsEvent) event.Subscription
	SubscribeLogsEvent(ch chan<- []*types.Log) event.Subscription

	BloomStatus() (uint64, uint64)
	ServiceFilter(ctx context.Context, session *bloombits.MatcherSession)
}

type Config

type Config struct {
	LogCacheSize int           // maximum number of cached blocks (default: 32)
	Timeout      time.Duration // how long filters stay active (default: 5min)
}

Config represents the configuration of the filter system.

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(sys *FilterSystem) *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 ethereum.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(txs chan []*types.Transaction) *Subscription

SubscribePendingTxs creates a subscription that writes transactions 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.

func (*Filter) Logs

func (f *Filter) Logs(ctx context.Context) ([]*types.Log, error)

Logs searches the blockchain for matching log entries, returning all from the first block that contains matches, updating the start of the filter accordingly.

type FilterAPI

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

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

func NewFilterAPI

func NewFilterAPI(system *FilterSystem) *FilterAPI

NewFilterAPI returns a new FilterAPI instance.

func (*FilterAPI) GetFilterChanges

func (api *FilterAPI) 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 (*FilterAPI) GetFilterLogs

func (api *FilterAPI) GetFilterLogs(ctx context.Context, id rpc.ID) ([]*types.Log, error)

GetFilterLogs returns the logs for the filter with the given id. If the filter could not be found an empty array of logs is returned.

func (*FilterAPI) GetLogs

func (api *FilterAPI) GetLogs(ctx context.Context, crit FilterCriteria) ([]*types.Log, error)

GetLogs returns logs matching the given argument that are stored within the state.

func (*FilterAPI) Logs

func (api *FilterAPI) 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 (*FilterAPI) NewBlockFilter

func (api *FilterAPI) 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 eth_getFilterChanges.

func (*FilterAPI) NewFilter

func (api *FilterAPI) 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.

Default criteria for the from and to block are "latest". Using "latest" as block number will return logs for mined blocks. Using "pending" as block number returns logs for not yet mined (pending) blocks. In case logs are removed (chain reorg) previously returned logs are returned again but with the removed property set to true.

In case "fromBlock" > "toBlock" an error is returned.

func (*FilterAPI) NewHeads

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

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

func (*FilterAPI) NewPendingTransactionFilter

func (api *FilterAPI) NewPendingTransactionFilter(fullTx *bool) rpc.ID

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

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

func (*FilterAPI) NewPendingTransactions

func (api *FilterAPI) NewPendingTransactions(ctx context.Context, fullTx *bool) (*rpc.Subscription, error)

NewPendingTransactions creates a subscription that is triggered each time a transaction enters the transaction pool. If fullTx is true the full tx is sent to the client, otherwise the hash is sent.

func (*FilterAPI) UninstallFilter

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

UninstallFilter removes the filter with the given filter id.

type FilterCriteria

type FilterCriteria ethereum.FilterQuery

FilterCriteria represents a request to create a new filter. Same as ethereum.FilterQuery but with UnmarshalJSON() method.

func (*FilterCriteria) UnmarshalJSON

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

UnmarshalJSON sets *args fields with given data.

type FilterSystem

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

FilterSystem holds resources shared by all filters.

func NewFilterSystem

func NewFilterSystem(backend Backend, config Config) *FilterSystem

NewFilterSystem creates a filter system.

func (*FilterSystem) NewBlockFilter

func (sys *FilterSystem) NewBlockFilter(block common.Hash, addresses []common.Address, topics [][]common.Hash) *Filter

NewBlockFilter creates a new filter which directly inspects the contents of a block to figure out whether it is interesting or not.

func (*FilterSystem) NewRangeFilter

func (sys *FilterSystem) NewRangeFilter(begin, end int64, addresses []common.Address, topics [][]common.Hash) *Filter

NewRangeFilter creates a new filter which uses a bloom filter on blocks to figure out whether a particular block is interesting or not.

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
	// PendingTransactionsSubscription queries for pending transactions entering
	// the pending state
	PendingTransactionsSubscription
	// BlocksSubscription queries hashes for blocks that are imported
	BlocksSubscription
	// LastIndexSubscription keeps track of the last index
	LastIndexSubscription
)