events

package
v0.2.0 Latest Latest
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 Go to latest Published: Oct 5, 2021 License: MIT Imports: 12 Imported by: 0

Documentation

Overview

Package events provides data structures and functions to stream and store events (logs) from the Ethereum blockchain.

Messages in the event stream have three possible actions: 

Append a Block
Rollback to a given Block (happens on chain reorganization)
SetNext to a given block number.

Depending on the event filter used to retrieve logs, the stream may not contain logs for every block. The SetNext message allows the stream to signal that blocks have been read, but no events found. The Append and Rollback messages are straightforward.

The central interfaces are Streamer and EventLog (which is also a Streamer). A Streamer knows how to stream events. The ChainStreamer implements this to stream from the Ethereum blockchain by overlapping eth_getLogs calls, sending Rollback messages when a chain reorganization is detected. An EventLog implements both the receiving methods of a stream (Append, Rollback, SetNext), and the Streamer interface to emit the stored events.

Index

Constants

View Source 
const DefaultBatchOverlap uint64 = 10 // overlap between polls
View Source 
const DefaultFetchBatchSize uint64 = 2000 // size of call to getLogs
View Source 
const DefaultPollInterval int = 15 // seconds
View Source 
const MaxEventlogSize uint64 = 1024 // blocks

Variables

This section is empty.

Functions

func AddTransactionData added in v0.2.0 

func AddTransactionData(ctx context.Context, client *ethclient.Client, bs *BlockSlice) error

func BigIntFromString 

func BigIntFromString(s string) (*big.Int, error)

func BigIntToString 

func BigIntToString(x *big.Int) string

func BlockSliceToProto 

func BlockSliceToProto(bs *BlockSlice) *epb.BlockSlice

func BlockToProto 

func BlockToProto(b *Block) *epb.Block
message Block {
    uint64 number = 1;
    bytes hash = 2;
    repeated Event events = 3;
}

func EventToProto 

func EventToProto(e *Event) *epb.Event

EventToProto creates a proto representation of an Event.

func FilterQueryFromProto 

func FilterQueryFromProto(pb *epb.FilterQuery) (ethereum.FilterQuery, error)

func FilterQueryToProto 

func FilterQueryToProto(q *ethereum.FilterQuery) *epb.FilterQuery

func MatchBlocks 

func MatchBlocks(new, old *BlockSlice) (bool, uint64, error)

MatchHistory compares the new blocks with the old where they overlap. It returns true if all blocks in the overlap have the same hash. The second return value indicates the latest block that agrees. If no block agrees, it returns (false, 0, nil).

Types

type Action 

type Action int
const (
	Append Action = iota
	Rollback
	SetNext
)

type Block 

type Block struct {
	Number uint64
	Hash   common.Hash
	Events []Event
}

func BlockFromProto 

func BlockFromProto(pb *epb.Block) (*Block, error)

type BlockSlice 

type BlockSlice struct {
	Start            uint64
	End              uint64
	DistanceFromHead uint64
	Blocks           []*Block
}

func BlockSliceFromProto 

func BlockSliceFromProto(pb *epb.BlockSlice) (*BlockSlice, error)

func EmptyBlockSlice 

func EmptyBlockSlice(from uint64) *BlockSlice

func GetLogs 

func GetLogs(ctx context.Context, client *ethclient.Client, q *ethereum.FilterQuery) (*BlockSlice, error)

GetLogs returns a batch of logs matching a query. The blocks in the block are guaranteed to be sorted by increasing Number, and the events therein by Index.

func (*BlockSlice) Append 

func (b *BlockSlice) Append(blk *Block) error

func (*BlockSlice) Concat 

func (b *BlockSlice) Concat(other *BlockSlice) error

func (*BlockSlice) DeleteBeforeBlock 

func (b *BlockSlice) DeleteBeforeBlock(n uint64)

func (*BlockSlice) DeleteFromBlock 

func (b *BlockSlice) DeleteFromBlock(n uint64)

func (*BlockSlice) Extend 

func (b *BlockSlice) Extend(n uint64) error

func (*BlockSlice) Rollback 

func (b *BlockSlice) Rollback(n uint64) error

type CanceledError 

type CanceledError string
const Canceled CanceledError = CanceledError("")

func (CanceledError) Error 

func (CanceledError) Error() string

type ChainStreamer 

type ChainStreamer struct {
	Ctx            context.Context
	Url            string
	Filter         ethereum.FilterQuery
	FetchBatchSize uint64
	BatchOverlap   uint64
	FetchTxDetails bool
}

ChainStreamer implements a Streamer for the Ethereum blockchain.

func (*ChainStreamer) Stream 

func (cr *ChainStreamer) Stream(done chan struct{}, from uint64) (*Subscription, error)

type Event 

type Event struct {
	Address common.Address
	Topics  []common.Hash
	Data    []byte

	BlockNumber uint64
	BlockHash   common.Hash
	Index       uint64 // index of log in block

	TxHash  common.Hash
	TxIndex uint64 // index of tx in block
	TxData  []byte
	TxValue *big.Int
	TxFrom  common.Address
	TxGas   uint64
}

func EventFromProto 

func EventFromProto(pb *epb.Event) (*Event, error)

EventFromProto creates an Event from its proto representation.

func (*Event) Log 

func (e *Event) Log() *types.Log

type EventLog 

type EventLog interface {
	Streamer

	Append(*Block) error
	Rollback(uint64) error
	SetNext(uint64) error
	FirstBlock() uint64
	NextBlock() uint64
	Filter() ethereum.FilterQuery
	Close() error
}

EventLog represents a sequence of events matching a filter.

type InMemoryEventLog 

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

InMemoryEventLog is an in-memory implementation of the EventLog interface.

func InMemoryEventLogFromProto 

func InMemoryEventLogFromProto(pb *epb.EventLogFile) (*InMemoryEventLog, error)

func NewInMemoryEventLog 

func NewInMemoryEventLog(from uint64, filter ethereum.FilterQuery) *InMemoryEventLog

func (*InMemoryEventLog) Append 

func (l *InMemoryEventLog) Append(b *Block) error

func (*InMemoryEventLog) Close 

func (l *InMemoryEventLog) Close() error

func (*InMemoryEventLog) Filter 

func (l *InMemoryEventLog) Filter() ethereum.FilterQuery

func (*InMemoryEventLog) FirstBlock 

func (l *InMemoryEventLog) FirstBlock() uint64

func (*InMemoryEventLog) NextBlock 

func (l *InMemoryEventLog) NextBlock() uint64

func (*InMemoryEventLog) Rollback 

func (l *InMemoryEventLog) Rollback(n uint64) error

func (*InMemoryEventLog) SetNext 

func (l *InMemoryEventLog) SetNext(n uint64) error

func (*InMemoryEventLog) Stream 

func (l *InMemoryEventLog) Stream(done chan struct{}, from uint64) (*Subscription, error)

func (*InMemoryEventLog) ToProto 

func (l *InMemoryEventLog) ToProto() *epb.EventLogFile

type LiveEventLog 

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

LiveEventLog combines an EventLog and a ChainStreamer to make a new Streamer that streams first from the EventLog, and then from the ChainStreamer. When streaming from the ChainStreamer the messages are both sent to the EventLog and the subscriber.

func NewLiveEventLog 

func NewLiveEventLog(e EventLog, s ChainStreamer) *LiveEventLog

func (*LiveEventLog) Stream 

func (l *LiveEventLog) Stream(done chan struct{}, from uint64) (*Subscription, error)

type Message 

type Message struct {
	Action Action
	Number uint64
	Block  *Block
}

type Streamer 

type Streamer interface {
	Stream(done chan struct{}, from uint64) (*Subscription, error)
}

type Subscription 

type Subscription struct {
	C    chan *Message
	Err  chan error
	Done chan struct{}
}

Source Files

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