fetch

Documentation

Overview

Package fetch contains mechanism to fetch Data from remote peers

Index

• Constants
• Variables
• func GetRandomPeer(peers []p2p.Peer) p2p.Peer
• type Config
  • func DefaultConfig() Config
• type ErrCouldNotSend
• type Fetch
  • func NewFetch(ctx context.Context, cfg Config, h *p2p.Host, dbs map[Hint]database.Getter, ...) *Fetch
  • func (f *Fetch) FetchRequestHandler(ctx context.Context, data []byte) ([]byte, error)
  • func (f *Fetch) GetHash(hash types.Hash32, h Hint, validateHash bool) chan HashDataPromiseResult
  • func (f *Fetch) GetHashes(hashes []types.Hash32, hint Hint, validateHash bool) map[types.Hash32]chan HashDataPromiseResult
  • func (f *Fetch) Start()
  • func (f *Fetch) Stop()
• type Fetcher
• type HashDataPromiseResult
• type Hint
• type LocalDataSource

Constants

const (
	// Low will perform batched calls.
	Low priority = 0
	// High will call fetch immediately.
	High priority = 1
)

Message priority constants.

Variables

var ErrExceedMaxRetries = errors.New("fetch failed after max retries for request")

ErrExceedMaxRetries is returned when MaxRetriesForRequest attempts has been made to fetch data for a hash and failed.

Functions

func GetRandomPeer

func GetRandomPeer(peers []p2p.Peer) p2p.Peer

GetRandomPeer returns a random peer from current peer list.

Types

type Config

type Config struct {
	BatchTimeout         int // in milliseconds
	MaxRetriesForPeer    int
	BatchSize            int
	RequestTimeout       int // in seconds
	MaxRetriesForRequest int
}

Config is the configuration file of the Fetch component.

func DefaultConfig

func DefaultConfig() Config

DefaultConfig is the default config for the fetch component.

type ErrCouldNotSend

type ErrCouldNotSend error

ErrCouldNotSend is a special type of error indicating fetch could not be done because message could not be sent to peers.

type Fetch

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

Fetch is the main struct that contains network peers and logic to batch and dispatch hash fetch requests.

func NewFetch

func NewFetch(ctx context.Context, cfg Config, h *p2p.Host, dbs map[Hint]database.Getter, logger log.Log) *Fetch

NewFetch creates a new Fetch struct.

func (*Fetch) FetchRequestHandler

func (f *Fetch) FetchRequestHandler(ctx context.Context, data []byte) ([]byte, error)

FetchRequestHandler handles requests for sync from peersProvider, and basically reads Data from database and puts it in a response batch.

func (*Fetch) GetHash

func (f *Fetch) GetHash(hash types.Hash32, h Hint, validateHash bool) chan HashDataPromiseResult

GetHash is the regular buffered call to get a specific hash, using provided hash, h as hint the receiving end will know where to look for the hash, this function returns HashDataPromiseResult channel that will hold Data received or error.

func (*Fetch) GetHashes

func (f *Fetch) GetHashes(hashes []types.Hash32, hint Hint, validateHash bool) map[types.Hash32]chan HashDataPromiseResult

GetHashes gets a list of hashes to be fetched and will return a map of hashes and their respective promise channels.

func (*Fetch) Start

func (f *Fetch) Start()

Start starts handling fetch requests.

func (*Fetch) Stop

func (f *Fetch) Stop()

Stop stops handling fetch requests.

type Fetcher

type Fetcher interface {
	GetHash(hash types.Hash32, h Hint, validateHash bool) chan HashDataPromiseResult
	GetHashes(hash []types.Hash32, hint Hint, validateHash bool) map[types.Hash32]chan HashDataPromiseResult
	Stop()
	Start()
}

Fetcher is the general interface of the fetching unit, capable of requesting bytes that corresponds to a hash from other remote peers.

type HashDataPromiseResult

type HashDataPromiseResult struct {
	Err     error
	Hash    types.Hash32
	Data    []byte
	IsLocal bool
}

HashDataPromiseResult is the result strict when requesting Data corresponding to the Hash.

type Hint

type Hint string

Hint marks which DB should be queried for a certain provided hash.

const (
	BlockDB Hint = "blocksDB"
	ATXDB   Hint = "ATXDB"
	TXDB    Hint = "TXDB"
	POETDB  Hint = "POETDB"
)

DB hints per DB.

type LocalDataSource

type LocalDataSource map[Hint]database.Getter

LocalDataSource defines the mapping between hint for local data source and the actual data source.