bitswap

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 Go to latest Published: Mar 7, 2022 License: MIT Imports: 34 Imported by: 0

README

go-bitswap

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An implementation of the bitswap protocol in go!

Lead Maintainer

Dirk McCormick

Table of Contents

Background

Bitswap is the data trading module for ipfs. It manages requesting and sending blocks to and from other peers in the network. Bitswap has two main jobs:

  • to acquire blocks requested by the client from the network
  • to judiciously send blocks in its possession to other peers who want them

Bitswap is a message based protocol, as opposed to request-response. All messages contain wantlists or blocks.

A node sends a wantlist to tell peers which blocks it wants. When a node receives a wantlist it should check which blocks it has from the wantlist, and consider sending the matching blocks to the requestor.

When a node receives blocks that it asked for, the node should send out a notification called a 'Cancel' to tell its peers that the node no longer wants those blocks.

go-bitswap provides an implementation of the Bitswap protocol in go.

Learn more about how Bitswap works

Install

go-bitswap requires Go >= 1.11 and can be installed using Go modules

Usage

Initializing a Bitswap Exchange
import (
  "context"
  bitswap "github.com/ipfs/go-bitswap"
  bsnet "github.com/ipfs/go-graphsync/network"
  blockstore "github.com/ipfs/go-ipfs-blockstore"
  "github.com/libp2p/go-libp2p-core/routing"
	"github.com/libp2p/go-libp2p-core/host"
)

var ctx context.Context
var host host.Host
var router routing.ContentRouting
var bstore blockstore.Blockstore

network := bsnet.NewFromIpfsHost(host, router)
exchange := bitswap.New(ctx, network, bstore)

Parameter Notes:

  1. ctx is just the parent context for all of Bitswap
  2. network is a network abstraction provided to Bitswap on top of libp2p & content routing.
  3. bstore is an IPFS blockstore
Get A Block Synchronously
var c cid.Cid
var ctx context.Context
var exchange bitswap.Bitswap

block, err := exchange.GetBlock(ctx, c)

Parameter Notes:

  1. ctx is the context for this request, which can be cancelled to cancel the request
  2. c is the content ID of the block you're requesting
Get Several Blocks Asynchronously
var cids []cid.Cid
var ctx context.Context
var exchange bitswap.Bitswap

blockChannel, err := exchange.GetBlocks(ctx, cids)

Parameter Notes:

  1. ctx is the context for this request, which can be cancelled to cancel the request
  2. cids is a slice of content IDs for the blocks you're requesting

In IPFS, content blocks are often connected to each other through a MerkleDAG. If you know ahead of time that block requests are related, Bitswap can make several optimizations internally in how it requests those blocks in order to get them faster. Bitswap provides a mechanism called a Bitswap Session to manage a series of block requests as part of a single higher level operation. You should initialize a Bitswap Session any time you intend to make a series of block requests that are related -- and whose responses are likely to come from the same peers.

var ctx context.Context
var cids []cids.cid
var exchange bitswap.Bitswap

session := exchange.NewSession(ctx)
blocksChannel, err := session.GetBlocks(ctx, cids)
// later
var relatedCids []cids.cid
relatedBlocksChannel, err := session.GetBlocks(ctx, relatedCids)

Note that NewSession returns an interface with GetBlock and GetBlocks methods that have the same signature as the overall Bitswap exchange.

Tell bitswap a new block was added to the local datastore
var blk blocks.Block
var exchange bitswap.Bitswap

err := exchange.HasBlock(blk)

Contribute

PRs are welcome!

Small note: If editing the Readme, please conform to the standard-readme specification.

License

MIT © Juan Batiz-Benet

Documentation

Overview

Package bitswap implements the IPFS exchange interface with the BitSwap bilateral exchange protocol.

Index

Constants

This section is empty.

Variables

View Source 
var (
	// HasBlockBufferSize is the buffer size of the channel for new blocks
	// that need to be provided. They should get pulled over by the
	// provideCollector even before they are actually provided.
	// TODO: Does this need to be this large givent that?
	HasBlockBufferSize = 256
)

Functions

func New 

func New(parent context.Context, network bsnet.BitSwapNetwork,
	bstore blockstore.Blockstore, options ...Option) exchange.Interface

New initializes a BitSwap instance that communicates over the provided BitSwapNetwork. This function registers the returned instance as the network delegate. Runs until context is cancelled or bitswap.Close is called.

Types

type Bitswap 

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

Bitswap instances implement the bitswap protocol.

func (*Bitswap) Close 

func (bs *Bitswap) Close() error

Close is called to shutdown Bitswap

func (*Bitswap) GetBlock 

func (bs *Bitswap) GetBlock(parent context.Context, k cid.Cid) (blocks.Block, error)

GetBlock attempts to retrieve a particular block from peers within the deadline enforced by the context. Command Get doesn't pass by here

func (*Bitswap) GetBlocks 

func (bs *Bitswap) GetBlocks(ctx context.Context, keys []cid.Cid) (<-chan blocks.Block, error)

Appelé dans un autre github (blockservice, fichier blockservice.go, fct getBlock) pour cmd/get crée une nouvelle session et réalise une nouvelle requête pour avoir les blocks. Une session a son propre ID et il augmente par nouvelle session.

func (*Bitswap) GetWantBlocks 

func (bs *Bitswap) GetWantBlocks() []cid.Cid

GetWantBlocks returns the current list of want-blocks.

func (*Bitswap) GetWantHaves 

func (bs *Bitswap) GetWantHaves() []cid.Cid

GetWanthaves returns the current list of want-haves.

func (*Bitswap) GetWantlist 

func (bs *Bitswap) GetWantlist() []cid.Cid

GetWantlist returns the current local wantlist (both want-blocks and want-haves).

func (*Bitswap) HasBlock 

func (bs *Bitswap) HasBlock(ctx context.Context, blk blocks.Block) error

HasBlock announces the existence of a block to this bitswap service. The service will potentially notify its peers.

func (*Bitswap) IsOnline 

func (bs *Bitswap) IsOnline() bool

IsOnline is needed to match go-ipfs-exchange-interface

func (*Bitswap) LedgerForPeer 

func (bs *Bitswap) LedgerForPeer(p peer.ID) *decision.Receipt

LedgerForPeer returns aggregated data about blocks swapped and communication with a given peer.

func (*Bitswap) NewSession 

func (bs *Bitswap) NewSession(ctx context.Context) exchange.Fetcher

NewSession generates a new Bitswap session. You should use this, rather that calling Bitswap.GetBlocks, any time you intend to do several related block requests in a row. The session returned will have it's own GetBlocks method, but the session will use the fact that the requests are related to be more efficient in its requests to peers. If you are using a session from go-blockservice, it will create a bitswap session automatically.

func (*Bitswap) PeerConnected 

func (bs *Bitswap) PeerConnected(p peer.ID)

PeerConnected is called by the network interface when a peer initiates a new connection to bitswap.

func (*Bitswap) PeerDisconnected 

func (bs *Bitswap) PeerDisconnected(p peer.ID)

PeerDisconnected is called by the network interface when a peer closes a connection

func (*Bitswap) ReceiveError 

func (bs *Bitswap) ReceiveError(err error)

ReceiveError is called by the network interface when an error happens at the network layer. Currently just logs error.

func (*Bitswap) ReceiveMessage 

func (bs *Bitswap) ReceiveMessage(ctx context.Context, p peer.ID, incoming bsmsg.BitSwapMessage)

ReceiveMessage is called by the network interface when a new message is received.

func (*Bitswap) Stat 

func (bs *Bitswap) Stat() (*Stat, error)

Stat returns aggregated statistics about bitswap operations

func (*Bitswap) WantlistForPeer 

func (bs *Bitswap) WantlistForPeer(p peer.ID) []cid.Cid

WantlistForPeer returns the currently understood list of blocks requested by a given peer.

type Option 

type Option func(*Bitswap)

Option defines the functional option type that can be used to configure bitswap instances

func EngineBlockstoreWorkerCount 

func EngineBlockstoreWorkerCount(count int) Option

EngineBlockstoreWorkerCount sets the number of worker threads used for blockstore operations in the decision engine

func EngineTaskWorkerCount 

func EngineTaskWorkerCount(count int) Option

EngineTaskWorkerCount sets the number of worker threads used inside the engine

func MaxOutstandingBytesPerPeer 

func MaxOutstandingBytesPerPeer(count int) Option

MaxOutstandingBytesPerPeer describes approximately how much work we are will to have outstanding to a peer at any given time. Setting it to 0 will disable any limiting.

func ProvideEnabled 

func ProvideEnabled(enabled bool) Option

ProvideEnabled is an option for enabling/disabling provide announcements

func ProviderSearchDelay 

func ProviderSearchDelay(newProvSearchDelay time.Duration) Option

ProviderSearchDelay overwrites the global provider search delay

func RebroadcastDelay 

func RebroadcastDelay(newRebroadcastDelay delay.D) Option

RebroadcastDelay overwrites the global provider rebroadcast delay

func SetSendDontHaves 

func SetSendDontHaves(send bool) Option

SetSendDontHaves indicates what to do when the engine receives a want-block for a block that is not in the blockstore. Either - Send a DONT_HAVE message - Simply don't respond This option is only used for testing.

func SetSimulateDontHavesOnTimeout 

func SetSimulateDontHavesOnTimeout(send bool) Option

func TaskWorkerCount 

func TaskWorkerCount(count int) Option

func WithScoreLedger 

func WithScoreLedger(scoreLedger deciface.ScoreLedger) Option

Configures the engine to use the given score decision logic.

func WithTargetMessageSize 

func WithTargetMessageSize(tms int) Option

func WithTaskComparator 

func WithTaskComparator(comparator TaskComparator) Option

WithTaskComparator configures custom task prioritization logic.

func WithTracer 

func WithTracer(tap Tracer) Option

Configures Bitswap to use given tracer.

type Stat 

type Stat struct {
	ProvideBufLen    int
	Wantlist         []cid.Cid
	Peers            []string
	BlocksReceived   uint64
	DataReceived     uint64
	BlocksSent       uint64
	DataSent         uint64
	DupBlksReceived  uint64
	DupDataReceived  uint64
	MessagesReceived uint64
}

Stat is a struct that provides various statistics on bitswap operations

type TaskComparator 

type TaskComparator = decision.TaskComparator

type TaskInfo 

type TaskInfo = decision.TaskInfo

type Tracer 

type Tracer interface {
	MessageReceived(peer.ID, bsmsg.BitSwapMessage)
	MessageSent(peer.ID, bsmsg.BitSwapMessage)
}

Tracer provides methods to access all messages sent and received by Bitswap. This interface can be used to implement various statistics (this is original intent).

Source Files

View all Source files

Directories

Path Synopsis
internal
blockpresencemanager
decision
Package decision implements the decision engine for the bitswap service.
 Package decision implements the decision engine for the bitswap service.
defaults
getter
messagequeue
notifications
peermanager
providerquerymanager
session
sessioninterestmanager
sessionmanager
sessionpeermanager
testutil
pb
Package wantlist implements an object for bitswap that contains the keys that a given peer wants.
 Package wantlist implements an object for bitswap that contains the keys that a given peer wants.

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