engine

package
v0.6.0 Latest Latest
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 Go to latest Published: Mar 25, 2022 License: Apache-2.0, MIT Imports: 30 Imported by: 0

Documentation

Overview

Package engine provides a reference implementation of the provider.Interface in order to advertise the availability of a list of multihashes to indexer nodes such as "storetheindex". See: https://github.com/filecoin-project/storetheindex

The advertisements are published as a chan of diffs that signal the list of multihashes that are added or removed represented as an IPLD DAG. Walking the chain of advertisements would then provide the latest state of the total multihashes provided by the engine. The list of multihashes are paginated as a collection of interlinked chunks. For the complete advertisement IPLD schema, see:

The engine internally uses "go-legs" to sync the IPLD DAG of advertisements. See: https://github.com/filecoin-project/go-legs

Example (AdvertiseHelloWorld)

Example_advertiseHelloWorld shows an example of instantiating an engine.Engine and publishing and advertisement for a sample content.

Note that the advertisement published uses metadata.BitswapMetadata. This is for demonstrative purposes only. The example does not set up the retrieval side for the content. 

package main

import (
	"context"
	"fmt"
	"io"

	provider "github.com/filecoin-project/index-provider"
	"github.com/filecoin-project/index-provider/engine"
	"github.com/filecoin-project/index-provider/metadata"
	"github.com/libp2p/go-libp2p"
	"github.com/multiformats/go-multihash"
)

// Example_advertiseHelloWorld shows an example of instantiating an engine.Engine and publishing
// and advertisement for a sample content.
//
// Note that the advertisement published uses metadata.BitswapMetadata. This is for demonstrative
// purposes only. The example does not set up the retrieval side for the content.
func main() {
	// Get the multihash of content to advertise
	content := "Hello World!"
	sayHelloCtxID := "Say hello"
	fmt.Printf("Preparing to advertise content: '%s'\n", string(content))
	mh, err := multihash.Sum([]byte(content), multihash.SHA2_256, -1)
	if err != nil {
		panic(err)
	}
	fmt.Printf("✓ Generated content multihash: %s\n", mh.B58String())

	// Create a new libp2p host
	h, err := libp2p.New()
	if err != nil {
		panic(err)
	}
	// Only print the first three characters to keep golang example output happy.
	fmt.Printf("✓ Instantiated new libp2p host with peer ID: %s...\n", h.ID().String()[:2])

	// Construct a new provider engine with given libp2p host that announces advertisements over
	// gossipsub and datatrasfer/graphsync.
	engine, err := engine.New(engine.WithHost(h), engine.WithPublisherKind(engine.DataTransferPublisher))
	if err != nil {
		panic(err)
	}
	fmt.Println("✓ Instantiated provider engine")
	defer engine.Shutdown()

	engine.RegisterMultihashLister(func(ctx context.Context, contextID []byte) (provider.MultihashIterator, error) {
		if string(contextID) == sayHelloCtxID {
			return &singleMhIterator{mh: mh}, nil
		}
		return nil, fmt.Errorf("no content is found for context ID: %v", contextID)
	})
	fmt.Printf("✓ Registered lister for context ID: %s\n", sayHelloCtxID)

	// Start the engine
	if err = engine.Start(context.Background()); err != nil {
		panic(err)
	}
	fmt.Println("✓ Provider engine started.")

	// Multiple transports can be included in metadata.
	md := metadata.New(metadata.Bitswap{})

	// Note that this example publishes an ad with bitswap metadata as an example.
	// But it does not instantiate a bitswap server to serve retrievals.
	adCid, err := engine.NotifyPut(context.Background(), []byte(sayHelloCtxID), md)
	if err != nil {
		panic(err)
	}
	// Only print the first three characters to keep golang example output happy.
	fmt.Printf("✓ Published advertisement for content with CID: %s...\n", adCid.String()[:3])

	if err := engine.Shutdown(); err != nil {
		panic(err)
	}

}

type singleMhIterator struct {
	offset int
	mh     multihash.Multihash
}

func (s *singleMhIterator) Next() (multihash.Multihash, error) {
	if s.offset == 0 {
		s.offset++
		return s.mh, nil
	}
	return nil, io.EOF
}

Output:

Preparing to advertise content: 'Hello World!'
✓ Generated content multihash: QmWvQxTqbG2Z9HPJgG57jjwR154cKhbtJenbyYTWkjgF3e
✓ Instantiated new libp2p host with peer ID: Qm...
✓ Instantiated provider engine
✓ Registered lister for context ID: Say hello
✓ Provider engine started.
✓ Published advertisement for content with CID: bag...

Index

Examples

Constants

This section is empty.

Variables

This section is empty.

Functions

This section is empty.

Types

type Engine 

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

Engine is an implementation of the core reference provider interface

func New 

func New(o ...Option) (*Engine, error)

New creates a new index provider Engine as the default implementation of provider.Interface. It provides the ability to advertise the availability of a list of multihashes associated to a context ID as a chain of linked advertisements as defined by the indexer node protocol implemented by "storetheindex". Engine internally uses "go-legs", a protocol for propagating and synchronizing changes an IPLD DAG, to publish advertisements. See:

Published advertisements are signed using the given private key. The retAddrs corresponds to the endpoints at which the data block associated to the advertised multihashes can be retrieved. Note that if no retAddrs is specified the listen addresses of the given libp2p host are used.

The engine also provides the ability to generate advertisements via Engine.NotifyPut and Engine.NotifyRemove as long as a provider.MultihashLister is registered. See: provider.MultihashLister, Engine.RegisterMultihashLister.

The engine must be started via Engine.Start before use and discarded via Engine.Shutdown when no longer needed. See: Engine.Start, Engine.Shutdown.

func (*Engine) GetAdv 

func (e *Engine) GetAdv(_ context.Context, adCid cid.Cid) (*schema.Advertisement, error)

GetAdv gets the advertisement associated to the given cid c. The context is not used.

func (*Engine) GetLatestAdv 

func (e *Engine) GetLatestAdv(ctx context.Context) (cid.Cid, *schema.Advertisement, error)

GetLatestAdv gets the latest advertisement by the provider. If there are not previously published advertisements, then cid.Undef is returned as the advertisement CID.

func (*Engine) NotifyPut 

func (e *Engine) NotifyPut(ctx context.Context, contextID []byte, md metadata.Metadata) (cid.Cid, error)

NotifyPut publishes an advertisement that signals the list of multihashes associated to the given contextID is available by this provider with the given metadata. A provider.MultihashLister is required, and is used to look up the list of multihashes associated to a context ID.

Note that prior to calling this function a provider.MultihashLister must be registered.

See: Engine.RegisterMultihashLister, Engine.Publish.

func (*Engine) NotifyRemove 

func (e *Engine) NotifyRemove(ctx context.Context, contextID []byte) (cid.Cid, error)

NotifyRemove publishes an advertisement that signals the list of multihashes associated to the given contextID is no longer available by this provider.

Note that prior to calling this function a provider.MultihashLister must be registered.

See: Engine.RegisterMultihashLister, Engine.Publish.

func (*Engine) Publish 

func (e *Engine) Publish(ctx context.Context, adv schema.Advertisement) (cid.Cid, error)

Publish stores the given advertisement locally via Engine.PublishLocal first, then publishes a message onto the gossipsub to signal the change in the latest advertisement by the provider to indexer nodes.

The publication mechanism uses legs.Publisher internally. See: https://github.com/filecoin-project/go-legs

func (*Engine) PublishLatest added in v0.2.2 

func (e *Engine) PublishLatest(ctx context.Context) error

PublishLatest re-publishes the latest existing advertisement to pubsub.

func (*Engine) PublishLocal 

func (e *Engine) PublishLocal(ctx context.Context, adv schema.Advertisement) (cid.Cid, error)

PublishLocal stores the advertisement in the local link system and marks it locally as the latest advertisement.

The context is used for storing internal mapping information onto the datastore.

See: Engine.Publish.

func (*Engine) RegisterMultihashLister added in v0.5.1 

func (e *Engine) RegisterMultihashLister(mhl provider.MultihashLister)

RegisterMultihashLister registers a provider.MultihashLister that is used to look up the list of multihashes associated to a context ID. At least one such registration must be registered before calls to Engine.NotifyPut and Engine.NotifyRemove.

Note that successive calls to this function will replace the previous registration. Only a single registration is supported.

See: provider.Interface

func (*Engine) Shutdown 

func (e *Engine) Shutdown() error

Shutdown shuts down the engine and discards all resources opened by the engine. The engine is no longer usable after the call to this function.

func (*Engine) Start 

func (e *Engine) Start(ctx context.Context) error

Start starts the engine by instantiating the internal storage and joins the configured gossipsub topic used for publishing advertisements.

The context is used to instantiate the internal LRU cache storage.

See: Engine.Shutdown, chunker.NewCachedEntriesChunker, dtsync.NewPublisherFromExisting.

type Option added in v0.2.7 

type Option func(*options) error

Option sets a configuration parameter for the provider engine.

func WithDataTransfer added in v0.4.0 

func WithDataTransfer(dt datatransfer.Manager) Option

WithDataTransfer sets the instance of datatransfer.Manager to use. If unspecified a new instance is created automatically.

Note that this option only takes effect if the PublisherKind is set to DataTransferPublisher. See: WithPublisherKind.

func WithDatastore added in v0.4.0 

func WithDatastore(ds datastore.Batching) Option

WithDatastore sets the datastore that is used by the engine to store advertisements. If unspecified, an ephemeral in-memory datastore is used. See: datastore.NewMapDatastore.

func WithEntriesCacheCapacity added in v0.4.0 

func WithEntriesCacheCapacity(s int) Option

WithEntriesCacheCapacity sets the maximum number of advertisement entries chains to cache. If unset, the default capacity of 1024 is used.

The cache is evicted using LRU policy. Note that the capacity dictates the number of complete chains that are cached, not individual entry chunks. This means, the maximum storage used by the cache is a factor of capacity, chunk size and the length of multihashes in each chunk.

As an example, for 128-bit long multihashes the cache with default capacity of 1024, and default chunk size of 16384 can grow up to 256MiB when full.

See: WithEntriesChunkSize, chunker.CachedEntriesChunker.

func WithEntriesChunkSize added in v0.4.0 

func WithEntriesChunkSize(s int) Option

WithEntriesChunkSize sets the maximum number of multihashes to include in a single entries chunk. If unset, the default size of 16384 is used.

See: WithEntriesCacheCapacity, chunker.CachedEntriesChunker

func WithExtraGossipData added in v0.2.7 

func WithExtraGossipData(extraData []byte) Option

WithExtraGossipData supplies extra data to include in the pubsub announcement. Note that this option only takes effect if the PublisherKind is set to DataTransferPublisher. See: WithPublisherKind.

func WithHost added in v0.4.0 

func WithHost(h host.Host) Option

WithHost specifies the host to which the provider engine belongs. If unspecified, a host is created automatically. See: libp2p.New.

func WithHttpPublisherListenAddr added in v0.4.0 

func WithHttpPublisherListenAddr(addr string) Option

WithHttpPublisherListenAddr sets the net listen address for the HTTP publisher. If unset, the default net listen address of '0.0.0.0:3104' is used.

Note that this option only takes effect if the PublisherKind is set to HttpPublisher. See: WithPublisherKind.

func WithPublisherKind added in v0.4.0 

func WithPublisherKind(k PublisherKind) Option

WithPublisherKind sets the kind of publisher used to announce new advertisements. If unset, advertisements are only stored locally and no announcements are made. See: PublisherKind.

func WithPurgeCacheOnStart added in v0.4.0 

func WithPurgeCacheOnStart(p bool) Option

WithPurgeCacheOnStart sets whether to clear any cached entries chunks when the provider engine starts. If unset, cache is rehydrated from previously cached entries stored in datastore if present. See: WithDatastore.

func WithRetrievalAddrs added in v0.4.0 

func WithRetrievalAddrs(addr ...multiaddr.Multiaddr) Option

WithRetrievalAddrs sets the addresses that specify where to get the content corresponding to an indexing advertisement. If unspecified, the libp2p host listen addresses are used. See: WithHost.

func WithTopic added in v0.4.0 

func WithTopic(t *pubsub.Topic) Option

WithTopic sets the pubsub topic on which new advertisements are announced. To use the default pubsub configuration with a specific topic name, use WithTopicName. If both options are specified, WithTopic takes presence.

Note that this option only takes effect if the PublisherKind is set to DataTransferPublisher. See: WithPublisherKind.

func WithTopicName added in v0.4.0 

func WithTopicName(t string) Option

WithTopicName sets toe topic name on which pubsub announcements are published. To override the default pubsub configuration, use WithTopic.

Note that this option only takes effect if the PublisherKind is set to DataTransferPublisher. See: WithPublisherKind.

type PublisherKind added in v0.4.0 

type PublisherKind string

PublisherKind represents the kind of publisher to use in order to announce a new advertisement to the network. See: WithPublisherKind, NoPublisher, DataTransferPublisher, HttpPublisher. 

const (
	// NoPublisher indicates that no announcements are made to the network and all advertisements
	// are only stored locally.
	NoPublisher PublisherKind = ""

	// DataTransferPublisher makes announcements over a gossipsub topic and exposes a
	// datatransfer/graphsync server that allows peers in the network to sync advertisements.
	DataTransferPublisher PublisherKind = "dtsync"

	// HttpPublisher exposes a HTTP server that announces published advertisements and allows peers
	// in the network to sync them over raw HTTP transport.
	HttpPublisher PublisherKind = "http"
)

Source Files

View all Source files

Directories

Path Synopsis
Package chunker provides functionality for chunking entries chain generated from provider.MultihashIterator, represented as EntriesChunker interface.
 Package chunker provides functionality for chunking entries chain generated from provider.MultihashIterator, represented as EntriesChunker interface.

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