feat: metadata book (#638)

* feat: metadata book

* chore: address review

* chore: address review

src/peer-store/README.md

@@ -75,7 +75,11 @@ A `peerId.toB58String()` identifier mapping to a `Set` of protocol identifier st
 
 #### Metadata Book
 
-**Not Yet Implemented**
+The `metadataBook` keeps track of the known metadata of a peer. Its metadata is stored in a key value fashion, where a key identifier (`string`) represents a metadata value (`Buffer`).
+
+`Map<string, Map<string, Buffer>>`
+
+A `peerId.toB58String()` identifier mapping to the peer metadata Map.
 
 ### API
 
@@ -85,6 +89,7 @@ Access to its underlying books:
 
 - `peerStore.addressBook.*`
 - `peerStore.keyBook.*`
+- `peerStore.metadataBook.*`
 - `peerStore.protoBook.*`
 
 ### Events
@@ -92,6 +97,8 @@ Access to its underlying books:
 - `peer` - emitted when a new peer is added.
 - `change:multiaadrs` - emitted when a known peer has a different set of multiaddrs.
 - `change:protocols` - emitted when a known peer supports a different set of protocols.
+- `change:pubkey` - emitted when a peer's public key is known.
+- `change:metadata` - emitted when known metadata of a peer changes.
 
 ## Data Persistence
 
@@ -123,8 +130,6 @@ All public keys are stored under the following pattern:
 
 **MetadataBook**
 
-_NOT_YET_IMPLEMENTED_
-
 Metadata is stored under the following key pattern:
 
 `/peers/metadata/<b32 peer id no padding>/<key>`

src/peer-store/address-book.js

@@ -97,7 +97,6 @@ class AddressBook extends Book {
   /**
    * Add known addresses of a provided peer.
    * If the peer is not known, it is set with the given addresses.
-   * @override
    * @param {PeerId} peerId
    * @param {Array<Multiaddr>} multiaddrs
    * @returns {AddressBook}

src/peer-store/index.js

@@ -10,6 +10,7 @@ const PeerId = require('peer-id')
 
 const AddressBook = require('./address-book')
 const KeyBook = require('./key-book')
+const MetadataBook = require('./metadata-book')
 const ProtoBook = require('./proto-book')
 
 const {
@@ -21,6 +22,8 @@ const {
  * @fires PeerStore#peer Emitted when a new peer is added.
  * @fires PeerStore#change:protocols Emitted when a known peer supports a different set of protocols.
  * @fires PeerStore#change:multiaddrs Emitted when a known peer has a different set of multiaddrs.
+ * @fires PeerStore#change:pubkey Emitted emitted when a peer's public key is known.
+ * @fires PeerStore#change:metadata Emitted when the known metadata of a peer change.
  */
 class PeerStore extends EventEmitter {
   /**
@@ -47,6 +50,11 @@ class PeerStore extends EventEmitter {
      */
     this.keyBook = new KeyBook(this)
 
+    /**
+     * MetadataBook containing a map of peerIdStr to their metadata Map.
+     */
+    this.metadataBook = new MetadataBook(this)
+
     /**
      * ProtoBook containing a map of peerIdStr to supported protocols.
      */
@@ -68,31 +76,17 @@ class PeerStore extends EventEmitter {
    * @returns {Map<string, Peer>}
    */
   get peers () {
+    const storedPeers = new Set([
+      ...this.addressBook.data.keys(),
+      ...this.keyBook.data.keys(),
+      ...this.protoBook.data.keys(),
+      ...this.metadataBook.data.keys()
+    ])
+
     const peersData = new Map()
-
-    // AddressBook
-    for (const [idStr, addresses] of this.addressBook.data.entries()) {
-      const id = this.keyBook.data.get(idStr) || PeerId.createFromCID(idStr)
-      peersData.set(idStr, {
-        id,
-        addresses,
-        protocols: this.protoBook.get(id) || []
-      })
-    }
-
-    // ProtoBook
-    for (const [idStr, protocols] of this.protoBook.data.entries()) {
-      const pData = peersData.get(idStr)
-      const id = this.keyBook.data.get(idStr) || PeerId.createFromCID(idStr)
-
-      if (!pData) {
-        peersData.set(idStr, {
-          id,
-          addresses: [],
-          protocols: Array.from(protocols)
-        })
-      }
-    }
+    storedPeers.forEach((idStr) => {
+      peersData.set(idStr, this.get(PeerId.createFromCID(idStr)))
+    })
 
     return peersData
   }
@@ -106,8 +100,9 @@ class PeerStore extends EventEmitter {
     const addressesDeleted = this.addressBook.delete(peerId)
     const keyDeleted = this.keyBook.delete(peerId)
     const protocolsDeleted = this.protoBook.delete(peerId)
+    const metadataDeleted = this.metadataBook.delete(peerId)
 
-    return addressesDeleted || keyDeleted || protocolsDeleted
+    return addressesDeleted || keyDeleted || protocolsDeleted || metadataDeleted
   }
 
   /**
@@ -122,16 +117,18 @@ class PeerStore extends EventEmitter {
 
     const id = this.keyBook.data.get(peerId.toB58String())
     const addresses = this.addressBook.get(peerId)
+    const metadata = this.metadataBook.get(peerId)
     const protocols = this.protoBook.get(peerId)
 
-    if (!addresses && !protocols) {
+    if (!id && !addresses && !metadata && !protocols) {
       return undefined
     }
 
     return {
       id: id || peerId,
       addresses: addresses || [],
-      protocols: protocols || []
+      protocols: protocols || [],
+      metadata: metadata
     }
   }
 }

src/peer-store/metadata-book.js

@@ -0,0 +1,161 @@
+'use strict'
+
+const errcode = require('err-code')
+const debug = require('debug')
+const log = debug('libp2p:peer-store:proto-book')
+log.error = debug('libp2p:peer-store:proto-book:error')
+
+const { Buffer } = require('buffer')
+
+const PeerId = require('peer-id')
+
+const Book = require('./book')
+
+const {
+  codes: { ERR_INVALID_PARAMETERS }
+} = require('../errors')
+
+/**
+ * The MetadataBook is responsible for keeping the known supported
+ * protocols of a peer.
+ * @fires MetadataBook#change:metadata
+ */
+class MetadataBook extends Book {
+  /**
+  * @constructor
+  * @param {PeerStore} peerStore
+  */
+  constructor (peerStore) {
+    /**
+     * PeerStore Event emitter, used by the MetadataBook to emit:
+     * "change:metadata" - emitted when the known metadata of a peer change.
+     */
+    super({
+      peerStore,
+      eventName: 'change:metadata',
+      eventProperty: 'metadata'
+    })
+
+    /**
+     * Map known peers to their known protocols.
+     * @type {Map<string, Map<string, Buffer>>}
+     */
+    this.data = new Map()
+  }
+
+  /**
+   * Set metadata key and value of a provided peer.
+   * @override
+   * @param {PeerId} peerId
+   * @param {string} key metadata key
+   * @param {Buffer} value metadata value
+   * @returns {ProtoBook}
+   */
+  set (peerId, key, value) {
+    if (!PeerId.isPeerId(peerId)) {
+      log.error('peerId must be an instance of peer-id to store data')
+      throw errcode(new Error('peerId must be an instance of peer-id'), ERR_INVALID_PARAMETERS)
+    }
+
+    if (typeof key !== 'string' || !Buffer.isBuffer(value)) {
+      log.error('valid key and value must be provided to store data')
+      throw errcode(new Error('valid key and value must be provided'), ERR_INVALID_PARAMETERS)
+    }
+
+    this._setValue(peerId, key, value)
+
+    return this
+  }
+
+  /**
+   * Set data into the datastructure
+   * @override
+   */
+  _setValue (peerId, key, value, { emit = true } = {}) {
+    const id = peerId.toB58String()
+    const rec = this.data.get(id) || new Map()
+    const recMap = rec.get(key)
+
+    // Already exists and is equal
+    if (recMap && value.equals(recMap)) {
+      log(`the metadata provided to store is equal to the already stored for ${id} on ${key}`)
+      return
+    }
+
+    rec.set(key, value)
+    this.data.set(id, rec)
+
+    emit && this._emit(peerId, key)
+  }
+
+  /**
+   * Get the known data of a provided peer.
+   * @param {PeerId} peerId
+   * @returns {Map<string, Buffer>}
+   */
+  get (peerId) {
+    if (!PeerId.isPeerId(peerId)) {
+      throw errcode(new Error('peerId must be an instance of peer-id'), ERR_INVALID_PARAMETERS)
+    }
+
+    return this.data.get(peerId.toB58String())
+  }
+
+  /**
+   * Get specific metadata value, if it exists
+   * @param {PeerId} peerId
+   * @param {string} key
+   * @returns {Buffer}
+   */
+  getValue (peerId, key) {
+    if (!PeerId.isPeerId(peerId)) {
+      throw errcode(new Error('peerId must be an instance of peer-id'), ERR_INVALID_PARAMETERS)
+    }
+
+    const rec = this.data.get(peerId.toB58String())
+    return rec && rec.get(key)
+  }
+
+  /**
+   * Deletes the provided peer from the book.
+   * @param {PeerId} peerId
+   * @returns {boolean}
+   */
+  delete (peerId) {
+    if (!PeerId.isPeerId(peerId)) {
+      throw errcode(new Error('peerId must be an instance of peer-id'), ERR_INVALID_PARAMETERS)
+    }
+
+    if (!this.data.delete(peerId.toB58String())) {
+      return false
+    }
+
+    this._emit(peerId)
+
+    return true
+  }
+
+  /**
+   * Deletes the provided peer metadata key from the book.
+   * @param {PeerId} peerId
+   * @param {string} key
+   * @returns {boolean}
+   */
+  deleteValue (peerId, key) {
+    if (!PeerId.isPeerId(peerId)) {
+      throw errcode(new Error('peerId must be an instance of peer-id'), ERR_INVALID_PARAMETERS)
+    }
+
+    const rec = this.data.get(peerId.toB58String())
+
+    if (!rec || !rec.delete(key)) {
+      return false
+    }
+
+    this._emit(peerId, key)
+
+    return true
+  }
+}
+
+module.exports = MetadataBook

src/peer-store/persistent/consts.js

@@ -8,5 +8,8 @@ module.exports.NAMESPACE_ADDRESS = '/peers/addrs/'
 // /peers/keys/<b32 peer id no padding>
 module.exports.NAMESPACE_KEYS = '/peers/keys/'
 
+// /peers/metadata/<b32 peer id no padding>/<key>
+module.exports.NAMESPACE_METADATA = '/peers/metadata/'
+
 // /peers/addrs/<b32 peer id no padding>
 module.exports.NAMESPACE_PROTOCOL = '/peers/protos/'

src/peer-store/persistent/index.js

@@ -14,6 +14,7 @@ const {
   NAMESPACE_ADDRESS,
   NAMESPACE_COMMON,
   NAMESPACE_KEYS,
+  NAMESPACE_METADATA,
   NAMESPACE_PROTOCOL
 } = require('./consts')
 
@@ -43,6 +44,12 @@ class PersistentPeerStore extends PeerStore {
      */
     this._dirtyPeers = new Set()
 
+    /**
+     * Peers metadata changed mapping peer identifers to metadata changed.
+     * @type {Map<string, Set<string>>}
+     */
+    this._dirtyMetadata = new Map()
+
     this.threshold = threshold
     this._addDirtyPeer = this._addDirtyPeer.bind(this)
   }
@@ -58,6 +65,7 @@ class PersistentPeerStore extends PeerStore {
     this.on('change:protocols', this._addDirtyPeer)
     this.on('change:multiaddrs', this._addDirtyPeer)
     this.on('change:pubkey', this._addDirtyPeer)
+    this.on('change:metadata', this._addDirtyPeerMetadata)
 
     // Load data
     for await (const entry of this._datastore.query({ prefix: NAMESPACE_COMMON })) {
@@ -92,6 +100,30 @@ class PersistentPeerStore extends PeerStore {
     }
   }
 
+  /**
+   * Add modified metadata peer to the set.
+   * @private
+   * @param {Object} params
+   * @param {PeerId} params.peerId
+   * @param {string} params.metadata
+   */
+  _addDirtyPeerMetadata ({ peerId, metadata }) {
+    const peerIdstr = peerId.toB58String()
+
+    log('add dirty metadata peer', peerIdstr)
+    this._dirtyPeers.add(peerIdstr)
+
+    // Add dirty metadata key
+    const mData = this._dirtyMetadata.get(peerIdstr) || new Set()
+    mData.add(metadata)
+    this._dirtyMetadata.set(peerIdstr, mData)
+
+    if (this._dirtyPeers.size >= this.threshold) {
+      // Commit current data
+      this._commitData()
+    }
+  }
+
   /**
    * Add all the peers current data to a datastore batch and commit it.
    * @private
@@ -120,6 +152,9 @@ class PersistentPeerStore extends PeerStore {
       // Key Book
       this._batchKeyBook(peerId, batch)
 
+      // Metadata Book
+      this._batchMetadataBook(peerId, batch)
+
       // Proto Book
       this._batchProtoBook(peerId, batch)
     }
@@ -184,6 +219,32 @@ class PersistentPeerStore extends PeerStore {
     }
   }
 
+  /**
+   * Add metadata book data of the peer to the batch.
+   * @private
+   * @param {PeerId} peerId
+   * @param {Object} batch
+   */
+  _batchMetadataBook (peerId, batch) {
+    const b32key = peerId.toString()
+    const dirtyMetada = this._dirtyMetadata.get(peerId.toB58String()) || []
+
+    try {
+      dirtyMetada.forEach((dirtyKey) => {
+        const key = new Key(`${NAMESPACE_METADATA}${b32key}/${dirtyKey}`)
+        const dirtyValue = this.metadataBook.getValue(peerId, dirtyKey)
+
+        if (dirtyValue) {
+          batch.put(key, dirtyValue)
+        } else {
+          batch.delete(key)
+        }
+      })
+    } catch (err) {
+      log.error(err)
+    }
+  }
+
   /**
    * Add proto book data of the peer to the batch.
    * @private
@@ -244,6 +305,13 @@ class PersistentPeerStore extends PeerStore {
             decoded,
             { emit: false })
           break
+        case 'metadata':
+          this.metadataBook._setValue(
+            peerId,
+            keyParts[4],
+            value,
+            { emit: false })
+          break
         case 'protos':
           decoded = Protocols.decode(value)
 

src/peer-store/proto-book.js

@@ -83,7 +83,6 @@ class ProtoBook extends Book {
   /**
    * Adds known protocols of a provided peer.
    * If the peer was not known before, it will be added.
-   * @override
    * @param {PeerId} peerId
    * @param {Array<string>} protocols
    * @returns {ProtoBook}