peerstore: better GC in membacked peerstore (#2960)

---------

Co-authored-by: sukun <sukunrt@gmail.com>

core/peerstore/peerstore.go

@@ -121,20 +121,10 @@ type AddrBook interface {
 	PeersWithAddrs() peer.IDSlice
 }
 
-// CertifiedAddrBook manages "self-certified" addresses for remote peers.
-// Self-certified addresses are contained in peer.PeerRecords
-// which are wrapped in a record.Envelope and signed by the peer
-// to whom they belong.
+// CertifiedAddrBook manages signed peer records and "self-certified" addresses
+// contained within them.
+// Use this interface with an `AddrBook`.
 //
-// Certified addresses (CA) are generally more secure than uncertified
-// addresses (UA). Consequently, CAs beat and displace UAs. When the
-// peerstore learns CAs for a peer, it will reject UAs for the same peer
-// (as long as the former haven't expired).
-// Furthermore, peer records act like sequenced snapshots of CAs. Therefore,
-// processing a peer record that's newer than the last one seen overwrites
-// all addresses with the incoming ones.
-//
-// This interface is most useful when combined with AddrBook.
 // To test whether a given AddrBook / Peerstore implementation supports
 // certified addresses, callers should use the GetCertifiedAddrBook helper or
 // type-assert on the CertifiedAddrBook interface:
@@ -143,41 +133,28 @@ type AddrBook interface {
 //	    cab.ConsumePeerRecord(signedPeerRecord, aTTL)
 //	}
 type CertifiedAddrBook interface {
-	// ConsumePeerRecord adds addresses from a signed peer.PeerRecord (contained in
-	// a record.Envelope), which will expire after the given TTL.
-	//
-	// The 'accepted' return value indicates that the record was successfully processed
-	// and integrated into the CertifiedAddrBook state. If 'accepted' is false but no
-	// error is returned, it means that the record was ignored, most likely because
-	// a newer record exists for the same peer.
-	//
-	// Signed records added via this method will be stored without
-	// alteration as long as the address TTLs remain valid. The Envelopes
-	// containing the PeerRecords can be retrieved by calling GetPeerRecord(peerID).
-	//
-	// If the signed PeerRecord belongs to a peer that already has certified
-	// addresses in the CertifiedAddrBook, the new addresses will replace the
-	// older ones, if the new record has a higher sequence number than the
-	// existing record. Attempting to add a peer record with a
-	// sequence number that's <= an existing record for the same peer will not
-	// result in an error, but the record will be ignored, and the 'accepted'
-	// bool return value will be false.
+	// ConsumePeerRecord stores a signed peer record and the contained addresses for
+	// for ttl duration.
+	// The addresses contained in the signed peer record will expire after ttl. If any
+	// address is already present in the peer store, it'll expire at max of existing ttl and
+	// provided ttl.
+	// The signed peer record itself will be expired when all the addresses associated with the peer,
+	// self-certified or not, are removed from the AddrBook.
+	// To delete the signed peer record, use `AddrBook.UpdateAddrs`,`AddrBook.SetAddrs`, or
+	// `AddrBook.ClearAddrs` with ttl 0.
+	// Note: Future calls to ConsumePeerRecord will not expire self-certified addresses from the
+	// previous calls.
 	//
-	// If the CertifiedAddrBook is also an AddrBook (which is most likely the case),
-	// adding certified addresses for a peer will *replace* any
-	// existing non-certified addresses for that peer, and only the certified
-	// addresses will be returned from AddrBook.Addrs thereafter.
+	// The `accepted` return value indicates that the record was successfully processed. If
+	// `accepted` is false but no error is returned, it means that the record was ignored, most
+	// likely because a newer record exists for the same peer with a greater seq value.
 	//
-	// Likewise, once certified addresses have been added for a given peer,
-	// any non-certified addresses added via AddrBook.AddAddrs or
-	// AddrBook.SetAddrs will be ignored. AddrBook.SetAddrs may still be used
-	// to update the TTL of certified addresses that have previously been
-	// added via ConsumePeerRecord.
+	// The Envelopes containing the signed peer records can be retrieved by calling
+	// GetPeerRecord(peerID).
 	ConsumePeerRecord(s *record.Envelope, ttl time.Duration) (accepted bool, err error)
 
-	// GetPeerRecord returns an Envelope containing a PeerRecord for the
-	// given peer id, if one exists.
-	// Returns nil if no signed PeerRecord exists for the peer.
+	// GetPeerRecord returns an Envelope containing a peer record for the
+	// peer, or nil if no record exists.
 	GetPeerRecord(p peer.ID) *record.Envelope
 }
 
@@ -196,7 +173,7 @@ func GetCertifiedAddrBook(ab AddrBook) (cab CertifiedAddrBook, ok bool) {
 
 // KeyBook tracks the keys of Peers.
 type KeyBook interface {
-	// PubKey stores the public key of a peer.
+	// PubKey returns the public key of a peer.
 	PubKey(peer.ID) ic.PubKey
 
 	// AddPubKey stores the public key of a peer.

p2p/host/basic/basic_host.go

@@ -459,9 +459,12 @@ func (h *BasicHost) SignalAddressChange() {
 	}
 }
 
-func makeUpdatedAddrEvent(prev, current []ma.Multiaddr) *event.EvtLocalAddressesUpdated {
+func (h *BasicHost) makeUpdatedAddrEvent(prev, current []ma.Multiaddr) *event.EvtLocalAddressesUpdated {
+	if prev == nil && current == nil {
+		return nil
+	}
 	prevmap := make(map[string]ma.Multiaddr, len(prev))
-	evt := event.EvtLocalAddressesUpdated{Diffs: true}
+	evt := &event.EvtLocalAddressesUpdated{Diffs: true}
 	addrsAdded := false
 
 	for _, addr := range prev {
@@ -488,7 +491,19 @@ func makeUpdatedAddrEvent(prev, current []ma.Multiaddr) *event.EvtLocalAddresses
 		return nil
 	}
 
-	return &evt
+	// Our addresses have changed. Make a new signed peer record.
+	if !h.disableSignedPeerRecord {
+		// add signed peer record to the event
+		sr, err := h.makeSignedPeerRecord(current)
+		if err != nil {
+			log.Errorf("error creating a signed peer record from the set of current addresses, err=%s", err)
+			// drop this change
+			return nil
+		}
+		evt.SignedPeerRecord = sr
+	}
+
+	return evt
 }
 
 func (h *BasicHost) makeSignedPeerRecord(addrs []ma.Multiaddr) (*record.Envelope, error) {
@@ -512,34 +527,27 @@ func (h *BasicHost) background() {
 	var lastAddrs []ma.Multiaddr
 
 	emitAddrChange := func(currentAddrs []ma.Multiaddr, lastAddrs []ma.Multiaddr) {
-		// nothing to do if both are nil..defensive check
-		if currentAddrs == nil && lastAddrs == nil {
-			return
-		}
-
-		changeEvt := makeUpdatedAddrEvent(lastAddrs, currentAddrs)
-
+		changeEvt := h.makeUpdatedAddrEvent(lastAddrs, currentAddrs)
 		if changeEvt == nil {
 			return
 		}
-
+		// Our addresses have changed.
+		// store the signed peer record in the peer store.
 		if !h.disableSignedPeerRecord {
-			// add signed peer record to the event
-			sr, err := h.makeSignedPeerRecord(currentAddrs)
-			if err != nil {
-				log.Errorf("error creating a signed peer record from the set of current addresses, err=%s", err)
-				return
-			}
-			changeEvt.SignedPeerRecord = sr
-
-			// persist the signed record to the peerstore
-			if _, err := h.caBook.ConsumePeerRecord(sr, peerstore.PermanentAddrTTL); err != nil {
+			if _, err := h.caBook.ConsumePeerRecord(changeEvt.SignedPeerRecord, peerstore.PermanentAddrTTL); err != nil {
 				log.Errorf("failed to persist signed peer record in peer store, err=%s", err)
 				return
 			}
 		}
+		// update host addresses in the peer store
+		removedAddrs := make([]ma.Multiaddr, 0, len(changeEvt.Removed))
+		for _, ua := range changeEvt.Removed {
+			removedAddrs = append(removedAddrs, ua.Address)
+		}
+		h.Peerstore().SetAddrs(h.ID(), currentAddrs, peerstore.PermanentAddrTTL)
+		h.Peerstore().SetAddrs(h.ID(), removedAddrs, 0)
 
-		// emit addr change event on the bus
+		// emit addr change event
 		if err := h.emitters.evtLocalAddrsUpdated.Emit(*changeEvt); err != nil {
 			log.Warnf("error emitting event for updated addrs: %s", err)
 		}
@@ -551,11 +559,10 @@ func (h *BasicHost) background() {
 	defer ticker.Stop()
 
 	for {
+		// Update our local IP addresses before checking our current addresses.
 		if len(h.network.ListenAddresses()) > 0 {
 			h.updateLocalIpAddr()
 		}
-		// Request addresses anyways because, technically, address filters still apply.
-		// The underlying AllAddrs call is effectively a no-op.
 		curr := h.Addrs()
 		emitAddrChange(curr, lastAddrs)
 		lastAddrs = curr