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package p2p
import (
"context"
"errors"
"fmt"
"math"
"math/rand"
"sort"
"sync"
"time"
"github.com/gogo/protobuf/proto"
"github.com/google/orderedcode"
dbm "github.com/tendermint/tm-db"
tmsync "github.com/tendermint/tendermint/internal/libs/sync"
p2pproto "github.com/tendermint/tendermint/proto/tendermint/p2p"
"github.com/tendermint/tendermint/types"
)
const (
// retryNever is returned by retryDelay() when retries are disabled.
retryNever time.Duration = math.MaxInt64
)
// PeerStatus is a peer status.
//
// The peer manager has many more internal states for a peer (e.g. dialing,
// connected, evicting, and so on), which are tracked separately. PeerStatus is
// for external use outside of the peer manager.
type PeerStatus string
const (
PeerStatusUp PeerStatus = "up" // connected and ready
PeerStatusDown PeerStatus = "down" // disconnected
PeerStatusGood PeerStatus = "good" // peer observed as good
PeerStatusBad PeerStatus = "bad" // peer observed as bad
)
// PeerScore is a numeric score assigned to a peer (higher is better).
type PeerScore uint8
const (
PeerScorePersistent PeerScore = math.MaxUint8 // persistent peers
)
// PeerUpdate is a peer update event sent via PeerUpdates.
type PeerUpdate struct {
NodeID types.NodeID
Status PeerStatus
}
// PeerUpdates is a peer update subscription with notifications about peer
// events (currently just status changes).
type PeerUpdates struct {
routerUpdatesCh chan PeerUpdate
reactorUpdatesCh chan PeerUpdate
closeCh chan struct{}
closeOnce sync.Once
}
// NewPeerUpdates creates a new PeerUpdates subscription. It is primarily for
// internal use, callers should typically use PeerManager.Subscribe(). The
// subscriber must call Close() when done.
func NewPeerUpdates(updatesCh chan PeerUpdate, buf int) *PeerUpdates {
return &PeerUpdates{
reactorUpdatesCh: updatesCh,
routerUpdatesCh: make(chan PeerUpdate, buf),
closeCh: make(chan struct{}),
}
}
// Updates returns a channel for consuming peer updates.
func (pu *PeerUpdates) Updates() <-chan PeerUpdate {
return pu.reactorUpdatesCh
}
// SendUpdate pushes information about a peer into the routing layer,
// presumably from a peer.
func (pu *PeerUpdates) SendUpdate(update PeerUpdate) {
select {
case <-pu.closeCh:
case pu.routerUpdatesCh <- update:
}
}
// Close closes the peer updates subscription.
func (pu *PeerUpdates) Close() {
pu.closeOnce.Do(func() {
// NOTE: We don't close updatesCh since multiple goroutines may be
// sending on it. The PeerManager senders will select on closeCh as well
// to avoid blocking on a closed subscription.
close(pu.closeCh)
})
}
// Done returns a channel that is closed when the subscription is closed.
func (pu *PeerUpdates) Done() <-chan struct{} {
return pu.closeCh
}
// PeerManagerOptions specifies options for a PeerManager.
type PeerManagerOptions struct {
// PersistentPeers are peers that we want to maintain persistent connections
// to. These will be scored higher than other peers, and if
// MaxConnectedUpgrade is non-zero any lower-scored peers will be evicted if
// necessary to make room for these.
PersistentPeers []types.NodeID
// MaxPeers is the maximum number of peers to track information about, i.e.
// store in the peer store. When exceeded, the lowest-scored unconnected peers
// will be deleted. 0 means no limit.
MaxPeers uint16
// MaxConnected is the maximum number of connected peers (inbound and
// outbound). 0 means no limit.
MaxConnected uint16
// MaxConnectedUpgrade is the maximum number of additional connections to
// use for probing any better-scored peers to upgrade to when all connection
// slots are full. 0 disables peer upgrading.
//
// For example, if we are already connected to MaxConnected peers, but we
// know or learn about better-scored peers (e.g. configured persistent
// peers) that we are not connected too, then we can probe these peers by
// using up to MaxConnectedUpgrade connections, and once connected evict the
// lowest-scored connected peers. This also works for inbound connections,
// i.e. if a higher-scored peer attempts to connect to us, we can accept
// the connection and evict a lower-scored peer.
MaxConnectedUpgrade uint16
// MinRetryTime is the minimum time to wait between retries. Retry times
// double for each retry, up to MaxRetryTime. 0 disables retries.
MinRetryTime time.Duration
// MaxRetryTime is the maximum time to wait between retries. 0 means
// no maximum, in which case the retry time will keep doubling.
MaxRetryTime time.Duration
// MaxRetryTimePersistent is the maximum time to wait between retries for
// peers listed in PersistentPeers. 0 uses MaxRetryTime instead.
MaxRetryTimePersistent time.Duration
// RetryTimeJitter is the upper bound of a random interval added to
// retry times, to avoid thundering herds. 0 disables jitter.
RetryTimeJitter time.Duration
// PeerScores sets fixed scores for specific peers. It is mainly used
// for testing. A score of 0 is ignored.
PeerScores map[types.NodeID]PeerScore
// PrivatePeerIDs defines a set of NodeID objects which the PEX reactor will
// consider private and never gossip.
PrivatePeers map[types.NodeID]struct{}
// SelfAddress is the address that will be advertised to peers for them to dial back to us.
// If Hostname and Port are unset, Advertise() will include no self-announcement
SelfAddress NodeAddress
// persistentPeers provides fast PersistentPeers lookups. It is built
// by optimize().
persistentPeers map[types.NodeID]bool
}
// Validate validates the options.
func (o *PeerManagerOptions) Validate() error {
for _, id := range o.PersistentPeers {
if err := id.Validate(); err != nil {
return fmt.Errorf("invalid PersistentPeer ID %q: %w", id, err)
}
}
for id := range o.PrivatePeers {
if err := id.Validate(); err != nil {
return fmt.Errorf("invalid private peer ID %q: %w", id, err)
}
}
if o.MaxConnected > 0 && len(o.PersistentPeers) > int(o.MaxConnected) {
return fmt.Errorf("number of persistent peers %v can't exceed MaxConnected %v",
len(o.PersistentPeers), o.MaxConnected)
}
if o.MaxPeers > 0 {
if o.MaxConnected == 0 || o.MaxConnected+o.MaxConnectedUpgrade > o.MaxPeers {
return fmt.Errorf(
"MaxConnected %v and MaxConnectedUpgrade %v can't exceed MaxPeers %v",
o.MaxConnected, o.MaxConnectedUpgrade, o.MaxPeers)
}
}
if o.MaxRetryTime > 0 {
if o.MinRetryTime == 0 {
return errors.New("can't set MaxRetryTime without MinRetryTime")
}
if o.MinRetryTime > o.MaxRetryTime {
return fmt.Errorf("MinRetryTime %v is greater than MaxRetryTime %v",
o.MinRetryTime, o.MaxRetryTime)
}
}
if o.MaxRetryTimePersistent > 0 {
if o.MinRetryTime == 0 {
return errors.New("can't set MaxRetryTimePersistent without MinRetryTime")
}
if o.MinRetryTime > o.MaxRetryTimePersistent {
return fmt.Errorf(
"MinRetryTime %v is greater than MaxRetryTimePersistent %v",
o.MinRetryTime, o.MaxRetryTimePersistent)
}
}
return nil
}
// isPersistentPeer checks if a peer is in PersistentPeers. It will panic
// if called before optimize().
func (o *PeerManagerOptions) isPersistent(id types.NodeID) bool {
if o.persistentPeers == nil {
panic("isPersistentPeer() called before optimize()")
}
return o.persistentPeers[id]
}
// optimize optimizes operations by pregenerating lookup structures. It's a
// separate method instead of memoizing during calls to avoid dealing with
// concurrency and mutex overhead.
func (o *PeerManagerOptions) optimize() {
o.persistentPeers = make(map[types.NodeID]bool, len(o.PersistentPeers))
for _, p := range o.PersistentPeers {
o.persistentPeers[p] = true
}
}
// PeerManager manages peer lifecycle information, using a peerStore for
// underlying storage. Its primary purpose is to determine which peer to connect
// to next (including retry timers), make sure a peer only has a single active
// connection (either inbound or outbound), and evict peers to make room for
// higher-scored peers. It does not manage actual connections (this is handled
// by the Router), only the peer lifecycle state.
//
// For an outbound connection, the flow is as follows:
// - DialNext: return a peer address to dial, mark peer as dialing.
// - DialFailed: report a dial failure, unmark as dialing.
// - Dialed: report a dial success, unmark as dialing and mark as connected
// (errors if already connected, e.g. by Accepted).
// - Ready: report routing is ready, mark as ready and broadcast PeerStatusUp.
// - Disconnected: report peer disconnect, unmark as connected and broadcasts
// PeerStatusDown.
//
// For an inbound connection, the flow is as follows:
// - Accepted: report inbound connection success, mark as connected (errors if
// already connected, e.g. by Dialed).
// - Ready: report routing is ready, mark as ready and broadcast PeerStatusUp.
// - Disconnected: report peer disconnect, unmark as connected and broadcasts
// PeerStatusDown.
//
// When evicting peers, either because peers are explicitly scheduled for
// eviction or we are connected to too many peers, the flow is as follows:
// - EvictNext: if marked evict and connected, unmark evict and mark evicting.
// If beyond MaxConnected, pick lowest-scored peer and mark evicting.
// - Disconnected: unmark connected, evicting, evict, and broadcast a
// PeerStatusDown peer update.
//
// If all connection slots are full (at MaxConnections), we can use up to
// MaxConnectionsUpgrade additional connections to probe any higher-scored
// unconnected peers, and if we reach them (or they reach us) we allow the
// connection and evict a lower-scored peer. We mark the lower-scored peer as
// upgrading[from]=to to make sure no other higher-scored peers can claim the
// same one for an upgrade. The flow is as follows:
// - Accepted: if upgrade is possible, mark connected and add lower-scored to evict.
// - DialNext: if upgrade is possible, mark upgrading[from]=to and dialing.
// - DialFailed: unmark upgrading[from]=to and dialing.
// - Dialed: unmark upgrading[from]=to and dialing, mark as connected, add
// lower-scored to evict.
// - EvictNext: pick peer from evict, mark as evicting.
// - Disconnected: unmark connected, upgrading[from]=to, evict, evicting.
type PeerManager struct {
selfID types.NodeID
options PeerManagerOptions
rand *rand.Rand
dialWaker *tmsync.Waker // wakes up DialNext() on relevant peer changes
evictWaker *tmsync.Waker // wakes up EvictNext() on relevant peer changes
closeCh chan struct{} // signal channel for Close()
closeOnce sync.Once
mtx sync.Mutex
store *peerStore
subscriptions map[*PeerUpdates]*PeerUpdates // keyed by struct identity (address)
dialing map[types.NodeID]bool // peers being dialed (DialNext → Dialed/DialFail)
upgrading map[types.NodeID]types.NodeID // peers claimed for upgrade (DialNext → Dialed/DialFail)
connected map[types.NodeID]bool // connected peers (Dialed/Accepted → Disconnected)
ready map[types.NodeID]bool // ready peers (Ready → Disconnected)
evict map[types.NodeID]bool // peers scheduled for eviction (Connected → EvictNext)
evicting map[types.NodeID]bool // peers being evicted (EvictNext → Disconnected)
}
// NewPeerManager creates a new peer manager.
func NewPeerManager(selfID types.NodeID, peerDB dbm.DB, options PeerManagerOptions) (*PeerManager, error) {
if selfID == "" {
return nil, errors.New("self ID not given")
}
if err := options.Validate(); err != nil {
return nil, err
}
options.optimize()
store, err := newPeerStore(peerDB)
if err != nil {
return nil, err
}
peerManager := &PeerManager{
selfID: selfID,
options: options,
rand: rand.New(rand.NewSource(time.Now().UnixNano())), // nolint:gosec
dialWaker: tmsync.NewWaker(),
evictWaker: tmsync.NewWaker(),
closeCh: make(chan struct{}),
store: store,
dialing: map[types.NodeID]bool{},
upgrading: map[types.NodeID]types.NodeID{},
connected: map[types.NodeID]bool{},
ready: map[types.NodeID]bool{},
evict: map[types.NodeID]bool{},
evicting: map[types.NodeID]bool{},
subscriptions: map[*PeerUpdates]*PeerUpdates{},
}
if err = peerManager.configurePeers(); err != nil {
return nil, err
}
if err = peerManager.prunePeers(); err != nil {
return nil, err
}
return peerManager, nil
}
// configurePeers configures peers in the peer store with ephemeral runtime
// configuration, e.g. PersistentPeers. It also removes ourself, if we're in the
// peer store. The caller must hold the mutex lock.
func (m *PeerManager) configurePeers() error {
if err := m.store.Delete(m.selfID); err != nil {
return err
}
configure := map[types.NodeID]bool{}
for _, id := range m.options.PersistentPeers {
configure[id] = true
}
for id := range m.options.PeerScores {
configure[id] = true
}
for id := range configure {
if peer, ok := m.store.Get(id); ok {
if err := m.store.Set(m.configurePeer(peer)); err != nil {
return err
}
}
}
return nil
}
// configurePeer configures a peer with ephemeral runtime configuration.
func (m *PeerManager) configurePeer(peer peerInfo) peerInfo {
peer.Persistent = m.options.isPersistent(peer.ID)
peer.FixedScore = m.options.PeerScores[peer.ID]
return peer
}
// newPeerInfo creates a peerInfo for a new peer.
func (m *PeerManager) newPeerInfo(id types.NodeID) peerInfo {
peerInfo := peerInfo{
ID: id,
AddressInfo: map[NodeAddress]*peerAddressInfo{},
}
return m.configurePeer(peerInfo)
}
// prunePeers removes low-scored peers from the peer store if it contains more
// than MaxPeers peers. The caller must hold the mutex lock.
func (m *PeerManager) prunePeers() error {
if m.options.MaxPeers == 0 || m.store.Size() <= int(m.options.MaxPeers) {
return nil
}
ranked := m.store.Ranked()
for i := len(ranked) - 1; i >= 0; i-- {
peerID := ranked[i].ID
switch {
case m.store.Size() <= int(m.options.MaxPeers):
return nil
case m.dialing[peerID]:
case m.connected[peerID]:
default:
if err := m.store.Delete(peerID); err != nil {
return err
}
}
}
return nil
}
// Add adds a peer to the manager, given as an address. If the peer already
// exists, the address is added to it if it isn't already present. This will push
// low scoring peers out of the address book if it exceeds the maximum size.
func (m *PeerManager) Add(address NodeAddress) (bool, error) {
if err := address.Validate(); err != nil {
return false, err
}
if address.NodeID == m.selfID {
return false, fmt.Errorf("can't add self (%v) to peer store", m.selfID)
}
m.mtx.Lock()
defer m.mtx.Unlock()
peer, ok := m.store.Get(address.NodeID)
if !ok {
peer = m.newPeerInfo(address.NodeID)
}
_, ok = peer.AddressInfo[address]
// if we already have the peer address, there's no need to continue
if ok {
return false, nil
}
// else add the new address
peer.AddressInfo[address] = &peerAddressInfo{Address: address}
if err := m.store.Set(peer); err != nil {
return false, err
}
if err := m.prunePeers(); err != nil {
return true, err
}
m.dialWaker.Wake()
return true, nil
}
// PeerRatio returns the ratio of peer addresses stored to the maximum size.
func (m *PeerManager) PeerRatio() float64 {
m.mtx.Lock()
defer m.mtx.Unlock()
if m.options.MaxPeers == 0 {
return 0
}
return float64(m.store.Size()) / float64(m.options.MaxPeers)
}
// DialNext finds an appropriate peer address to dial, and marks it as dialing.
// If no peer is found, or all connection slots are full, it blocks until one
// becomes available. The caller must call Dialed() or DialFailed() for the
// returned peer.
func (m *PeerManager) DialNext(ctx context.Context) (NodeAddress, error) {
for {
address, err := m.TryDialNext()
if err != nil || (address != NodeAddress{}) {
return address, err
}
select {
case <-m.dialWaker.Sleep():
case <-ctx.Done():
return NodeAddress{}, ctx.Err()
}
}
}
// TryDialNext is equivalent to DialNext(), but immediately returns an empty
// address if no peers or connection slots are available.
func (m *PeerManager) TryDialNext() (NodeAddress, error) {
m.mtx.Lock()
defer m.mtx.Unlock()
// We allow dialing MaxConnected+MaxConnectedUpgrade peers. Including
// MaxConnectedUpgrade allows us to probe additional peers that have a
// higher score than any other peers, and if successful evict it.
if m.options.MaxConnected > 0 && len(m.connected)+len(m.dialing) >=
int(m.options.MaxConnected)+int(m.options.MaxConnectedUpgrade) {
return NodeAddress{}, nil
}
for _, peer := range m.store.Ranked() {
if m.dialing[peer.ID] || m.connected[peer.ID] {
continue
}
for _, addressInfo := range peer.AddressInfo {
if time.Since(addressInfo.LastDialFailure) < m.retryDelay(addressInfo.DialFailures, peer.Persistent) {
continue
}
// We now have an eligible address to dial. If we're full but have
// upgrade capacity (as checked above), we find a lower-scored peer
// we can replace and mark it as upgrading so noone else claims it.
//
// If we don't find one, there is no point in trying additional
// peers, since they will all have the same or lower score than this
// peer (since they're ordered by score via peerStore.Ranked).
if m.options.MaxConnected > 0 && len(m.connected) >= int(m.options.MaxConnected) {
upgradeFromPeer := m.findUpgradeCandidate(peer.ID, peer.Score())
if upgradeFromPeer == "" {
return NodeAddress{}, nil
}
m.upgrading[upgradeFromPeer] = peer.ID
}
m.dialing[peer.ID] = true
return addressInfo.Address, nil
}
}
return NodeAddress{}, nil
}
// DialFailed reports a failed dial attempt. This will make the peer available
// for dialing again when appropriate (possibly after a retry timeout).
//
// FIXME: This should probably delete or mark bad addresses/peers after some time.
func (m *PeerManager) DialFailed(address NodeAddress) error {
m.mtx.Lock()
defer m.mtx.Unlock()
delete(m.dialing, address.NodeID)
for from, to := range m.upgrading {
if to == address.NodeID {
delete(m.upgrading, from) // Unmark failed upgrade attempt.
}
}
peer, ok := m.store.Get(address.NodeID)
if !ok { // Peer may have been removed while dialing, ignore.
return nil
}
addressInfo, ok := peer.AddressInfo[address]
if !ok {
return nil // Assume the address has been removed, ignore.
}
addressInfo.LastDialFailure = time.Now().UTC()
addressInfo.DialFailures++
if err := m.store.Set(peer); err != nil {
return err
}
// We spawn a goroutine that notifies DialNext() again when the retry
// timeout has elapsed, so that we can consider dialing it again. We
// calculate the retry delay outside the goroutine, since it must hold
// the mutex lock.
if d := m.retryDelay(addressInfo.DialFailures, peer.Persistent); d != 0 && d != retryNever {
go func() {
// Use an explicit timer with deferred cleanup instead of
// time.After(), to avoid leaking goroutines on PeerManager.Close().
timer := time.NewTimer(d)
defer timer.Stop()
select {
case <-timer.C:
m.dialWaker.Wake()
case <-m.closeCh:
}
}()
} else {
m.dialWaker.Wake()
}
return nil
}
// Dialed marks a peer as successfully dialed. Any further connections will be
// rejected, and once disconnected the peer may be dialed again.
func (m *PeerManager) Dialed(address NodeAddress) error {
m.mtx.Lock()
defer m.mtx.Unlock()
delete(m.dialing, address.NodeID)
var upgradeFromPeer types.NodeID
for from, to := range m.upgrading {
if to == address.NodeID {
delete(m.upgrading, from)
upgradeFromPeer = from
// Don't break, just in case this peer was marked as upgrading for
// multiple lower-scored peers (shouldn't really happen).
}
}
if address.NodeID == m.selfID {
return fmt.Errorf("rejecting connection to self (%v)", address.NodeID)
}
if m.connected[address.NodeID] {
return fmt.Errorf("peer %v is already connected", address.NodeID)
}
if m.options.MaxConnected > 0 && len(m.connected) >= int(m.options.MaxConnected) {
if upgradeFromPeer == "" || len(m.connected) >=
int(m.options.MaxConnected)+int(m.options.MaxConnectedUpgrade) {
return fmt.Errorf("already connected to maximum number of peers")
}
}
peer, ok := m.store.Get(address.NodeID)
if !ok {
return fmt.Errorf("peer %q was removed while dialing", address.NodeID)
}
now := time.Now().UTC()
peer.LastConnected = now
if addressInfo, ok := peer.AddressInfo[address]; ok {
addressInfo.DialFailures = 0
addressInfo.LastDialSuccess = now
// If not found, assume address has been removed.
}
if err := m.store.Set(peer); err != nil {
return err
}
if upgradeFromPeer != "" && m.options.MaxConnected > 0 &&
len(m.connected) >= int(m.options.MaxConnected) {
// Look for an even lower-scored peer that may have appeared since we
// started the upgrade.
if p, ok := m.store.Get(upgradeFromPeer); ok {
if u := m.findUpgradeCandidate(p.ID, p.Score()); u != "" {
upgradeFromPeer = u
}
}
m.evict[upgradeFromPeer] = true
}
m.connected[peer.ID] = true
m.evictWaker.Wake()
return nil
}
// Accepted marks an incoming peer connection successfully accepted. If the peer
// is already connected or we don't allow additional connections then this will
// return an error.
//
// If full but MaxConnectedUpgrade is non-zero and the incoming peer is
// better-scored than any existing peers, then we accept it and evict a
// lower-scored peer.
//
// NOTE: We can't take an address here, since e.g. TCP uses a different port
// number for outbound traffic than inbound traffic, so the peer's endpoint
// wouldn't necessarily be an appropriate address to dial.
//
// FIXME: When we accept a connection from a peer, we should register that
// peer's address in the peer store so that we can dial it later. In order to do
// that, we'll need to get the remote address after all, but as noted above that
// can't be the remote endpoint since that will usually have the wrong port
// number.
func (m *PeerManager) Accepted(peerID types.NodeID) error {
m.mtx.Lock()
defer m.mtx.Unlock()
if peerID == m.selfID {
return fmt.Errorf("rejecting connection from self (%v)", peerID)
}
if m.connected[peerID] {
return fmt.Errorf("peer %q is already connected", peerID)
}
if m.options.MaxConnected > 0 &&
len(m.connected) >= int(m.options.MaxConnected)+int(m.options.MaxConnectedUpgrade) {
return fmt.Errorf("already connected to maximum number of peers")
}
peer, ok := m.store.Get(peerID)
if !ok {
peer = m.newPeerInfo(peerID)
}
// reset this to avoid penalizing peers for their past transgressions
for _, addr := range peer.AddressInfo {
addr.DialFailures = 0
}
// If all connections slots are full, but we allow upgrades (and we checked
// above that we have upgrade capacity), then we can look for a lower-scored
// peer to replace and if found accept the connection anyway and evict it.
var upgradeFromPeer types.NodeID
if m.options.MaxConnected > 0 && len(m.connected) >= int(m.options.MaxConnected) {
upgradeFromPeer = m.findUpgradeCandidate(peer.ID, peer.Score())
if upgradeFromPeer == "" {
return fmt.Errorf("already connected to maximum number of peers")
}
}
peer.LastConnected = time.Now().UTC()
if err := m.store.Set(peer); err != nil {
return err
}
m.connected[peerID] = true
if upgradeFromPeer != "" {
m.evict[upgradeFromPeer] = true
}
m.evictWaker.Wake()
return nil
}
// Ready marks a peer as ready, broadcasting status updates to subscribers. The
// peer must already be marked as connected. This is separate from Dialed() and
// Accepted() to allow the router to set up its internal queues before reactors
// start sending messages.
func (m *PeerManager) Ready(peerID types.NodeID) {
m.mtx.Lock()
defer m.mtx.Unlock()
if m.connected[peerID] {
m.ready[peerID] = true
m.broadcast(PeerUpdate{
NodeID: peerID,
Status: PeerStatusUp,
})
}
}
// EvictNext returns the next peer to evict (i.e. disconnect). If no evictable
// peers are found, the call will block until one becomes available.
func (m *PeerManager) EvictNext(ctx context.Context) (types.NodeID, error) {
for {
id, err := m.TryEvictNext()
if err != nil || id != "" {
return id, err
}
select {
case <-m.evictWaker.Sleep():
case <-ctx.Done():
return "", ctx.Err()
}
}
}
// TryEvictNext is equivalent to EvictNext, but immediately returns an empty
// node ID if no evictable peers are found.
func (m *PeerManager) TryEvictNext() (types.NodeID, error) {
m.mtx.Lock()
defer m.mtx.Unlock()
// If any connected peers are explicitly scheduled for eviction, we return a
// random one.
for peerID := range m.evict {
delete(m.evict, peerID)
if m.connected[peerID] && !m.evicting[peerID] {
m.evicting[peerID] = true
return peerID, nil
}
}
// If we're below capacity, we don't need to evict anything.
if m.options.MaxConnected == 0 ||
len(m.connected)-len(m.evicting) <= int(m.options.MaxConnected) {
return "", nil
}
// If we're above capacity (shouldn't really happen), just pick the
// lowest-ranked peer to evict.
ranked := m.store.Ranked()
for i := len(ranked) - 1; i >= 0; i-- {
peer := ranked[i]
if m.connected[peer.ID] && !m.evicting[peer.ID] {
m.evicting[peer.ID] = true
return peer.ID, nil
}
}
return "", nil
}
// Disconnected unmarks a peer as connected, allowing it to be dialed or
// accepted again as appropriate.
func (m *PeerManager) Disconnected(peerID types.NodeID) {
m.mtx.Lock()
defer m.mtx.Unlock()
ready := m.ready[peerID]
delete(m.connected, peerID)
delete(m.upgrading, peerID)
delete(m.evict, peerID)
delete(m.evicting, peerID)
delete(m.ready, peerID)
if ready {
m.broadcast(PeerUpdate{
NodeID: peerID,
Status: PeerStatusDown,
})
}
m.dialWaker.Wake()
}
// Errored reports a peer error, causing the peer to be evicted if it's
// currently connected.
//
// FIXME: This should probably be replaced with a peer behavior API, see
// PeerError comments for more details.
//
// FIXME: This will cause the peer manager to immediately try to reconnect to
// the peer, which is probably not always what we want.
func (m *PeerManager) Errored(peerID types.NodeID, err error) {
m.mtx.Lock()
defer m.mtx.Unlock()
if m.connected[peerID] {
m.evict[peerID] = true
}
m.evictWaker.Wake()
}
// Advertise returns a list of peer addresses to advertise to a peer.
//
// FIXME: This is fairly naïve and only returns the addresses of the
// highest-ranked peers.
func (m *PeerManager) Advertise(peerID types.NodeID, limit uint16) []NodeAddress {
m.mtx.Lock()
defer m.mtx.Unlock()
addresses := make([]NodeAddress, 0, limit)
// advertise ourselves, to let everyone know how to dial us back
// and enable mutual address discovery
if m.options.SelfAddress.Hostname != "" && m.options.SelfAddress.Port != 0 {
addresses = append(addresses, m.options.SelfAddress)
}
for _, peer := range m.store.Ranked() {
if peer.ID == peerID {
continue
}
for nodeAddr, addressInfo := range peer.AddressInfo {
if len(addresses) >= int(limit) {
return addresses
}
// only add non-private NodeIDs
if _, ok := m.options.PrivatePeers[nodeAddr.NodeID]; !ok {
addresses = append(addresses, addressInfo.Address)
}
}
}
return addresses
}
// Subscribe subscribes to peer updates. The caller must consume the peer
// updates in a timely fashion and close the subscription when done, otherwise
// the PeerManager will halt.
func (m *PeerManager) Subscribe() *PeerUpdates {
// FIXME: We use a size 1 buffer here. When we broadcast a peer update
// we have to loop over all of the subscriptions, and we want to avoid
// having to block and wait for a context switch before continuing on
// to the next subscriptions. This also prevents tail latencies from
// compounding. Limiting it to 1 means that the subscribers are still
// reasonably in sync. However, this should probably be benchmarked.
peerUpdates := NewPeerUpdates(make(chan PeerUpdate, 1), 1)
m.Register(peerUpdates)
return peerUpdates
}
// Register allows you to inject a custom PeerUpdate instance into the
// PeerManager, rather than relying on the instance constructed by the
// Subscribe method, which wraps the functionality of the Register
// method.
//
// The caller must consume the peer updates from this PeerUpdates
// instance in a timely fashion and close the subscription when done,
// otherwise the PeerManager will halt.
func (m *PeerManager) Register(peerUpdates *PeerUpdates) {
m.mtx.Lock()
m.subscriptions[peerUpdates] = peerUpdates
m.mtx.Unlock()
go func() {
for {
select {
case <-peerUpdates.closeCh:
return
case <-m.closeCh:
return
case pu := <-peerUpdates.routerUpdatesCh:
m.processPeerEvent(pu)
}
}
}()
go func() {
select {
case <-peerUpdates.Done():
m.mtx.Lock()
delete(m.subscriptions, peerUpdates)
m.mtx.Unlock()
case <-m.closeCh:
}
}()
}
func (m *PeerManager) processPeerEvent(pu PeerUpdate) {
m.mtx.Lock()
defer m.mtx.Unlock()
if _, ok := m.store.peers[pu.NodeID]; !ok {
m.store.peers[pu.NodeID] = &peerInfo{}
}
switch pu.Status {
case PeerStatusBad:
m.store.peers[pu.NodeID].MutableScore--
case PeerStatusGood:
m.store.peers[pu.NodeID].MutableScore++
}
}
// broadcast broadcasts a peer update to all subscriptions. The caller must
// already hold the mutex lock, to make sure updates are sent in the same order
// as the PeerManager processes them, but this means subscribers must be
// responsive at all times or the entire PeerManager will halt.
//
// FIXME: Consider using an internal channel to buffer updates while also
// maintaining order if this is a problem.
func (m *PeerManager) broadcast(peerUpdate PeerUpdate) {
for _, sub := range m.subscriptions {
// We have to check closeCh separately first, otherwise there's a 50%
// chance the second select will send on a closed subscription.
select {
case <-sub.closeCh:
continue
default:
}
select {
case sub.reactorUpdatesCh <- peerUpdate:
case <-sub.closeCh:
}
}
}
// Close closes the peer manager, releasing resources (i.e. goroutines).
func (m *PeerManager) Close() {
m.closeOnce.Do(func() {
close(m.closeCh)
})
}
// Addresses returns all known addresses for a peer, primarily for testing.
// The order is arbitrary.
func (m *PeerManager) Addresses(peerID types.NodeID) []NodeAddress {
m.mtx.Lock()
defer m.mtx.Unlock()
addresses := []NodeAddress{}
if peer, ok := m.store.Get(peerID); ok {
for _, addressInfo := range peer.AddressInfo {
addresses = append(addresses, addressInfo.Address)
}
}
return addresses
}
// Peers returns all known peers, primarily for testing. The order is arbitrary.
func (m *PeerManager) Peers() []types.NodeID {
m.mtx.Lock()
defer m.mtx.Unlock()
peers := []types.NodeID{}
for _, peer := range m.store.Ranked() {
peers = append(peers, peer.ID)
}
return peers
}
// Scores returns the peer scores for all known peers, primarily for testing.
func (m *PeerManager) Scores() map[types.NodeID]PeerScore {
m.mtx.Lock()
defer m.mtx.Unlock()
scores := map[types.NodeID]PeerScore{}
for _, peer := range m.store.Ranked() {
scores[peer.ID] = peer.Score()
}
return scores
}
// Status returns the status for a peer, primarily for testing.
func (m *PeerManager) Status(id types.NodeID) PeerStatus {
m.mtx.Lock()
defer m.mtx.Unlock()
switch {
case m.ready[id]:
return PeerStatusUp
default:
return PeerStatusDown
}
}
// findUpgradeCandidate looks for a lower-scored peer that we could evict
// to make room for the given peer. Returns an empty ID if none is found.
// If the peer is already being upgraded to, we return that same upgrade.
// The caller must hold the mutex lock.
func (m *PeerManager) findUpgradeCandidate(id types.NodeID, score PeerScore) types.NodeID {
for from, to := range m.upgrading {
if to == id {
return from
}
}
ranked := m.store.Ranked()
for i := len(ranked) - 1; i >= 0; i-- {
candidate := ranked[i]
switch {
case candidate.Score() >= score:
return "" // no further peers can be scored lower, due to sorting
case !m.connected[candidate.ID]:
case m.evict[candidate.ID]:
case m.evicting[candidate.ID]:
case m.upgrading[candidate.ID] != "":
default:
return candidate.ID
}
}
return ""
}
// retryDelay calculates a dial retry delay using exponential backoff, based on
// retry settings in PeerManagerOptions. If retries are disabled (i.e.
// MinRetryTime is 0), this returns retryNever (i.e. an infinite retry delay).
// The caller must hold the mutex lock (for m.rand which is not thread-safe).
func (m *PeerManager) retryDelay(failures uint32, persistent bool) time.Duration {
if failures == 0 {
return 0
}
if m.options.MinRetryTime == 0 {
return retryNever
}
maxDelay := m.options.MaxRetryTime
if persistent && m.options.MaxRetryTimePersistent > 0 {
maxDelay = m.options.MaxRetryTimePersistent
}
delay := m.options.MinRetryTime * time.Duration(failures)
if m.options.RetryTimeJitter > 0 {
delay += time.Duration(m.rand.Int63n(int64(m.options.RetryTimeJitter)))
}
if maxDelay > 0 && delay > maxDelay {
delay = maxDelay
}
return delay
}
// GetHeight returns a peer's height, as reported via SetHeight, or 0 if the
// peer or height is unknown.
//
// FIXME: This is a temporary workaround to share state between the consensus
// and mempool reactors, carried over from the legacy P2P stack. Reactors should
// not have dependencies on each other, instead tracking this themselves.
func (m *PeerManager) GetHeight(peerID types.NodeID) int64 {
m.mtx.Lock()
defer m.mtx.Unlock()
peer, _ := m.store.Get(peerID)
return peer.Height
}
// SetHeight stores a peer's height, making it available via GetHeight.
//
// FIXME: This is a temporary workaround to share state between the consensus
// and mempool reactors, carried over from the legacy P2P stack. Reactors should
// not have dependencies on each other, instead tracking this themselves.
func (m *PeerManager) SetHeight(peerID types.NodeID, height int64) error {
m.mtx.Lock()
defer m.mtx.Unlock()
peer, ok := m.store.Get(peerID)
if !ok {
peer = m.newPeerInfo(peerID)
}
peer.Height = height
return m.store.Set(peer)
}
// peerStore stores information about peers. It is not thread-safe, assuming it
// is only used by PeerManager which handles concurrency control. This allows
// the manager to execute multiple operations atomically via its own mutex.
//
// The entire set of peers is kept in memory, for performance. It is loaded
// from disk on initialization, and any changes are written back to disk
// (without fsync, since we can afford to lose recent writes).
type peerStore struct {
db dbm.DB
peers map[types.NodeID]*peerInfo
ranked []*peerInfo // cache for Ranked(), nil invalidates cache
}
// newPeerStore creates a new peer store, loading all persisted peers from the
// database into memory.
func newPeerStore(db dbm.DB) (*peerStore, error) {
if db == nil {
return nil, errors.New("no database provided")
}
store := &peerStore{db: db}
if err := store.loadPeers(); err != nil {
return nil, err
}
return store, nil
}
// loadPeers loads all peers from the database into memory.
func (s *peerStore) loadPeers() error {
peers := map[types.NodeID]*peerInfo{}
start, end := keyPeerInfoRange()
iter, err := s.db.Iterator(start, end)
if err != nil {
return err
}
defer iter.Close()
for ; iter.Valid(); iter.Next() {
// FIXME: We may want to tolerate failures here, by simply logging
// the errors and ignoring the faulty peer entries.
msg := new(p2pproto.PeerInfo)
if err := proto.Unmarshal(iter.Value(), msg); err != nil {
return fmt.Errorf("invalid peer Protobuf data: %w", err)
}
peer, err := peerInfoFromProto(msg)
if err != nil {
return fmt.Errorf("invalid peer data: %w", err)
}
peers[peer.ID] = peer
}
if iter.Error() != nil {
return iter.Error()
}
s.peers = peers
s.ranked = nil // invalidate cache if populated
return nil
}
// Get fetches a peer. The boolean indicates whether the peer existed or not.
// The returned peer info is a copy, and can be mutated at will.
func (s *peerStore) Get(id types.NodeID) (peerInfo, bool) {
peer, ok := s.peers[id]
return peer.Copy(), ok
}
// Set stores peer data. The input data will be copied, and can safely be reused
// by the caller.
func (s *peerStore) Set(peer peerInfo) error {
if err := peer.Validate(); err != nil {
return err
}
peer = peer.Copy()
// FIXME: We may want to optimize this by avoiding saving to the database
// if there haven't been any changes to persisted fields.
bz, err := peer.ToProto().Marshal()
if err != nil {
return err
}
if err = s.db.Set(keyPeerInfo(peer.ID), bz); err != nil {
return err
}
if current, ok := s.peers[peer.ID]; !ok || current.Score() != peer.Score() {
// If the peer is new, or its score changes, we invalidate the Ranked() cache.
s.peers[peer.ID] = &peer
s.ranked = nil
} else {
// Otherwise, since s.ranked contains pointers to the old data and we
// want those pointers to remain valid with the new data, we have to
// update the existing pointer address.
*current = peer
}
return nil
}
// Delete deletes a peer, or does nothing if it does not exist.
func (s *peerStore) Delete(id types.NodeID) error {
if _, ok := s.peers[id]; !ok {
return nil
}
if err := s.db.Delete(keyPeerInfo(id)); err != nil {
return err
}
delete(s.peers, id)
s.ranked = nil
return nil
}
// List retrieves all peers in an arbitrary order. The returned data is a copy,
// and can be mutated at will.
func (s *peerStore) List() []peerInfo {
peers := make([]peerInfo, 0, len(s.peers))
for _, peer := range s.peers {
peers = append(peers, peer.Copy())
}
return peers
}
// Ranked returns a list of peers ordered by score (better peers first). Peers
// with equal scores are returned in an arbitrary order. The returned list must
// not be mutated or accessed concurrently by the caller, since it returns
// pointers to internal peerStore data for performance.
//
// Ranked is used to determine both which peers to dial, which ones to evict,
// and which ones to delete completely.
//
// FIXME: For now, we simply maintain a cache in s.ranked which is invalidated
// by setting it to nil, but if necessary we should use a better data structure
// for this (e.g. a heap or ordered map).
//
// FIXME: The scoring logic is currently very naïve, see peerInfo.Score().
func (s *peerStore) Ranked() []*peerInfo {
if s.ranked != nil {
return s.ranked
}
s.ranked = make([]*peerInfo, 0, len(s.peers))
for _, peer := range s.peers {
s.ranked = append(s.ranked, peer)
}
sort.Slice(s.ranked, func(i, j int) bool {
// FIXME: If necessary, consider precomputing scores before sorting,
// to reduce the number of Score() calls.
return s.ranked[i].Score() > s.ranked[j].Score()
})
return s.ranked
}
// Size returns the number of peers in the peer store.
func (s *peerStore) Size() int {
return len(s.peers)
}
// peerInfo contains peer information stored in a peerStore.
type peerInfo struct {
ID types.NodeID
AddressInfo map[NodeAddress]*peerAddressInfo
LastConnected time.Time
// These fields are ephemeral, i.e. not persisted to the database.
Persistent bool
Height int64
FixedScore PeerScore // mainly for tests
MutableScore int64 // updated by router
}
// peerInfoFromProto converts a Protobuf PeerInfo message to a peerInfo,
// erroring if the data is invalid.
func peerInfoFromProto(msg *p2pproto.PeerInfo) (*peerInfo, error) {
p := &peerInfo{
ID: types.NodeID(msg.ID),
AddressInfo: map[NodeAddress]*peerAddressInfo{},
}
if msg.LastConnected != nil {
p.LastConnected = *msg.LastConnected
}
for _, a := range msg.AddressInfo {
addressInfo, err := peerAddressInfoFromProto(a)
if err != nil {
return nil, err
}
p.AddressInfo[addressInfo.Address] = addressInfo
}
return p, p.Validate()
}
// ToProto converts the peerInfo to p2pproto.PeerInfo for database storage. The
// Protobuf type only contains persisted fields, while ephemeral fields are
// discarded. The returned message may contain pointers to original data, since
// it is expected to be serialized immediately.
func (p *peerInfo) ToProto() *p2pproto.PeerInfo {
msg := &p2pproto.PeerInfo{
ID: string(p.ID),
LastConnected: &p.LastConnected,
}
for _, addressInfo := range p.AddressInfo {
msg.AddressInfo = append(msg.AddressInfo, addressInfo.ToProto())
}
if msg.LastConnected.IsZero() {
msg.LastConnected = nil
}
return msg
}
// Copy returns a deep copy of the peer info.
func (p *peerInfo) Copy() peerInfo {
if p == nil {
return peerInfo{}
}
c := *p
for i, addressInfo := range c.AddressInfo {
addressInfoCopy := addressInfo.Copy()
c.AddressInfo[i] = &addressInfoCopy
}
return c
}
// Score calculates a score for the peer. Higher-scored peers will be
// preferred over lower scores.
func (p *peerInfo) Score() PeerScore {
if p.FixedScore > 0 {
return p.FixedScore
}
if p.Persistent {
return PeerScorePersistent
}
score := p.MutableScore
for _, addr := range p.AddressInfo {
// DialFailures is reset when dials succeed, so this
// is either the number of dial failures or 0.
score -= int64(addr.DialFailures)
}
if score <= 0 {
return 0
}
if score >= math.MaxUint8 {
return PeerScore(math.MaxUint8)
}
return PeerScore(score)
}
// Validate validates the peer info.
func (p *peerInfo) Validate() error {
if p.ID == "" {
return errors.New("no peer ID")
}
return nil
}
// peerAddressInfo contains information and statistics about a peer address.
type peerAddressInfo struct {
Address NodeAddress
LastDialSuccess time.Time
LastDialFailure time.Time
DialFailures uint32 // since last successful dial
}
// peerAddressInfoFromProto converts a Protobuf PeerAddressInfo message
// to a peerAddressInfo.
func peerAddressInfoFromProto(msg *p2pproto.PeerAddressInfo) (*peerAddressInfo, error) {
address, err := ParseNodeAddress(msg.Address)
if err != nil {
return nil, fmt.Errorf("invalid address %q: %w", address, err)
}
addressInfo := &peerAddressInfo{
Address: address,
DialFailures: msg.DialFailures,
}
if msg.LastDialSuccess != nil {
addressInfo.LastDialSuccess = *msg.LastDialSuccess
}
if msg.LastDialFailure != nil {
addressInfo.LastDialFailure = *msg.LastDialFailure
}
return addressInfo, addressInfo.Validate()
}
// ToProto converts the address into to a Protobuf message for serialization.
func (a *peerAddressInfo) ToProto() *p2pproto.PeerAddressInfo {
msg := &p2pproto.PeerAddressInfo{
Address: a.Address.String(),
LastDialSuccess: &a.LastDialSuccess,
LastDialFailure: &a.LastDialFailure,
DialFailures: a.DialFailures,
}
if msg.LastDialSuccess.IsZero() {
msg.LastDialSuccess = nil
}
if msg.LastDialFailure.IsZero() {
msg.LastDialFailure = nil
}
return msg
}
// Copy returns a copy of the address info.
func (a *peerAddressInfo) Copy() peerAddressInfo {
return *a
}
// Validate validates the address info.
func (a *peerAddressInfo) Validate() error {
return a.Address.Validate()
}
// Database key prefixes.
const (
prefixPeerInfo int64 = 1
)
// keyPeerInfo generates a peerInfo database key.
func keyPeerInfo(id types.NodeID) []byte {
key, err := orderedcode.Append(nil, prefixPeerInfo, string(id))
if err != nil {
panic(err)
}
return key
}
// keyPeerInfoRange generates start/end keys for the entire peerInfo key range.
func keyPeerInfoRange() ([]byte, []byte) {
start, err := orderedcode.Append(nil, prefixPeerInfo, "")
if err != nil {
panic(err)
}
end, err := orderedcode.Append(nil, prefixPeerInfo, orderedcode.Infinity)
if err != nil {
panic(err)
}
return start, end
}