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driver_rdv.go
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driver_rdv.go
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// from https://github.com/libp2p/go-libp2p-rendezvous/blob/implement-spec/discovery.go
// @NOTE(gfanton): we need to dedup this file to add unregister method
package tinder
import (
"context"
"math"
mrand "math/rand"
"sync"
"time"
"github.com/libp2p/go-libp2p-core/discovery"
"github.com/libp2p/go-libp2p-core/host"
"github.com/libp2p/go-libp2p-core/peer"
p2p_rp "github.com/libp2p/go-libp2p-rendezvous"
"go.uber.org/zap"
)
type rendezvousDiscovery struct {
logger *zap.Logger
rp p2p_rp.RendezvousPoint
peerCache map[string]*rpCache
peerCacheMux sync.RWMutex
rng *mrand.Rand
rngMux sync.Mutex
selfID peer.ID
}
type rpCache struct {
recs map[peer.ID]*rpRecord
cookie []byte
mux sync.Mutex
}
type rpRecord struct {
peer peer.AddrInfo
expire int64
}
func NewRendezvousDiscovery(logger *zap.Logger, host host.Host, rdvPeer peer.ID, rng *mrand.Rand) UnregisterDiscovery {
rp := p2p_rp.NewRendezvousPoint(host, rdvPeer)
return &rendezvousDiscovery{
logger: logger.Named("tinder/rdvp"),
rp: rp,
rng: rng,
peerCache: make(map[string]*rpCache),
selfID: host.ID(),
}
}
func (c *rendezvousDiscovery) Advertise(ctx context.Context, ns string, opts ...discovery.Option) (time.Duration, error) {
// Get options
var options discovery.Options
err := options.Apply(opts...)
if err != nil {
return 0, err
}
ttl := options.Ttl
var ttlSeconds int
if ttl == 0 {
ttlSeconds = 7200
} else {
ttlSeconds = int(math.Round(ttl.Seconds()))
}
rttl, err := c.rp.Register(ctx, ns, ttlSeconds)
if err != nil {
return 0, err
}
return rttl, nil
}
func (c *rendezvousDiscovery) FindPeers(ctx context.Context, ns string, opts ...discovery.Option) (<-chan peer.AddrInfo, error) {
// Get options
var options discovery.Options
err := options.Apply(opts...)
if err != nil {
return nil, err
}
const maxLimit = 1000
limit := options.Limit
if limit == 0 || limit > maxLimit {
limit = maxLimit
}
// Get cached peers
var cache *rpCache
c.peerCacheMux.RLock()
cache, ok := c.peerCache[ns]
c.peerCacheMux.RUnlock()
if !ok {
c.peerCacheMux.Lock()
cache, ok = c.peerCache[ns]
if !ok {
cache = &rpCache{recs: make(map[peer.ID]*rpRecord)}
c.peerCache[ns] = cache
}
c.peerCacheMux.Unlock()
}
cache.mux.Lock()
defer cache.mux.Unlock()
// Remove all expired entries from cache
currentTime := time.Now().Unix()
newCacheSize := len(cache.recs)
for p := range cache.recs {
rec := cache.recs[p]
if rec.expire < currentTime {
newCacheSize--
delete(cache.recs, p)
}
}
cookie := cache.cookie
// Discover new records if we don't have enough
if newCacheSize < limit {
// TODO: Should we return error even if we have valid cached results?
var regs []p2p_rp.Registration
var newCookie []byte
if regs, newCookie, err = c.rp.Discover(ctx, ns, limit, cookie); err == nil {
for _, reg := range regs {
rec := &rpRecord{peer: reg.Peer, expire: int64(reg.Ttl) + currentTime}
cache.recs[rec.peer.ID] = rec
}
cache.cookie = newCookie
}
}
// Randomize and fill channel with available records
count := len(cache.recs)
if limit < count {
count = limit
}
// c.logger.Debug("found peers", zap.String("key", ns), zap.Int("count", count))
// fmt.Printf("rdvp findpeers found [%s]: %d peers found\n", ns, count)
chPeer := make(chan peer.AddrInfo, count)
c.rngMux.Lock()
perm := c.rng.Perm(len(cache.recs))[0:count]
c.rngMux.Unlock()
permSet := make(map[int]int)
for i, v := range perm {
permSet[v] = i
}
sendLst := make([]*peer.AddrInfo, count)
iter := 0
for k := range cache.recs {
if sendIndex, ok := permSet[iter]; ok {
sendLst[sendIndex] = &cache.recs[k].peer
}
iter++
}
for _, send := range sendLst {
chPeer <- *send
}
close(chPeer)
return chPeer, err
}
func (c *rendezvousDiscovery) Unregister(ctx context.Context, ns string) error {
c.peerCacheMux.RLock()
cache, ok := c.peerCache[ns]
c.peerCacheMux.RUnlock()
if ok {
cache.mux.Lock()
delete(cache.recs, c.selfID)
cache.mux.Unlock()
}
return c.rp.Unregister(ctx, ns)
}