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package p2p
import (
"sync"
)
// IPeerSet has a (immutable) subset of the methods of PeerSet.
type IPeerSet interface {
Has(key string) bool
Get(key string) *Peer
List() []*Peer
Size() int
}
//-----------------------------------------------------------------------------
// PeerSet is a special structure for keeping a table of peers.
// Iteration over the peers is super fast and thread-safe.
// We also track how many peers per IP range and avoid too many
type PeerSet struct {
mtx sync.Mutex
lookup map[string]*peerSetItem
list []*Peer
}
type peerSetItem struct {
peer *Peer
index int
}
func NewPeerSet() *PeerSet {
return &PeerSet{
lookup: make(map[string]*peerSetItem),
list: make([]*Peer, 0, 256),
}
}
// Returns false if peer with key (PubKeyEd25519) is already in set
// or if we have too many peers from the peer's IP range
func (ps *PeerSet) Add(peer *Peer) error {
ps.mtx.Lock()
defer ps.mtx.Unlock()
if ps.lookup[peer.Key] != nil {
return ErrSwitchDuplicatePeer
}
index := len(ps.list)
// Appending is safe even with other goroutines
// iterating over the ps.list slice.
ps.list = append(ps.list, peer)
ps.lookup[peer.Key] = &peerSetItem{peer, index}
return nil
}
func (ps *PeerSet) Has(peerKey string) bool {
ps.mtx.Lock()
defer ps.mtx.Unlock()
_, ok := ps.lookup[peerKey]
return ok
}
func (ps *PeerSet) Get(peerKey string) *Peer {
ps.mtx.Lock()
defer ps.mtx.Unlock()
item, ok := ps.lookup[peerKey]
if ok {
return item.peer
} else {
return nil
}
}
func (ps *PeerSet) Remove(peer *Peer) {
ps.mtx.Lock()
defer ps.mtx.Unlock()
item := ps.lookup[peer.Key]
if item == nil {
return
}
index := item.index
// Copy the list but without the last element.
// (we must copy because we're mutating the list)
newList := make([]*Peer, len(ps.list)-1)
copy(newList, ps.list)
// If it's the last peer, that's an easy special case.
if index == len(ps.list)-1 {
ps.list = newList
delete(ps.lookup, peer.Key)
return
}
// Move the last item from ps.list to "index" in list.
lastPeer := ps.list[len(ps.list)-1]
lastPeerKey := lastPeer.Key
lastPeerItem := ps.lookup[lastPeerKey]
newList[index] = lastPeer
lastPeerItem.index = index
ps.list = newList
delete(ps.lookup, peer.Key)
}
func (ps *PeerSet) Size() int {
ps.mtx.Lock()
defer ps.mtx.Unlock()
return len(ps.list)
}
// threadsafe list of peers.
func (ps *PeerSet) List() []*Peer {
ps.mtx.Lock()
defer ps.mtx.Unlock()
return ps.list
}
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