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package dht
import (
"container/heap"
"sync"
)
type rItem struct {
value *remoteNode
distance int
index int // Index in heap
}
type priorityQueue []*rItem
type routingTable struct {
id Infohash
max int
items priorityQueue
addresses map[string]*remoteNode
sync.Mutex
}
func newRoutingTable(id Infohash, max int) (*routingTable, error) {
k := &routingTable{
id: id,
max: max,
}
k.flush()
heap.Init(&k.items)
return k, nil
}
// Len implements sort.Interface
func (pq priorityQueue) Len() int { return len(pq) }
// Less implements sort.Interface
func (pq priorityQueue) Less(i, j int) bool {
return pq[i].distance > pq[j].distance
}
// Swap implements sort.Interface
func (pq priorityQueue) Swap(i, j int) {
pq[i], pq[j] = pq[j], pq[i]
pq[i].index = i
pq[j].index = j
}
// Push implements heap.Interface
func (pq *priorityQueue) Push(x interface{}) {
n := len(*pq)
item := x.(*rItem)
item.index = n
*pq = append(*pq, item)
}
// Pop implements heap.Interface
func (pq *priorityQueue) Pop() interface{} {
old := *pq
n := len(old)
item := old[n-1]
item.index = -1 // for safety
*pq = old[0 : n-1]
return item
}
func (k *routingTable) add(rn *remoteNode) {
// Check IP and ports are valid and not self
if !rn.id.Valid() || rn.id.Equal(k.id) {
return
}
k.Lock()
defer k.Unlock()
if _, ok := k.addresses[rn.address.String()]; ok {
return
}
k.addresses[rn.address.String()] = rn
item := &rItem{
value: rn,
distance: k.id.Distance(rn.id),
}
heap.Push(&k.items, item)
if len(k.items) > k.max {
for i := k.max - 1; i < len(k.items); i++ {
old := k.items[i]
delete(k.addresses, old.value.address.String())
heap.Remove(&k.items, i)
}
}
}
func (k *routingTable) get(n int) (out []*remoteNode) {
if n == 0 {
n = len(k.items)
}
for i := 0; i < n && i < len(k.items); i++ {
out = append(out, k.items[i].value)
}
return out
}
func (k *routingTable) flush() {
k.Lock()
defer k.Unlock()
k.items = make(priorityQueue, 0)
k.addresses = make(map[string]*remoteNode, k.max)
}
func (k *routingTable) isEmpty() bool {
k.Lock()
defer k.Unlock()
return len(k.items) == 0
}
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