worst_conns.go

   1 package torrent
   2
   3 import (
   4         "time"
   5 )
   6
   7 // Implements heap functions such that [0] is the worst connection.
   8 type worstConns struct {
   9         c  []*connection
  10         t  *Torrent
  11         cl *Client
  12 }
  13
  14 func (wc *worstConns) Len() int      { return len(wc.c) }
  15 func (wc *worstConns) Swap(i, j int) { wc.c[i], wc.c[j] = wc.c[j], wc.c[i] }
  16
  17 func (wc *worstConns) Pop() (ret interface{}) {
  18         old := wc.c
  19         n := len(old)
  20         ret = old[n-1]
  21         wc.c = old[:n-1]
  22         return
  23 }
  24
  25 func (wc *worstConns) Push(x interface{}) {
  26         wc.c = append(wc.c, x.(*connection))
  27 }
  28
  29 type worstConnsSortKey struct {
  30         useful      bool
  31         lastHelpful time.Time
  32         connected   time.Time
  33 }
  34
  35 func (wc worstConnsSortKey) Less(other worstConnsSortKey) bool {
  36         if wc.useful != other.useful {
  37                 return !wc.useful
  38         }
  39         if !wc.lastHelpful.Equal(other.lastHelpful) {
  40                 return wc.lastHelpful.Before(other.lastHelpful)
  41         }
  42         return wc.connected.Before(other.connected)
  43 }
  44
  45 func (wc *worstConns) key(i int) (key worstConnsSortKey) {
  46         c := wc.c[i]
  47         key.useful = wc.cl.usefulConn(wc.t, c)
  48         if wc.cl.seeding(wc.t) {
  49                 key.lastHelpful = c.lastChunkSent
  50         }
  51         // Intentionally consider the last time a chunk was received when seeding,
  52         // because we might go from seeding back to leeching.
  53         if c.lastUsefulChunkReceived.After(key.lastHelpful) {
  54                 key.lastHelpful = c.lastUsefulChunkReceived
  55         }
  56         key.connected = c.completedHandshake
  57         return
  58 }
  59
  60 func (wc worstConns) Less(i, j int) bool {
  61         return wc.key(i).Less(wc.key(j))
  62 }