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limiter.go
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limiter.go
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package swarm
import (
"context"
"sync"
"time"
addrutil "github.com/libp2p/go-addr-util"
peer "github.com/libp2p/go-libp2p-peer"
transport "github.com/libp2p/go-libp2p-transport"
ma "github.com/multiformats/go-multiaddr"
)
type dialResult struct {
Conn transport.Conn
Addr ma.Multiaddr
Err error
}
type dialJob struct {
addr ma.Multiaddr
peer peer.ID
ctx context.Context
resp chan dialResult
}
func (dj *dialJob) cancelled() bool {
select {
case <-dj.ctx.Done():
return true
default:
return false
}
}
func (dj *dialJob) dialTimeout() time.Duration {
timeout := transport.DialTimeout
if lowTimeoutFilters.AddrBlocked(dj.addr) {
timeout = DialTimeoutLocal
}
return timeout
}
type dialLimiter struct {
lk sync.Mutex
fdConsuming int
fdLimit int
waitingOnFd []*dialJob
dialFunc dialfunc
activePerPeer map[peer.ID]int
perPeerLimit int
waitingOnPeerLimit map[peer.ID][]*dialJob
}
type dialfunc func(context.Context, peer.ID, ma.Multiaddr) (transport.Conn, error)
func newDialLimiter(df dialfunc) *dialLimiter {
return newDialLimiterWithParams(df, ConcurrentFdDials, DefaultPerPeerRateLimit)
}
func newDialLimiterWithParams(df dialfunc, fdLimit, perPeerLimit int) *dialLimiter {
return &dialLimiter{
fdLimit: fdLimit,
perPeerLimit: perPeerLimit,
waitingOnPeerLimit: make(map[peer.ID][]*dialJob),
activePerPeer: make(map[peer.ID]int),
dialFunc: df,
}
}
// freeFDToken frees FD token and if there are any schedules another waiting dialJob
// in it's place
func (dl *dialLimiter) freeFDToken() {
dl.fdConsuming--
if len(dl.waitingOnFd) > 0 {
next := dl.waitingOnFd[0]
dl.waitingOnFd[0] = nil // clear out memory
dl.waitingOnFd = dl.waitingOnFd[1:]
if len(dl.waitingOnFd) == 0 {
dl.waitingOnFd = nil // clear out memory
}
dl.fdConsuming++
// we already have activePerPeer token at this point so we can just dial
go dl.executeDial(next)
}
}
func (dl *dialLimiter) freePeerToken(dj *dialJob) {
// release tokens in reverse order than we take them
dl.activePerPeer[dj.peer]--
if dl.activePerPeer[dj.peer] == 0 {
delete(dl.activePerPeer, dj.peer)
}
waitlist := dl.waitingOnPeerLimit[dj.peer]
if len(waitlist) > 0 {
next := waitlist[0]
if len(waitlist) == 1 {
delete(dl.waitingOnPeerLimit, next.peer)
} else {
waitlist[0] = nil // clear out memory
dl.waitingOnPeerLimit[next.peer] = waitlist[1:]
}
dl.activePerPeer[next.peer]++ // just kidding, we still want this token
dl.addCheckFdLimit(next)
}
}
func (dl *dialLimiter) finishedDial(dj *dialJob) {
dl.lk.Lock()
defer dl.lk.Unlock()
if addrutil.IsFDCostlyTransport(dj.addr) {
dl.freeFDToken()
}
dl.freePeerToken(dj)
}
func (dl *dialLimiter) addCheckFdLimit(dj *dialJob) {
if addrutil.IsFDCostlyTransport(dj.addr) {
if dl.fdConsuming >= dl.fdLimit {
dl.waitingOnFd = append(dl.waitingOnFd, dj)
return
}
// take token
dl.fdConsuming++
}
go dl.executeDial(dj)
}
func (dl *dialLimiter) addCheckPeerLimit(dj *dialJob) {
if dl.activePerPeer[dj.peer] >= dl.perPeerLimit {
wlist := dl.waitingOnPeerLimit[dj.peer]
dl.waitingOnPeerLimit[dj.peer] = append(wlist, dj)
return
}
dl.activePerPeer[dj.peer]++
dl.addCheckFdLimit(dj)
}
// AddDialJob tries to take the needed tokens for starting the given dial job.
// If it acquires all needed tokens, it immediately starts the dial, otherwise
// it will put it on the waitlist for the requested token.
func (dl *dialLimiter) AddDialJob(dj *dialJob) {
dl.lk.Lock()
defer dl.lk.Unlock()
dl.addCheckPeerLimit(dj)
}
func (dl *dialLimiter) clearAllPeerDials(p peer.ID) {
dl.lk.Lock()
defer dl.lk.Unlock()
delete(dl.waitingOnPeerLimit, p)
// NB: the waitingOnFd list doesn't need to be cleaned out here, we will
// remove them as we encounter them because they are 'cancelled' at this
// point
}
// executeDial calls the dialFunc, and reports the result through the response
// channel when finished. Once the response is sent it also releases all tokens
// it held during the dial.
func (dl *dialLimiter) executeDial(j *dialJob) {
defer dl.finishedDial(j)
if j.cancelled() {
return
}
dctx, cancel := context.WithTimeout(j.ctx, j.dialTimeout())
defer cancel()
con, err := dl.dialFunc(dctx, j.peer, j.addr)
select {
case j.resp <- dialResult{Conn: con, Addr: j.addr, Err: err}:
case <-j.ctx.Done():
if err == nil {
con.Close()
}
}
}