// WithProcessClosing returns a context.Context derived from ctx that
// is cancelled as p is Closing (after: <-p.Closing()). It is simply:
//
// func WithProcessClosing(ctx context.Context, p goprocess.Process) context.Context {
// ctx, cancel := context.WithCancel(ctx)
// go func() {
// <-p.Closing()
// cancel()
// }()
// return ctx
// }
//
func WithProcessClosing(ctx context.Context, p goprocess.Process) context.Context {
ctx, cancel := context.WithCancel(ctx)
go func() {
<-p.Closing()
cancel()
}()
return ctx
}
func (d *datastore) runQuery(worker goprocess.Process, qrb *dsq.ResultBuilder) {
var rnge *util.Range
if qrb.Query.Prefix != "" {
rnge = util.BytesPrefix([]byte(qrb.Query.Prefix))
}
i := d.DB.NewIterator(rnge, nil)
defer i.Release()
// advance iterator for offset
if qrb.Query.Offset > 0 {
for j := 0; j < qrb.Query.Offset; j++ {
i.Next()
}
}
// iterate, and handle limit, too
for sent := 0; i.Next(); sent++ {
// end early if we hit the limit
if qrb.Query.Limit > 0 && sent >= qrb.Query.Limit {
break
}
k := ds.NewKey(string(i.Key())).String()
e := dsq.Entry{Key: k}
if !qrb.Query.KeysOnly {
buf := make([]byte, len(i.Value()))
copy(buf, i.Value())
e.Value = buf
}
select {
case qrb.Output <- dsq.Result{Entry: e}: // we sent it out
case <-worker.Closing(): // client told us to end early.
break
}
}
if err := i.Error(); err != nil {
select {
case qrb.Output <- dsq.Result{Error: err}: // client read our error
case <-worker.Closing(): // client told us to end.
return
}
}
}
func (bs *Bitswap) provideWorker(px process.Process) {
limiter := ratelimit.NewRateLimiter(px, provideWorkerMax)
limitedGoProvide := func(k key.Key, wid int) {
ev := logging.LoggableMap{"ID": wid}
limiter.LimitedGo(func(px process.Process) {
ctx := procctx.OnClosingContext(px) // derive ctx from px
defer log.EventBegin(ctx, "Bitswap.ProvideWorker.Work", ev, &k).Done()
ctx, cancel := context.WithTimeout(ctx, provideTimeout) // timeout ctx
defer cancel()
if err := bs.network.Provide(ctx, k); err != nil {
log.Error(err)
}
})
}
// worker spawner, reads from bs.provideKeys until it closes, spawning a
// _ratelimited_ number of workers to handle each key.
limiter.Go(func(px process.Process) {
for wid := 2; ; wid++ {
ev := logging.LoggableMap{"ID": 1}
log.Event(procctx.OnClosingContext(px), "Bitswap.ProvideWorker.Loop", ev)
select {
case <-px.Closing():
return
case k, ok := <-bs.provideKeys:
if !ok {
log.Debug("provideKeys channel closed")
return
}
limitedGoProvide(k, wid)
}
}
})
}
// transport will grab message arrival times, wait until that time, and
// then write the message out when it is scheduled to arrive
func (s *stream) transport(proc process.Process) {
bufsize := 256
buf := new(bytes.Buffer)
ticker := time.NewTicker(time.Millisecond * 4)
// writeBuf writes the contents of buf through to the s.Writer.
// done only when arrival time makes sense.
drainBuf := func() {
if buf.Len() > 0 {
_, err := s.Writer.Write(buf.Bytes())
if err != nil {
return
}
buf.Reset()
}
}
// deliverOrWait is a helper func that processes
// an incoming packet. it waits until the arrival time,
// and then writes things out.
deliverOrWait := func(o *transportObject) {
buffered := len(o.msg) + buf.Len()
now := time.Now()
if now.Before(o.arrivalTime) {
if buffered < bufsize {
buf.Write(o.msg)
return
}
// we do not buffer + return here, instead hanging the
// call (i.e. not accepting any more transportObjects)
// so that we apply back-pressure to the sender.
// this sleep should wake up same time as ticker.
time.Sleep(o.arrivalTime.Sub(now))
}
// ok, we waited our due time. now rite the buf + msg.
// drainBuf first, before we write this message.
drainBuf()
// write this message.
_, err := s.Writer.Write(o.msg)
if err != nil {
log.Error("mock_stream", err)
}
}
for {
select {
case <-proc.Closing():
return // bail out of here.
case o, ok := <-s.toDeliver:
if !ok {
return
}
deliverOrWait(o)
case <-ticker.C: // ok, due to write it out.
drainBuf()
}
}
}
// OnClosingContext derives a context from a given goprocess that will
// be 'Done' when the process is closing
func OnClosingContext(p goprocess.Process) context.Context {
return &procContext{
done: p.Closing(),
which: closing,
}
}
func (r *dhtQueryRunner) queryPeer(proc process.Process, p peer.ID) {
// make sure we rate limit concurrency.
select {
case <-r.rateLimit:
case <-proc.Closing():
r.peersRemaining.Decrement(1)
return
}
// ok let's do this!
// create a context from our proc.
ctx := ctxproc.OnClosingContext(proc)
// make sure we do this when we exit
defer func() {
// signal we're done proccessing peer p
r.peersRemaining.Decrement(1)
r.rateLimit <- struct{}{}
}()
// make sure we're connected to the peer.
// FIXME abstract away into the network layer
if conns := r.query.dht.host.Network().ConnsToPeer(p); len(conns) == 0 {
log.Infof("not connected. dialing.")
// while we dial, we do not take up a rate limit. this is to allow
// forward progress during potentially very high latency dials.
r.rateLimit <- struct{}{}
pi := peer.PeerInfo{ID: p}
if err := r.query.dht.host.Connect(ctx, pi); err != nil {
log.Debugf("Error connecting: %s", err)
notif.PublishQueryEvent(ctx, ¬if.QueryEvent{
Type: notif.QueryError,
Extra: err.Error(),
})
r.Lock()
r.errs = append(r.errs, err)
r.Unlock()
<-r.rateLimit // need to grab it again, as we deferred.
return
}
<-r.rateLimit // need to grab it again, as we deferred.
log.Debugf("connected. dial success.")
}
// finally, run the query against this peer
res, err := r.query.qfunc(ctx, p)
if err != nil {
log.Debugf("ERROR worker for: %v %v", p, err)
r.Lock()
r.errs = append(r.errs, err)
r.Unlock()
} else if res.success {
log.Debugf("SUCCESS worker for: %v %s", p, res)
r.Lock()
r.result = res
r.Unlock()
go r.proc.Close() // signal to everyone that we're done.
// must be async, as we're one of the children, and Close blocks.
} else if len(res.closerPeers) > 0 {
log.Debugf("PEERS CLOSER -- worker for: %v (%d closer peers)", p, len(res.closerPeers))
for _, next := range res.closerPeers {
if next.ID == r.query.dht.self { // dont add self.
log.Debugf("PEERS CLOSER -- worker for: %v found self", p)
continue
}
// add their addresses to the dialer's peerstore
r.query.dht.peerstore.AddAddrs(next.ID, next.Addrs, peer.TempAddrTTL)
r.addPeerToQuery(next.ID)
log.Debugf("PEERS CLOSER -- worker for: %v added %v (%v)", p, next.ID, next.Addrs)
}
} else {
log.Debugf("QUERY worker for: %v - not found, and no closer peers.", p)
}
}