func (cq *ChanQueue) process(ctx context.Context) {
// construct the channels here to be able to use them bidirectionally
enqChan := make(chan peer.ID)
deqChan := make(chan peer.ID)
cq.EnqChan = enqChan
cq.DeqChan = deqChan
go func() {
log.Debug("processing")
defer log.Debug("closed")
defer close(deqChan)
var next peer.ID
var item peer.ID
var more bool
for {
if cq.Queue.Len() == 0 {
// log.Debug("wait for enqueue")
select {
case next, more = <-enqChan:
if !more {
return
}
// log.Debug("got", next)
case <-ctx.Done():
return
}
} else {
next = cq.Queue.Dequeue()
// log.Debug("peek", next)
}
select {
case item, more = <-enqChan:
if !more {
if cq.Queue.Len() > 0 {
return // we're done done.
}
enqChan = nil // closed, so no use.
}
// log.Debug("got", item)
cq.Queue.Enqueue(item)
cq.Queue.Enqueue(next) // order may have changed.
next = ""
case deqChan <- next:
// log.Debug("dequeued", next)
next = ""
case <-ctx.Done():
return
}
}
}()
}
// Do sends an HTTP request with the provided http.Client and returns an HTTP response.
// If the client is nil, http.DefaultClient is used.
// If the context is canceled or times out, ctx.Err() will be returned.
func Do(ctx context.Context, client *http.Client, req *http.Request) (*http.Response, error) {
if client == nil {
client = http.DefaultClient
}
// Request cancelation changed in Go 1.5, see cancelreq.go and cancelreq_go14.go.
cancel := canceler(client, req)
type responseAndError struct {
resp *http.Response
err error
}
result := make(chan responseAndError, 1)
go func() {
resp, err := client.Do(req)
result <- responseAndError{resp, err}
}()
select {
case <-ctx.Done():
cancel()
return nil, ctx.Err()
case r := <-result:
return r.resp, r.err
}
}
func (ps *PingService) Ping(ctx context.Context, p peer.ID) (<-chan time.Duration, error) {
s, err := ps.Host.NewStream(ID, p)
if err != nil {
return nil, err
}
out := make(chan time.Duration)
go func() {
defer close(out)
for {
select {
case <-ctx.Done():
return
default:
t, err := ping(s)
if err != nil {
log.Debugf("ping error: %s", err)
return
}
select {
case out <- t:
case <-ctx.Done():
return
}
}
}
}()
return out, nil
}
func MetadataFromContext(ctx context.Context) (Metadata, error) {
value := ctx.Value(metadataKey)
if value != nil {
metadata, ok := value.(Metadata)
if ok {
return metadata, nil
}
}
return nil, errors.New("context contains no metadata")
}
// CloseAfterContext schedules the process to close after the given
// context is done. It is the equivalent of:
//
// func CloseAfterContext(p goprocess.Process, ctx context.Context) {
// go func() {
// <-ctx.Done()
// p.Close()
// }()
// }
//
func CloseAfterContext(p goprocess.Process, ctx context.Context) {
if p == nil {
panic("nil Process")
}
if ctx == nil {
panic("nil Context")
}
// context.Background(). if ctx.Done() is nil, it will never be done.
// we check for this to avoid wasting a goroutine forever.
if ctx.Done() == nil {
return
}
go func() {
<-ctx.Done()
p.Close()
}()
}
func readMsgCtx(ctx context.Context, r msgio.Reader, p proto.Message) ([]byte, error) {
var msg []byte
// read in a goroutine so we can exit when our context is cancelled.
done := make(chan error)
go func() {
var err error
msg, err = r.ReadMsg()
select {
case done <- err:
case <-ctx.Done():
}
}()
select {
case <-ctx.Done():
return nil, ctx.Err()
case e := <-done:
if e != nil {
return nil, e
}
}
return msg, proto.Unmarshal(msg, p)
}
func echoListen(ctx context.Context, listener Listener) {
for {
c, err := listener.Accept()
if err != nil {
select {
case <-ctx.Done():
return
default:
}
if ne, ok := err.(net.Error); ok && ne.Temporary() {
<-time.After(time.Microsecond * 10)
continue
}
log.Debugf("echoListen: listener appears to be closing")
return
}
go echo(c.(Conn))
}
}
// dialPeer opens a connection to peer, and makes sure to identify
// the connection once it has been opened.
func (h *BasicHost) dialPeer(ctx context.Context, p peer.ID) error {
log.Debugf("host %s dialing %s", h.ID, p)
c, err := h.Network().DialPeer(ctx, p)
if err != nil {
return err
}
// identify the connection before returning.
done := make(chan struct{})
go func() {
h.ids.IdentifyConn(c)
close(done)
}()
// respect don contexteone
select {
case <-done:
case <-ctx.Done():
return ctx.Err()
}
log.Debugf("host %s finished dialing %s", h.ID, p)
return nil
}
// writeMsgCtx is used by the
func writeMsgCtx(ctx context.Context, w msgio.Writer, msg proto.Message) ([]byte, error) {
enc, err := proto.Marshal(msg)
if err != nil {
return nil, err
}
// write in a goroutine so we can exit when our context is cancelled.
done := make(chan error)
go func(m []byte) {
err := w.WriteMsg(m)
select {
case done <- err:
case <-ctx.Done():
}
}(enc)
select {
case <-ctx.Done():
return nil, ctx.Err()
case e := <-done:
return enc, e
}
}
func (s *Swarm) dialAddrs(ctx context.Context, p peer.ID, remoteAddrs []ma.Multiaddr) (conn.Conn, error) {
// sort addresses so preferred addresses are dialed sooner
sort.Sort(AddrList(remoteAddrs))
// try to connect to one of the peer's known addresses.
// we dial concurrently to each of the addresses, which:
// * makes the process faster overall
// * attempts to get the fastest connection available.
// * mitigates the waste of trying bad addresses
log.Debugf("%s swarm dialing %s %s", s.local, p, remoteAddrs)
ctx, cancel := context.WithCancel(ctx)
defer cancel() // cancel work when we exit func
conns := make(chan conn.Conn)
errs := make(chan error, len(remoteAddrs))
// dialSingleAddr is used in the rate-limited async thing below.
dialSingleAddr := func(addr ma.Multiaddr) {
// rebind chans in scope so we can nil them out easily
connsout := conns
errsout := errs
connC, err := s.dialAddr(ctx, p, addr)
if err != nil {
connsout = nil
} else if connC == nil {
// NOTE: this really should never happen
log.Errorf("failed to dial %s %s and got no error!", p, addr)
err = fmt.Errorf("failed to dial %s %s", p, addr)
connsout = nil
} else {
errsout = nil
}
// check parent still wants our results
select {
case <-ctx.Done():
if connC != nil {
connC.Close()
}
case errsout <- err:
case connsout <- connC:
}
}
// this whole thing is in a goroutine so we can use foundConn
// to end early.
go func() {
limiter := make(chan struct{}, 8)
for _, addr := range remoteAddrs {
// returns whatever ratelimiting is acceptable for workerAddr.
// may not rate limit at all.
rl := s.addrDialRateLimit(addr)
select {
case <-ctx.Done(): // our context was cancelled
return
case rl <- struct{}{}:
// take the token, move on
}
select {
case <-ctx.Done(): // our context was cancelled
return
case limiter <- struct{}{}:
// take the token, move on
}
go func(rlc <-chan struct{}, a ma.Multiaddr) {
dialSingleAddr(a)
<-limiter
<-rlc
}(rl, addr)
}
}()
// wair for the results.
exitErr := fmt.Errorf("failed to dial %s", p)
for range remoteAddrs {
select {
case exitErr = <-errs: //
log.Debug("dial error: ", exitErr)
case connC := <-conns:
// take the first + return asap
return connC, nil
case <-ctx.Done():
// break out and return error
break
}
}
return nil, exitErr
}
// gatedDialAttempt is an attempt to dial a node. It is gated by the swarm's
// dial synchronization systems: dialsync and dialbackoff.
func (s *Swarm) gatedDialAttempt(ctx context.Context, p peer.ID) (*Conn, error) {
var logdial = lgbl.Dial("swarm", s.LocalPeer(), p, nil, nil)
defer log.EventBegin(ctx, "swarmDialAttemptSync", logdial).Done()
// check if we already have an open connection first
conn := s.bestConnectionToPeer(p)
if conn != nil {
return conn, nil
}
// check if there's an ongoing dial to this peer
if ok, wait := s.dsync.Lock(p); ok {
defer s.dsync.Unlock(p)
// if this peer has been backed off, lets get out of here
if s.backf.Backoff(p) {
log.Event(ctx, "swarmDialBackoff", logdial)
return nil, ErrDialBackoff
}
// ok, we have been charged to dial! let's do it.
// if it succeeds, dial will add the conn to the swarm itself.
defer log.EventBegin(ctx, "swarmDialAttemptStart", logdial).Done()
ctxT, cancel := context.WithTimeout(ctx, s.dialT)
conn, err := s.dial(ctxT, p)
cancel()
log.Debugf("dial end %s", conn)
if err != nil {
log.Event(ctx, "swarmDialBackoffAdd", logdial)
s.backf.AddBackoff(p) // let others know to backoff
// ok, we failed. try again. (if loop is done, our error is output)
return nil, fmt.Errorf("dial attempt failed: %s", err)
}
log.Event(ctx, "swarmDialBackoffClear", logdial)
s.backf.Clear(p) // okay, no longer need to backoff
return conn, nil
} else {
// we did not dial. we must wait for someone else to dial.
// check whether we should backoff first...
if s.backf.Backoff(p) {
log.Event(ctx, "swarmDialBackoff", logdial)
return nil, ErrDialBackoff
}
defer log.EventBegin(ctx, "swarmDialWait", logdial).Done()
select {
case <-wait: // wait for that other dial to finish.
// see if it worked, OR we got an incoming dial in the meantime...
conn := s.bestConnectionToPeer(p)
if conn != nil {
return conn, nil
}
return nil, ErrDialFailed
case <-ctx.Done(): // or we may have to bail...
return nil, ctx.Err()
}
}
}
// Dial connects to a peer over a particular address
// Ensures raddr is part of peer.Addresses()
// Example: d.DialAddr(ctx, peer.Addresses()[0], peer)
func (d *Dialer) Dial(ctx context.Context, raddr ma.Multiaddr, remote peer.ID) (Conn, error) {
logdial := lgbl.Dial("conn", d.LocalPeer, remote, nil, raddr)
logdial["encrypted"] = (d.PrivateKey != nil) // log wether this will be an encrypted dial or not.
defer log.EventBegin(ctx, "connDial", logdial).Done()
var connOut Conn
var errOut error
done := make(chan struct{})
// do it async to ensure we respect don contexteone
go func() {
defer func() {
select {
case done <- struct{}{}:
case <-ctx.Done():
}
}()
maconn, err := d.rawConnDial(ctx, raddr, remote)
if err != nil {
errOut = err
return
}
if d.Wrapper != nil {
maconn = d.Wrapper(maconn)
}
c, err := newSingleConn(ctx, d.LocalPeer, remote, maconn)
if err != nil {
maconn.Close()
errOut = err
return
}
if d.PrivateKey == nil || EncryptConnections == false {
log.Warning("dialer %s dialing INSECURELY %s at %s!", d, remote, raddr)
connOut = c
return
}
c2, err := newSecureConn(ctx, d.PrivateKey, c)
if err != nil {
errOut = err
c.Close()
return
}
connOut = c2
}()
select {
case <-ctx.Done():
logdial["error"] = ctx.Err()
logdial["dial"] = "failure"
return nil, ctx.Err()
case <-done:
// whew, finished.
}
if errOut != nil {
logdial["error"] = errOut
logdial["dial"] = "failure"
return nil, errOut
}
logdial["dial"] = "success"
return connOut, nil
}