query: fix race condition: redux

this time just move to goprocess

Author: jbenet

routing/dht/ext_test.go

@@ -52,7 +52,7 @@ func TestGetFailures(t *testing.T) {
 			err = merr[0]
 		}
 
-		if err != context.DeadlineExceeded {
+		if err != context.DeadlineExceeded && err != context.Canceled {
 			t.Fatal("Got different error than we expected", err)
 		}
 	} else {

routing/dht/query.go

@@ -12,7 +12,8 @@ import (
 	pset "github.com/jbenet/go-ipfs/util/peerset"
 	todoctr "github.com/jbenet/go-ipfs/util/todocounter"
 
-	ctxgroup "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/go-ctxgroup"
+	process "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/goprocess"
+	ctxproc "github.com/jbenet/go-ipfs/Godeps/_workspace/src/github.com/jbenet/goprocess/context"
 	context "github.com/jbenet/go-ipfs/Godeps/_workspace/src/golang.org/x/net/context"
 )
 
@@ -61,8 +62,8 @@ func (q *dhtQuery) Run(ctx context.Context, peers []peer.ID) (*dhtQueryResult, e
 	ctx, cancel := context.WithCancel(ctx)
 	defer cancel()
 
-	runner := newQueryRunner(ctx, q)
-	return runner.Run(peers)
+	runner := newQueryRunner(q)
+	return runner.Run(ctx, peers)
 }
 
 type dhtQueryRunner struct {
@@ -77,22 +78,24 @@ type dhtQueryRunner struct {
 	rateLimit chan struct{} // processing semaphore
 	log       eventlog.EventLogger
 
-	cg ctxgroup.ContextGroup
+	proc process.Process
 	sync.RWMutex
 }
 
-func newQueryRunner(ctx context.Context, q *dhtQuery) *dhtQueryRunner {
+func newQueryRunner(q *dhtQuery) *dhtQueryRunner {
+	proc := process.WithParent(process.Background())
+	ctx := ctxproc.WithProcessClosing(context.Background(), proc)
 	return &dhtQueryRunner{
 		query:          q,
 		peersToQuery:   queue.NewChanQueue(ctx, queue.NewXORDistancePQ(q.key)),
 		peersRemaining: todoctr.NewSyncCounter(),
 		peersSeen:      pset.New(),
 		rateLimit:      make(chan struct{}, q.concurrency),
-		cg:             ctxgroup.WithContext(ctx),
+		proc:           proc,
 	}
 }
 
-func (r *dhtQueryRunner) Run(peers []peer.ID) (*dhtQueryResult, error) {
+func (r *dhtQueryRunner) Run(ctx context.Context, peers []peer.ID) (*dhtQueryResult, error) {
 	r.log = log
 
 	if len(peers) == 0 {
@@ -107,31 +110,30 @@ func (r *dhtQueryRunner) Run(peers []peer.ID) (*dhtQueryResult, error) {
 
 	// add all the peers we got first.
 	for _, p := range peers {
-		r.addPeerToQuery(r.cg.Context(), p)
-	}
-
-	// may be closed already. this caused an odd race (where we attempt to
-	// add a child to an already closed ctxgroup). this is a temp workaround
-	// as we'll switch to using a proc here soon.
-	select {
-	case <-r.cg.Closed():
-		return nil, r.cg.Context().Err()
-	default:
+		r.addPeerToQuery(p)
 	}
 
 	// go do this thing.
-	// do it as a child func to make sure Run exits
+	// do it as a child proc to make sure Run exits
 	// ONLY AFTER spawn workers has exited.
-	r.cg.AddChildFunc(r.spawnWorkers)
+	r.proc.Go(r.spawnWorkers)
 
 	// so workers are working.
 
 	// wait until they're done.
 	err := routing.ErrNotFound
 
+	// now, if the context finishes, close the proc.
+	// we have to do it here because the logic before is setup, which
+	// should run without closing the proc.
+	go func() {
+		<-ctx.Done()
+		r.proc.Close()
+	}()
+
 	select {
 	case <-r.peersRemaining.Done():
-		r.cg.Close()
+		r.proc.Close()
 		r.RLock()
 		defer r.RUnlock()
 
@@ -143,12 +145,10 @@ func (r *dhtQueryRunner) Run(peers []peer.ID) (*dhtQueryResult, error) {
 			err = r.errs[0]
 		}
 
-	case <-r.cg.Closed():
-		log.Debug("r.cg.Closed()")
-
+	case <-r.proc.Closed():
 		r.RLock()
 		defer r.RUnlock()
-		err = r.cg.Context().Err() // collect the error.
+		err = context.DeadlineExceeded
 	}
 
 	if r.result != nil && r.result.success {
@@ -158,7 +158,7 @@ func (r *dhtQueryRunner) Run(peers []peer.ID) (*dhtQueryResult, error) {
 	return nil, err
 }
 
-func (r *dhtQueryRunner) addPeerToQuery(ctx context.Context, next peer.ID) {
+func (r *dhtQueryRunner) addPeerToQuery(next peer.ID) {
 	// if new peer is ourselves...
 	if next == r.query.dht.self {
 		r.log.Debug("addPeerToQuery skip self")
@@ -172,18 +172,18 @@ func (r *dhtQueryRunner) addPeerToQuery(ctx context.Context, next peer.ID) {
 	r.peersRemaining.Increment(1)
 	select {
 	case r.peersToQuery.EnqChan <- next:
-	case <-ctx.Done():
+	case <-r.proc.Closing():
 	}
 }
 
-func (r *dhtQueryRunner) spawnWorkers(parent ctxgroup.ContextGroup) {
+func (r *dhtQueryRunner) spawnWorkers(proc process.Process) {
 	for {
 
 		select {
 		case <-r.peersRemaining.Done():
 			return
 
-		case <-r.cg.Closing():
+		case <-r.proc.Closing():
 			return
 
 		case p, more := <-r.peersToQuery.DeqChan:
@@ -193,24 +193,27 @@ func (r *dhtQueryRunner) spawnWorkers(parent ctxgroup.ContextGroup) {
 
 			// do it as a child func to make sure Run exits
 			// ONLY AFTER spawn workers has exited.
-			parent.AddChildFunc(func(cg ctxgroup.ContextGroup) {
-				r.queryPeer(cg, p)
+			proc.Go(func(proc process.Process) {
+				r.queryPeer(proc, p)
 			})
 		}
 	}
 }
 
-func (r *dhtQueryRunner) queryPeer(cg ctxgroup.ContextGroup, p peer.ID) {
+func (r *dhtQueryRunner) queryPeer(proc process.Process, p peer.ID) {
 	// make sure we rate limit concurrency.
 	select {
 	case <-r.rateLimit:
-	case <-cg.Closing():
+	case <-proc.Closing():
 		r.peersRemaining.Decrement(1)
 		return
 	}
 
 	// ok let's do this!
 
+	// create a context from our proc.
+	ctx := ctxproc.WithProcessClosing(context.Background(), proc)
+
 	// make sure we do this when we exit
 	defer func() {
 		// signal we're done proccessing peer p
@@ -227,10 +230,11 @@ func (r *dhtQueryRunner) queryPeer(cg ctxgroup.ContextGroup, p peer.ID) {
 		r.rateLimit <- struct{}{}
 
 		pi := peer.PeerInfo{ID: p}
-		if err := r.query.dht.host.Connect(cg.Context(), pi); err != nil {
+
+		if err := r.query.dht.host.Connect(ctx, pi); err != nil {
 			log.Debugf("Error connecting: %s", err)
 
-			notif.PublishQueryEvent(cg.Context(), &notif.QueryEvent{
+			notif.PublishQueryEvent(ctx, &notif.QueryEvent{
 				Type:  notif.QueryError,
 				Extra: err.Error(),
 			})
@@ -246,7 +250,7 @@ func (r *dhtQueryRunner) queryPeer(cg ctxgroup.ContextGroup, p peer.ID) {
 	}
 
 	// finally, run the query against this peer
-	res, err := r.query.qfunc(cg.Context(), p)
+	res, err := r.query.qfunc(ctx, p)
 
 	if err != nil {
 		log.Debugf("ERROR worker for: %v %v", p, err)
@@ -259,7 +263,7 @@ func (r *dhtQueryRunner) queryPeer(cg ctxgroup.ContextGroup, p peer.ID) {
 		r.Lock()
 		r.result = res
 		r.Unlock()
-		go r.cg.Close() // signal to everyone that we're done.
+		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 {
@@ -272,7 +276,7 @@ func (r *dhtQueryRunner) queryPeer(cg ctxgroup.ContextGroup, p peer.ID) {
 
 			// add their addresses to the dialer's peerstore
 			r.query.dht.peerstore.AddAddrs(next.ID, next.Addrs, peer.TempAddrTTL)
-			r.addPeerToQuery(cg.Context(), next.ID)
+			r.addPeerToQuery(next.ID)
 			log.Debugf("PEERS CLOSER -- worker for: %v added %v (%v)", p, next.ID, next.Addrs)
 		}
 	} else {