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fix race condition in driver closure #7

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fix race condition in driver closure #7

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48 changes: 27 additions & 21 deletions rpc/driver.go
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Original file line number Diff line number Diff line change
Expand Up @@ -121,21 +121,27 @@ func ReceiveChan(ctx context.Context, t Transport) <-chan *Message {
// Create a channel for sending messages through a Transport. Creates
// a thread that won't exit until the returned channel is closed.
// Does not close the underlying Transport.
func SendChan(t Transport, onErr func(uint32, error)) chan<- *Message {
ret := make(chan *Message, 1)
go func(c <-chan *Message) {
func SendChan(t Transport, onErr func(uint32, error)) (chan<- *Message, chan<- struct{}) {
ch := make(chan *Message, 1)
chClose := make(chan struct{})
go func(ch <-chan *Message, cancel <-chan struct{}) {
for {
if m, ok := <-c; !ok {
select {
case <-cancel:
return
} else {
xid := m.Xid()
if err := t.Send(m); err != nil && onErr != nil {
onErr(xid, err)
case m, ok := <-ch:
if !ok {
return
} else {
xid := m.Xid()
if err := t.Send(m); err != nil && onErr != nil {
onErr(xid, err)
}
}
}
}
}(ret)
return ret
}(ch, chClose)
return ch, chClose
}

// RPC driver implements all Transport-agnostic logic for handling
Expand Down Expand Up @@ -184,13 +190,14 @@ type Driver struct {
// If non-nil, all panics arising from service method implementations are passed to PanicHandle.
PanicHandler PanicHandler

srv RpcSrv
ctx context.Context
cancel context.CancelFunc
out chan<- *Message
in <-chan *Message
cs CallSet
started int32
srv RpcSrv
ctx context.Context
cancel context.CancelFunc
out chan<- *Message
outClose chan<- struct{}
in <-chan *Message
cs CallSet
started int32
}

// PanicHandler defines a handler for panics arising from service method implementations.
Expand All @@ -213,7 +220,7 @@ func (r *Driver) logXdr(t xdr.XdrType, f string, args ...interface{}) {
var out bytes.Buffer
fmt.Fprintf(&out, f, args...)
out.WriteByte('\n')
t.XdrMarshal(xdr.XdrPrint{&out}, "")
t.XdrMarshal(xdr.XdrPrint{Out: &out}, "")
r.Log.Write(out.Bytes())
}

Expand All @@ -235,13 +242,13 @@ func NewDriver(ctx context.Context, t Transport) *Driver {
cancel: cancel,
in: ReceiveChan(ctx, t),
}
ret.out = SendChan(t, func(xid uint32, _ error) {
ret.out, ret.outClose = SendChan(t, func(xid uint32, _ error) {
ret.cs.Cancel(xid, SEND_ERR)
})
go func() {
<-ctx.Done()
t.Close()
close(ret.out)
close(ret.outClose)
}()

return &ret
Expand All @@ -260,7 +267,6 @@ func (r *Driver) Close() {
}

func (r *Driver) safeSend(ctx context.Context, m *Message) (ok bool) {
defer func() { recover() }()
select {
case r.out <- m:
return true
Expand Down
2 changes: 1 addition & 1 deletion rpc/rpc_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -69,7 +69,7 @@ func TestChannels(t *testing.T) {
tx1, tx2 := rpc.NewStreamTransport(cs[0]), rpc.NewStreamTransport(cs[1])
r := rpc.ReceiveChan(ctx, tx1)
defer tx1.Close()
s := rpc.SendChan(tx2, nil)
s, _ := rpc.SendChan(tx2, nil)
go func() {
defer close(s)
defer tx2.Close()
Expand Down