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client: handle empty address lists correctly in addrConn.updateAddrs (#…
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…6354) (#6385)

Co-authored-by: Doug Fawley <dfawley@google.com>
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zasweq and dfawley authored Jun 21, 2023
1 parent 997c1ea commit d0f5150
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Showing 2 changed files with 129 additions and 2 deletions.
6 changes: 4 additions & 2 deletions clientconn.go
Original file line number Diff line number Diff line change
Expand Up @@ -1033,8 +1033,10 @@ func (ac *addrConn) updateAddrs(addrs []resolver.Address) {

// We have to defer here because GracefulClose => Close => onClose, which
// requires locking ac.mu.
defer ac.transport.GracefulClose()
ac.transport = nil
if ac.transport != nil {
defer ac.transport.GracefulClose()
ac.transport = nil
}

if len(addrs) == 0 {
ac.updateConnectivityState(connectivity.Idle, nil)
Expand Down
125 changes: 125 additions & 0 deletions test/subconn_test.go
Original file line number Diff line number Diff line change
@@ -0,0 +1,125 @@
/*
*
* Copyright 2023 gRPC authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
*/

package test

import (
"context"
"errors"
"fmt"
"testing"
"time"

"google.golang.org/grpc"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/balancer/base"
"google.golang.org/grpc/connectivity"
"google.golang.org/grpc/internal/balancer/stub"
"google.golang.org/grpc/internal/stubserver"
testpb "google.golang.org/grpc/interop/grpc_testing"
"google.golang.org/grpc/resolver"
)

type tsccPicker struct {
sc balancer.SubConn
}

func (p *tsccPicker) Pick(info balancer.PickInfo) (balancer.PickResult, error) {
return balancer.PickResult{SubConn: p.sc}, nil
}

// TestSubConnEmpty tests that removing all addresses from a SubConn and then
// re-adding them does not cause a panic and properly reconnects.
func (s) TestSubConnEmpty(t *testing.T) {
ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
defer cancel()

// sc is the one SubConn used throughout the test. Created on demand and
// re-used on every update.
var sc balancer.SubConn

// Simple custom balancer that sets the address list to empty if the
// resolver produces no addresses. Pickfirst, by default, will remove the
// SubConn in this case instead.
bal := stub.BalancerFuncs{
UpdateClientConnState: func(d *stub.BalancerData, ccs balancer.ClientConnState) error {
if sc == nil {
var err error
sc, err = d.ClientConn.NewSubConn(ccs.ResolverState.Addresses, balancer.NewSubConnOptions{})
if err != nil {
t.Errorf("error creating initial subconn: %v", err)
}
} else {
d.ClientConn.UpdateAddresses(sc, ccs.ResolverState.Addresses)
}
sc.Connect()

if len(ccs.ResolverState.Addresses) == 0 {
d.ClientConn.UpdateState(balancer.State{
ConnectivityState: connectivity.TransientFailure,
Picker: base.NewErrPicker(errors.New("no addresses")),
})
} else {
d.ClientConn.UpdateState(balancer.State{
ConnectivityState: connectivity.Connecting,
Picker: &tsccPicker{sc: sc},
})
}
return nil
},
UpdateSubConnState: func(d *stub.BalancerData, sc balancer.SubConn, scs balancer.SubConnState) {
switch scs.ConnectivityState {
case connectivity.Ready:
d.ClientConn.UpdateState(balancer.State{
ConnectivityState: connectivity.Ready,
Picker: &tsccPicker{sc: sc},
})
case connectivity.TransientFailure:
d.ClientConn.UpdateState(balancer.State{
ConnectivityState: connectivity.TransientFailure,
Picker: base.NewErrPicker(fmt.Errorf("error connecting: %v", scs.ConnectionError)),
})
}
},
}
stub.Register("tscc", bal)

// Start the stub server with our stub balancer.
ss := &stubserver.StubServer{
EmptyCallF: func(ctx context.Context, in *testpb.Empty) (*testpb.Empty, error) {
return &testpb.Empty{}, nil
},
}
if err := ss.Start(nil, grpc.WithDefaultServiceConfig(`{"loadBalancingConfig": [{"tscc":{}}]}`)); err != nil {
t.Fatalf("Error starting server: %v", err)
}
defer ss.Stop()
if _, err := ss.Client.EmptyCall(ctx, &testpb.Empty{}); err != nil {
t.Fatalf("EmptyCall failed: %v", err)
}

t.Log("Removing addresses from resolver and SubConn")
ss.R.UpdateState(resolver.State{Addresses: []resolver.Address{}})
awaitState(ctx, t, ss.CC, connectivity.TransientFailure)

t.Log("Re-adding addresses to resolver and SubConn")
ss.R.UpdateState(resolver.State{Addresses: []resolver.Address{{Addr: ss.Address}}})
if _, err := ss.Client.EmptyCall(ctx, &testpb.Empty{}); err != nil {
t.Fatalf("EmptyCall failed: %v", err)
}
}

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