293 lines
8.1 KiB
Go
293 lines
8.1 KiB
Go
/*
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*
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* Copyright 2017 gRPC authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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*/
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package grpc
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import (
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"fmt"
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"sync"
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"google.golang.org/grpc/balancer"
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"google.golang.org/grpc/connectivity"
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"google.golang.org/grpc/internal/buffer"
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"google.golang.org/grpc/internal/channelz"
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"google.golang.org/grpc/internal/grpcsync"
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"google.golang.org/grpc/resolver"
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)
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// scStateUpdate contains the subConn and the new state it changed to.
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type scStateUpdate struct {
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sc balancer.SubConn
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state connectivity.State
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err error
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}
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// exitIdle contains no data and is just a signal sent on the updateCh in
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// ccBalancerWrapper to instruct the balancer to exit idle.
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type exitIdle struct{}
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// ccBalancerWrapper is a wrapper on top of cc for balancers.
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// It implements balancer.ClientConn interface.
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type ccBalancerWrapper struct {
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cc *ClientConn
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balancerMu sync.Mutex // synchronizes calls to the balancer
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balancer balancer.Balancer
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hasExitIdle bool
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updateCh *buffer.Unbounded
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closed *grpcsync.Event
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done *grpcsync.Event
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mu sync.Mutex
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subConns map[*acBalancerWrapper]struct{}
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}
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func newCCBalancerWrapper(cc *ClientConn, b balancer.Builder, bopts balancer.BuildOptions) *ccBalancerWrapper {
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ccb := &ccBalancerWrapper{
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cc: cc,
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updateCh: buffer.NewUnbounded(),
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closed: grpcsync.NewEvent(),
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done: grpcsync.NewEvent(),
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subConns: make(map[*acBalancerWrapper]struct{}),
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}
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go ccb.watcher()
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ccb.balancer = b.Build(ccb, bopts)
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_, ccb.hasExitIdle = ccb.balancer.(balancer.ExitIdler)
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return ccb
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}
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// watcher balancer functions sequentially, so the balancer can be implemented
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// lock-free.
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func (ccb *ccBalancerWrapper) watcher() {
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for {
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select {
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case t := <-ccb.updateCh.Get():
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ccb.updateCh.Load()
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if ccb.closed.HasFired() {
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break
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}
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switch u := t.(type) {
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case *scStateUpdate:
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ccb.balancerMu.Lock()
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ccb.balancer.UpdateSubConnState(u.sc, balancer.SubConnState{ConnectivityState: u.state, ConnectionError: u.err})
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ccb.balancerMu.Unlock()
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case *acBalancerWrapper:
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ccb.mu.Lock()
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if ccb.subConns != nil {
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delete(ccb.subConns, u)
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ccb.cc.removeAddrConn(u.getAddrConn(), errConnDrain)
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}
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ccb.mu.Unlock()
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case exitIdle:
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if ccb.cc.GetState() == connectivity.Idle {
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if ei, ok := ccb.balancer.(balancer.ExitIdler); ok {
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// We already checked that the balancer implements
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// ExitIdle before pushing the event to updateCh, but
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// check conditionally again as defensive programming.
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ccb.balancerMu.Lock()
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ei.ExitIdle()
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ccb.balancerMu.Unlock()
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}
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}
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default:
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logger.Errorf("ccBalancerWrapper.watcher: unknown update %+v, type %T", t, t)
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}
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case <-ccb.closed.Done():
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}
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if ccb.closed.HasFired() {
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ccb.balancerMu.Lock()
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ccb.balancer.Close()
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ccb.balancerMu.Unlock()
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ccb.mu.Lock()
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scs := ccb.subConns
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ccb.subConns = nil
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ccb.mu.Unlock()
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ccb.UpdateState(balancer.State{ConnectivityState: connectivity.Connecting, Picker: nil})
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ccb.done.Fire()
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// Fire done before removing the addr conns. We can safely unblock
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// ccb.close and allow the removeAddrConns to happen
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// asynchronously.
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for acbw := range scs {
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ccb.cc.removeAddrConn(acbw.getAddrConn(), errConnDrain)
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}
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return
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}
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}
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}
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func (ccb *ccBalancerWrapper) close() {
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ccb.closed.Fire()
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<-ccb.done.Done()
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}
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func (ccb *ccBalancerWrapper) exitIdle() bool {
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if !ccb.hasExitIdle {
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return false
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}
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ccb.updateCh.Put(exitIdle{})
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return true
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}
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func (ccb *ccBalancerWrapper) handleSubConnStateChange(sc balancer.SubConn, s connectivity.State, err error) {
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// When updating addresses for a SubConn, if the address in use is not in
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// the new addresses, the old ac will be tearDown() and a new ac will be
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// created. tearDown() generates a state change with Shutdown state, we
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// don't want the balancer to receive this state change. So before
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// tearDown() on the old ac, ac.acbw (acWrapper) will be set to nil, and
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// this function will be called with (nil, Shutdown). We don't need to call
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// balancer method in this case.
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if sc == nil {
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return
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}
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ccb.updateCh.Put(&scStateUpdate{
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sc: sc,
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state: s,
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err: err,
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})
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}
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func (ccb *ccBalancerWrapper) updateClientConnState(ccs *balancer.ClientConnState) error {
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ccb.balancerMu.Lock()
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defer ccb.balancerMu.Unlock()
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return ccb.balancer.UpdateClientConnState(*ccs)
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}
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func (ccb *ccBalancerWrapper) resolverError(err error) {
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ccb.balancerMu.Lock()
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defer ccb.balancerMu.Unlock()
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ccb.balancer.ResolverError(err)
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}
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func (ccb *ccBalancerWrapper) NewSubConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (balancer.SubConn, error) {
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if len(addrs) <= 0 {
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return nil, fmt.Errorf("grpc: cannot create SubConn with empty address list")
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}
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ccb.mu.Lock()
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defer ccb.mu.Unlock()
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if ccb.subConns == nil {
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return nil, fmt.Errorf("grpc: ClientConn balancer wrapper was closed")
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}
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ac, err := ccb.cc.newAddrConn(addrs, opts)
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if err != nil {
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return nil, err
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}
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acbw := &acBalancerWrapper{ac: ac}
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acbw.ac.mu.Lock()
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ac.acbw = acbw
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acbw.ac.mu.Unlock()
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ccb.subConns[acbw] = struct{}{}
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return acbw, nil
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}
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func (ccb *ccBalancerWrapper) RemoveSubConn(sc balancer.SubConn) {
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// The RemoveSubConn() is handled in the run() goroutine, to avoid deadlock
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// during switchBalancer() if the old balancer calls RemoveSubConn() in its
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// Close().
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ccb.updateCh.Put(sc)
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}
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func (ccb *ccBalancerWrapper) UpdateAddresses(sc balancer.SubConn, addrs []resolver.Address) {
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acbw, ok := sc.(*acBalancerWrapper)
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if !ok {
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return
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}
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acbw.UpdateAddresses(addrs)
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}
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func (ccb *ccBalancerWrapper) UpdateState(s balancer.State) {
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ccb.mu.Lock()
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defer ccb.mu.Unlock()
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if ccb.subConns == nil {
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return
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}
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// Update picker before updating state. Even though the ordering here does
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// not matter, it can lead to multiple calls of Pick in the common start-up
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// case where we wait for ready and then perform an RPC. If the picker is
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// updated later, we could call the "connecting" picker when the state is
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// updated, and then call the "ready" picker after the picker gets updated.
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ccb.cc.blockingpicker.updatePicker(s.Picker)
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ccb.cc.csMgr.updateState(s.ConnectivityState)
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}
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func (ccb *ccBalancerWrapper) ResolveNow(o resolver.ResolveNowOptions) {
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ccb.cc.resolveNow(o)
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}
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func (ccb *ccBalancerWrapper) Target() string {
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return ccb.cc.target
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}
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// acBalancerWrapper is a wrapper on top of ac for balancers.
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// It implements balancer.SubConn interface.
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type acBalancerWrapper struct {
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mu sync.Mutex
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ac *addrConn
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}
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func (acbw *acBalancerWrapper) UpdateAddresses(addrs []resolver.Address) {
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acbw.mu.Lock()
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defer acbw.mu.Unlock()
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if len(addrs) <= 0 {
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acbw.ac.cc.removeAddrConn(acbw.ac, errConnDrain)
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return
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}
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if !acbw.ac.tryUpdateAddrs(addrs) {
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cc := acbw.ac.cc
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opts := acbw.ac.scopts
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acbw.ac.mu.Lock()
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// Set old ac.acbw to nil so the Shutdown state update will be ignored
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// by balancer.
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//
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// TODO(bar) the state transition could be wrong when tearDown() old ac
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// and creating new ac, fix the transition.
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acbw.ac.acbw = nil
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acbw.ac.mu.Unlock()
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acState := acbw.ac.getState()
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acbw.ac.cc.removeAddrConn(acbw.ac, errConnDrain)
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if acState == connectivity.Shutdown {
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return
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}
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newAC, err := cc.newAddrConn(addrs, opts)
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if err != nil {
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channelz.Warningf(logger, acbw.ac.channelzID, "acBalancerWrapper: UpdateAddresses: failed to newAddrConn: %v", err)
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return
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}
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acbw.ac = newAC
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newAC.mu.Lock()
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newAC.acbw = acbw
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newAC.mu.Unlock()
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if acState != connectivity.Idle {
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go newAC.connect()
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}
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}
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}
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func (acbw *acBalancerWrapper) Connect() {
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acbw.mu.Lock()
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defer acbw.mu.Unlock()
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go acbw.ac.connect()
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}
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func (acbw *acBalancerWrapper) getAddrConn() *addrConn {
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acbw.mu.Lock()
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defer acbw.mu.Unlock()
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return acbw.ac
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}
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