diff options
Diffstat (limited to 'vendor/google.golang.org/grpc/balancer_conn_wrappers.go')
-rw-r--r-- | vendor/google.golang.org/grpc/balancer_conn_wrappers.go | 248 |
1 files changed, 248 insertions, 0 deletions
diff --git a/vendor/google.golang.org/grpc/balancer_conn_wrappers.go b/vendor/google.golang.org/grpc/balancer_conn_wrappers.go new file mode 100644 index 0000000..e4a95fd --- /dev/null +++ b/vendor/google.golang.org/grpc/balancer_conn_wrappers.go @@ -0,0 +1,248 @@ +/* + * + * Copyright 2017 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 grpc + +import ( + "sync" + + "google.golang.org/grpc/balancer" + "google.golang.org/grpc/connectivity" + "google.golang.org/grpc/grpclog" + "google.golang.org/grpc/resolver" +) + +// scStateUpdate contains the subConn and the new state it changed to. +type scStateUpdate struct { + sc balancer.SubConn + state connectivity.State +} + +// scStateUpdateBuffer is an unbounded channel for scStateChangeTuple. +// TODO make a general purpose buffer that uses interface{}. +type scStateUpdateBuffer struct { + c chan *scStateUpdate + mu sync.Mutex + backlog []*scStateUpdate +} + +func newSCStateUpdateBuffer() *scStateUpdateBuffer { + return &scStateUpdateBuffer{ + c: make(chan *scStateUpdate, 1), + } +} + +func (b *scStateUpdateBuffer) put(t *scStateUpdate) { + b.mu.Lock() + defer b.mu.Unlock() + if len(b.backlog) == 0 { + select { + case b.c <- t: + return + default: + } + } + b.backlog = append(b.backlog, t) +} + +func (b *scStateUpdateBuffer) load() { + b.mu.Lock() + defer b.mu.Unlock() + if len(b.backlog) > 0 { + select { + case b.c <- b.backlog[0]: + b.backlog[0] = nil + b.backlog = b.backlog[1:] + default: + } + } +} + +// get returns the channel that receives a recvMsg in the buffer. +// +// Upon receiving, the caller should call load to send another +// scStateChangeTuple onto the channel if there is any. +func (b *scStateUpdateBuffer) get() <-chan *scStateUpdate { + return b.c +} + +// resolverUpdate contains the new resolved addresses or error if there's +// any. +type resolverUpdate struct { + addrs []resolver.Address + err error +} + +// ccBalancerWrapper is a wrapper on top of cc for balancers. +// It implements balancer.ClientConn interface. +type ccBalancerWrapper struct { + cc *ClientConn + balancer balancer.Balancer + stateChangeQueue *scStateUpdateBuffer + resolverUpdateCh chan *resolverUpdate + done chan struct{} +} + +func newCCBalancerWrapper(cc *ClientConn, b balancer.Builder, bopts balancer.BuildOptions) *ccBalancerWrapper { + ccb := &ccBalancerWrapper{ + cc: cc, + stateChangeQueue: newSCStateUpdateBuffer(), + resolverUpdateCh: make(chan *resolverUpdate, 1), + done: make(chan struct{}), + } + go ccb.watcher() + ccb.balancer = b.Build(ccb, bopts) + return ccb +} + +// watcher balancer functions sequencially, so the balancer can be implemeneted +// lock-free. +func (ccb *ccBalancerWrapper) watcher() { + for { + select { + case t := <-ccb.stateChangeQueue.get(): + ccb.stateChangeQueue.load() + ccb.balancer.HandleSubConnStateChange(t.sc, t.state) + case t := <-ccb.resolverUpdateCh: + ccb.balancer.HandleResolvedAddrs(t.addrs, t.err) + case <-ccb.done: + } + + select { + case <-ccb.done: + ccb.balancer.Close() + return + default: + } + } +} + +func (ccb *ccBalancerWrapper) close() { + close(ccb.done) +} + +func (ccb *ccBalancerWrapper) handleSubConnStateChange(sc balancer.SubConn, s connectivity.State) { + // When updating addresses for a SubConn, if the address in use is not in + // the new addresses, the old ac will be tearDown() and a new ac will be + // created. tearDown() generates a state change with Shutdown state, we + // don't want the balancer to receive this state change. So before + // tearDown() on the old ac, ac.acbw (acWrapper) will be set to nil, and + // this function will be called with (nil, Shutdown). We don't need to call + // balancer method in this case. + if sc == nil { + return + } + ccb.stateChangeQueue.put(&scStateUpdate{ + sc: sc, + state: s, + }) +} + +func (ccb *ccBalancerWrapper) handleResolvedAddrs(addrs []resolver.Address, err error) { + select { + case <-ccb.resolverUpdateCh: + default: + } + ccb.resolverUpdateCh <- &resolverUpdate{ + addrs: addrs, + err: err, + } +} + +func (ccb *ccBalancerWrapper) NewSubConn(addrs []resolver.Address, opts balancer.NewSubConnOptions) (balancer.SubConn, error) { + grpclog.Infof("ccBalancerWrapper: new subconn: %v", addrs) + ac, err := ccb.cc.newAddrConn(addrs) + if err != nil { + return nil, err + } + acbw := &acBalancerWrapper{ac: ac} + ac.acbw = acbw + return acbw, nil +} + +func (ccb *ccBalancerWrapper) RemoveSubConn(sc balancer.SubConn) { + grpclog.Infof("ccBalancerWrapper: removing subconn") + acbw, ok := sc.(*acBalancerWrapper) + if !ok { + return + } + ccb.cc.removeAddrConn(acbw.getAddrConn(), errConnDrain) +} + +func (ccb *ccBalancerWrapper) UpdateBalancerState(s connectivity.State, p balancer.Picker) { + grpclog.Infof("ccBalancerWrapper: updating state and picker called by balancer: %v, %p", s, p) + ccb.cc.csMgr.updateState(s) + ccb.cc.blockingpicker.updatePicker(p) +} + +func (ccb *ccBalancerWrapper) Target() string { + return ccb.cc.target +} + +// acBalancerWrapper is a wrapper on top of ac for balancers. +// It implements balancer.SubConn interface. +type acBalancerWrapper struct { + mu sync.Mutex + ac *addrConn +} + +func (acbw *acBalancerWrapper) UpdateAddresses(addrs []resolver.Address) { + grpclog.Infof("acBalancerWrapper: UpdateAddresses called with %v", addrs) + acbw.mu.Lock() + defer acbw.mu.Unlock() + if !acbw.ac.tryUpdateAddrs(addrs) { + cc := acbw.ac.cc + acbw.ac.mu.Lock() + // Set old ac.acbw to nil so the Shutdown state update will be ignored + // by balancer. + // + // TODO(bar) the state transition could be wrong when tearDown() old ac + // and creating new ac, fix the transition. + acbw.ac.acbw = nil + acbw.ac.mu.Unlock() + acState := acbw.ac.getState() + acbw.ac.tearDown(errConnDrain) + + if acState == connectivity.Shutdown { + return + } + + ac, err := cc.newAddrConn(addrs) + if err != nil { + grpclog.Warningf("acBalancerWrapper: UpdateAddresses: failed to newAddrConn: %v", err) + return + } + acbw.ac = ac + ac.acbw = acbw + if acState != connectivity.Idle { + ac.connect(false) + } + } +} + +func (acbw *acBalancerWrapper) Connect() { + acbw.mu.Lock() + defer acbw.mu.Unlock() + acbw.ac.connect(false) +} + +func (acbw *acBalancerWrapper) getAddrConn() *addrConn { + acbw.mu.Lock() + defer acbw.mu.Unlock() + return acbw.ac +} |