diff options
Diffstat (limited to 'vendor/google.golang.org/grpc/picker_wrapper.go')
-rw-r--r-- | vendor/google.golang.org/grpc/picker_wrapper.go | 141 |
1 files changed, 141 insertions, 0 deletions
diff --git a/vendor/google.golang.org/grpc/picker_wrapper.go b/vendor/google.golang.org/grpc/picker_wrapper.go new file mode 100644 index 0000000..9085dbc --- /dev/null +++ b/vendor/google.golang.org/grpc/picker_wrapper.go @@ -0,0 +1,141 @@ +/* + * + * 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" + + "golang.org/x/net/context" + "google.golang.org/grpc/balancer" + "google.golang.org/grpc/codes" + "google.golang.org/grpc/grpclog" + "google.golang.org/grpc/status" + "google.golang.org/grpc/transport" +) + +// pickerWrapper is a wrapper of balancer.Picker. It blocks on certain pick +// actions and unblock when there's a picker update. +type pickerWrapper struct { + mu sync.Mutex + done bool + blockingCh chan struct{} + picker balancer.Picker +} + +func newPickerWrapper() *pickerWrapper { + bp := &pickerWrapper{blockingCh: make(chan struct{})} + return bp +} + +// updatePicker is called by UpdateBalancerState. It unblocks all blocked pick. +func (bp *pickerWrapper) updatePicker(p balancer.Picker) { + bp.mu.Lock() + if bp.done { + bp.mu.Unlock() + return + } + bp.picker = p + // bp.blockingCh should never be nil. + close(bp.blockingCh) + bp.blockingCh = make(chan struct{}) + bp.mu.Unlock() +} + +// pick returns the transport that will be used for the RPC. +// It may block in the following cases: +// - there's no picker +// - the current picker returns ErrNoSubConnAvailable +// - the current picker returns other errors and failfast is false. +// - the subConn returned by the current picker is not READY +// When one of these situations happens, pick blocks until the picker gets updated. +func (bp *pickerWrapper) pick(ctx context.Context, failfast bool, opts balancer.PickOptions) (transport.ClientTransport, func(balancer.DoneInfo), error) { + var ( + p balancer.Picker + ch chan struct{} + ) + + for { + bp.mu.Lock() + if bp.done { + bp.mu.Unlock() + return nil, nil, ErrClientConnClosing + } + + if bp.picker == nil { + ch = bp.blockingCh + } + if ch == bp.blockingCh { + // This could happen when either: + // - bp.picker is nil (the previous if condition), or + // - has called pick on the current picker. + bp.mu.Unlock() + select { + case <-ctx.Done(): + return nil, nil, ctx.Err() + case <-ch: + } + continue + } + + ch = bp.blockingCh + p = bp.picker + bp.mu.Unlock() + + subConn, put, err := p.Pick(ctx, opts) + + if err != nil { + switch err { + case balancer.ErrNoSubConnAvailable: + continue + case balancer.ErrTransientFailure: + if !failfast { + continue + } + return nil, nil, status.Errorf(codes.Unavailable, "%v", err) + default: + // err is some other error. + return nil, nil, toRPCErr(err) + } + } + + acw, ok := subConn.(*acBalancerWrapper) + if !ok { + grpclog.Infof("subconn returned from pick is not *acBalancerWrapper") + continue + } + if t, ok := acw.getAddrConn().getReadyTransport(); ok { + return t, put, nil + } + grpclog.Infof("blockingPicker: the picked transport is not ready, loop back to repick") + // If ok == false, ac.state is not READY. + // A valid picker always returns READY subConn. This means the state of ac + // just changed, and picker will be updated shortly. + // continue back to the beginning of the for loop to repick. + } +} + +func (bp *pickerWrapper) close() { + bp.mu.Lock() + defer bp.mu.Unlock() + if bp.done { + return + } + bp.done = true + close(bp.blockingCh) +} |