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roundrobin_balanced.go
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/
roundrobin_balanced.go
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// Copyright 2018 The etcd 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 picker
import (
"context"
"sync"
"go.uber.org/zap"
"go.uber.org/zap/zapcore"
"google.golang.org/grpc/balancer"
"google.golang.org/grpc/resolver"
)
// newRoundrobinBalanced returns a new roundrobin balanced picker.
func newRoundrobinBalanced(cfg Config) Picker {
scs := make([]balancer.SubConn, 0, len(cfg.SubConnToResolverAddress))
for sc := range cfg.SubConnToResolverAddress {
scs = append(scs, sc)
}
return &rrBalanced{
p: RoundrobinBalanced,
lg: cfg.Logger,
scs: scs,
scToAddr: cfg.SubConnToResolverAddress,
}
}
type rrBalanced struct {
p Policy
lg *zap.Logger
mu sync.RWMutex
next int
scs []balancer.SubConn
scToAddr map[balancer.SubConn]resolver.Address
}
func (rb *rrBalanced) String() string { return rb.p.String() }
// Pick is called for every client request.
func (rb *rrBalanced) Pick(ctx context.Context, opts balancer.PickOptions) (balancer.SubConn, func(balancer.DoneInfo), error) {
rb.mu.RLock()
n := len(rb.scs)
rb.mu.RUnlock()
if n == 0 {
return nil, nil, balancer.ErrNoSubConnAvailable
}
rb.mu.Lock()
cur := rb.next
sc := rb.scs[cur]
picked := rb.scToAddr[sc].Addr
rb.next = (rb.next + 1) % len(rb.scs)
rb.mu.Unlock()
rb.lg.Debug(
"picked",
zap.String("picker", rb.p.String()),
zap.String("address", picked),
zap.Int("subconn-index", cur),
zap.Int("subconn-size", n),
)
doneFunc := func(info balancer.DoneInfo) {
// TODO: error handling?
fss := []zapcore.Field{
zap.Error(info.Err),
zap.String("picker", rb.p.String()),
zap.String("address", picked),
zap.Bool("success", info.Err == nil),
zap.Bool("bytes-sent", info.BytesSent),
zap.Bool("bytes-received", info.BytesReceived),
}
if info.Err == nil {
rb.lg.Debug("balancer done", fss...)
} else {
rb.lg.Warn("balancer failed", fss...)
}
}
return sc, doneFunc, nil
}