https://github.com/coreos/etcd
Tip revision: d40982fc9160b7471cd832bff34d09e218b12e0e authored by Anthony Romano on 09 September 2016, 20:14:44 UTC
version: bump to v3.0.8
version: bump to v3.0.8
Tip revision: d40982f
balancer.go
// Copyright 2016 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 clientv3
import (
"net/url"
"strings"
"sync"
"golang.org/x/net/context"
"google.golang.org/grpc"
)
// simpleBalancer does the bare minimum to expose multiple eps
// to the grpc reconnection code path
type simpleBalancer struct {
// addrs are the client's endpoints for grpc
addrs []grpc.Address
// notifyCh notifies grpc of the set of addresses for connecting
notifyCh chan []grpc.Address
// readyc closes once the first connection is up
readyc chan struct{}
readyOnce sync.Once
// mu protects upEps, pinAddr, and connectingAddr
mu sync.RWMutex
// upEps holds the current endpoints that have an active connection
upEps map[string]struct{}
// upc closes when upEps transitions from empty to non-zero or the balancer closes.
upc chan struct{}
// pinAddr is the currently pinned address; set to the empty string on
// intialization and shutdown.
pinAddr string
}
func newSimpleBalancer(eps []string) *simpleBalancer {
notifyCh := make(chan []grpc.Address, 1)
addrs := make([]grpc.Address, len(eps))
for i := range eps {
addrs[i].Addr = getHost(eps[i])
}
notifyCh <- addrs
sb := &simpleBalancer{
addrs: addrs,
notifyCh: notifyCh,
readyc: make(chan struct{}),
upEps: make(map[string]struct{}),
upc: make(chan struct{}),
}
return sb
}
func (b *simpleBalancer) Start(target string) error { return nil }
func (b *simpleBalancer) ConnectNotify() <-chan struct{} {
b.mu.Lock()
defer b.mu.Unlock()
return b.upc
}
func (b *simpleBalancer) Up(addr grpc.Address) func(error) {
b.mu.Lock()
if len(b.upEps) == 0 {
// notify waiting Get()s and pin first connected address
close(b.upc)
b.pinAddr = addr.Addr
}
b.upEps[addr.Addr] = struct{}{}
b.mu.Unlock()
// notify client that a connection is up
b.readyOnce.Do(func() { close(b.readyc) })
return func(err error) {
b.mu.Lock()
delete(b.upEps, addr.Addr)
if len(b.upEps) == 0 && b.pinAddr != "" {
b.upc = make(chan struct{})
} else if b.pinAddr == addr.Addr {
// choose new random up endpoint
for k := range b.upEps {
b.pinAddr = k
break
}
}
b.mu.Unlock()
}
}
func (b *simpleBalancer) Get(ctx context.Context, opts grpc.BalancerGetOptions) (grpc.Address, func(), error) {
var addr string
for {
b.mu.RLock()
ch := b.upc
b.mu.RUnlock()
select {
case <-ch:
case <-ctx.Done():
return grpc.Address{Addr: ""}, nil, ctx.Err()
}
b.mu.RLock()
addr = b.pinAddr
upEps := len(b.upEps)
b.mu.RUnlock()
if addr == "" {
return grpc.Address{Addr: ""}, nil, grpc.ErrClientConnClosing
}
if upEps > 0 {
break
}
}
return grpc.Address{Addr: addr}, func() {}, nil
}
func (b *simpleBalancer) Notify() <-chan []grpc.Address { return b.notifyCh }
func (b *simpleBalancer) Close() error {
b.mu.Lock()
close(b.notifyCh)
// terminate all waiting Get()s
b.pinAddr = ""
if len(b.upEps) == 0 {
close(b.upc)
}
b.mu.Unlock()
return nil
}
func getHost(ep string) string {
url, uerr := url.Parse(ep)
if uerr != nil || !strings.Contains(ep, "://") {
return ep
}
return url.Host
}