mirror of
https://github.com/etcd-io/etcd.git
synced 2024-09-27 06:25:44 +00:00
127 lines
3.0 KiB
Go
127 lines
3.0 KiB
Go
// Copyright 2016 The etcd 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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package command
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import (
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"context"
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"errors"
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"fmt"
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"github.com/coreos/etcd/clientv3/concurrency"
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"github.com/spf13/cobra"
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)
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// NewElectionCommand returns the cobra command for "election runner".
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func NewElectionCommand() *cobra.Command {
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cmd := &cobra.Command{
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Use: "election",
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Short: "Performs election operation",
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Run: runElectionFunc,
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}
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cmd.Flags().IntVar(&rounds, "rounds", 100, "number of rounds to run")
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cmd.Flags().IntVar(&totalClientConnections, "total-client-connections", 10, "total number of client connections")
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return cmd
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}
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func runElectionFunc(cmd *cobra.Command, args []string) {
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if len(args) > 0 {
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ExitWithError(ExitBadArgs, errors.New("election does not take any argument"))
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}
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rcs := make([]roundClient, totalClientConnections)
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validatec, releasec := make(chan struct{}, len(rcs)), make(chan struct{}, len(rcs))
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for range rcs {
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releasec <- struct{}{}
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}
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eps := endpointsFromFlag(cmd)
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dialTimeout := dialTimeoutFromCmd(cmd)
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for i := range rcs {
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v := fmt.Sprintf("%d", i)
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observedLeader := ""
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validateWaiters := 0
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rcs[i].c = newClient(eps, dialTimeout)
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var (
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s *concurrency.Session
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err error
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)
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for {
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s, err = concurrency.NewSession(rcs[i].c)
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if err == nil {
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break
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}
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}
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e := concurrency.NewElection(s, "electors")
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rcs[i].acquire = func() error {
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<-releasec
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ctx, cancel := context.WithCancel(context.Background())
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go func() {
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if ol, ok := <-e.Observe(ctx); ok {
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observedLeader = string(ol.Kvs[0].Value)
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if observedLeader != v {
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cancel()
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}
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}
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}()
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err = e.Campaign(ctx, v)
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if err == nil {
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observedLeader = v
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}
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if observedLeader == v {
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validateWaiters = len(rcs)
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}
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select {
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case <-ctx.Done():
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return nil
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default:
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cancel()
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return err
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}
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}
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rcs[i].validate = func() error {
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if l, err := e.Leader(context.TODO()); err == nil && l != observedLeader {
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return fmt.Errorf("expected leader %q, got %q", observedLeader, l)
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}
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validatec <- struct{}{}
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return nil
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}
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rcs[i].release = func() error {
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for validateWaiters > 0 {
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select {
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case <-validatec:
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validateWaiters--
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default:
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return fmt.Errorf("waiting on followers")
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}
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}
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if err := e.Resign(context.TODO()); err != nil {
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return err
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}
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if observedLeader == v {
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for range rcs {
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releasec <- struct{}{}
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}
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}
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observedLeader = ""
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return nil
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}
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}
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doRounds(rcs, rounds)
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}
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