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// Copyright 2015 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 command
import (
"bufio"
"fmt"
"os"
"strings"
"github.com/coreos/etcd/clientv3"
"github.com/spf13/cobra"
"golang.org/x/net/context"
)
var (
watchRev int64
watchPrefix bool
watchInteractive bool
watchPrevKey bool
)
// NewWatchCommand returns the cobra command for "watch".
func NewWatchCommand() *cobra.Command {
cmd := &cobra.Command{
Use: "watch [options] [key or prefix] [range_end]",
Short: "Watches events stream on keys or prefixes",
Run: watchCommandFunc,
}
cmd.Flags().BoolVarP(&watchInteractive, "interactive", "i", false, "Interactive mode")
cmd.Flags().BoolVar(&watchPrefix, "prefix", false, "Watch on a prefix if prefix is set")
cmd.Flags().Int64Var(&watchRev, "rev", 0, "Revision to start watching")
cmd.Flags().BoolVar(&watchPrevKey, "prev-kv", false, "get the previous key-value pair before the event happens")
return cmd
}
// watchCommandFunc executes the "watch" command.
func watchCommandFunc(cmd *cobra.Command, args []string) {
if watchInteractive {
watchInteractiveFunc(cmd, args)
return
}
c := mustClientFromCmd(cmd)
wc, err := getWatchChan(c, args)
if err != nil {
ExitWithError(ExitBadArgs, err)
}
printWatchCh(wc)
if err = c.Close(); err != nil {
ExitWithError(ExitBadConnection, err)
}
ExitWithError(ExitInterrupted, fmt.Errorf("watch is canceled by the server"))
}
func watchInteractiveFunc(cmd *cobra.Command, args []string) {
c := mustClientFromCmd(cmd)
reader := bufio.NewReader(os.Stdin)
for {
l, err := reader.ReadString('\n')
if err != nil {
ExitWithError(ExitInvalidInput, fmt.Errorf("Error reading watch request line: %v", err))
}
l = strings.TrimSuffix(l, "\n")
args := argify(l)
if len(args) < 2 {
fmt.Fprintf(os.Stderr, "Invalid command %s (command type or key is not provided)\n", l)
continue
}
if args[0] != "watch" {
fmt.Fprintf(os.Stderr, "Invalid command %s (only support watch)\n", l)
continue
}
flagset := NewWatchCommand().Flags()
err = flagset.Parse(args[1:])
if err != nil {
fmt.Fprintf(os.Stderr, "Invalid command %s (%v)\n", l, err)
continue
}
ch, err := getWatchChan(c, flagset.Args())
if err != nil {
fmt.Fprintf(os.Stderr, "Invalid command %s (%v)\n", l, err)
continue
}
go printWatchCh(ch)
}
}
func getWatchChan(c *clientv3.Client, args []string) (clientv3.WatchChan, error) {
if len(args) < 1 || len(args) > 2 {
return nil, fmt.Errorf("bad number of arguments")
}
key := args[0]
opts := []clientv3.OpOption{clientv3.WithRev(watchRev)}
if len(args) == 2 {
if watchPrefix {
return nil, fmt.Errorf("`range_end` and `--prefix` are mutually exclusive")
}
opts = append(opts, clientv3.WithRange(args[1]))
}
if watchPrefix {
opts = append(opts, clientv3.WithPrefix())
}
if watchPrevKey {
opts = append(opts, clientv3.WithPrevKV())
}
return c.Watch(context.TODO(), key, opts...), nil
}
func printWatchCh(ch clientv3.WatchChan) {
for resp := range ch {
display.Watch(resp)
}
}
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