improve plugins discovery performance

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

Author: crazy-max

cli-plugins/manager/manager.go

@@ -1,15 +1,18 @@
 package manager
 
 import (
+	"context"
 	"os"
 	"path/filepath"
 	"sort"
 	"strings"
+	"sync"
 
 	"github.com/docker/cli/cli/command"
 	"github.com/docker/cli/cli/config"
 	"github.com/fvbommel/sortorder"
 	"github.com/spf13/cobra"
+	"golang.org/x/sync/errgroup"
 	exec "golang.org/x/sys/execabs"
 )
 
@@ -146,19 +149,31 @@ func ListPlugins(dockerCli command.Cli, rootcmd *cobra.Command) ([]Plugin, error
 	}
 
 	var plugins []Plugin
+	var mu sync.Mutex
+	eg, _ := errgroup.WithContext(context.TODO())
 	for _, paths := range candidates {
-		if len(paths) == 0 {
-			continue
-		}
-		c := &candidate{paths[0]}
-		p, err := newPlugin(c, rootcmd)
-		if err != nil {
-			return nil, err
-		}
-		if !IsNotFound(p.Err) {
-			p.ShadowedPaths = paths[1:]
-			plugins = append(plugins, p)
-		}
+		func(paths []string) {
+			eg.Go(func() error {
+				if len(paths) == 0 {
+					return nil
+				}
+				c := &candidate{paths[0]}
+				p, err := newPlugin(c, rootcmd)
+				if err != nil {
+					return err
+				}
+				if !IsNotFound(p.Err) {
+					p.ShadowedPaths = paths[1:]
+					mu.Lock()
+					defer mu.Unlock()
+					plugins = append(plugins, p)
+				}
+				return nil
+			})
+		}(paths)
+	}
+	if err := eg.Wait(); err != nil {
+		return nil, err
 	}
 
 	sort.Slice(plugins, func(i, j int) bool {

vendor.mod

@@ -37,6 +37,7 @@ require (
 	github.com/theupdateframework/notary v0.7.1-0.20210315103452-bf96a202a09a
 	github.com/tonistiigi/go-rosetta v0.0.0-20200727161949-f79598599c5d
 	github.com/xeipuuv/gojsonschema v1.2.0
+	golang.org/x/sync v0.1.0
 	golang.org/x/sys v0.5.0
 	golang.org/x/term v0.5.0
 	golang.org/x/text v0.7.0

vendor.sum

@@ -524,6 +524,8 @@ golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20200625203802-6e8e738ad208/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201207232520-09787c993a3a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.1.0 h1:wsuoTGHzEhffawBOhz5CYhcrV4IdKZbEyZjBMuTp12o=
+golang.org/x/sync v0.1.0/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20180909124046-d0be0721c37e/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=

vendor/golang.org/x/sync/LICENSE

@@ -276,6 +276,9 @@ golang.org/x/net/internal/socks
 golang.org/x/net/internal/timeseries
 golang.org/x/net/proxy
 golang.org/x/net/trace
+# golang.org/x/sync v0.1.0
+## explicit
+golang.org/x/sync/errgroup
 # golang.org/x/sys v0.5.0
 ## explicit; go 1.17
 golang.org/x/sys/execabs