improve plugins listing performance

We can slightly improve plugins listing by spawning a
goroutine for each iteration.

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>
(cherry picked from commit 89583b92b7)

# Conflicts:
#	vendor.mod
#	vendor/modules.txt

cli-plugins/manager/candidate_test.go

@@ -74,7 +74,7 @@ func TestValidateCandidate(t *testing.T) {
 		{name: "experimental + allowing experimental", c: &fakeCandidate{path: goodPluginPath, exec: true, meta: metaExperimental}},
 	} {
 		t.Run(tc.name, func(t *testing.T) {
-			p, err := newPlugin(tc.c, fakeroot)
+			p, err := newPlugin(tc.c, fakeroot.Commands())
 			if tc.err != "" {
 				assert.ErrorContains(t, err, tc.err)
 			} else if tc.invalid != "" {

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"
 )
 
@@ -120,7 +123,7 @@ func GetPlugin(name string, dockerCli command.Cli, rootcmd *cobra.Command) (*Plu
 			return nil, errPluginNotFound(name)
 		}
 		c := &candidate{paths[0]}
-		p, err := newPlugin(c, rootcmd)
+		p, err := newPlugin(c, rootcmd.Commands())
 		if err != nil {
 			return nil, err
 		}
@@ -146,19 +149,32 @@ func ListPlugins(dockerCli command.Cli, rootcmd *cobra.Command) ([]Plugin, error
 	}
 
 	var plugins []Plugin
+	var mu sync.Mutex
+	eg, _ := errgroup.WithContext(context.TODO())
+	cmds := rootcmd.Commands()
 	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, cmds)
+				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 {
@@ -199,7 +215,7 @@ func PluginRunCommand(dockerCli command.Cli, name string, rootcmd *cobra.Command
 		}
 
 		c := &candidate{path: path}
-		plugin, err := newPlugin(c, rootcmd)
+		plugin, err := newPlugin(c, rootcmd.Commands())
 		if err != nil {
 			return nil, err
 		}

cli-plugins/manager/plugin.go

@@ -31,7 +31,7 @@ type Plugin struct {
 // is set, and is always a `pluginError`, but the `Plugin` is still
 // returned with no error. An error is only returned due to a
 // non-recoverable error.
-func newPlugin(c Candidate, rootcmd *cobra.Command) (Plugin, error) {
+func newPlugin(c Candidate, cmds []*cobra.Command) (Plugin, error) {
 	path := c.Path()
 	if path == "" {
 		return Plugin{}, errors.New("plugin candidate path cannot be empty")
@@ -62,22 +62,20 @@ func newPlugin(c Candidate, rootcmd *cobra.Command) (Plugin, error) {
 		return p, nil
 	}
 
-	if rootcmd != nil {
-		for _, cmd := range rootcmd.Commands() {
-			// Ignore conflicts with commands which are
-			// just plugin stubs (i.e. from a previous
-			// call to AddPluginCommandStubs).
-			if IsPluginCommand(cmd) {
-				continue
-			}
-			if cmd.Name() == p.Name {
-				p.Err = NewPluginError("plugin %q duplicates builtin command", p.Name)
-				return p, nil
-			}
-			if cmd.HasAlias(p.Name) {
-				p.Err = NewPluginError("plugin %q duplicates an alias of builtin command %q", p.Name, cmd.Name())
-				return p, nil
-			}
+	for _, cmd := range cmds {
+		// Ignore conflicts with commands which are
+		// just plugin stubs (i.e. from a previous
+		// call to AddPluginCommandStubs).
+		if IsPluginCommand(cmd) {
+			continue
+		}
+		if cmd.Name() == p.Name {
+			p.Err = NewPluginError("plugin %q duplicates builtin command", p.Name)
+			return p, nil
+		}
+		if cmd.HasAlias(p.Name) {
+			p.Err = NewPluginError("plugin %q duplicates an alias of builtin command %q", p.Name, cmd.Name())
+			return p, nil
 		}
 	}