From 1d2ae644a769bf6d326c0f5dbbd05c743859e9d1 Mon Sep 17 00:00:00 2001
From: Camden Cheek <camden@ccheek.com>
Date: Tue, 11 Oct 2022 10:31:22 -0600
Subject: [PATCH] Backend: replace uses of `errors.Group` with `lib/group`
 (#42787)

---
 dev/sg/internal/generate/golang/golang.go | 15 +++-----
 lib/errors/group.go                       | 40 ---------------------
 lib/errors/group_test.go                  | 43 -----------------------
 3 files changed, 4 insertions(+), 94 deletions(-)
 delete mode 100644 lib/errors/group.go
 delete mode 100644 lib/errors/group_test.go

diff --git a/dev/sg/internal/generate/golang/golang.go b/dev/sg/internal/generate/golang/golang.go
index 57a389d471f..754ccf6d063 100644
--- a/dev/sg/internal/generate/golang/golang.go
+++ b/dev/sg/internal/generate/golang/golang.go
@@ -16,12 +16,12 @@ import (
 
 	"github.com/grafana/regexp"
 	"github.com/sourcegraph/run"
-	"golang.org/x/sync/semaphore"
 
 	"github.com/sourcegraph/sourcegraph/dev/sg/internal/generate"
 	"github.com/sourcegraph/sourcegraph/dev/sg/internal/std"
 	"github.com/sourcegraph/sourcegraph/dev/sg/root"
 	"github.com/sourcegraph/sourcegraph/lib/errors"
+	"github.com/sourcegraph/sourcegraph/lib/group"
 	"github.com/sourcegraph/sourcegraph/lib/output"
 )
 
@@ -214,22 +214,15 @@ func runGoGenerateOnPaths(ctx context.Context, pkgPaths []string, progressBar bo
 	}
 
 	var (
-		m   sync.Mutex
-		g   = errors.Group{}
-		sem = semaphore.NewWeighted(int64(runtime.GOMAXPROCS(0)))
+		m sync.Mutex
+		g = group.New().WithContext(ctx).WithMaxConcurrency(runtime.GOMAXPROCS(0))
 	)
 
 	for _, pkgPath := range pkgPaths {
-		if err := sem.Acquire(ctx, 1); err != nil {
-			return err
-		}
-
 		// Do not capture loop variable in goroutine below
 		pkgPath := pkgPath
 
-		g.Go(func() error {
-			defer sem.Release(1)
-
+		g.Go(func(ctx context.Context) error {
 			if verbosity == VerboseOutput {
 				progress.Writef("Generating %s...", pkgPath)
 			}
diff --git a/lib/errors/group.go b/lib/errors/group.go
deleted file mode 100644
index 5a2c1033914..00000000000
--- a/lib/errors/group.go
+++ /dev/null
@@ -1,40 +0,0 @@
-package errors
-
-import "sync"
-
-// Group is a collection of goroutines which return errors that need to be
-// coalesced.
-//
-// Implementation and tests are based on https://sourcegraph.com/github.com/hashicorp/go-multierror/-/blob/group.go
-type Group struct {
-	mutex sync.Mutex
-	err   MultiError
-	wg    sync.WaitGroup
-}
-
-// Go calls the given function in a new goroutine.
-//
-// If the function returns an error it is added to the group multierror which
-// is returned by Wait.
-func (g *Group) Go(f func() error) {
-	g.wg.Add(1)
-
-	go func() {
-		defer g.wg.Done()
-
-		if err := f(); err != nil {
-			g.mutex.Lock()
-			g.err = CombineErrors(g.err, err)
-			g.mutex.Unlock()
-		}
-	}()
-}
-
-// Wait blocks until all function calls from the Go method have returned, then
-// returns the multierror.
-func (g *Group) Wait() MultiError {
-	g.wg.Wait()
-	g.mutex.Lock()
-	defer g.mutex.Unlock()
-	return g.err
-}
diff --git a/lib/errors/group_test.go b/lib/errors/group_test.go
deleted file mode 100644
index 17a81aac3b4..00000000000
--- a/lib/errors/group_test.go
+++ /dev/null
@@ -1,43 +0,0 @@
-package errors
-
-import (
-	"strings"
-	"testing"
-)
-
-func TestGroup(t *testing.T) {
-	err1 := New("group_test: 1")
-	err2 := New("group_test: 2")
-
-	cases := []struct {
-		errs      []error
-		nilResult bool
-	}{
-		{errs: []error{}, nilResult: true},
-		{errs: []error{nil}, nilResult: true},
-		{errs: []error{err1}},
-		{errs: []error{err1, nil}},
-		{errs: []error{err1, nil, err2}},
-	}
-
-	for _, tc := range cases {
-		var g Group
-
-		for _, err := range tc.errs {
-			err := err
-			g.Go(func() error { return err })
-
-		}
-
-		gErr := g.Wait()
-		if gErr != nil {
-			for i := range tc.errs {
-				if tc.errs[i] != nil && !strings.Contains(gErr.Error(), tc.errs[i].Error()) {
-					t.Fatalf("expected error to contain %q, actual: %v", tc.errs[i].Error(), gErr)
-				}
-			}
-		} else if !tc.nilResult {
-			t.Fatalf("Group.Wait() should not have returned nil for errs: %v", tc.errs)
-		}
-	}
-}