cmd/go: add tracing for querying and downloading from the proxy

This CL adds tracing spans for modload.queryPattern, modload.queryProxy,
modload.QueryPattern, modload.QueryPattern.queryModule,
modload.queryPrefixModules and modfetch.Download.

Updates #38714

Change-Id: I537c7fa4f466c691c1b60ec73ef8a2277af49cd7
Reviewed-on: https://go-review.googlesource.com/c/go/+/242786
Run-TryBot: Michael Matloob <matloob@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Bryan C. Mills <bcmills@google.com>
Reviewed-by: Jay Conrod <jayconrod@google.com>

1 files changed, 15 insertions, 6 deletions

diff --git a/src/cmd/go/internal/modfetch/fetch.go b/src/cmd/go/internal/modfetch/fetch.go
index 6606612658..e29eb0a942 100644
--- a/src/cmd/go/internal/modfetch/fetch.go
+++ b/src/cmd/go/internal/modfetch/fetch.go
@@ -24,6 +24,7 @@ import (
 	"cmd/go/internal/par"
 	"cmd/go/internal/renameio"
 	"cmd/go/internal/robustio"
+	"cmd/go/internal/trace"
 
 	"golang.org/x/mod/module"
 	"golang.org/x/mod/sumdb/dirhash"
@@ -48,7 +49,7 @@ func Download(ctx context.Context, mod module.Version) (dir string, err error) {
 		err error
 	}
 	c := downloadCache.Do(mod, func() interface{} {
-		dir, err := download(mod)
+		dir, err := download(ctx, mod)
 		if err != nil {
 			return cached{"", err}
 		}
@@ -58,7 +59,10 @@ func Download(ctx context.Context, mod module.Version) (dir string, err error) {
 	return c.dir, c.err
 }
 
-func download(mod module.Version) (dir string, err error) {
+func download(ctx context.Context, mod module.Version) (dir string, err error) {
+	ctx, span := trace.StartSpan(ctx, "modfetch.download "+mod.String())
+	defer span.Done()
+
 	// If the directory exists, and no .partial file exists, the module has
 	// already been completely extracted. .partial files may be created when a
 	// module zip directory is extracted in place instead of being extracted to a
@@ -73,7 +77,7 @@ func download(mod module.Version) (dir string, err error) {
 	// To avoid cluttering the cache with extraneous files,
 	// DownloadZip uses the same lockfile as Download.
 	// Invoke DownloadZip before locking the file.
-	zipfile, err := DownloadZip(mod)
+	zipfile, err := DownloadZip(ctx, mod)
 	if err != nil {
 		return "", err
 	}
@@ -143,6 +147,7 @@ func download(mod module.Version) (dir string, err error) {
 		return "", err
 	}
 
+	ctx, span = trace.StartSpan(ctx, "unzip "+zipfile)
 	if unzipInPlace {
 		if err := ioutil.WriteFile(partialPath, nil, 0666); err != nil {
 			return "", err
@@ -172,6 +177,7 @@ func download(mod module.Version) (dir string, err error) {
 			return "", err
 		}
 	}
+	defer span.Done()
 
 	if !cfg.ModCacheRW {
 		// Make dir read-only only *after* renaming it.
@@ -196,7 +202,7 @@ var downloadZipCache par.Cache
 
 // DownloadZip downloads the specific module version to the
 // local zip cache and returns the name of the zip file.
-func DownloadZip(mod module.Version) (zipfile string, err error) {
+func DownloadZip(ctx context.Context, mod module.Version) (zipfile string, err error) {
 	// The par.Cache here avoids duplicate work.
 	type cached struct {
 		zipfile string
@@ -231,7 +237,7 @@ func DownloadZip(mod module.Version) (zipfile string, err error) {
 		if err := os.MkdirAll(filepath.Dir(zipfile), 0777); err != nil {
 			return cached{"", err}
 		}
-		if err := downloadZip(mod, zipfile); err != nil {
+		if err := downloadZip(ctx, mod, zipfile); err != nil {
 			return cached{"", err}
 		}
 		return cached{zipfile, nil}
@@ -239,7 +245,10 @@ func DownloadZip(mod module.Version) (zipfile string, err error) {
 	return c.zipfile, c.err
 }
 
-func downloadZip(mod module.Version, zipfile string) (err error) {
+func downloadZip(ctx context.Context, mod module.Version, zipfile string) (err error) {
+	ctx, span := trace.StartSpan(ctx, "modfetch.downloadZip "+zipfile)
+	defer span.Done()
+
 	// Clean up any remaining tempfiles from previous runs.
 	// This is only safe to do because the lock file ensures that their
 	// writers are no longer active.