internal/relui: wait for all files in uploadArtifacts

CL 429275 and CL 429536 have hidden partially-written files from the
release test. I think a remaining race was that uploadArtifacts only
waits for the main artifact file, and uploadArtifact copies that one
first. So it was possible for fakeCDNLoad to periodically copy all the
main files but not yet one of the .sha256 files, and the test release
workflow would complete too early, before fakeCDNLoad finished its work.

This race is very unlikely to happen in production since everything
else takes longer. Still, we consider the .sha256 metadata file as
non-optional, so modify uploadArtifacts to wait for all files to be
made available before considering its job as done.

Fixes golang/go#55178. (Third time's the charm, right?)
Updates golang/go#53972.

Change-Id: Id470da1fb94ba91b292c63a53e34705b30ba8d66
Reviewed-on: https://go-review.googlesource.com/c/build/+/448135
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Heschi Kreinick <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Run-TryBot: Dmitri Shuralyov <[email protected]>

Author: dmitshur

internal/relui/workflows.go

@@ -914,26 +914,30 @@ func (tasks *BuildReleaseTasks) uploadArtifacts(ctx *wf.TaskContext, artifacts [
 		return err
 	}
 
-	todo := map[artifact]bool{}
+	todo := map[string]bool{} // URLs we're waiting on becoming available.
 	for _, a := range artifacts {
 		if err := uploadArtifact(scratchFS, servingFS, a); err != nil {
 			return err
 		}
-		todo[a] = true
+		todo[tasks.DownloadURL+"/"+a.Filename] = true
+		todo[tasks.DownloadURL+"/"+a.Filename+".sha256"] = true
+		if a.GPGSignature != "" {
+			todo[tasks.DownloadURL+"/"+a.Filename+".asc"] = true
+		}
 	}
 
 	check := func() (int, bool, error) {
-		for _, a := range artifacts {
+		for url := range todo {
 			ctx, cancel := context.WithTimeout(ctx, 5*time.Second)
 			defer cancel()
-			resp, err := ctxhttp.Head(ctx, http.DefaultClient, tasks.DownloadURL+"/"+a.Filename)
+			resp, err := ctxhttp.Head(ctx, http.DefaultClient, url)
 			if err != nil && err != context.DeadlineExceeded {
 				return 0, false, err
 			}
 			resp.Body.Close()
 			cancel()
 			if resp.StatusCode == http.StatusOK {
-				delete(todo, a)
+				delete(todo, url)
 			}
 		}
 		return 0, len(todo) == 0, nil
@@ -942,6 +946,8 @@ func (tasks *BuildReleaseTasks) uploadArtifacts(ctx *wf.TaskContext, artifacts [
 	return err
 }
 
+// uploadArtifact copies the artifact a and its metadata files
+// from scratchFS to servingFS.
 func uploadArtifact(scratchFS, servingFS fs.FS, a artifact) error {
 	in, err := scratchFS.Open(a.ScratchPath)
 	if err != nil {
@@ -964,12 +970,12 @@ func uploadArtifact(scratchFS, servingFS fs.FS, a artifact) error {
 	if err := gcsfs.WriteFile(servingFS, a.Filename+".sha256", []byte(a.SHA256)); err != nil {
 		return err
 	}
-
 	if a.GPGSignature != "" {
 		if err := gcsfs.WriteFile(servingFS, a.Filename+".asc", []byte(a.GPGSignature)); err != nil {
 			return err
 		}
 	}
+
 	return nil
 }