From fa98444be7845009aceef06b9621df3ccb46eb9f Mon Sep 17 00:00:00 2001
From: Heschi Kreinick <heschi@google.com>
Date: Mon, 17 Oct 2022 15:59:29 -0400
Subject: [PATCH] internal/task: handle missing commit in greenness

I wanted the greenness check to handle the case where the commit had
aged off the first page of results, and have it pick an arbitrary commit
it could in that case. But I didn't consider that the dashboard doesn't
observe commits instantaneously, and relui can't distinguish the two
cases.

For now, refuse to proceed if the commit isn't on the result page.

For golang/go#48523.

Change-Id: I0a8c9977c1b159f794f2a1d209ef749e606fc422
Reviewed-on: https://go-review.googlesource.com/c/build/+/443436
Auto-Submit: Heschi Kreinick <heschi@google.com>
Run-TryBot: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
---
 internal/task/tagx.go      | 12 ++++++++++++
 internal/task/tagx_test.go | 20 ++++++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/internal/task/tagx.go b/internal/task/tagx.go
index 87c91631..d6e63a5a 100644
--- a/internal/task/tagx.go
+++ b/internal/task/tagx.go
@@ -471,6 +471,18 @@ func (x *TagXReposTasks) findGreen(ctx *wf.TaskContext, repo TagRepo, commit str
 		}
 	}
 
+	foundCommit := false
+	for _, rev := range repoStatus.Revisions {
+		if rev.Revision == commit {
+			foundCommit = true
+			break
+		}
+	}
+	if !foundCommit {
+		ctx.Printf("commit %v not found on first page of results; too old or too new?", commit)
+		return "", false, nil
+	}
+
 	// x/ repo statuses are:
 	// <x commit> <go commit>
 	//            <go commit>
diff --git a/internal/task/tagx_test.go b/internal/task/tagx_test.go
index f1a287ef..0ac3916c 100644
--- a/internal/task/tagx_test.go
+++ b/internal/task/tagx_test.go
@@ -199,6 +199,26 @@ func TestIsGreen(t *testing.T) {
 			},
 			wantGreenRev: "tools-1",
 		},
+		{
+			name: "not green yet",
+			rev:  "tools-1",
+			lines: []revLine{
+				{"master", 3, 1, true},
+				{"release-branch.go1.19", 1, 1, false},
+				{"release-branch.go1.18", 1, 1, true},
+			},
+			wantGreenRev: "",
+		},
+		{
+			name: "commit not registered on dashboard",
+			rev:  "tools-2",
+			lines: []revLine{
+				{"master", 1, 1, true},
+				{"release-branch.go1.19", 1, 1, true},
+				{"release-branch.go1.18", 1, 1, true},
+			},
+			wantGreenRev: "",
+		},
 	}
 	for _, tt := range tests {