internal/worker,etc.: improvements to latest-version info

- Fetch and update the latest-version info before processing a module
  rather than after, so the information in the DB matches what
  InsertModule is using.

- Pass latest-version info to InsertModule so it can use it to decide
  whether the version being inserted is the latest version.

- InsertModule writes the good latest version to the latest_module_versions
  table while holding the advisory lock, avoiding a race condition
  where two different versions both think they're the latest.

For golang/go#44710

Change-Id: Id5e8fa7a384ec6d4d86257362fd33a8fcd5215f7
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/301929
Trust: Jonathan Amsterdam <jba@google.com>
Run-TryBot: Jonathan Amsterdam <jba@google.com>
TryBot-Result: kokoro <noreply+kokoro@google.com>
Reviewed-by: Julie Qiu <julie@golang.org>

1 files changed, 6 insertions, 5 deletions

diff --git a/internal/postgres/unit_test.go b/internal/postgres/unit_test.go
index 5a80254f..df031284 100644
--- a/internal/postgres/unit_test.go
+++ b/internal/postgres/unit_test.go
@@ -649,14 +649,15 @@ func TestGetLatestUnitVersion(t *testing.T) {
 			testDB, release := acquire(t)
 			defer release()
 
+			lmvs := map[string]*internal.LatestModuleVersions{}
+			for _, l := range test.latests {
+				modFile := fmt.Sprintf("module %s\n%s", l.module, l.goMod)
+				lmvs[l.module] = addLatest(ctx, t, testDB, l.module, l.version, modFile)
+			}
 			for _, p := range test.packages {
 				mod, ver, pkg := parseModuleVersionPackage(p)
 				m := sample.Module(mod, ver, pkg)
-				MustInsertModule(ctx, t, testDB, m)
-			}
-			for _, l := range test.latests {
-				modFile := fmt.Sprintf("module %s\n%s", l.module, l.goMod)
-				addLatest(ctx, t, testDB, l.module, l.version, modFile)
+				MustInsertModuleLMV(ctx, t, testDB, m, lmvs[mod])
 			}
 			if test.modulePath == "" {
 				test.modulePath = internal.UnknownModulePath