internal: remove unit-meta-with-latest experiment

For golang/go#43265

Change-Id: I1d056a893fdff60744ff328ab9f4a1b6665b3e32
Reviewed-on: https://go-review.googlesource.com/c/pkgsite/+/309709
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>

2 files changed, 11 insertions, 243 deletions

diff --git a/internal/postgres/unit.go b/internal/postgres/unit.go
index 5cac3e2a..ce98ec20 100644
--- a/internal/postgres/unit.go
+++ b/internal/postgres/unit.go
@@ -16,7 +16,6 @@ import (
 	"golang.org/x/pkgsite/internal"
 	"golang.org/x/pkgsite/internal/database"
 	"golang.org/x/pkgsite/internal/derrors"
-	"golang.org/x/pkgsite/internal/experiment"
 	"golang.org/x/pkgsite/internal/middleware"
 	"golang.org/x/pkgsite/internal/stdlib"
 	"golang.org/x/pkgsite/internal/version"
@@ -39,19 +38,16 @@ func (db *DB) GetUnitMeta(ctx context.Context, fullPath, requestedModulePath, re
 	defer derrors.WrapStack(&err, "DB.GetUnitMeta(ctx, %q, %q, %q)", fullPath, requestedModulePath, requestedVersion)
 	defer middleware.ElapsedStat(ctx, "GetUnitMeta")()
 
-	if experiment.IsActive(ctx, internal.ExperimentUnitMetaWithLatest) {
-		modulePath := requestedModulePath
-		version := requestedVersion
-		var lmv *internal.LatestModuleVersions
-		if requestedVersion == internal.LatestVersion {
-			modulePath, version, lmv, err = db.getLatestUnitVersion(ctx, fullPath, requestedModulePath)
-			if err != nil {
-				return nil, err
-			}
+	modulePath := requestedModulePath
+	version := requestedVersion
+	var lmv *internal.LatestModuleVersions
+	if requestedVersion == internal.LatestVersion {
+		modulePath, version, lmv, err = db.getLatestUnitVersion(ctx, fullPath, requestedModulePath)
+		if err != nil {
+			return nil, err
 		}
-		return db.getUnitMetaWithKnownLatestVersion(ctx, fullPath, modulePath, version, lmv)
 	}
-	return db.legacyGetUnitMeta(ctx, fullPath, requestedModulePath, requestedVersion)
+	return db.getUnitMetaWithKnownLatestVersion(ctx, fullPath, modulePath, version, lmv)
 }
 
 func (db *DB) getUnitMetaWithKnownLatestVersion(ctx context.Context, fullPath, modulePath, version string, lmv *internal.LatestModuleVersions) (_ *internal.UnitMeta, err error) {
@@ -225,131 +221,6 @@ func (db *DB) getLatestUnitVersion(ctx context.Context, fullPath, requestedModul
 	return modulePath, latestVersion, nil, nil
 }
 
-func (db *DB) legacyGetUnitMeta(ctx context.Context, fullPath, requestedModulePath, requestedVersion string) (_ *internal.UnitMeta, err error) {
-	defer derrors.WrapStack(&err, "DB.legacyGetUnitMeta(ctx, %q, %q, %q)", fullPath, requestedModulePath, requestedVersion)
-
-	var (
-		q    string
-		args []interface{}
-	)
-	q, args, err = getUnitMetaQuery(fullPath, requestedModulePath, requestedVersion).PlaceholderFormat(squirrel.Dollar).ToSql()
-	if err != nil {
-		return nil, fmt.Errorf("squirrel.ToSql: %v", err)
-	}
-	var (
-		licenseTypes []string
-		licensePaths []string
-		um           = internal.UnitMeta{Path: fullPath}
-	)
-	err = db.db.QueryRow(ctx, q, args...).Scan(
-		&um.ModulePath,
-		&um.Version,
-		&um.CommitTime,
-		jsonbScanner{&um.SourceInfo},
-		&um.HasGoMod,
-		&um.ModuleInfo.IsRedistributable,
-		&um.Name,
-		&um.IsRedistributable,
-		pq.Array(&licenseTypes),
-		pq.Array(&licensePaths))
-	switch err {
-	case sql.ErrNoRows:
-		return nil, derrors.NotFound
-	case nil:
-		lics, err := zipLicenseMetadata(licenseTypes, licensePaths)
-		if err != nil {
-			return nil, err
-		}
-
-		if db.bypassLicenseCheck {
-			um.IsRedistributable = true
-		}
-
-		um.Licenses = lics
-		if err := populateLatestInfo(ctx, db, &um.ModuleInfo); err != nil {
-			return nil, err
-		}
-		return &um, nil
-	default:
-		return nil, err
-	}
-}
-
-func getUnitMetaQuery(fullPath, requestedModulePath, requestedVersion string) squirrel.SelectBuilder {
-	query := squirrel.Select(
-		"m.module_path",
-		"m.version",
-		"m.commit_time",
-		"m.source_info",
-		"m.has_go_mod",
-		"m.redistributable",
-		"u.name",
-		"u.redistributable",
-		"u.license_types",
-		"u.license_paths",
-	)
-	if requestedVersion != internal.LatestVersion {
-		query = query.From("modules m").
-			Join("units u on u.module_id = m.id").
-			Join("paths p ON p.id = u.path_id").Where(squirrel.Eq{"p.path": fullPath})
-		if requestedModulePath != internal.UnknownModulePath {
-			query = query.Where(squirrel.Eq{"m.module_path": requestedModulePath})
-		}
-		if internal.DefaultBranches[requestedVersion] {
-			query = query.Join("version_map vm ON m.id = vm.module_id").Where("vm.requested_version = ? ", requestedVersion)
-		} else if requestedVersion != internal.LatestVersion {
-			query = query.Where(squirrel.Eq{"version": requestedVersion})
-		}
-		return orderByLatest(query).Limit(1)
-	}
-
-	// Use a nested select to fetch the latest version of the unit, then JOIN
-	// on units to fetch other relevant information. This allows us to use the
-	// index on units.id and paths.path to get the latest path. We can then
-	// look up only the relevant information from the units table.
-	nestedSelect := orderByLatest(squirrel.Select(
-		"m.id",
-		"m.module_path",
-		"m.version",
-		"m.commit_time",
-		"m.source_info",
-		"m.has_go_mod",
-		"m.redistributable",
-		"u.id AS unit_id",
-	).From("modules m").
-		Join("units u ON u.module_id = m.id").
-		Join("paths p ON p.id = u.path_id").
-		Where(squirrel.Eq{"p.path": fullPath}))
-	if requestedModulePath != internal.UnknownModulePath {
-		nestedSelect = nestedSelect.Where(squirrel.Eq{"m.module_path": requestedModulePath})
-	}
-	nestedSelect = nestedSelect.Limit(1)
-	return query.From("units u").JoinClause(nestedSelect.Prefix("JOIN (").Suffix(") m ON u.id = m.unit_id"))
-}
-
-// orderByLatest orders paths according to the go command.
-// Versions are ordered by:
-// (1) release (non-incompatible)
-// (2) prerelease (non-incompatible)
-// (3) release, incompatible
-// (4) prerelease, incompatible
-// (5) pseudo
-// They are then sorted based on semver, then decreasing module path length (so
-// that nested modules are preferred).
-func orderByLatest(q squirrel.SelectBuilder) squirrel.SelectBuilder {
-	return q.OrderBy(
-		`CASE
-			WHEN m.version_type = 'release' AND NOT m.incompatible THEN 1
-			WHEN m.version_type = 'prerelease' AND NOT m.incompatible THEN 2
-			WHEN m.version_type = 'release' THEN 3
-			WHEN m.version_type = 'prerelease' THEN 4
-			ELSE 5
-		END`,
-		"m.series_path DESC",
-		"m.sort_version DESC",
-	).PlaceholderFormat(squirrel.Dollar)
-}
-
 // GetUnit returns a unit from the database, along with all of the data
 // associated with that unit.
 func (db *DB) GetUnit(ctx context.Context, um *internal.UnitMeta, fields internal.FieldSet) (_ *internal.Unit, err error) {
diff --git a/internal/postgres/unit_test.go b/internal/postgres/unit_test.go
index 37780f35..47de46d6 100644
--- a/internal/postgres/unit_test.go
+++ b/internal/postgres/unit_test.go
@@ -26,12 +26,7 @@ func TestGetUnitMeta(t *testing.T) {
 	t.Parallel()
 	ctx, cancel := context.WithTimeout(context.Background(), testTimeout*2)
 	defer cancel()
-	t.Run("legacy", func(t *testing.T) {
-		testGetUnitMeta(t, ctx)
-	})
-	t.Run("latest", func(t *testing.T) {
-		testGetUnitMeta(t, experiment.NewContext(ctx, internal.ExperimentUnitMetaWithLatest))
-	})
+	testGetUnitMeta(t, ctx)
 }
 
 func testGetUnitMeta(t *testing.T, ctx context.Context) {
@@ -207,104 +202,6 @@ func testGetUnitMeta(t *testing.T, ctx context.Context) {
 	}
 }
 
-func TestGetUnitMetaDiffs(t *testing.T) {
-	// Demonstrate differences between legacy and latest-version GetUnitMeta
-	// implementations.
-
-	t.Parallel()
-
-	type latest struct { // latest-version info
-		module  string
-		version string // latest raw and cooked version
-		goMod   string // go.mod file contents after "module" line
-	}
-
-	modver := func(u *internal.UnitMeta) string { return u.ModulePath + "@" + u.Version }
-
-	for _, test := range []struct {
-		name                   string
-		packages               []string // mod@ver/pkg
-		latests                []latest
-		path                   string
-		wantLatest, wantLegacy string
-	}{
-		{
-			name: "incompatible",
-			// When there are incompatible versions and no go.mod at the latest
-			// compatible version, the go command selects the highest
-			// incompatible version, but legacy GetUnitMeta selects the highest
-			// compatible version.
-			packages: []string{
-				"m.com@v1.0.0/a",
-				"m.com@v2.0.0+incompatible/a",
-			},
-			latests:    []latest{{"m.com", "v2.0.0+incompatible", ""}},
-			path:       "m.com/a",
-			wantLatest: "m.com@v2.0.0+incompatible",
-			wantLegacy: "m.com@v1.0.0",
-		},
-		{
-			name: "shorter",
-			// The go command prefers the longer path if both have latest-version information,
-			// but legacy GetUnitMeta prefers the shorter path if it has a release version.
-			packages: []string{
-				"m.com@v1.0.0/a/b",     // shorter path, release version
-				"m.com/a@v1.0.0-pre/b", // longer path, pre-release version
-			},
-			latests:    []latest{{"m.com", "v1.0.0", ""}, {"m.com/a", "v1.0.0-pre", ""}},
-			path:       "m.com/a/b",
-			wantLatest: "m.com/a@v1.0.0-pre",
-			wantLegacy: "m.com@v1.0.0",
-		},
-		{
-			name: "retraction",
-			// Legacy GetUnitMeta ignores retractions when picking the latest version.
-			packages: []string{
-				"m.com@v1.0.0/a",
-				"m.com@v1.1.0/a", // latest, also retracted
-			},
-			latests:    []latest{{"m.com", "v1.1.0", "retract v1.1.0"}},
-			path:       "m.com/a",
-			wantLatest: "m.com@v1.0.0",
-			wantLegacy: "m.com@v1.1.0",
-		},
-	} {
-		t.Run(test.name, func(t *testing.T) {
-			ctx := context.Background()
-			testDB, release := acquire(t)
-			defer release()
-
-			for _, p := range test.packages {
-				mod, ver, pkg := parseModuleVersionPackage(p)
-				m := sample.Module(mod, ver, pkg)
-				goMod := "module " + mod
-				for _, l := range test.latests {
-					if l.module == mod && l.version == ver {
-						goMod += "\n" + l.goMod
-						break
-					}
-				}
-				MustInsertModuleGoMod(ctx, t, testDB, m, goMod)
-			}
-			gotLegacy, err := testDB.GetUnitMeta(ctx, test.path, internal.UnknownModulePath, internal.LatestVersion)
-			if err != nil {
-				t.Fatal(err)
-			}
-			if got := modver(gotLegacy); got != test.wantLegacy {
-				t.Errorf("legacy: got %s, want %s", got, test.wantLegacy)
-			}
-			gotLatest, err := testDB.GetUnitMeta(experiment.NewContext(ctx, internal.ExperimentUnitMetaWithLatest),
-				test.path, internal.UnknownModulePath, internal.LatestVersion)
-			if err != nil {
-				t.Fatal(err)
-			}
-			if got := modver(gotLatest); got != test.wantLatest {
-				t.Errorf("latest: got %s, want %s", got, test.wantLatest)
-			}
-		})
-	}
-}
-
 func TestGetUnitMetaBypass(t *testing.T) {
 	t.Parallel()
 	testDB, release := acquire(t)
@@ -318,13 +215,13 @@ func TestGetUnitMetaBypass(t *testing.T) {
 		module, version, packageSuffix string
 		isMaster                       bool
 	}{
+		{"m.com", "v2.0.0+incompatible", "a", false},
+		{"m.com/b", "v2.0.0+incompatible", "a", true},
 		{"m.com", "v1.0.0", "a", false},
 		{"m.com", "v1.0.1", "dir/a", false},
 		{"m.com", "v1.1.0", "a/b", false},
 		{"m.com", "v1.2.0-pre", "a", true},
-		{"m.com", "v2.0.0+incompatible", "a", false},
 		{"m.com/a", "v1.1.0", "b", false},
-		{"m.com/b", "v2.0.0+incompatible", "a", true},
 	} {
 		m := sample.Module(testModule.module, testModule.version, testModule.packageSuffix)
 		makeModuleNonRedistributable(m)