feat: fail CI when pubsub.Publish calls are found in db transactions (#17903)

dannykopping · Emyrk · web-flow · commit 87dc2478a9f6 · 2025-05-19T14:52:51.000Z
Publishing inside a db transaction can lead to database connection starvation/contention since it requires its own connection. This ruleguard rule (one-shotted by Claude Sonnet 3.7 and finalized by @Emyrk) will detect two of the following 3 instances: ```go type Nested struct { ps pubsub.Pubsub } func TestFail(t *testing.T) { t.Parallel() db, ps := dbtestutil.NewDB(t) nested := &Nested{ ps: ps, } // will catch this _ = db.InTx(func(_ database.Store) error { _, _ = fmt.Printf("") _ = ps.Publish("", []byte{}) return nil }, nil) // will catch this _ = db.InTx(func(_ database.Store) error { _ = nested.ps.Publish("", []byte{}) return nil }, nil) // will NOT catch this _ = db.InTx(func(_ database.Store) error { blah(ps) return nil }, nil) } func blah(ps pubsub.Pubsub) { ps.Publish("", []byte{}) } ``` The ruleguard doesn't recursively introspect function calls so only the first two cases will be guarded against, but it's better than nothing. <img width="1444" alt="image" src="https://github.com/user-attachments/assets/8ffa0d88-16a0-41a9-9521-21211910dec9" /> --------- Signed-off-by: Danny Kopping <dannykopping@gmail.com> Co-authored-by: Steven Masley <stevenmasley@gmail.com>
diff --git a/scripts/rules.go b/scripts/rules.go
@@ -134,6 +134,42 @@ func databaseImport(m dsl.Matcher) {
 		Where(m.File().PkgPath.Matches("github.com/coder/coder/v2/codersdk"))
 }
 
+// publishInTransaction detects calls to Publish inside database transactions
+// which can lead to connection starvation.
+//
+//nolint:unused,deadcode,varnamelen
+func publishInTransaction(m dsl.Matcher) {
+	m.Import("github.com/coder/coder/v2/coderd/database/pubsub")
+
+	// Match direct calls to the Publish method of a pubsub instance inside InTx
+	m.Match(`
+		$_.InTx(func($x) error {
+			$*_
+			$_ = $ps.Publish($evt, $msg)
+			$*_
+		}, $*_)
+	`,
+		// Alternative with short variable declaration
+		`
+		$_.InTx(func($x) error {
+			$*_
+			$_ := $ps.Publish($evt, $msg)
+			$*_
+		}, $*_)
+	`,
+		// Without catching error return
+		`
+		$_.InTx(func($x) error {
+			$*_
+			$ps.Publish($evt, $msg)
+			$*_
+		}, $*_)
+	`).
+		Where(m["ps"].Type.Is("pubsub.Pubsub")).
+		At(m["ps"]).
+		Report("Avoid calling pubsub.Publish() inside database transactions as this may lead to connection deadlocks. Move the Publish() call outside the transaction.")
+}
+
 // doNotCallTFailNowInsideGoroutine enforces not calling t.FailNow or
 // functions that may themselves call t.FailNow in goroutines outside
 // the main test goroutine. See testing.go:834 for why.
