Protect against missing guard in check_return.

Author: samuel-williams-shopify

lib/async/safe/monitor.rb

@@ -16,6 +16,10 @@ module Safe
 		# Uses TracePoint to track in-flight method calls and detect concurrent access.
 		class Monitor
 			ASYNC_SAFE = true
+
+			IS_A = Kernel.instance_method(:is_a?)
+			FROZEN = Kernel.instance_method(:frozen?)
+			CLASS = Kernel.instance_method(:class)
 
 			# Initialize a new concurrency monitor.
 			def initialize
@@ -66,15 +70,15 @@ def transfer(*objects)
 				object = trace_point.self
 
 				# Skip tracking class/module methods:
-				return if object.is_a?(Module)
+				return if IS_A.bind_call(object, Module)
 
 				# Skip frozen objects:
-				return if object.frozen?
+				return if FROZEN.bind_call(object)
 
 				method = trace_point.method_id
 
 				# Check the object's actual class:
-				klass = object.class
+				klass = CLASS.bind_call(object)
 
 				# Check if the class or method is marked as async-safe:
 				# Returns: true (skip), false (simple tracking), or Symbol (guard-based tracking)
@@ -140,15 +144,15 @@ def transfer(*objects)
 				object = trace_point.self
 
 				# Skip tracking class/module methods:
-				return if object.is_a?(Module)
+				return if IS_A.bind_call(object, Module)
 
 				# Skip frozen objects:
-				return if object.frozen?
+				return if FROZEN.bind_call(object)
 
 				method = trace_point.method_id
 
 				# Check the object's actual class:
-				klass = object.class
+				klass = CLASS.bind_call(object)
 
 				# Check if the class or method is marked as async-safe:
 				safe = klass.async_safe?(method)
@@ -159,6 +163,9 @@ def transfer(*objects)
 				@mutex.synchronize do
 					entry = @guards[object]
 
+					# No guard held, nothing to release:
+					return unless entry
+					
 					if safe == false
 						# Simple tracking (single guard)
 						# Release if this fiber holds it

releases.md

@@ -1,5 +1,10 @@
 # Releases
 
+## Unreleased
+
+  - Protect against missing guard in `check_return`.
+  - Use `Kernel` instance methods to handle broken proxy objects directly.
+
 ## v0.5.0
 
   - More conservative tracking of objects using call/return for ownership transfer.