refactor: inline the instance lookup queries

Put each lookup at its only call site, and drop the two helpers that
forwarded a single query. Assert that every worker in the create race
test finishes, and kill any worker that outlives its timeout, so a
worker cannot hold a pooled connection while the assertions run.

Author: cardmagic

lib/solid_objects/mailbox.rb

@@ -107,19 +107,14 @@ def with_instance_retry
 
     # @rbs (Reference, Class) -> Instance
     def find_or_create_instance(reference, actor_class)
-      identifier = instance_identifier(reference)
+      identifier = Instance
+        .where(actor_type: reference.actor_type, actor_id: reference.actor_id)
+        .pick(:id)
       return lock_instance!(identifier) if identifier
 
       create_locked_instance(reference, actor_class)
     end
 
-    # @rbs (Reference) -> Integer?
-    def instance_identifier(reference)
-      Instance
-        .where(actor_type: reference.actor_type, actor_id: reference.actor_id)
-        .pick(:id)
-    end
-
     # @rbs (Reference, Class) -> Instance
     def create_locked_instance(reference, actor_class)
       Instance.transaction(requires_new: true) do
@@ -131,14 +126,10 @@ def create_locked_instance(reference, actor_class)
         )
       end
     rescue ActiveRecord::RecordNotUnique
-      lock_instance!(committed_instance_identifier(reference))
-    end
-
-    # @rbs (Reference) -> Integer?
-    def committed_instance_identifier(reference)
-      database_adapter.share_locked(
+      identifier = database_adapter.share_locked(
         Instance.where(actor_type: reference.actor_type, actor_id: reference.actor_id)
       ).pick(:id)
+      lock_instance!(identifier)
     end
 
     # @rbs (Integer?) -> Instance

sig/generated/lib/solid_objects/mailbox.rbs

@@ -28,15 +28,9 @@ module SolidObjects
     # @rbs (Reference, Class) -> Instance
     def find_or_create_instance: (Reference, Class) -> Instance
 
-    # @rbs (Reference) -> Integer?
-    def instance_identifier: (Reference) -> Integer?
-
     # @rbs (Reference, Class) -> Instance
     def create_locked_instance: (Reference, Class) -> Instance
 
-    # @rbs (Reference) -> Integer?
-    def committed_instance_identifier: (Reference) -> Integer?
-
     # @rbs (Integer?) -> Instance
     def lock_instance!: (Integer?) -> Instance
 

test/integration/enqueue_test.rb

@@ -116,8 +116,10 @@ def add(product_id:)
     end
 
     threads.length.times { start << true }
-    threads.each { |thread| thread.join(30) }
+    unfinished = threads.reject { |thread| thread.join(30) }
+    unfinished.each(&:kill).each(&:join)
 
+    assert_empty unfinished, "an enqueue was still running after its timeout"
     assert_empty errors.size.times.map { errors.pop }
     assert_equal (1..8).to_a, sequences.size.times.map { sequences.pop }.sort
     assert_equal 1, SolidObjects::Instance.where(actor_type: "enqueue-carts", actor_id: "alice").count