Referential: Raise an error if the table lock times out

Paired with Johan on this one. There's an internal timeout on our table
lock. If it's reached, an
`ActiveRecord::StatementInvalid<PG::LockNotAvailable>` error is raised.
Use a custom error instead by "overriding" `#save` with a method that
raises our custom error in that case instead. This will enable us to
provide a custom user-facing error in the event this happens.

Refs #5024

1 files changed, 57 insertions, 2 deletions

diff --git a/spec/models/referential/referential_lock_during_creation_spec.rb b/spec/models/referential/referential_lock_during_creation_spec.rb
index 0002af549..d17327d39 100644
--- a/spec/models/referential/referential_lock_during_creation_spec.rb
+++ b/spec/models/referential/referential_lock_during_creation_spec.rb
@@ -1,8 +1,7 @@
 RSpec.describe Referential, type: :model do
+  let (:workbench) { create(:workbench) }
 
   context "when two identical Referentials are created, only one is saved" do
-    let( :workbench ){ create :workbench }
-
     it "works synchronously" do
       referential_1 = build(
         :referential,
@@ -76,5 +75,61 @@ RSpec.describe Referential, type: :model do
         end
       end
     end
+
+  context "when two Referentials are created at the same time" do
+    it "raises an error when the DB lock timeout is reached", truncation: true do
+      begin
+        referential_1 = build(
+          :referential,
+          workbench: workbench,
+          organisation: workbench.organisation
+        )
+        referential_2 = referential_1.dup
+        referential_2.slug = "#{referential_1.slug}_different"
+        referential_3 = nil
+
+        metadata_1 = build(:referential_metadata, referential: nil)
+        metadata_2 = metadata_1.dup
+
+        referential_1.metadatas << metadata_1
+        referential_2.metadatas << metadata_2
+
+        thread_1 = Thread.new do
+          ActiveRecord::Base.transaction do
+            ActiveRecord::Base.connection.execute("SET LOCAL lock_timeout = '1s'")
+
+            # seize LOCK
+            referential_1.save
+            sleep 10
+            # release LOCK
+          end
+        end
+
+        thread_2 = Thread.new do
+          sleep 5
+          ActiveRecord::Base.transaction do
+            ActiveRecord::Base.connection.execute("SET LOCAL lock_timeout = '1s'")
+            # waits for LOCK, (because of sleep 5)
+            referential_2.save
+            # when lock was eventually obtained validation failed
+            referential_3 = create(:referential)
+          end
+        end
+
+        thread_1.join
+        expect do
+          thread_2.join
+        end.to raise_error(TableLockTimeoutError)
+
+        expect(referential_1).to be_persisted
+      ensure
+        Apartment::Tenant.drop(referential_1.slug) if referential_1.persisted?
+        Apartment::Tenant.drop(referential_2.slug) if referential_2.persisted?
+
+        if referential_3.try(:persisted?)
+          Apartment::Tenant.drop(referential_3.slug)
+        end
+      end
+    end
   end
 end