Backpressure final touches (#3019)

Author: comandeo-mongo

lib/mongo/session.rb

@@ -1408,10 +1408,16 @@ def backoff_would_exceed_deadline?(deadline, backoff_seconds)
     end
 
     # Implements makeTimeoutError(lastError) from the transactions-convenient-api spec.
-    # In CSOT mode raises TimeoutError with last_error's message included as a substring.
+    # In CSOT mode raises TimeoutError with last_error's message and labels copied.
     # In non-CSOT mode re-raises last_error directly.
     def make_timeout_error_from(last_error, timeout_message)
-      raise Mongo::Error::TimeoutError, "#{timeout_message}: #{last_error}" if @with_transaction_timeout_ms
+      if @with_transaction_timeout_ms
+        timeout_error = Mongo::Error::TimeoutError.new("#{timeout_message}: #{last_error}")
+        if last_error.respond_to?(:labels)
+          last_error.labels.each { |label| timeout_error.add_label(label) }
+        end
+        raise timeout_error
+      end
 
       raise last_error
     end

spec/mongo/retryable/retryable_writes_error_propagation_prose_spec.rb

@@ -132,8 +132,11 @@
   # some errors with NoWritesPerformed and some without.
   context 'Case 3: mixed errors with and without NoWritesPerformed' do
     it 'returns the error without NoWritesPerformed (91)' do
-      # Step 2: Via CommandFailedEvent, configure a fail point with
-      # error code 91 and NoWritesPerformed for subsequent retries.
+      # Step 3 (set up before step 2 so the listener is active when
+      # the first failure occurs): Via CommandFailedEvent, configure
+      # a fail point with error code 91 and NoWritesPerformed for
+      # subsequent retries. Configure only if the failed event is for
+      # the first error configured in step 2.
       failpoint_set = false
       subscriber = Mrss::EventSubscriber.new
       client.subscribe(Mongo::Monitoring::COMMAND, subscriber)
@@ -154,8 +157,9 @@
         end
       end
 
-      # Step 3: Configure initial fail point with error code 91
-      # WITHOUT NoWritesPerformed.
+      # Step 2: Configure initial fail point with error code 91
+      # (ShutdownInProgress) with RetryableError and
+      # SystemOverloadedError labels, without NoWritesPerformed.
       admin_client.command(
         configureFailPoint: 'failCommand',
         mode: { times: 1 },

spec/mongo/session/with_transaction_timeout_spec.rb

@@ -120,10 +120,13 @@ def make_commit_overload_error
     context 'when callback raises TransientTransactionError and retry timeout is exceeded' do
       let(:transient_error) { make_transient_error }
 
-      it 'propagates the error as TimeoutError including the transient error message' do
+      it 'propagates the error as TimeoutError with the same labels as the wrapped error' do
         with_expired_deadline_after(initial_calls: 1) do
           ex = expect { session.with_transaction(timeout_ms: 1) { raise transient_error } }
-          ex.to raise_error(Mongo::Error::TimeoutError) { |e| expect(e.message).to include(transient_error.message) }
+          ex.to raise_error(Mongo::Error::TimeoutError) do |e|
+            expect(e.message).to include(transient_error.message)
+            expect(e.labels).to match_array(transient_error.labels)
+          end
         end
       end
     end
@@ -133,14 +136,17 @@ def make_commit_overload_error
 
       before { allow(session).to receive(:commit_transaction) { raise commit_error } }
 
-      it 'propagates the error as TimeoutError including the commit error message' do
+      it 'propagates the error as TimeoutError with the same labels as the wrapped error' do
         with_expired_deadline_after(initial_calls: 2) do
           ex = expect do
             session.with_transaction(timeout_ms: 1) do
               session.instance_variable_set(:@state, Mongo::Session::TRANSACTION_IN_PROGRESS_STATE)
             end
           end
-          ex.to raise_error(Mongo::Error::TimeoutError) { |e| expect(e.message).to include(commit_error.message) }
+          ex.to raise_error(Mongo::Error::TimeoutError) do |e|
+            expect(e.message).to include(commit_error.message)
+            expect(e.labels).to match_array(commit_error.labels)
+          end
         end
       end
     end
@@ -150,14 +156,17 @@ def make_commit_overload_error
 
       before { allow(session).to receive(:commit_transaction) { raise commit_error } }
 
-      it 'propagates the error as TimeoutError including the commit error message' do
+      it 'propagates the error as TimeoutError with the same labels as the wrapped error' do
         with_expired_deadline_after(initial_calls: 2) do
           ex = expect do
             session.with_transaction(timeout_ms: 1) do
               session.instance_variable_set(:@state, Mongo::Session::TRANSACTION_IN_PROGRESS_STATE)
             end
           end
-          ex.to raise_error(Mongo::Error::TimeoutError) { |e| expect(e.message).to include(commit_error.message) }
+          ex.to raise_error(Mongo::Error::TimeoutError) do |e|
+            expect(e.message).to include(commit_error.message)
+            expect(e.labels).to match_array(commit_error.labels)
+          end
         end
       end
     end

spec/spec_tests/data/sdam/errors/error_handling_handshake.yml

@@ -37,7 +37,9 @@ phases:
     type: timeout
   outcome: *outcome
 
-- description: Mark server unknown on network timeout application error (beforeHandshakeCompletes)
+- description: Ignore network timeout application error (beforeHandshakeCompletes)
+  # The test runner may need to add the SystemOverloadedError label for the pre-handshake network timeout.
+  # The SystemOverloadedError label causes the error to be ignored.
   applicationErrors:
   - address: a:27017
     when: beforeHandshakeCompletes