Fix RUBY-1661 Non-mongo exception in abort_transaction does not change session state (#1207)

Author: p-mongo

docs/tutorials/ruby-driver-transactions.txt

@@ -110,6 +110,39 @@ To commit or abort a transaction, call ``commit_transaction`` or
 
   session.abort_transaction
 
+Note: an outstanding transaction can hold locks to various objects in the
+server, such as the database. For example, the drop call in the following
+snippet will hang for `transactionLifetimeLimitSeconds
+<https://docs.mongodb.com/manual/reference/parameters/#param.transactionLifetimeLimitSeconds>`_
+seconds (default 60) until the server expires and aborts the transaction:
+
+.. code-block:: ruby
+
+  c1 = Mongo::Client.new(['127.0.0.1:27017']).use(:test_db)
+  session = c1.start_session
+  c1['foo'].insert_one(test: 1)
+  session.start_transaction
+  c1['foo'].insert_one({test: 2}, session: session)
+  
+  c2 = Mongo::Client.new(['127.0.0.1:27017']).use(:test_db)
+  # hangs
+  c2.database.drop
+
+Since transactions are associated with server-side sessions, closing the client
+does not abort a transaction that this client initiated - the application must
+either call ``abort_transaction`` or wait for the transaction to time out on
+the server side. In addition to committing or aborting the transaction, an
+application can also end the session which will abort a transaction on this
+session if one is in progress:
+
+.. code-block:: ruby
+
+  session.end_session
+
+  c2 = Mongo::Client.new(['127.0.0.1:27017']).use(:test_db)
+  # ok
+  c2.database.drop
+
 
 Retrying Commits
 ----------------

lib/mongo/session.rb

@@ -697,6 +697,9 @@ def abort_transaction
         raise
       rescue Mongo::Error
         @state = TRANSACTION_ABORTED_STATE
+      rescue Exception
+        @state = TRANSACTION_ABORTED_STATE
+        raise
       end
     end
 

spec/mongo/session_transaction_spec.rb

@@ -22,6 +22,54 @@ class SessionTransactionSpecError < StandardError; end
     collection.delete_many
   end
 
+  describe '#abort_transaction' do
+    require_topology :replica_set
+
+    context 'when a non-Mongo error is raised' do
+      before do
+        collection.insert_one({foo: 1})
+      end
+
+      it 'propagates the exception and sets state to transaction aborted' do
+        session.start_transaction
+        collection.insert_one({foo: 1}, session: session)
+        expect(session).to receive(:write_with_retry).and_raise(SessionTransactionSpecError)
+        expect do
+          session.abort_transaction
+        end.to raise_error(SessionTransactionSpecError)
+        expect(session.send(:within_states?, Mongo::Session::TRANSACTION_ABORTED_STATE)).to be true
+
+        # Since we failed abort_transaction call, the transaction is still
+        # outstanding. It will cause subsequent tests to stall until it times
+        # out on the server side. End the session to force the server
+        # to close the transaction.
+        kill_all_server_sessions
+      end
+    end
+
+    context 'when a Mongo error is raised' do
+      before do
+        collection.insert_one({foo: 1})
+      end
+
+      it 'swallows the exception and sets state to transaction aborted' do
+        session.start_transaction
+        collection.insert_one({foo: 1}, session: session)
+        expect(session).to receive(:write_with_retry).and_raise(Mongo::Error::SocketError)
+        expect do
+          session.abort_transaction
+        end.not_to raise_error
+        expect(session.send(:within_states?, Mongo::Session::TRANSACTION_ABORTED_STATE)).to be true
+
+        # Since we failed abort_transaction call, the transaction is still
+        # outstanding. It will cause subsequent tests to stall until it times
+        # out on the server side. End the session to force the server
+        # to close the transaction.
+        kill_all_server_sessions
+      end
+    end
+  end
+
   describe '#with_transaction' do
     context 'callback successful' do
       it 'commits' do

spec/spec_helper.rb

@@ -15,6 +15,12 @@
 RSpec.configure do |config|
   config.include(Authorization)
   config.extend(Constraints)
+
+  config.before(:all) do
+    if ClusterConfig.instance.fcv_ish >= '3.6'
+      kill_all_server_sessions
+    end
+  end
 end
 
 # Determine whether the test clients are connecting to a sharded cluster

spec/support/common_shortcuts.rb

@@ -12,6 +12,19 @@ def declare_topology_double
   end
 
   module InstanceMethods
+    def kill_all_server_sessions
+      begin
+        ClientRegistry.instance.global_client('root_authorized').command(killAllSessions: [])
+      # killAllSessions also kills the implicit session which the driver uses
+      # to send this command, as a result it always fails
+      rescue Mongo::Error::OperationFailure => e
+        # "operation was interrupted"
+        unless e.code == 11601
+          raise
+        end
+      end
+    end
+
     def wait_for_all_servers(cluster)
       # Cluster waits for initial round of sdam until the primary
       # is discovered, which means by the time a connection is obtained