kep-808 - a garbage collection callback is added to a session as it i…

…s added to the session pool

pbft/pbft.cpp

@@ -1894,7 +1894,7 @@ void pbft::add_session_to_pool(const std::string& msg_hash, std::shared_ptr<bzn:
     if (session)
     {
         this->sessions_waiting_on_forwarded_requests[msg_hash] = session;
-        session->add_shutdown_handler([&]()
+        session->add_shutdown_handler([msg_hash, this]()
                                         {
                                             std::lock_guard<std::mutex> lock(this->pbft_lock);
                                             auto it = this->sessions_waiting_on_forwarded_requests.find(msg_hash);

pbft/pbft.hpp

@@ -50,6 +50,7 @@ namespace bzn
     {
         // fwd declare test as it's not in the same namespace...
         class pbft_test_database_response_is_forwarded_to_session_Test;
+        class pbft_test_add_session_to_pool_can_add_a_session_and_shutdown_handler_removes_session_from_pool_Test;
     }
 
     using request_hash_t = std::string;
@@ -298,6 +299,7 @@ namespace bzn
         FRIEND_TEST(pbft_newview_test, get_sequences_and_request_hashes_from_proofs);
         FRIEND_TEST(pbft_newview_test, test_last_sequence_in_newview_prepared_proofs);
         FRIEND_TEST(bzn::test::pbft_test, database_response_is_forwarded_to_session);
+        FRIEND_TEST(bzn::test::pbft_test, add_session_to_pool_can_add_a_session_and_shutdown_handler_removes_session_from_pool);
 
         friend class pbft_proto_test;
         friend class pbft_join_leave_test;

pbft/test/pbft_test.cpp

@@ -200,6 +200,34 @@ namespace bzn::test
         this->database_response_handler(this->request_msg, mock_session);
     }
 
+    TEST_F(pbft_test, add_session_to_pool_can_add_a_session_and_shutdown_handler_removes_session_from_pool)
+    {
+        this->build_pbft();
+
+        EXPECT_EQ(size_t(0), this->pbft->sessions_waiting_on_forwarded_requests.size());
+
+        bzn::session_shutdown_handler shutdown_handler{0};
+
+        EXPECT_CALL(*mock_session, add_shutdown_handler(_))
+            .Times(Exactly(1))
+            .WillRepeatedly(Invoke([&](auto handler) {
+                shutdown_handler = handler;
+            }));
+
+        EXPECT_CALL(*mock_session, is_open())
+            .WillOnce(Return(false));
+
+        pbft->handle_database_message(this->request_msg, this->mock_session);
+
+        EXPECT_EQ(size_t(1), this->pbft->sessions_waiting_on_forwarded_requests.size());
+
+        EXPECT_TRUE(shutdown_handler != nullptr);
+
+        shutdown_handler();
+
+        EXPECT_EQ(size_t(0), this->pbft->sessions_waiting_on_forwarded_requests.size());
+    }
+
 
     TEST_F(pbft_test, client_request_executed_results_in_message_response)
     {