Simplified locking in sha256 tests by using GET_LOCK

test/integration/db_setup_sha256.sql

@@ -27,10 +27,4 @@ ALTER USER 'csha2p_empty_password_user'@'%' IDENTIFIED BY '';
 GRANT ALL PRIVILEGES ON boost_mysql_integtests.* TO 'csha2p_empty_password_user'@'%';
 
 
--- caching_sha2_password behaves differently on sha256 cache hit and miss.
--- These tests require exclusive access to the cache, and lock this table
--- to avoid race conditions (e.g. between concurrent b2 runs)
-DROP TABLE IF EXISTS sha256_mutex;
-CREATE TABLE sha256_mutex (dummy INT);
-
-FLUSH PRIVILEGES;
+FLUSH PRIVILEGES;

test/integration/test/handshake.cpp

@@ -165,8 +165,8 @@ BOOST_FIXTURE_TEST_CASE(tcp_connection_, tcp_connection_fixture)
 
 BOOST_AUTO_TEST_SUITE_END()  // mysql_native_password
 
-// caching_sha2_password. We acquire a lock on the sha256_mutex
-// (dummy table, used as a mutex) to avoid race conditions with other test runs
+// caching_sha2_password. We acquire a named lock
+// to avoid race conditions with other test runs
 // (which happens in b2 builds).
 // The sha256 cache is shared between all clients.
 struct caching_sha2_lock : any_connection_fixture
@@ -177,9 +177,9 @@ struct caching_sha2_lock : any_connection_fixture
         conn.async_connect(connect_params_builder().credentials("root", "").build(), as_netresult)
             .validate_no_error();
 
-        // Acquire the lock
+        // Acquire the lock. -1 = no timeout
         results r;
-        conn.async_execute("LOCK TABLE sha256_mutex WRITE", r, as_netresult).validate_no_error();
+        conn.async_execute("DO GET_LOCK('sha256_cache', -1)", r, as_netresult).validate_no_error();
 
         // The lock is released on fixture destruction, when the connection is closed
     }