MDEV-16277 tcp_nodelay session variable to enable / disable Nagle algorithm

1 files changed, 36 insertions, 8 deletions

diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc
index 3ac84fb61cc..75a962939ae 100644
--- a/sql/sys_vars.cc
+++ b/sql/sys_vars.cc
@@ -4039,6 +4039,16 @@ static bool fix_sql_log_bin_after_update(sys_var *self, THD *thd,
   return FALSE;
 }
 
+static bool check_session_only_variable(sys_var *self, THD *,set_var *var)
+{
+  if (unlikely(var->type == OPT_GLOBAL))
+  {
+    my_error(ER_INCORRECT_GLOBAL_LOCAL_VAR, MYF(0), self->name.str, "SESSION");
+    return true;
+  }
+  return false;
+}
+
 /**
   This function checks if the sql_log_bin can be changed,
   what is possible if:
@@ -4054,20 +4064,17 @@ static bool fix_sql_log_bin_after_update(sys_var *self, THD *thd,
 static bool check_sql_log_bin(sys_var *self, THD *thd, set_var *var)
 {
   if (check_has_super(self, thd, var))
-    return TRUE;
+    return true;
 
-  if (unlikely(var->type == OPT_GLOBAL))
-  {
-    my_error(ER_INCORRECT_GLOBAL_LOCAL_VAR, MYF(0), self->name.str, "SESSION");
-    return TRUE;
-  }
+  if (check_session_only_variable(self, thd, var))
+    return true;
 
   if (unlikely(error_if_in_trans_or_substatement(thd,
                                                  ER_STORED_FUNCTION_PREVENTS_SWITCH_SQL_LOG_BIN,
                                                  ER_INSIDE_TRANSACTION_PREVENTS_SWITCH_SQL_LOG_BIN)))
-    return TRUE;
+    return true;
 
-  return FALSE;
+  return false;
 }
 
 static Sys_var_mybool Sys_log_binlog(	
@@ -5579,6 +5586,27 @@ static Sys_var_int Sys_keepalive_probes(
        BLOCK_SIZE(1),
        NO_MUTEX_GUARD, NOT_IN_BINLOG, ON_CHECK(NULL));
 
+
+static bool update_tcp_nodelay(sys_var *self, THD *thd,
+  enum_var_type type)
+{
+  DBUG_ASSERT(thd);
+
+  Vio *vio = thd->net.vio;
+  if (vio)
+    return (MY_TEST(vio_nodelay(vio, thd->variables.tcp_nodelay)));
+
+  return false;
+}
+
+static Sys_var_mybool Sys_tcp_nodelay(
+       "tcp_nodelay",
+       "Set option TCP_NODELAY (disable Nagle's algorithm) on socket",
+       SESSION_VAR(tcp_nodelay), CMD_LINE(OPT_ARG),
+       DEFAULT(TRUE),NO_MUTEX_GUARD, NOT_IN_BINLOG,
+       ON_CHECK(check_session_only_variable),
+       ON_UPDATE(update_tcp_nodelay));
+
 static Sys_var_charptr Sys_ignore_db_dirs(
        "ignore_db_dirs",
        "Specifies a directory to add to the ignore list when collecting "