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Fix slave reconnection regression

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The state of the backend needs to be checked before any pending session
commands are executed on it.

Added debug assertions to catch invalid use of the status functions of
closed backends.
This commit is contained in:
Markus Mäkelä
2018-06-16 17:24:44 +03:00
parent 7a354bb28e
commit 1f166482b2
3 changed files with 9 additions and 4 deletions
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1
include/maxscale/backend.hh
View File

@ -100,6 +100,7 @@ public:
*/
inline bool has_session_commands() const
{
ss_dassert(in_use());
return !m_session_commands.empty();
}

4
server/modules/routing/readwritesplit/rwsplit_route_stmt.cc
View File

@ -64,8 +64,8 @@ static SRWBackend compare_backends(SRWBackend a, SRWBackend b, select_criteria_t
}
// Prefer servers that are not busy executing session commands
bool a_busy = a->has_session_commands();
bool b_busy = b->has_session_commands();
bool a_busy = a->in_use() && a->has_session_commands();
bool b_busy = b->in_use() && b->has_session_commands();
if (a_busy && !b_busy)
{

8
server/modules/routing/readwritesplit/rwsplitsession.cc
View File

@ -547,12 +547,14 @@ void RWSplitSession::clientReply(GWBUF *writebuf, DCB *backend_dcb)
if (backend->has_session_commands())
{
/** Reply to an executed session command */
/** Process the reply to an executed session command. This function can
* close the backend if it's a slave. */
process_sescmd_response(backend, &writebuf);
}
if (backend->has_session_commands())
if (backend->in_use() && backend->has_session_commands())
{
// Backend is still in use and has more session commands to execute
if (backend->execute_session_command() && backend->is_waiting_result())
{
m_expected_responses++;
@ -560,12 +562,14 @@ void RWSplitSession::clientReply(GWBUF *writebuf, DCB *backend_dcb)
}
else if (m_expected_responses == 0 && m_query_queue)
{
// All replies received, route any stored queries
route_stored_query();
}
if (writebuf)
{
ss_dassert(client_dcb);
ss_info_dassert(backend->in_use(), "Backend should be in use when routing reply");
/** Write reply to client DCB */
MXS_SESSION_ROUTE_REPLY(backend_dcb->session, writebuf);
}