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MXS-1516: Validate the connection on each query

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A subset of the checks done at connection creation time need to be done at
query routing time. This guarantees that the connection is closed if the
server no longer qualifies as a valid candidate.

Added teset case that checks that a change in the replication topology
correctly breaks the connection.
This commit is contained in:
Markus Mäkelä
2018-01-02 11:00:56 +02:00
parent 3f0ef7481e
commit bacc11d28e
3 changed files with 68 additions and 3 deletions
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41
server/modules/routing/readconnroute/readconnroute.c
View File

@ -510,7 +510,7 @@ closeSession(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session)
/** Log routing failure due to closed session */
static void log_closed_session(mysql_server_cmd_t mysql_command, bool is_closed,
SERVER_REF *ref)
SERVER_REF *ref, bool valid)
{
char msg[MAX_SERVER_NAME_LEN + 200] = ""; // Extra space for message
@ -526,11 +526,44 @@ static void log_closed_session(mysql_server_cmd_t mysql_command, bool is_closed,
{
sprintf(msg, "Server '%s' is in maintenance.", ref->server->unique_name);
}
else if (!valid)
{
sprintf(msg, "Server '%s' no longer qualifies as a target server.",
ref->server->unique_name);
}
MXS_ERROR("Failed to route MySQL command %d to backend server. %s",
mysql_command, msg);
}
/**
* Check if the server we're connected to is still valid
*
* @param inst Router instance
* @param router_cli_ses Router session
*
* @return True if the backend connection is still valid
*/
static inline bool connection_is_valid(ROUTER_INSTANCE* inst, ROUTER_CLIENT_SES* router_cli_ses)
{
bool rval = false;
if (SERVER_IS_RUNNING(router_cli_ses->backend->server) &&
(router_cli_ses->backend->server->status & inst->bitmask & inst->bitvalue))
{
if (inst->bitvalue & SERVER_MASTER)
{
rval = router_cli_ses->backend == get_root_master(inst->service->dbref);
}
else
{
rval = true;
}
}
return rval;
}
/**
* We have data from the client, we must route it to the backend.
* This is simply a case of sending it to the connection that was
@ -574,10 +607,12 @@ routeQuery(MXS_ROUTER *instance, MXS_ROUTER_SESSION *router_session, GWBUF *queu
rses_end_locked_router_action(router_cli_ses);
}
bool valid;
if (rses_is_closed || backend_dcb == NULL ||
!SERVER_IS_RUNNING(router_cli_ses->backend->server))
(valid = !connection_is_valid(inst, router_cli_ses)))
{
log_closed_session(mysql_command, rses_is_closed, router_cli_ses->backend);
log_closed_session(mysql_command, rses_is_closed, router_cli_ses->backend, valid);
gwbuf_free(queue);
goto return_rc;