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Refactor readwritesplit session creation

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Moved the initialization of the router session's member variables into the
constructor. Changed two functions that calculated server counts into the
router instance as they don't relate to a particular session.
This commit is contained in:
Markus Mäkelä
2017-08-16 22:11:58 +03:00
parent ec33eaada1
commit 46b7db1d45
4 changed files with 90 additions and 130 deletions
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215
server/modules/routing/readwritesplit/readwritesplit.cc
View File

@ -60,43 +60,12 @@ static void handle_error_reply_client(MXS_SESSION *ses, RWSplitSession *rses,
static bool handle_error_new_connection(RWSplit *inst,
RWSplitSession **rses,
DCB *backend_dcb, GWBUF *errmsg);
static bool have_enough_servers(RWSplitSession *rses, const int min_nsrv,
int router_nsrv, RWSplit *router);
static bool route_stored_query(RWSplitSession *rses);
/**
* Internal functions
*/
/**
* @brief Get count of backend servers that are slaves.
*
* Find out the number of read backend servers.
* Depending on the configuration value type, either copy direct count
* of slave connections or calculate the count from percentage value.
*
* @param rses Router client session
* @param router_nservers The number of backend servers in total
*/
int rses_get_max_slavecount(RWSplitSession *rses)
{
int conf_max_nslaves;
int router_nservers = rses->rses_nbackends;
CHK_CLIENT_RSES(rses);
if (rses->rses_config.max_slave_connections > 0)
{
conf_max_nslaves = rses->rses_config.max_slave_connections;
}
else
{
conf_max_nslaves = (router_nservers * rses->rses_config.rw_max_slave_conn_percent) / 100;
}
return MXS_MIN(router_nservers - 1, MXS_MAX(1, conf_max_nslaves));
}
/*
* @brief Get the maximum replication lag for this router
*
@ -448,7 +417,7 @@ static bool handle_error_new_connection(RWSplit *inst,
route_stored_query(myrses);
}
int max_nslaves = rses_get_max_slavecount(myrses);
int max_nslaves = inst->max_slave_count();
bool succp;
/**
* Try to get replacement slave or at least the minimum
@ -456,7 +425,7 @@ static bool handle_error_new_connection(RWSplit *inst,
*/
if (inst->config().disable_sescmd_history)
{
succp = have_enough_servers(myrses, 1, myrses->rses_nbackends, inst) ? true : false;
succp = inst->have_enough_servers();
}
else
{
@ -469,64 +438,6 @@ static bool handle_error_new_connection(RWSplit *inst,
return succp;
}
/**
* @brief Calculate whether we have enough servers to route a query
*
* @param p_rses Router session
* @param min_nsrv Minimum number of servers that is sufficient
* @param nsrv Actual number of servers
* @param router Router instance
*
* @return bool - whether enough, side effect is error logging
*/
static bool have_enough_servers(RWSplitSession *rses, const int min_nsrv,
int router_nsrv, RWSplit *router)
{
bool succp = true;
/** With too few servers session is not created */
if (router_nsrv < min_nsrv ||
MXS_MAX((rses)->rses_config.max_slave_connections,
(router_nsrv * (rses)->rses_config.rw_max_slave_conn_percent) /
100) < min_nsrv)
{
if (router_nsrv < min_nsrv)
{
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers available. Found %d "
"when %d is required.",
router->service()->name, router_nsrv, min_nsrv);
}
else
{
int pct = (rses)->rses_config.rw_max_slave_conn_percent / 100;
int nservers = router_nsrv * pct;
if ((rses)->rses_config.max_slave_connections < min_nsrv)
{
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers configured in "
"MaxScale.cnf. Found %d when %d is required.",
router->service()->name,
(rses)->rses_config.max_slave_connections, min_nsrv);
}
if (nservers < min_nsrv)
{
double dbgpct = ((double)min_nsrv / (double)router_nsrv) * 100.0;
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers configured in "
"MaxScale.cnf. Found %d%% when at least %.0f%% "
"would be required.",
router->service()->name,
(rses)->rses_config.rw_max_slave_conn_percent, dbgpct);
}
}
succp = false;
}
return succp;
}
/**
* @brief Route a stored query
*
@ -708,9 +619,85 @@ Stats& RWSplit::stats()
return m_stats;
}
RWSplitSession::RWSplitSession(const Config& config):
rses_config(config)
int RWSplit::max_slave_count() const
{
int router_nservers = m_service->n_dbref;
int conf_max_nslaves = m_config.max_slave_connections > 0 ?
m_config.max_slave_connections :
(router_nservers * m_config.rw_max_slave_conn_percent) / 100;
return MXS_MIN(router_nservers - 1, MXS_MAX(1, conf_max_nslaves));
}
bool RWSplit::have_enough_servers() const
{
bool succp = true;
const int min_nsrv = 1;
const int router_nsrv = m_service->n_dbref;
int n_serv = MXS_MAX(m_config.max_slave_connections,
(router_nsrv * m_config.rw_max_slave_conn_percent) / 100);
/** With too few servers session is not created */
if (router_nsrv < min_nsrv || n_serv < min_nsrv)
{
if (router_nsrv < min_nsrv)
{
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers available. Found %d "
"when %d is required.", m_service->name, router_nsrv, min_nsrv);
}
else
{
int pct = m_config.rw_max_slave_conn_percent / 100;
int nservers = router_nsrv * pct;
if (m_config.max_slave_connections < min_nsrv)
{
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers configured in "
"MaxScale.cnf. Found %d when %d is required.",
m_service->name, m_config.max_slave_connections, min_nsrv);
}
if (nservers < min_nsrv)
{
double dbgpct = ((double)min_nsrv / (double)router_nsrv) * 100.0;
MXS_ERROR("Unable to start %s service. There are "
"too few backend servers configured in "
"MaxScale.cnf. Found %d%% when at least %.0f%% "
"would be required.", m_service->name,
m_config.rw_max_slave_conn_percent, dbgpct);
}
}
succp = false;
}
return succp;
}
RWSplitSession::RWSplitSession(RWSplit* instance, MXS_SESSION* session):
rses_chk_top(CHK_NUM_ROUTER_SES),
rses_closed(false),
rses_config(instance->config()),
rses_nbackends(instance->service()->n_dbref),
load_data_state(LOAD_DATA_INACTIVE),
have_tmp_tables(false),
rses_load_data_sent(0),
client_dcb(session->client_dcb),
sescmd_count(1), // Needs to be a positive number to work
expected_responses(0),
query_queue(NULL),
router(instance),
sent_sescmd(0),
recv_sescmd(0),
rses_chk_tail(CHK_NUM_ROUTER_SES)
{
if (rses_config.rw_max_slave_conn_percent)
{
int n_conn = 0;
double pct = (double)rses_config.rw_max_slave_conn_percent / 100.0;
n_conn = MXS_MAX(floor((double)rses_nbackends * pct), 1);
rses_config.max_slave_connections = n_conn;
}
}
/**
@ -769,33 +756,17 @@ static MXS_ROUTER* createInstance(SERVICE *service, char **options)
*/
static MXS_ROUTER_SESSION* newSession(MXS_ROUTER *router_inst, MXS_SESSION *session)
{
RWSplit* router = (RWSplit*)router_inst;
RWSplitSession* client_rses = new (std::nothrow) RWSplitSession(router->config());
RWSplit* router = reinterpret_cast<RWSplit*>(router_inst);
if (client_rses == NULL)
if (!router->have_enough_servers())
{
return NULL;
}
client_rses->rses_chk_top = CHK_NUM_ROUTER_SES;
client_rses->rses_chk_tail = CHK_NUM_ROUTER_SES;
client_rses->rses_closed = false;
client_rses->router = router;
client_rses->client_dcb = session->client_dcb;
client_rses->have_tmp_tables = false;
client_rses->expected_responses = 0;
client_rses->query_queue = NULL;
client_rses->load_data_state = LOAD_DATA_INACTIVE;
client_rses->sent_sescmd = 0;
client_rses->recv_sescmd = 0;
client_rses->sescmd_count = 1; // Needs to be a positive number to work
RWSplitSession* client_rses = new (std::nothrow) RWSplitSession(router, session);
int router_nservers = router->service()->n_dbref;
const int min_nservers = 1;
if (!have_enough_servers(client_rses, min_nservers, router_nservers, router))
if (client_rses == NULL)
{
delete client_rses;
return NULL;
}
@ -807,12 +778,8 @@ static MXS_ROUTER_SESSION* newSession(MXS_ROUTER *router_inst, MXS_SESSION *sess
}
}
client_rses->rses_nbackends = router_nservers;
int max_nslaves = rses_get_max_slavecount(client_rses);
if (!select_connect_backend_servers(router_nservers, max_nslaves,
client_rses->rses_config.slave_selection_criteria,
if (!select_connect_backend_servers(router->service()->n_dbref, router->max_slave_count(),
router->config().slave_selection_criteria,
session, router, client_rses,
connection_type::ALL))
{
@ -824,17 +791,9 @@ static MXS_ROUTER_SESSION* newSession(MXS_ROUTER *router_inst, MXS_SESSION *sess
return NULL;
}
if (client_rses->rses_config.rw_max_slave_conn_percent)
{
int n_conn = 0;
double pct = (double)client_rses->rses_config.rw_max_slave_conn_percent / 100.0;
n_conn = MXS_MAX(floor((double)client_rses->rses_nbackends * pct), 1);
client_rses->rses_config.max_slave_connections = n_conn;
}
router->stats().n_sessions += 1;
return (MXS_ROUTER_SESSION*)client_rses;
return reinterpret_cast<MXS_ROUTER_SESSION*>(client_rses);
}
/**

2
server/modules/routing/readwritesplit/readwritesplit.hh
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@ -226,6 +226,8 @@ public:
SERVICE* service() const;
const Config& config() const;
Stats& stats();
int max_slave_count() const;
bool have_enough_servers() const;
private:
SERVICE* m_service; /**< Service where the router belongs*/

1
server/modules/routing/readwritesplit/rwsplit_internal.hh
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@ -61,7 +61,6 @@ bool send_readonly_error(DCB *dcb);
*/
int router_handle_state_switch(DCB *dcb, DCB_REASON reason, void *data);
SRWBackend get_backend_from_dcb(RWSplitSession *rses, DCB *dcb);
int rses_get_max_slavecount(RWSplitSession *rses);
int rses_get_max_replication_lag(RWSplitSession *rses);
/*

2
server/modules/routing/readwritesplit/rwsplitsession.hh
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@ -73,7 +73,7 @@ class RWSplitSession
RWSplitSession& operator=(const RWSplitSession&);
public:
RWSplitSession(const Config& config);
RWSplitSession(RWSplit* instance, MXS_SESSION* session);
// TODO: Make member variables private
skygw_chk_t rses_chk_top;