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MXS-2313: Clean up readwritesplit connection creation

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The connection creation is now internal to RWSplitSession. This makes the
code more readable by removing the need to pass parameters and allowing
easier reuse of existing functions. The various conditions require to
create connections are now also checked in only one place.
This commit is contained in:
Markus Mäkelä
2019-03-08 14:41:16 +02:00
parent 54a09e93df
commit ba448cb12c
5 changed files with 80 additions and 124 deletions
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83
server/modules/routing/readwritesplit/rwsplit_select_backends.cc
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@ -12,6 +12,7 @@
*/
#include "readwritesplit.hh"
#include "rwsplitsession.hh"
#include <stdio.h>
#include <strings.h>
@ -378,93 +379,71 @@ std::pair<int, int> get_slave_counts(PRWBackends& backends, RWBackend* master)
/**
* Select and connect to backend servers
*
* @param inst Router instance
* @param session Client session
* @param backends List of backend servers
* @param current_master The current master server
* @param sescmd_list List of session commands to execute
* @param expected_responses Pointer where number of expected responses are written
* @param type Connection type, ALL for all types, SLAVE for slaves only
*
* @return True if session can continue
*/
bool RWSplit::select_connect_backend_servers(MXS_SESSION* session,
mxs::PRWBackends& backends,
mxs::RWBackend** current_master,
SessionCommandList* sescmd_list,
int* expected_responses,
connection_type type)
bool RWSplitSession::open_connections()
{
const Config& cnf {config()};
RWBackend* master = get_root_master(backends, *current_master, cnf.backend_select_fct);
if (m_config.lazy_connect)
{
return true; // No need to create connections
}
if ((!master || !master->can_connect()) && cnf.master_failure_mode == RW_FAIL_INSTANTLY)
RWBackend* master = get_root_master(m_raw_backends, m_current_master, m_config.backend_select_fct);
if ((!master || !master->can_connect()) && m_config.master_failure_mode == RW_FAIL_INSTANTLY)
{
if (!master)
{
MXS_ERROR("Couldn't find suitable Master from %lu candidates.", backends.size());
MXS_ERROR("Couldn't find suitable Master from %lu candidates.", m_raw_backends.size());
}
else
{
MXS_ERROR("Master exists (%s), but it is being drained and cannot be used.",
master->server()->address);
}
return false;
}
auto select_criteria = cnf.slave_selection_criteria;
if (mxs_log_is_priority_enabled(LOG_INFO))
{
log_server_connections(select_criteria, backends);
log_server_connections(m_config.slave_selection_criteria, m_raw_backends);
}
if (type == ALL && master && master->connect(session))
if (can_recover_servers())
{
MXS_INFO("Selected Master: %s", master->name());
*current_master = master;
// A master connection can be safely attempted
if (master && !master->in_use() && master->can_connect() && prepare_connection(master))
{
MXS_INFO("Selected Master: %s", master->name());
m_current_master = master;
}
}
auto counts = get_slave_counts(backends, master);
int slaves_connected = counts.second;
int max_nslaves = max_slave_count();
mxb_assert(slaves_connected <= max_nslaves || max_nslaves == 0);
int n_slaves = get_slave_counts(m_raw_backends, master).second;
int max_nslaves = m_router->max_slave_count();
PRWBackends candidates;
for (auto& pBackend : backends)
mxb_assert(n_slaves <= max_nslaves || max_nslaves == 0);
for (auto& pBackend : m_raw_backends)
{
if (!pBackend->in_use()
&& pBackend->can_connect()
&& valid_for_slave(pBackend, master))
if (!pBackend->in_use() && pBackend->can_connect() && valid_for_slave(pBackend, master))
{
candidates.push_back(pBackend);
}
}
while (slaves_connected < max_nslaves && candidates.size())
for (auto ite = m_config.backend_select_fct(candidates);
n_slaves < max_nslaves && !candidates.empty() && ite != candidates.end();
ite = m_config.backend_select_fct(candidates))
{
auto ite = m_config->backend_select_fct(candidates);
if (ite == candidates.end())
if (prepare_connection(*ite))
{
break;
MXS_INFO("Selected Slave: %s", (*ite)->name());
++n_slaves;
}
auto& backend = *ite;
if (backend->connect(session, sescmd_list))
{
MXS_INFO("Selected Slave: %s", backend->name());
if (sescmd_list && sescmd_list->size() && expected_responses)
{
(*expected_responses)++;
}
++slaves_connected;
}
candidates.erase(ite);
}
return true;
}