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MXS-2313: Pick best available master

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Readwritesplit now picks the best available master if no open master
connection is available. This is required if the server rank is to be
taken into account when master selection is done.
This commit is contained in:
Markus Mäkelä
2019-03-08 08:57:51 +02:00
parent 8251389813
commit 9e9cd0c596
3 changed files with 26 additions and 27 deletions
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3
server/modules/routing/readwritesplit/readwritesplit.hh
View File

@ -391,7 +391,8 @@ static inline const char* failure_mode_to_str(enum failure_mode type)
void closed_session_reply(GWBUF* querybuf); void closed_session_reply(GWBUF* querybuf);
bool send_readonly_error(DCB* dcb); bool send_readonly_error(DCB* dcb);
mxs::RWBackend* get_root_master(const mxs::PRWBackends& backends); mxs::RWBackend* get_root_master(const mxs::PRWBackends& backends, mxs::RWBackend* current_master,
const BackendSelectFunction& func);
/** /**
* Get total slave count and connected slave count * Get total slave count and connected slave count

2
server/modules/routing/readwritesplit/rwsplit_route_stmt.cc
View File

@ -696,7 +696,7 @@ RWBackend* RWSplitSession::get_master_backend()
{ {
RWBackend* rval = nullptr; RWBackend* rval = nullptr;
/** get root master from available servers */ /** get root master from available servers */
RWBackend* master = get_root_master(m_raw_backends); RWBackend* master = get_root_master(m_raw_backends, m_current_master, m_config.backend_select_fct);
if (master) if (master)
{ {

48
server/modules/routing/readwritesplit/rwsplit_select_backends.cc
View File

@ -335,18 +335,29 @@ static void log_server_connections(select_criteria_t criteria, const PRWBackends
} }
} }
RWBackend* get_root_master(const PRWBackends& backends) namespace
{ {
RWBackend* master = nullptr; // Buffer used for selecting the best master
for (auto candidate : backends) thread_local PRWBackends sort_buffer;
}
RWBackend* get_root_master(const PRWBackends& backends, RWBackend* current_master,
const BackendSelectFunction& func)
{
if (current_master && current_master->in_use() && current_master->is_master())
{ {
if (candidate->is_master()) return current_master;
{
master = candidate;
break;
}
} }
std::copy_if(backends.begin(), backends.end(), std::back_inserter(sort_buffer),
[](RWBackend* backend) {
return backend->can_connect() && backend->is_master();
});
auto it = func(sort_buffer);
auto master = it != sort_buffer.end() ? *it : nullptr;
sort_buffer.clear();
return master; return master;
} }
@ -394,8 +405,8 @@ bool RWSplit::select_connect_backend_servers(MXS_SESSION* session,
int* expected_responses, int* expected_responses,
connection_type type) connection_type type)
{ {
RWBackend* master = get_root_master(backends);
const Config& cnf {config()}; const Config& cnf {config()};
RWBackend* master = get_root_master(backends, *current_master, cnf.backend_select_fct);
if ((!master || !master->can_connect()) && cnf.master_failure_mode == RW_FAIL_INSTANTLY) if ((!master || !master->can_connect()) && cnf.master_failure_mode == RW_FAIL_INSTANTLY)
{ {
@ -419,23 +430,10 @@ bool RWSplit::select_connect_backend_servers(MXS_SESSION* session,
log_server_connections(select_criteria, backends); log_server_connections(select_criteria, backends);
} }
if (type == ALL) if (type == ALL && master && master->connect(session))
{ {
/** Find a master server */ MXS_INFO("Selected Master: %s", master->name());
for (PRWBackends::const_iterator it = backends.begin(); it != backends.end(); it++) *current_master = master;
{
RWBackend* backend = *it;
if (backend->can_connect() && master && backend == master)
{
if (backend->connect(session))
{
MXS_INFO("Selected Master: %s", backend->name());
*current_master = backend;
}
break;
}
}
} }
auto counts = get_slave_counts(backends, master); auto counts = get_slave_counts(backends, master);