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MXS-1845 Add redirection code

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Should work with multimaster replication.
This commit is contained in:
Esa Korhonen
2018-09-28 16:18:38 +03:00
parent 75f9921ca2
commit 1ca5d02abb
4 changed files with 112 additions and 12 deletions
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56
server/modules/monitor/mariadbmon/cluster_manipulation.cc
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@ -22,6 +22,7 @@
using std::string;
using std::unique_ptr;
using maxscale::string_printf;
using maxbase::StopWatch;
static const char RE_ENABLE_FMT[] = "To re-enable automatic %s, manually set '%s' to 'true' "
"for monitor '%s' via MaxAdmin or the REST API, or restart MaxScale.";
@ -417,6 +418,46 @@ int MariaDBMonitor::redirect_slaves(MariaDBServer* new_master,
return successes;
}
/**
* Redirect slaves to replicate from the promotion target.
*
* @param op Operation descriptor
* @param slaves An array of slaves to redirect
* @param redirected_slaves A vector where to insert successfully redirected slaves
* @return The number of slaves successfully redirected
*/
int MariaDBMonitor::redirect_slaves_ex(ClusterOperation& op, const ServerArray& slaves,
ServerArray* redirected_slaves)
{
mxb_assert(redirected_slaves != NULL);
if (slaves.empty())
{
// This is ok, nothing to do.
return 0;
}
string slave_names = monitored_servers_to_string(slaves);
MXS_NOTICE("Redirecting %s to replicate from %s instead of %s.",
slave_names.c_str(), op.promotion_target->name(), op.demotion_target->name());
int successes = 0;
for (MariaDBServer* redirectable : slaves)
{
if (redirectable->redirect_existing_slave_conn(op))
{
successes++;
redirected_slaves->push_back(redirectable);
}
}
if (size_t(successes) == slaves.size())
{
MXS_NOTICE("All redirects successful.");
}
else
{
MXS_WARNING("%lu out of %lu redirects failed.", slaves.size() - successes, slaves.size());
}
return successes;
}
/**
* Set the new master to replicate from the cluster external master.
*
@ -723,13 +764,11 @@ bool MariaDBMonitor::switchover_perform(ClusterOperation& op)
{
redirected_slaves.push_back(demotion_target);
}
int redirects = redirect_slaves(promotion_target, redirectable_slaves, &redirected_slaves);
int redirects = redirect_slaves_ex(op, redirectable_slaves, &redirected_slaves);
bool success = redirectable_slaves.empty() ? start_ok : start_ok || redirects > 0;
if (success)
{
op.time_remaining -= timer.restart();
// Step 6: Finally, add an event to the new master to advance gtid and wait for the slaves
// to receive it. If using external replication, skip this step. Come up with an
// alternative later.
@ -793,7 +832,6 @@ bool MariaDBMonitor::failover_perform(ClusterOperation& op)
{
mxb_assert(op.promotion_target && op.demotion_target);
MariaDBServer* const promotion_target = op.promotion_target;
maxbase::StopWatch timer;
// Step 1: Populate a vector with all slaves not the selected master.
ServerArray redirectable_slaves = get_redirectables(promotion_target, op.demotion_target);
@ -802,17 +840,17 @@ bool MariaDBMonitor::failover_perform(ClusterOperation& op)
// Step 2: Stop and reset slave, set read-only to 0.
if (promotion_target->promote(op))
{
// Point of no return. Even if following steps fail, do not try to undo.
m_next_master = promotion_target;
m_cluster_modified = true;
// Step 3: Redirect slaves.
ServerArray redirected_slaves;
int redirects = redirect_slaves(promotion_target, redirectable_slaves, &redirected_slaves);
int redirects = redirect_slaves_ex(op, redirectable_slaves, &redirected_slaves);
bool success = redirectable_slaves.empty() ? true : redirects > 0;
if (success)
{
op.time_remaining -= timer.restart();
StopWatch timer;
// Step 4: Finally, add an event to the new master to advance gtid and wait for the slaves
// to receive it. seconds_remaining can be 0 or less at this point. Even in such a case
// wait_cluster_stabilization() may succeed if replication is fast enough. If using external
@ -1679,9 +1717,9 @@ void MariaDBMonitor::check_cluster_operations_support()
* @return The first connected slave or NULL if none found
*/
const MariaDBServer* MariaDBMonitor::slave_receiving_events(const MariaDBServer* demotion_target,
maxbase::Duration* event_age_out)
maxbase::Duration* event_age_out)
{
auto time_now = maxbase::Clock::now();
auto time_now = maxbase::Clock::now();
maxbase::Clock::time_point alive_after = time_now - std::chrono::seconds(m_master_failure_timeout);
const MariaDBServer* connected_slave = NULL;