mirror of
https://github.com/ClickHouse/ClickHouse.git
synced 2024-12-18 12:22:12 +00:00
55 lines
1.5 KiB
C++
55 lines
1.5 KiB
C++
#include "DNSCacheUpdater.h"
|
|
#include <Common/DNSResolver.h>
|
|
#include <Interpreters/Context.h>
|
|
#include <Core/BackgroundSchedulePool.h>
|
|
|
|
namespace DB
|
|
{
|
|
|
|
DNSCacheUpdater::DNSCacheUpdater(Context & context_, Int32 update_period_seconds_)
|
|
: context(context_),
|
|
update_period_seconds(update_period_seconds_),
|
|
pool(context_.getSchedulePool())
|
|
{
|
|
task_handle = pool.createTask("DNSCacheUpdater", [this]{ run(); });
|
|
}
|
|
|
|
void DNSCacheUpdater::run()
|
|
{
|
|
auto & resolver = DNSResolver::instance();
|
|
|
|
/// Reload cluster config if IP of any host has been changed since last update.
|
|
if (resolver.updateCache())
|
|
{
|
|
LOG_INFO(&Poco::Logger::get("DNSCacheUpdater"),
|
|
"IPs of some hosts have been changed. Will reload cluster config.");
|
|
try
|
|
{
|
|
context.reloadClusterConfig();
|
|
}
|
|
catch (...)
|
|
{
|
|
tryLogCurrentException(__PRETTY_FUNCTION__);
|
|
}
|
|
}
|
|
|
|
/** DNS resolution may take a while and by this reason, actual update period will be longer than update_period_seconds.
|
|
* We intentionally allow this "drift" for two reasons:
|
|
* - automatically throttle when DNS requests take longer time;
|
|
* - add natural randomization on huge clusters - avoid sending all requests at the same moment of time from different servers.
|
|
*/
|
|
task_handle->scheduleAfter(update_period_seconds * 1000);
|
|
}
|
|
|
|
void DNSCacheUpdater::start()
|
|
{
|
|
task_handle->activateAndSchedule();
|
|
}
|
|
|
|
DNSCacheUpdater::~DNSCacheUpdater()
|
|
{
|
|
task_handle->deactivate();
|
|
}
|
|
|
|
}
|