Files
scylladb/utils/disk_space_monitor.hh
Tomasz Grabiec d01cc16d1e config, disk_space_monitor: Allow overriding capacity via config
Intended for testing, or hot-fixing out-of-space issues in production.

Tablet load balancer uses this information for determining per-shard load
so reducing capacity will cause tablets to be migrated away from the node.
2025-03-06 13:35:37 +01:00

99 lines
2.8 KiB
C++

/*
* Copyright (C) 2024-present ScyllaDB
*/
/*
* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.0
*/
#pragma once
#include <filesystem>
#include <any>
#include <boost/signals2/connection.hpp>
#include <boost/signals2/signal_type.hpp>
#include <boost/signals2/dummy_mutex.hpp>
#include <seastar/core/abort_source.hh>
#include <seastar/core/future.hh>
#include <seastar/core/lowres_clock.hh>
#include <seastar/util/optimized_optional.hh>
#include <seastar/core/condition-variable.hh>
#include "seastarx.hh"
#include "utils/updateable_value.hh"
#include "utils/phased_barrier.hh"
namespace utils {
// Instantiated only on shard 0
class disk_space_monitor {
public:
using clock_type = lowres_clock;
using signal_type = boost::signals2::signal_type<void (), boost::signals2::keywords::mutex_type<boost::signals2::dummy_mutex>>::type;
using signal_callback_type = std::function<future<>(const disk_space_monitor&)>;
using signal_connection_type = boost::signals2::scoped_connection;
using space_source_fn = std::function<future<std::filesystem::space_info>()>;
struct config {
scheduling_group sched_group;
updateable_value<int> normal_polling_interval;
updateable_value<int> high_polling_interval;
// Use high_polling_interval above this threshold
updateable_value<float> polling_interval_threshold;
updateable_value<uint64_t> capacity_override; // 0 means no override.
};
private:
abort_source _as;
optimized_optional<abort_source::subscription> _as_sub;
future<> _poller_fut = make_ready_future();
condition_variable _poll_cv;
utils::phased_barrier _signal_barrier;
signal_type _signal_source;
std::filesystem::space_info _space_info;
std::filesystem::path _data_dir;
config _cfg;
space_source_fn _space_source;
std::any _capacity_observer;
public:
disk_space_monitor(abort_source& as, std::filesystem::path data_dir, config cfg);
~disk_space_monitor();
future<> start();
future<> stop() noexcept;
const std::filesystem::path& data_dir() const noexcept {
return _data_dir;
}
std::filesystem::space_info space() const noexcept {
return _space_info;
}
float disk_utilization() const noexcept {
return _space_info.capacity ? (float)(_space_info.capacity - _space_info.available) / _space_info.capacity : -1;
}
signal_connection_type listen(signal_callback_type callback);
// Replaces default way of obtaining file system usage information.
void set_space_source(space_source_fn space_source) {
_space_source = std::move(space_source);
}
void trigger_poll() noexcept;
private:
future<> poll();
future<std::filesystem::space_info> get_filesystem_space();
clock_type::duration get_polling_interval() const noexcept;
};
} // namespace utils