ece2bd2f6e
these unused includes were identified by clangd. see https://clangd.llvm.org/guides/include-cleaner#unused-include-warning for more details on the "Unused include" warning. Signed-off-by: Kefu Chai <kefu.chai@scylladb.com> Closes scylladb/scylladb#16764
103 lines
3.3 KiB
C++
103 lines
3.3 KiB
C++
/*
|
|
* Copyright (C) 2023-present ScyllaDB
|
|
*/
|
|
|
|
/*
|
|
* SPDX-License-Identifier: AGPL-3.0-or-later
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include "replica/database.hh"
|
|
#include "locator/tablets.hh"
|
|
|
|
namespace service {
|
|
|
|
/// Represents intention to move a single tablet replica from src to dst.
|
|
struct tablet_migration_info {
|
|
locator::global_tablet_id tablet;
|
|
locator::tablet_replica src;
|
|
locator::tablet_replica dst;
|
|
};
|
|
|
|
class migration_plan {
|
|
public:
|
|
using migrations_vector = utils::chunked_vector<tablet_migration_info>;
|
|
private:
|
|
migrations_vector _migrations;
|
|
bool _has_nodes_to_drain = false;
|
|
public:
|
|
/// Returns true iff there are decommissioning nodes which own some tablet replicas.
|
|
bool has_nodes_to_drain() const { return _has_nodes_to_drain; }
|
|
|
|
const migrations_vector& migrations() const { return _migrations; }
|
|
bool empty() const { return _migrations.empty(); }
|
|
size_t size() const { return _migrations.size(); }
|
|
|
|
void add(tablet_migration_info info) {
|
|
_migrations.emplace_back(std::move(info));
|
|
}
|
|
|
|
void merge(migration_plan&& other) {
|
|
std::move(other._migrations.begin(), other._migrations.end(), std::back_inserter(_migrations));
|
|
_has_nodes_to_drain |= other._has_nodes_to_drain;
|
|
}
|
|
|
|
void set_has_nodes_to_drain(bool b) {
|
|
_has_nodes_to_drain = b;
|
|
}
|
|
};
|
|
|
|
class tablet_allocator_impl;
|
|
|
|
class tablet_allocator {
|
|
public:
|
|
class impl {
|
|
public:
|
|
virtual ~impl() = default;
|
|
};
|
|
private:
|
|
std::unique_ptr<impl> _impl;
|
|
tablet_allocator_impl& impl();
|
|
public:
|
|
tablet_allocator(service::migration_notifier& mn, replica::database& db);
|
|
public:
|
|
future<> stop();
|
|
|
|
/// Returns a tablet migration plan that aims to achieve better load balance in the whole cluster.
|
|
/// The plan is computed based on information in the given token_metadata snapshot
|
|
/// and thus should be executed and reflected, at least as pending tablet transitions, in token_metadata
|
|
/// before this is called again.
|
|
///
|
|
/// For any given global_tablet_id there is at most one tablet_migration_info in the returned plan.
|
|
///
|
|
/// To achieve full balance, do:
|
|
///
|
|
/// while (true) {
|
|
/// auto plan = co_await balance_tablets(get_token_metadata());
|
|
/// if (plan.empty()) {
|
|
/// break;
|
|
/// }
|
|
/// co_await execute(plan);
|
|
/// }
|
|
///
|
|
/// It is ok to invoke the algorithm with already active tablet migrations. The algorithm will take them into account
|
|
/// when balancing the load as if they already succeeded. This means that applying a series of migration plans
|
|
/// produced by this function will give the same result regardless of whether applying means they are fully executed or
|
|
/// only initiated by creating corresponding transitions in tablet metadata.
|
|
///
|
|
/// The algorithm takes care of limiting the streaming load on the system, also by taking active migrations into account.
|
|
///
|
|
future<migration_plan> balance_tablets(locator::token_metadata_ptr);
|
|
|
|
/// Should be called when the node is no longer a leader.
|
|
void on_leadership_lost();
|
|
};
|
|
|
|
}
|
|
|
|
template <>
|
|
struct fmt::formatter<service::tablet_migration_info> : fmt::formatter<std::string_view> {
|
|
auto format(const service::tablet_migration_info&, fmt::format_context& ctx) const -> decltype(ctx.out());
|
|
};
|