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78 lines
1.7 KiB
C++
78 lines
1.7 KiB
C++
/*
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* Copyright (C) 2018-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: LicenseRef-ScyllaDB-Source-Available-1.1
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*/
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#pragma once
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#include <seastar/util/bool_class.hh>
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#include <seastar/util/noncopyable_function.hh>
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#include <seastar/core/preempt.hh>
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#include <seastar/core/thread.hh>
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#include "seastarx.hh"
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class is_preemptible_tag;
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using is_preemptible = bool_class<is_preemptible_tag>;
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/// A function which decides when to preempt.
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/// If it returns true then the algorithm will be interrupted.
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using preemption_check = noncopyable_function<bool() noexcept>;
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inline
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preemption_check default_preemption_check() {
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return [] () noexcept {
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return seastar::need_preempt();
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};
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}
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inline
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preemption_check never_preempt() {
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return [] () noexcept {
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return false;
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};
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}
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inline
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preemption_check always_preempt() {
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return [] () noexcept {
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return true;
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};
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}
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struct basic_preemption_source {
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bool should_preempt() {
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return seastar::need_preempt();
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}
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void thread_yield() {
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seastar::thread::yield();
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}
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};
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struct custom_preemption_source {
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struct impl {
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virtual bool should_preempt() = 0;
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virtual void thread_yield() = 0;
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virtual ~impl() = default;
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};
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std::unique_ptr<impl> _impl;
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bool should_preempt() {
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return _impl ? _impl->should_preempt() : seastar::need_preempt();
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}
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void thread_yield() {
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_impl ? _impl->thread_yield() : seastar::thread::yield();
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}
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custom_preemption_source() = default;
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custom_preemption_source(std::unique_ptr<impl> i) : _impl(std::move(i)) {}
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};
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#ifdef SCYLLA_ENABLE_PREEMPTION_SOURCE
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using preemption_source = custom_preemption_source;
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#else
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using preemption_source = basic_preemption_source;
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#endif
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