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bb23986826
The wasm::engine exists as a sharded<> service in main, but it's only passed by local reference into database on start. There's no much profit in keeping it at main scope, things get much simpler if keeping the engine purely on database. Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>
73 lines
2.1 KiB
C++
73 lines
2.1 KiB
C++
/*
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* Copyright (C) 2021-present ScyllaDB
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*/
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/*
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* This file is part of Scylla.
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*
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* Scylla is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* Scylla is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with Scylla. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include <seastar/core/future.hh>
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#include <seastar/core/sharded.hh>
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#ifdef SCYLLA_ENABLE_WASMTIME
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#include "wasmtime.hh"
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namespace wasm {
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// Fuel defines more or less how many bytecode instructions
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// can be performed at once. Empirically, 20k units
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// allow for considerably less than 0.5ms of preemption-free execution time.
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// TODO: investigate other configuration variables.
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// We're particularly interested in limiting resource usage
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// and yielding in the middle of execution - which is possible
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// in the original wasmtime implementation for Rust and tightly
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// bound with its native async support, but not yet possible
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// in wasmtime.hh binding at the time of this writing.
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// It's highly probable that a more generic support for yielding
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// can be contributed to wasmtime.
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constexpr uint64_t default_initial_fuel_amount = 20*1024;
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class engine {
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wasmtime::Engine _engine;
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uint64_t _initial_fuel_amount;
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public:
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engine(uint64_t initial_fuel_amount = default_initial_fuel_amount)
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: _engine(make_config())
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, _initial_fuel_amount(initial_fuel_amount)
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{}
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wasmtime::Engine& get() { return _engine; }
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uint64_t initial_fuel_amount() { return _initial_fuel_amount; };
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private:
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wasmtime::Config make_config() {
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wasmtime::Config cfg;
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cfg.consume_fuel(true);
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return cfg;
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}
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};
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}
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#else
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namespace wasm {
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class engine {};
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}
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#endif
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