fcb8d040e8
Instead of lengthy blurbs, switch to single-line, machine-readable standardized (https://spdx.dev) license identifiers. The Linux kernel switched long ago, so there is strong precedent. Three cases are handled: AGPL-only, Apache-only, and dual licensed. For the latter case, I chose (AGPL-3.0-or-later and Apache-2.0), reasoning that our changes are extensive enough to apply our license. The changes we applied mechanically with a script, except to licenses/README.md. Closes #9937
60 lines
1.5 KiB
C++
60 lines
1.5 KiB
C++
/*
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* Copyright (C) 2021-present ScyllaDB
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*/
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/*
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* SPDX-License-Identifier: AGPL-3.0-or-later
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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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