mirror of
https://gitea.wildfiregames.com/0ad/0ad
synced 2026-06-16 13:23:56 -07:00
e4b604982a
Shrinking GCs dump the JITted code, which leads to redundant recompilations, lowers performance, and makes profiling JS more difficult.
They may still happen if the runtime is at risk of OOM.
(cherry picked from commit af32d386b9)
Signed-off-by: Itms <itms@wildfiregames.com>
122 lines
3.9 KiB
C++
122 lines
3.9 KiB
C++
/* Copyright (C) 2024 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. 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 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef INCLUDED_SCRIPTCONTEXT
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#define INCLUDED_SCRIPTCONTEXT
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#include "ScriptTypes.h"
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#include "ScriptExtraHeaders.h"
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#include <list>
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// Those are minimal defaults. The runtime for the main game is larger and GCs upon a larger growth.
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constexpr int DEFAULT_CONTEXT_SIZE = 16 * 1024 * 1024;
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constexpr uint32_t DEFAULT_HEAP_GROWTH_BYTES_GCTRIGGER = 2 * 1024 * 1024;
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namespace Script
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{
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class JobQueue;
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}
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/**
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* Abstraction around a SpiderMonkey JSContext.
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*
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* A single ScriptContext, with the associated context,
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* should only be used on a single thread.
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*
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* (One means to share data between threads and contexts is to create
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* a Script::StructuredClone.)
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*/
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class ScriptContext
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{
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public:
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ScriptContext(int contextSize, uint32_t heapGrowthBytesGCTrigger);
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~ScriptContext();
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/**
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* Returns a context, in which any number of ScriptInterfaces compartments can live.
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* Each context should only ever be used on a single thread.
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* @param parentContext Parent context from the parent thread, with which we share some thread-safe data
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* @param contextSize Maximum size in bytes of the new context
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* @param heapGrowthBytesGCTrigger Size in bytes of cumulated allocations after which a GC will be triggered
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*/
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static std::shared_ptr<ScriptContext> CreateContext(
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int contextSize = DEFAULT_CONTEXT_SIZE,
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uint32_t heapGrowthBytesGCTrigger = DEFAULT_HEAP_GROWTH_BYTES_GCTRIGGER);
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/**
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* MaybeIncrementalGC checks if running a GC is worth the time that will take.
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* The logic is custom as Spidermonkey tends to assume 'idle time' will exist,
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* which is a thing in websites but not really in 0 A.D.
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* This can have a few behaviours:
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* - doing nothing
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* - starting a new incremental GC
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* - running a GC slice
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* - finishing the incremental GC
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* For details, check the SM doc in e.g. GC.cpp and GCapi.cpp
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*/
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void MaybeIncrementalGC();
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/**
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* Does a non-incremental, shrinking GC.
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* A shrinking GC dumps JIT code and tries to defragment memory.
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*/
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void ShrinkingGC();
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/**
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* This is used to keep track of realms which should be prepared for a GC.
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*/
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void RegisterRealm(JS::Realm* realm);
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void UnRegisterRealm(JS::Realm* realm);
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/**
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* Runs the promise continuation.
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* On contexts where promises can be used this function has to be
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* called.
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* This function has to be called frequently.
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*/
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void RunJobs();
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/**
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* GetGeneralJSContext returns the context without starting a GC request and without
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* entering any compartment. It should only be used in specific situations, such as
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* creating a new compartment, or when initializing a persistent rooted.
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* If you need the compartmented context of a ScriptInterface, you should create a
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* ScriptRequest and use the context from that.
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*/
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JSContext* GetGeneralJSContext() const { return m_cx; }
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private:
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JSContext* m_cx;
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const std::unique_ptr<Script::JobQueue> m_JobQueue;
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void PrepareZonesForIncrementalGC() const;
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std::list<JS::Realm*> m_Realms;
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int m_ContextSize;
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uint32_t m_HeapGrowthBytesGCTrigger;
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uint32_t m_LastGCBytes{0};
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};
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// Using a global object for the context is a workaround until Simulation, AI, etc,
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// use their own threads and also their own contexts.
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extern thread_local std::shared_ptr<ScriptContext> g_ScriptContext;
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#endif // INCLUDED_SCRIPTCONTEXT
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