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forked from 0ad/0ad
0ad/source/scriptinterface/ScriptContext.h
phosit f9114a87f2 Get a promise when starting a GUIpage
When calling `Engine.PushGuiPage` a promise is returned. The promise is
settled when the "child" page is closed. That allows to `await` it
inside `async` functions.
Previously the callback was run right inside the call to
`Engine.PopGuiPage`. Now the continuation of the promise is called at
the end of the "tick".

This won't help performance. It will more likely make things worse.
Since gui pages aren't opened or closed that frequently, it doesn't
matter that much.

Refs: 86c151ebaa

For the engine side:
The promise is stored in the `CGUIManager::SGUIPage` (like previously
the callback). When the promise is fulfilled it enqueues a callback in
the `JobQueue` of the `JSContext`.

Original patch by: @wraitii
Comments by: @wraitii, @Stan, @Polakrity, @lyv, @elexis, @vladislavbelov
Differential Revision: https://code.wildfiregames.com/D3807
This was SVN commit r28145.
2024-07-08 19:07:04 +00:00

118 lines
4.2 KiB
C++

/* Copyright (C) 2024 Wildfire Games.
* This file is part of 0 A.D.
*
* 0 A.D. is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* 0 A.D. is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef INCLUDED_SCRIPTCONTEXT
#define INCLUDED_SCRIPTCONTEXT
#include "ScriptTypes.h"
#include "ScriptExtraHeaders.h"
#include <list>
// Those are minimal defaults. The runtime for the main game is larger and GCs upon a larger growth.
constexpr int DEFAULT_CONTEXT_SIZE = 16 * 1024 * 1024;
constexpr int DEFAULT_HEAP_GROWTH_BYTES_GCTRIGGER = 2 * 1024 * 1024;
namespace Script
{
class JobQueue;
}
/**
* Abstraction around a SpiderMonkey JSContext.
*
* A single ScriptContext, with the associated context,
* should only be used on a single thread.
*
* (One means to share data between threads and contexts is to create
* a Script::StructuredClone.)
*/
class ScriptContext
{
public:
ScriptContext(int contextSize, int heapGrowthBytesGCTrigger);
~ScriptContext();
/**
* Returns a context, in which any number of ScriptInterfaces compartments can live.
* Each context should only ever be used on a single thread.
* @param parentContext Parent context from the parent thread, with which we share some thread-safe data
* @param contextSize Maximum size in bytes of the new context
* @param heapGrowthBytesGCTrigger Size in bytes of cumulated allocations after which a GC will be triggered
*/
static std::shared_ptr<ScriptContext> CreateContext(
int contextSize = DEFAULT_CONTEXT_SIZE,
int heapGrowthBytesGCTrigger = DEFAULT_HEAP_GROWTH_BYTES_GCTRIGGER);
/**
* MaybeIncrementalGC tries to determine whether a context-wide garbage collection would free up enough memory to
* be worth the amount of time it would take. It does this with our own logic and NOT some predefined JSAPI logic because
* such functionality currently isn't available out of the box.
* It does incremental GC which means it will collect one slice each time it's called until the garbage collection is done.
* This can and should be called quite regularly. The delay parameter allows you to specify a minimum time since the last GC
* in seconds (the delay should be a fraction of a second in most cases though).
* It will only start a new incremental GC or another GC slice if this time is exceeded. The user of this function is
* responsible for ensuring that GC can run with a small enough delay to get done with the work.
*/
void MaybeIncrementalGC(double delay);
void ShrinkingGC();
/**
* This is used to keep track of realms which should be prepared for a GC.
*/
void RegisterRealm(JS::Realm* realm);
void UnRegisterRealm(JS::Realm* realm);
/**
* Runs the promise continuation.
* On contexts where promises can be used this function has to be
* called.
* This function has to be called frequently.
*/
void RunJobs();
/**
* GetGeneralJSContext returns the context without starting a GC request and without
* entering any compartment. It should only be used in specific situations, such as
* creating a new compartment, or when initializing a persistent rooted.
* If you need the compartmented context of a ScriptInterface, you should create a
* ScriptRequest and use the context from that.
*/
JSContext* GetGeneralJSContext() const { return m_cx; }
private:
JSContext* m_cx;
const std::unique_ptr<Script::JobQueue> m_JobQueue;
void PrepareZonesForIncrementalGC() const;
std::list<JS::Realm*> m_Realms;
int m_ContextSize;
int m_HeapGrowthBytesGCTrigger;
int m_LastGCBytes{0};
double m_LastGCCheck{0.0};
};
// Using a global object for the context is a workaround until Simulation, AI, etc,
// use their own threads and also their own contexts.
extern thread_local std::shared_ptr<ScriptContext> g_ScriptContext;
#endif // INCLUDED_SCRIPTCONTEXT