fix: use state instead of source in reactive classes
#16239
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,9 +1,10 @@ | ||
| /** @import { Reaction, Source } from '#client' */ | ||
| import { DEV } from 'esm-env'; | ||
| import { set, source, state } from '../internal/client/reactivity/sources.js'; | ||
| import { label, tag } from '../internal/client/dev/tracing.js'; | ||
| import { active_reaction, get } from '../internal/client/runtime.js'; | ||
| import { increment } from './utils.js'; | ||
| import { teardown } from '../internal/client/reactivity/effects.js'; | ||
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| /** | ||
| * A reactive version of the built-in [`Map`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map) object. | ||
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@@ -56,13 +57,24 @@ export class SvelteMap extends Map { | |
| #sources = new Map(); | ||
| #version = state(0); | ||
| #size = state(0); | ||
| /**@type {Reaction | null} */ | ||
| #initial_reaction = null; | ||
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| /** | ||
| * @param {Iterable<readonly [K, V]> | null | undefined} [value] | ||
| */ | ||
| constructor(value) { | ||
| super(); | ||
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| if (active_reaction !== null) { | ||
| this.#initial_reaction = active_reaction; | ||
| // since we only need `initial_reaction` as long as we are in a derived/effect we can | ||
| // safely create a teardown function that will reset it to null and allow for GC | ||
| teardown(() => { | ||
| this.#initial_reaction = null; | ||
| }); | ||
|
Comment on lines
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There was a problem hiding this comment. presumably if there's a situation that would create a memory leak with this (which I guess means smuggling a reference to the map to something outside the current reaction?), do we therefore need a way to run code as soon as the current reaction has finished updating? #16316 There was a problem hiding this comment. The alternative is to use a weak ref to reference the reaction. Perf impact should be close to zero since it only applies once for new sources There was a problem hiding this comment. We could also use WeakRef, we were discussing with Simon this morning that this seems the perfect use case for it |
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| } | ||
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| if (DEV) { | ||
| // If the value is invalid then the native exception will fire here | ||
| value = new Map(value); | ||
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@@ -79,6 +91,22 @@ export class SvelteMap extends Map { | |
| } | ||
| } | ||
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| /** | ||
| * If the active_reaction is the same as the reaction that created this SvelteMap, | ||
| * we use state so that it will not be a dependency of the reaction. Otherwise we | ||
| * use source so it will be. | ||
| * | ||
| * @template T | ||
| * @param {T} value | ||
| * @returns {Source<T>} | ||
| */ | ||
| #source(value) { | ||
| if (this.#initial_reaction === active_reaction) { | ||
| return state(value); | ||
| } | ||
| return source(value); | ||
| } | ||
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| /** @param {K} key */ | ||
| has(key) { | ||
| var sources = this.#sources; | ||
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@@ -87,7 +115,7 @@ export class SvelteMap extends Map { | |
| if (s === undefined) { | ||
| var ret = super.get(key); | ||
| if (ret !== undefined) { | ||
| s = this.#source(0); | ||
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| if (DEV) { | ||
| tag(s, `SvelteMap get(${label(key)})`); | ||
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@@ -123,7 +151,7 @@ export class SvelteMap extends Map { | |
| if (s === undefined) { | ||
| var ret = super.get(key); | ||
| if (ret !== undefined) { | ||
| s = this.#source(0); | ||
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| if (DEV) { | ||
| tag(s, `SvelteMap get(${label(key)})`); | ||
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@@ -154,7 +182,7 @@ export class SvelteMap extends Map { | |
| var version = this.#version; | ||
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| if (s === undefined) { | ||
| s = this.#source(0); | ||
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| if (DEV) { | ||
| tag(s, `SvelteMap get(${label(key)})`); | ||
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@@ -219,8 +247,7 @@ export class SvelteMap extends Map { | |
| if (this.#size.v !== sources.size) { | ||
| for (var key of super.keys()) { | ||
| if (!sources.has(key)) { | ||
| var s = this.#source(0); | ||
| if (DEV) { | ||
| tag(s, `SvelteMap get(${label(key)})`); | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,27 +1,101 @@ | ||
| <script> | ||
| import { SvelteMap } from 'svelte/reactivity'; | ||
| let outside_basic = $state(false); | ||
| let outside_basic_map = new SvelteMap(); | ||
| const throw_basic = $derived.by(() => { | ||
| outside_basic_map.set(1, 1); | ||
| return outside_basic_map; | ||
| }); | ||
| let inside_basic = $state(false); | ||
| const works_basic = $derived.by(() => { | ||
| let inside = new SvelteMap(); | ||
| inside.set(1, 1); | ||
| return inside; | ||
| }); | ||
| let outside_has = $state(false); | ||
| let outside_has_map = new SvelteMap([[1, 1]]); | ||
| const throw_has = $derived.by(() => { | ||
| outside_has_map.has(1); | ||
| outside_has_map.set(1, 2); | ||
| return outside_has_map; | ||
| }); | ||
| let inside_has = $state(false); | ||
| const works_has = $derived.by(() => { | ||
| let inside = new SvelteMap([[1, 1]]); | ||
| inside.has(1); | ||
| inside.set(1, 1); | ||
| return inside; | ||
| }); | ||
| let outside_get = $state(false); | ||
| let outside_get_map = new SvelteMap([[1, 1]]); | ||
| const throw_get = $derived.by(() => { | ||
| outside_get_map.get(1); | ||
| outside_get_map.set(1, 2); | ||
| return outside_get_map; | ||
| }); | ||
| let inside_get = $state(false); | ||
| const works_get = $derived.by(() => { | ||
| let inside = new SvelteMap([[1, 1]]); | ||
| inside.get(1); | ||
| inside.set(1, 1); | ||
| return inside; | ||
| }); | ||
| let outside_values = $state(false); | ||
| let outside_values_map = new SvelteMap([[1, 1]]); | ||
| const throw_values = $derived.by(() => { | ||
| outside_values_map.values(1); | ||
| outside_values_map.set(1, 2); | ||
| return outside_values_map; | ||
| }); | ||
| let inside_values = $state(false); | ||
| const works_values = $derived.by(() => { | ||
| let inside = new SvelteMap([[1, 1]]); | ||
| inside.values(); | ||
| inside.set(1, 1); | ||
| return inside; | ||
| }); | ||
| </script> | ||
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| <button onclick={() => (outside_basic = true)}>external</button> | ||
| {#if outside_basic} | ||
| {throw_basic} | ||
| {/if} | ||
| <button onclick={() => (inside_basic = true)}>internal</button> | ||
| {#if inside_basic} | ||
| {works_basic} | ||
| {/if} | ||
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| <button onclick={() => (outside_has = true)}>external</button> | ||
| {#if outside_has} | ||
| {throw_has} | ||
| {/if} | ||
| <button onclick={() => (inside_has = true)}>internal</button> | ||
| {#if inside_has} | ||
| {works_has} | ||
| {/if} | ||
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| <button onclick={() => (outside_get = true)}>external</button> | ||
| {#if outside_get} | ||
| {throw_get} | ||
| {/if} | ||
| <button onclick={() => (inside_get = true)}>internal</button> | ||
| {#if inside_get} | ||
| {works_get} | ||
| {/if} | ||
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| <button onclick={() => (outside_values = true)}>external</button> | ||
| {#if outside_values} | ||
| {throw_values} | ||
| {/if} | ||
| <button onclick={() => (inside_values = true)}>internal</button> | ||
| {#if inside_values} | ||
| {works_values} | ||
| {/if} |
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Wondering if there are cases when map still lives, while the reaction could have been GCed and this would prevent it?
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Yeah I was wondering about that too...technically it shouldn't be the case because either there's no active reaction (it's outside of a derived/effect) or it's inside it but this means that when the derived/effect is no longer used the function should be GCd and everything inside it too...but I need to do a better check
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Maybe this can become
initial_reaction = WeakSet(active_reaction)and we can check withthis.initial_reaction.has(active_reaction)?There was a problem hiding this comment.
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Just for the sake of history, I've also discovered there is a WeakRef struct that could be alternative here. In case of any future issues might be a possible alternative implementation