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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,92 @@ | ||
| /** | ||
| * A map that automatically removes entries after a defined time period | ||
| * or when the map size limit is reached | ||
| */ | ||
| export class VolatileMap<K,V> extends Map<K,V> { | ||
|
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| static readonly MAX_MAP_ENTRIES = 2**24 | ||
| static readonly MAP_ENTRIES_CLEANUP_CHUNK = 1000 | ||
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| #options: VolatileMapOptions | ||
| #timeouts = new Map<K, number>() | ||
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| constructor(iterable?: Iterable<readonly [K, V]> | null, options: Partial<VolatileMapOptions> = {}) { | ||
| super(iterable) | ||
| this.#options = options as VolatileMapOptions; | ||
| this.#options.entryLifetime ??= 30*60 // 30min | ||
| this.#options.preventMapOverflow ??= true | ||
| } | ||
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| /** | ||
| * Resets the lifetime of the entry. | ||
| * @param key | ||
| * @param overrideLifetime optionally specify a lifetime for this entry that differs from options.entryLifetime | ||
| * @returns the current value for the key | ||
| */ | ||
| keepalive(key: K, overrideLifetime?: number) { | ||
| this.#setTimeout(key, overrideLifetime); | ||
| return this.get(key) | ||
| } | ||
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| set(key: K, value: V): this { | ||
| // create new lifetime timeout | ||
| this.#setTimeout(key) | ||
| // maximum map size reached? | ||
| if (this.#options.preventMapOverflow && this.size >= VolatileMap.MAX_MAP_ENTRIES) { | ||
| console.log("VolatileMap size limit ("+VolatileMap.MAX_MAP_ENTRIES+") reached. Force removing "+VolatileMap.MAP_ENTRIES_CLEANUP_CHUNK+" entries.") | ||
| let i = 0; | ||
| for (const key of this.keys()) { | ||
| if (i == VolatileMap.MAP_ENTRIES_CLEANUP_CHUNK) break; | ||
| this.delete(key) | ||
| i++; | ||
| } | ||
| } | ||
| return super.set(key, value) | ||
| } | ||
|
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| delete(key: K): boolean { | ||
| this.#clearTimeout(key); | ||
| return super.delete(key) | ||
| } | ||
|
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| clear(): void { | ||
| for (const key of this.keys()) this.#clearTimeout(key); | ||
| return super.clear(); | ||
| } | ||
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| #clearTimeout(key: K) { | ||
| if (this.#timeouts.has(key)) { | ||
| clearTimeout(this.#timeouts.get(key)); | ||
| this.#timeouts.delete(key); | ||
| } | ||
| } | ||
|
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| #setTimeout(key: K, overrideLifetime?: number) { | ||
| // reset previous timeout | ||
| this.#clearTimeout(key); | ||
| const lifetime = overrideLifetime ?? this.#options.entryLifetime; | ||
| if (Number.isFinite(lifetime)) { | ||
| this.#timeouts.set(key, setTimeout(() => { | ||
| this.delete(key) | ||
| }, lifetime * 1000)) | ||
| } | ||
| } | ||
| } | ||
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| export type VolatileMapOptions = { | ||
| /** | ||
| * Entry lifetime in seconds. If set to Infinity, | ||
| * entries are only automatically removed if the map size limit | ||
| * is reached and preventMapOverflow is set to true. | ||
| * Default value: 1800 (30min) | ||
| */ | ||
| entryLifetime: number, | ||
| /** | ||
| * Automatically deletes the oldest entries if the number of map entries | ||
| * exceeds the maximum allowed number (2^24), even if their lifetime | ||
| * is not yet expired. | ||
| * Default value: true | ||
| */ | ||
| preventMapOverflow: boolean | ||
| } |