forked from MapComplete/MapComplete
108 lines
3.6 KiB
TypeScript
108 lines
3.6 KiB
TypeScript
import { IdbLocalStorage } from "../../Web/IdbLocalStorage"
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import { UIEventSource } from "../../UIEventSource"
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/**
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* A class which allows to read/write a tile to local storage.
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*
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* Does the heavy lifting for LocalStorageFeatureSource and SaveFeatureToLocalStorage.
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*
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* Note: OSM-features with a negative id are ignored
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*/
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export default class TileLocalStorage<T> {
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private static perLayer: Record<string, TileLocalStorage<any>> = {}
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private static readonly useIndexedDb = typeof indexedDB !== "undefined"
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private readonly _layername: string
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private readonly inUse = new UIEventSource(false)
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private readonly cachedSources: Record<number, UIEventSource<T> & { flush: () => void }> = {}
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private readonly _maxAgeSeconds: number
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private constructor(layername: string, maxAgeSeconds: number) {
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this._layername = layername
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this._maxAgeSeconds = maxAgeSeconds
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}
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public static construct<T>(
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backend: string,
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layername: string,
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maxAgeS: number
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): TileLocalStorage<T> {
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const key = backend + "_" + layername
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const cached = TileLocalStorage.perLayer[key]
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if (cached) {
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return cached
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}
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const tls = new TileLocalStorage<T>(key, maxAgeS)
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TileLocalStorage.perLayer[key] = tls
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return tls
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}
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/**
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* Constructs a UIEventSource element which is synced with localStorage.
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* Supports 'flush'
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*/
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public getTileSource(tileIndex: number): UIEventSource<T> & { flush: () => void } {
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const cached = this.cachedSources[tileIndex]
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if (cached) {
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return cached
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}
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const src = <UIEventSource<T> & { flush: () => void }>(
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UIEventSource.FromPromise(this.GetIdb(tileIndex))
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)
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src.flush = () => this.SetIdb(tileIndex, src.data)
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src.addCallbackD((data) => this.SetIdb(tileIndex, data))
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this.cachedSources[tileIndex] = src
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return src
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}
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private async SetIdb(tileIndex: number, data: any): Promise<void> {
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if (!TileLocalStorage.useIndexedDb) {
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return
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}
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try {
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await this.inUse.AsPromise((inUse) => !inUse)
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this.inUse.setData(true)
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await IdbLocalStorage.SetDirectly(this._layername + "_" + tileIndex, data)
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await IdbLocalStorage.SetDirectly(
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this._layername + "_" + tileIndex + "_date",
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Date.now()
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)
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this.inUse.setData(false)
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} catch (e) {
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console.error(
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"Could not save tile to indexed-db: ",
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e,
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"tileIndex is:",
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tileIndex,
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"for layer",
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this._layername,
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"data is",
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data
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)
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}
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}
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private async GetIdb(tileIndex: number): Promise<any> {
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if (!TileLocalStorage.useIndexedDb) {
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return undefined
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}
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const date = <any>(
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await IdbLocalStorage.GetDirectly(this._layername + "_" + tileIndex + "_date")
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)
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const maxAge = this._maxAgeSeconds
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const timeDiff = Date.now() - date
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if (timeDiff >= maxAge) {
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console.debug("Dropping cache for", this._layername, tileIndex, "out of date")
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await IdbLocalStorage.SetDirectly(this._layername + "_" + tileIndex, undefined)
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return undefined
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}
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const data = await IdbLocalStorage.GetDirectly(this._layername + "_" + tileIndex)
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return <any>data
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}
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invalidate(zoomlevel: number, tileIndex) {
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this.getTileSource(tileIndex).setData(undefined)
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}
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}
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