135 lines
2.9 KiB
TypeScript
135 lines
2.9 KiB
TypeScript
import { applyPatch, calcPatch } from "fast-myers-diff";
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import { Packr } from "msgpackr";
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import { gunzip, gzip } from "zlib";
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const MAX_HISTORY = 10;
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const packr = new Packr({});
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type PATCH_RESULT<T> =
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| {
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mode: "new";
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ts: string;
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data: number[];
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}
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| {
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mode: "patch";
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ts: string;
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diff: any;
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};
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export class Diff<T> {
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ts = "";
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mode: "client" | "server" = "server";
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private _data: number[] = [];
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private _history = {} as Record<string, number[]>;
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constructor() {}
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get data() {
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const _data = new Uint8Array(this._data);
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return new Promise<T>((done) => {
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if (typeof window === "undefined") {
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gunzipAsync(_data).then((result) => {
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done(packr.unpack(result));
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});
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}
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});
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}
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async update(data: T) {
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if (this.mode === "server") {
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this._data = (await gzipAsync(packr.pack(data))).toJSON().data;
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this.ts =
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(Date.now() + "").substring(5) + Math.round(performance.now() * 10000);
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this._history[this.ts] = this._data;
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let i = 0;
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for (const k of Object.keys(this._history).sort(
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(a, b) => parseInt(b) - parseInt(a)
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)) {
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if (i > MAX_HISTORY) {
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delete this._history[k];
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}
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i++;
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}
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}
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}
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getPatch(ts: "new" | string): PATCH_RESULT<T> {
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if (ts !== "new") {
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const old_data = this._history[ts];
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if (old_data) {
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const result_diff = [...calcPatch(old_data, this._data)];
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return { diff: result_diff, mode: "patch", ts: this.ts };
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}
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}
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return { data: this._data, mode: "new", ts: this.ts };
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}
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async applyPatch(patch: PATCH_RESULT<T>) {
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if (patch.mode === "new") {
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this.ts = patch.ts;
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if (patch.data) this._data = patch.data;
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} else {
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this.ts = patch.ts;
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const num_array = [];
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for (const num of applyPatch(this._data, patch.diff)) {
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if (Array.isArray(num)) {
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for (const n of num) {
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num_array.push(n);
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}
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} else {
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num_array.push(num);
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}
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}
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this._data = num_array;
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}
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}
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static async server<T>(str: T) {
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const diff = new Diff<T>();
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await diff.update(str);
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return diff;
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}
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static async client<T>(patch: PATCH_RESULT<T>) {
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const diff = new Diff<T>();
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diff.mode = "client";
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if (patch.mode === "new") {
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diff.ts = patch.ts;
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if (patch.data) diff._data = patch.data;
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}
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return diff;
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}
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}
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export const gzipAsync = (bin: Uint8Array | string) => {
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return new Promise<Buffer>((resolve, reject) => {
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gzip(bin, (err, res) => {
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if (err) {
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reject(err);
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} else {
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resolve(res);
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}
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});
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});
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};
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export const gunzipAsync = (bin: Uint8Array) => {
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return new Promise<Buffer>((resolve, reject) => {
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gunzip(bin, (err, result) => {
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if (err) {
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reject(err);
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} else {
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resolve(result);
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}
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});
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});
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};
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