gristlabs_grist-core/app/server/lib/Requests.ts

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import {SandboxRequest} from 'app/common/ActionBundle';
import {ActiveDoc} from 'app/server/lib/ActiveDoc';
import {makeExceptionalDocSession} from 'app/server/lib/DocSession';
import {httpEncoding} from 'app/server/lib/httpEncoding';
import fetch from 'node-fetch';
import * as path from 'path';
import * as tmp from 'tmp';
import * as fse from 'fs-extra';
import log from 'app/server/lib/log';
import {proxyAgent} from "app/server/lib/ProxyAgent";
import chunk = require('lodash/chunk');
import fromPairs = require('lodash/fromPairs');
import zipObject = require('lodash/zipObject');
export class DocRequests {
// Request responses are briefly cached in files only to handle multiple requests in a formula
// and only as long as needed to finish calculating all formulas.
// When _numPending reaches 0 again, _cacheDir is deleted.
private _numPending: number = 0;
private _cacheDir: tmp.SynchrounousResult | null = null;
constructor(private readonly _activeDoc: ActiveDoc) {}
public async handleRequestsBatchFromUserActions(requests: Record<string, SandboxRequest>) {
const numRequests = Object.keys(requests).length;
this._numPending += numRequests;
try {
// Perform batches of requests in parallel for speed, and hope it doesn't cause rate limiting...
for (const keys of chunk(Object.keys(requests), 10)) {
const responses: Response[] = await Promise.all(keys.map(async key => {
const request = requests[key];
const response = await this.handleSingleRequestWithCache(key, request);
return {
...response,
// Tells the engine which cell(s) made the request and should be recalculated to use the response
deps: request.deps,
};
}));
// Tell the sandbox which previous responses we have cached in files.
// This lets it know it can immediately and synchronously get those responses again.
const cachedRequestKeys = await fse.readdir(this._cacheDir!.name);
// Recalculate formulas using this batch of responses.
const action = ["RespondToRequests", zipObject(keys, responses), cachedRequestKeys];
await this._activeDoc.applyUserActions(makeExceptionalDocSession("system"), [action]);
}
} finally {
this._numPending -= numRequests;
if (this._numPending === 0) {
log.debug(`Removing DocRequests._cacheDir: ${this._cacheDir!.name}`);
this._cacheDir!.removeCallback();
this._cacheDir = null;
}
}
}
public async handleSingleRequestWithCache(key: string, request: SandboxRequest): Promise<Response> {
if (!this._cacheDir) {
// Use the sync API because otherwise multiple requests being handled at the same time
// all reach this point, `await`, and create different dirs.
// `unsafeCleanup: true` means the directory can be deleted even if it's not empty, which is what we expect.
this._cacheDir = tmp.dirSync({unsafeCleanup: true});
log.debug(`Created DocRequests._cacheDir: ${this._cacheDir.name}`);
}
const cachePath = path.resolve(this._cacheDir.name, key);
try {
const result = await fse.readJSON(cachePath);
result.content = Buffer.from(result.content, "base64");
return result;
} catch {
const result = await this._handleSingleRequestRaw(request);
const resultForJson = {...result} as any;
if ('content' in result) {
resultForJson.content = result.content.toString("base64");
}
fse.writeJSON(cachePath, resultForJson).catch(e => log.warn(`Failed to save response to cache file: ${e}`));
return result;
}
}
private async _handleSingleRequestRaw(request: SandboxRequest): Promise<Response> {
try {
if (process.env.GRIST_EXPERIMENTAL_PLUGINS != '1') {
throw new Error("REQUEST is not enabled");
}
const {url, params, headers} = request;
const urlObj = new URL(url);
log.rawInfo("Handling sandbox request", {host: urlObj.host, docId: this._activeDoc.docName});
for (const [param, value] of Object.entries(params || {})) {
urlObj.searchParams.append(param, value);
}
const response = await fetch(urlObj.toString(), {headers: headers || {}, agent: proxyAgent(urlObj)});
const content = await response.buffer();
const {status, statusText} = response;
const encoding = httpEncoding(response.headers.get('content-type'), content);
return {
content, status, statusText, encoding,
headers: fromPairs([...response.headers]),
};
} catch (e) {
return {error: String(e)};
}
}
}
interface SuccessfulResponse {
content: Buffer;
status: number;
statusText: string;
encoding?: string;
headers: Record<string, string>;
}
interface RequestError {
error: string;
}
type Response = RequestError | SuccessfulResponse;