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RequestHandler.js
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RequestHandler.js
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'use strict';
const { AsyncQueue } = require('@sapphire/async-queue');
const DiscordAPIError = require('./DiscordAPIError');
const HTTPError = require('./HTTPError');
const {
Events: { RATE_LIMIT, INVALID_REQUEST_WARNING },
} = require('../util/Constants');
const Util = require('../util/Util');
function parseResponse(res) {
if (res.headers.get('content-type').startsWith('application/json')) return res.json();
return res.buffer();
}
function getAPIOffset(serverDate) {
return new Date(serverDate).getTime() - Date.now();
}
function calculateReset(reset, resetAfter, serverDate) {
// Use direct reset time when available, server date becomes irrelevant in this case
if (resetAfter) {
return Date.now() + Number(resetAfter) * 1000;
}
return new Date(Number(reset) * 1000).getTime() - getAPIOffset(serverDate);
}
/* Invalid request limiting is done on a per-IP basis, not a per-token basis.
* The best we can do is track invalid counts process-wide (on the theory that
* users could have multiple bots run from one process) rather than per-bot.
* Therefore, store these at file scope here rather than in the client's
* RESTManager object.
*/
let invalidCount = 0;
let invalidCountResetTime = null;
class RequestHandler {
constructor(manager) {
this.manager = manager;
this.queue = new AsyncQueue();
this.reset = -1;
this.remaining = -1;
this.limit = -1;
}
async push(request) {
await this.queue.wait();
try {
return await this.execute(request);
} finally {
this.queue.shift();
}
}
get globalLimited() {
return this.manager.globalRemaining <= 0 && Date.now() < this.manager.globalReset;
}
get localLimited() {
return this.remaining <= 0 && Date.now() < this.reset;
}
get limited() {
return this.globalLimited || this.localLimited;
}
get _inactive() {
return this.queue.remaining === 0 && !this.limited;
}
globalDelayFor(ms) {
return new Promise(resolve => {
this.manager.client.setTimeout(() => {
this.manager.globalDelay = null;
resolve();
}, ms);
});
}
async execute(request) {
/*
* After calculations have been done, pre-emptively stop further requests
* Potentially loop until this task can run if e.g. the global rate limit is hit twice
*/
while (this.limited) {
const isGlobal = this.globalLimited;
let limit, timeout, delayPromise;
if (isGlobal) {
// Set the variables based on the global rate limit
limit = this.manager.globalLimit;
timeout = this.manager.globalReset + this.manager.client.options.restTimeOffset - Date.now();
// If this is the first task to reach the global timeout, set the global delay
if (!this.manager.globalDelay) {
// The global delay function should clear the global delay state when it is resolved
this.manager.globalDelay = this.globalDelayFor(timeout);
}
delayPromise = this.manager.globalDelay;
} else {
// Set the variables based on the route-specific rate limit
limit = this.limit;
timeout = this.reset + this.manager.client.options.restTimeOffset - Date.now();
delayPromise = Util.delayFor(timeout);
}
if (this.manager.client.listenerCount(RATE_LIMIT)) {
/**
* Emitted when the client hits a rate limit while making a request
* @event Client#rateLimit
* @param {Object} rateLimitInfo Object containing the rate limit info
* @param {number} rateLimitInfo.timeout Timeout in ms
* @param {number} rateLimitInfo.limit Number of requests that can be made to this endpoint
* @param {string} rateLimitInfo.method HTTP method used for request that triggered this event
* @param {string} rateLimitInfo.path Path used for request that triggered this event
* @param {string} rateLimitInfo.route Route used for request that triggered this event
* @param {boolean} rateLimitInfo.global Whether the rate limit that was reached was the global limit
*/
this.manager.client.emit(RATE_LIMIT, {
timeout,
limit,
method: request.method,
path: request.path,
route: request.route,
global: isGlobal,
});
}
// Wait for the timeout to expire in order to avoid an actual 429
await delayPromise; // eslint-disable-line no-await-in-loop
}
// As the request goes out, update the global usage information
if (!this.manager.globalReset || this.manager.globalReset < Date.now()) {
this.manager.globalReset = Date.now() + 1000;
this.manager.globalRemaining = this.manager.globalLimit;
}
this.manager.globalRemaining--;
// Perform the request
let res;
try {
res = await request.make();
} catch (error) {
// Retry the specified number of times for request abortions
if (request.retries === this.manager.client.options.retryLimit) {
throw new HTTPError(error.message, error.constructor.name, error.status, request);
}
request.retries++;
return this.execute(request);
}
let sublimitTimeout;
if (res && res.headers) {
const serverDate = res.headers.get('date');
const limit = res.headers.get('x-ratelimit-limit');
const remaining = res.headers.get('x-ratelimit-remaining');
const reset = res.headers.get('x-ratelimit-reset');
const resetAfter = res.headers.get('x-ratelimit-reset-after');
this.limit = limit ? Number(limit) : Infinity;
this.remaining = remaining ? Number(remaining) : 1;
this.reset = reset || resetAfter ? calculateReset(reset, resetAfter, serverDate) : Date.now();
// https://github.com/discordapp/discord-api-docs/issues/182
if (!resetAfter && request.route.includes('reactions')) {
this.reset = new Date(serverDate).getTime() - getAPIOffset(serverDate) + 250;
}
// Handle retryAfter, which means we have actually hit a rate limit
let retryAfter = res.headers.get('retry-after');
retryAfter = retryAfter ? Number(retryAfter) * 1000 : -1;
if (retryAfter > 0) {
// If the global ratelimit header is set, that means we hit the global rate limit
if (res.headers.get('x-ratelimit-global')) {
this.manager.globalRemaining = 0;
this.manager.globalReset = Date.now() + retryAfter;
} else if (!this.localLimited) {
/*
* This is a sublimit (e.g. 2 channel name changes/10 minutes) since the headers don't indicate a
* route-wide rate limit. Don't update remaining or reset to avoid rate limiting the whole
* endpoint, just set a reset time on the request itself to avoid retrying too soon.
*/
sublimitTimeout = retryAfter;
}
}
}
// Count the invalid requests
if (res.status === 401 || res.status === 403 || res.status === 429) {
if (!invalidCountResetTime || invalidCountResetTime < Date.now()) {
invalidCountResetTime = Date.now() + 1000 * 60 * 10;
invalidCount = 0;
}
invalidCount++;
const emitInvalid =
this.manager.client.listenerCount(INVALID_REQUEST_WARNING) &&
this.manager.client.options.invalidRequestWarningInterval > 0 &&
invalidCount % this.manager.client.options.invalidRequestWarningInterval === 0;
if (emitInvalid) {
/**
* Emitted periodically when the process sends invalid messages to let users avoid the
* 10k invalid requests in 10 minutes threshold that causes a ban
* @event Client#invalidRequestWarning
* @param {number} invalidRequestWarningInfo.count Number of invalid requests that have been made in the window
* @param {number} invalidRequestWarningInfo.remainingTime Time in ms remaining before the count resets
*/
this.manager.client.emit(INVALID_REQUEST_WARNING, {
count: invalidCount,
remainingTime: invalidCountResetTime - Date.now(),
});
}
}
// Handle 2xx and 3xx responses
if (res.ok) {
// Nothing wrong with the request, proceed with the next one
return parseResponse(res);
}
// Handle 4xx responses
if (res.status >= 400 && res.status < 500) {
// Handle ratelimited requests
if (res.status === 429) {
// A ratelimit was hit - this should never happen
this.manager.client.emit('debug', `429 hit on route ${request.route}${sublimitTimeout ? ' for sublimit' : ''}`);
// If caused by a sublimit, wait it out here so other requests on the route can be handled
if (sublimitTimeout) {
await Util.delayFor(sublimitTimeout);
}
return this.execute(request);
}
// Handle possible malformed requests
let data;
try {
data = await parseResponse(res);
} catch (err) {
throw new HTTPError(err.message, err.constructor.name, err.status, request);
}
throw new DiscordAPIError(data, res.status, request);
}
// Handle 5xx responses
if (res.status >= 500 && res.status < 600) {
// Retry the specified number of times for possible serverside issues
if (request.retries === this.manager.client.options.retryLimit) {
throw new HTTPError(res.statusText, res.constructor.name, res.status, request);
}
request.retries++;
return this.execute(request);
}
// Fallback in the rare case a status code outside the range 200..=599 is returned
return null;
}
}
module.exports = RequestHandler;