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'use strict';
const { internalBinding } = require('internal/bootstrap/loaders');
const { safeToString } = internalBinding('util');
const maybeUnhandledPromises = new WeakMap();
const pendingUnhandledRejections = [];
const asyncHandledRejections = [];
const promiseRejectEvents = {};
let lastPromiseId = 0;
exports.setup = setupPromises;
function setupPromises(_setupPromises) {
_setupPromises(handler, promiseRejectEvents);
return emitPromiseRejectionWarnings;
}
function handler(type, promise, reason) {
switch (type) {
case promiseRejectEvents.kPromiseRejectWithNoHandler:
return unhandledRejection(promise, reason);
case promiseRejectEvents.kPromiseHandlerAddedAfterReject:
return handledRejection(promise);
case promiseRejectEvents.kPromiseResolveAfterResolved:
return resolveError('resolve', promise, reason);
case promiseRejectEvents.kPromiseRejectAfterResolved:
return resolveError('reject', promise, reason);
}
}
function resolveError(type, promise, reason) {
// We have to wrap this in a next tick. Otherwise the error could be caught by
// the executed promise.
process.nextTick(() => {
process.emit('multipleResolves', type, promise, reason);
});
}
function unhandledRejection(promise, reason) {
maybeUnhandledPromises.set(promise, {
reason,
uid: ++lastPromiseId,
warned: false
});
pendingUnhandledRejections.push(promise);
return true;
}
function handledRejection(promise) {
const promiseInfo = maybeUnhandledPromises.get(promise);
if (promiseInfo !== undefined) {
maybeUnhandledPromises.delete(promise);
if (promiseInfo.warned) {
const { uid } = promiseInfo;
// Generate the warning object early to get a good stack trace.
// eslint-disable-next-line no-restricted-syntax
const warning = new Error('Promise rejection was handled ' +
`asynchronously (rejection id: ${uid})`);
warning.name = 'PromiseRejectionHandledWarning';
warning.id = uid;
asyncHandledRejections.push({ promise, warning });
return true;
}
}
return false;
}
const unhandledRejectionErrName = 'UnhandledPromiseRejectionWarning';
function emitWarning(uid, reason) {
// eslint-disable-next-line no-restricted-syntax
const warning = new Error(
'Unhandled promise rejection. This error originated either by ' +
'throwing inside of an async function without a catch block, ' +
'or by rejecting a promise which was not handled with .catch(). ' +
`(rejection id: ${uid})`
);
warning.name = unhandledRejectionErrName;
try {
if (reason instanceof Error) {
warning.stack = reason.stack;
process.emitWarning(reason.stack, unhandledRejectionErrName);
} else {
process.emitWarning(safeToString(reason), unhandledRejectionErrName);
}
} catch {}
process.emitWarning(warning);
emitDeprecationWarning();
}
let deprecationWarned = false;
function emitDeprecationWarning() {
if (!deprecationWarned) {
deprecationWarned = true;
process.emitWarning(
'Unhandled promise rejections are deprecated. In the future, ' +
'promise rejections that are not handled will terminate the ' +
'Node.js process with a non-zero exit code.',
'DeprecationWarning', 'DEP0018');
}
}
function emitPromiseRejectionWarnings() {
while (asyncHandledRejections.length > 0) {
const { promise, warning } = asyncHandledRejections.shift();
if (!process.emit('rejectionHandled', promise)) {
process.emitWarning(warning);
}
}
let hadListeners = false;
let len = pendingUnhandledRejections.length;
while (len--) {
const promise = pendingUnhandledRejections.shift();
const promiseInfo = maybeUnhandledPromises.get(promise);
if (promiseInfo !== undefined) {
promiseInfo.warned = true;
const { reason, uid } = promiseInfo;
if (!process.emit('unhandledRejection', reason, promise)) {
emitWarning(uid, reason);
} else {
hadListeners = true;
}
}
}
return hadListeners || pendingUnhandledRejections.length !== 0;
}
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