Current File : //lib/node_modules/pm2/node_modules/async/memoize.js
'use strict';
Object.defineProperty(exports, "__esModule", {
value: true
});
exports.default = memoize;
var _setImmediate = require('./internal/setImmediate.js');
var _setImmediate2 = _interopRequireDefault(_setImmediate);
var _initialParams = require('./internal/initialParams.js');
var _initialParams2 = _interopRequireDefault(_initialParams);
var _wrapAsync = require('./internal/wrapAsync.js');
var _wrapAsync2 = _interopRequireDefault(_wrapAsync);
function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
/**
* Caches the results of an async function. When creating a hash to store
* function results against, the callback is omitted from the hash and an
* optional hash function can be used.
*
* **Note: if the async function errs, the result will not be cached and
* subsequent calls will call the wrapped function.**
*
* If no hash function is specified, the first argument is used as a hash key,
* which may work reasonably if it is a string or a data type that converts to a
* distinct string. Note that objects and arrays will not behave reasonably.
* Neither will cases where the other arguments are significant. In such cases,
* specify your own hash function.
*
* The cache of results is exposed as the `memo` property of the function
* returned by `memoize`.
*
* @name memoize
* @static
* @memberOf module:Utils
* @method
* @category Util
* @param {AsyncFunction} fn - The async function to proxy and cache results from.
* @param {Function} hasher - An optional function for generating a custom hash
* for storing results. It has all the arguments applied to it apart from the
* callback, and must be synchronous.
* @returns {AsyncFunction} a memoized version of `fn`
* @example
*
* var slow_fn = function(name, callback) {
* // do something
* callback(null, result);
* };
* var fn = async.memoize(slow_fn);
*
* // fn can now be used as if it were slow_fn
* fn('some name', function() {
* // callback
* });
*/
function memoize(fn, hasher = v => v) {
var memo = Object.create(null);
var queues = Object.create(null);
var _fn = (0, _wrapAsync2.default)(fn);
var memoized = (0, _initialParams2.default)((args, callback) => {
var key = hasher(...args);
if (key in memo) {
(0, _setImmediate2.default)(() => callback(null, ...memo[key]));
} else if (key in queues) {
queues[key].push(callback);
} else {
queues[key] = [callback];
_fn(...args, (err, ...resultArgs) => {
// #1465 don't memoize if an error occurred
if (!err) {
memo[key] = resultArgs;
}
var q = queues[key];
delete queues[key];
for (var i = 0, l = q.length; i < l; i++) {
q[i](err, ...resultArgs);
}
});
}
});
memoized.memo = memo;
memoized.unmemoized = fn;
return memoized;
}
module.exports = exports['default'];
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