stromjs/dist/functions/rate.js

Dependency-free streams utils for Node.js

"use strict";
var __assign = (this && this.__assign) || function () {
    __assign = Object.assign || function(t) {
        for (var s, i = 1, n = arguments.length; i < n; i++) {
            s = arguments[i];
            for (var p in s) if (Object.prototype.hasOwnProperty.call(s, p))
                t[p] = s[p];
        }
        return t;
    };
    return __assign.apply(this, arguments);
};
var __awaiter = (this && this.__awaiter) || function (thisArg, _arguments, P, generator) {
    function adopt(value) { return value instanceof P ? value : new P(function (resolve) { resolve(value); }); }
    return new (P || (P = Promise))(function (resolve, reject) {
        function fulfilled(value) { try { step(generator.next(value)); } catch (e) { reject(e); } }
        function rejected(value) { try { step(generator["throw"](value)); } catch (e) { reject(e); } }
        function step(result) { result.done ? resolve(result.value) : adopt(result.value).then(fulfilled, rejected); }
        step((generator = generator.apply(thisArg, _arguments || [])).next());
    });
};
var __generator = (this && this.__generator) || function (thisArg, body) {
    var _ = { label: 0, sent: function() { if (t[0] & 1) throw t[1]; return t[1]; }, trys: [], ops: [] }, f, y, t, g;
    return g = { next: verb(0), "throw": verb(1), "return": verb(2) }, typeof Symbol === "function" && (g[Symbol.iterator] = function() { return this; }), g;
    function verb(n) { return function (v) { return step([n, v]); }; }
    function step(op) {
        if (f) throw new TypeError("Generator is already executing.");
        while (g && (g = 0, op[0] && (_ = 0)), _) try {
            if (f = 1, y && (t = op[0] & 2 ? y["return"] : op[0] ? y["throw"] || ((t = y["return"]) && t.call(y), 0) : y.next) && !(t = t.call(y, op[1])).done) return t;
            if (y = 0, t) op = [op[0] & 2, t.value];
            switch (op[0]) {
                case 0: case 1: t = op; break;
                case 4: _.label++; return { value: op[1], done: false };
                case 5: _.label++; y = op[1]; op = [0]; continue;
                case 7: op = _.ops.pop(); _.trys.pop(); continue;
                default:
                    if (!(t = _.trys, t = t.length > 0 && t[t.length - 1]) && (op[0] === 6 || op[0] === 2)) { _ = 0; continue; }
                    if (op[0] === 3 && (!t || (op[1] > t[0] && op[1] < t[3]))) { _.label = op[1]; break; }
                    if (op[0] === 6 && _.label < t[1]) { _.label = t[1]; t = op; break; }
                    if (t && _.label < t[2]) { _.label = t[2]; _.ops.push(op); break; }
                    if (t[2]) _.ops.pop();
                    _.trys.pop(); continue;
            }
            op = body.call(thisArg, _);
        } catch (e) { op = [6, e]; y = 0; } finally { f = t = 0; }
        if (op[0] & 5) throw op[1]; return { value: op[0] ? op[1] : void 0, done: true };
    }
};
exports.__esModule = true;
exports.rate = exports.Behavior = void 0;
var stream_1 = require("stream");
var perf_hooks_1 = require("perf_hooks");
var helpers_1 = require("../helpers");
var Behavior;
(function (Behavior) {
    Behavior[Behavior["BUFFER"] = 0] = "BUFFER";
    Behavior[Behavior["DROP"] = 1] = "DROP";
})(Behavior = exports.Behavior || (exports.Behavior = {}));
function rate(targetRate, period, options) {
    if (targetRate === void 0) { targetRate = 50; }
    if (period === void 0) { period = 1; }
    var deltaMS = ((1 / targetRate) * 1000) / period; // Skip a full period
    var total = 0;
    var window = (options === null || options === void 0 ? void 0 : options.window) || Infinity;
    var behavior = (options === null || options === void 0 ? void 0 : options.behavior) || Behavior.BUFFER;
    var start = perf_hooks_1.performance.now();
    return new stream_1.Transform(__assign(__assign({}, options), { transform: function (data, encoding, callback) {
            return __awaiter(this, void 0, void 0, function () {
                var now, currentRate;
                return __generator(this, function (_a) {
                    switch (_a.label) {
                        case 0:
                            now = perf_hooks_1.performance.now();
                            if (now - start >= window) {
                                start = now - window;
                            }
                            currentRate = (total / (now - start)) * 1000;
                            if (!(targetRate && currentRate > targetRate)) return [3 /*break*/, 3];
                            if (!(behavior === Behavior.DROP)) return [3 /*break*/, 1];
                            callback(undefined);
                            return [2 /*return*/];
                        case 1: return [4 /*yield*/, (0, helpers_1.sleep)(deltaMS)];
                        case 2:
                            _a.sent();
                            _a.label = 3;
                        case 3:
                            total += 1;
                            callback(undefined, data);
                            return [2 /*return*/];
                    }
                });
            });
        } }));
}
exports.rate = rate;