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- import { Transport } from "../transport.js";
- import { randomString } from "../util.js";
- import { encodePayload, decodePayload } from "engine.io-parser";
- export class Polling extends Transport {
- constructor() {
- super(...arguments);
- this._polling = false;
- }
- get name() {
- return "polling";
- }
- /**
- * Opens the socket (triggers polling). We write a PING message to determine
- * when the transport is open.
- *
- * @protected
- */
- doOpen() {
- this._poll();
- }
- /**
- * Pauses polling.
- *
- * @param {Function} onPause - callback upon buffers are flushed and transport is paused
- * @package
- */
- pause(onPause) {
- this.readyState = "pausing";
- const pause = () => {
- this.readyState = "paused";
- onPause();
- };
- if (this._polling || !this.writable) {
- let total = 0;
- if (this._polling) {
- total++;
- this.once("pollComplete", function () {
- --total || pause();
- });
- }
- if (!this.writable) {
- total++;
- this.once("drain", function () {
- --total || pause();
- });
- }
- }
- else {
- pause();
- }
- }
- /**
- * Starts polling cycle.
- *
- * @private
- */
- _poll() {
- this._polling = true;
- this.doPoll();
- this.emitReserved("poll");
- }
- /**
- * Overloads onData to detect payloads.
- *
- * @protected
- */
- onData(data) {
- const callback = (packet) => {
- // if its the first message we consider the transport open
- if ("opening" === this.readyState && packet.type === "open") {
- this.onOpen();
- }
- // if its a close packet, we close the ongoing requests
- if ("close" === packet.type) {
- this.onClose({ description: "transport closed by the server" });
- return false;
- }
- // otherwise bypass onData and handle the message
- this.onPacket(packet);
- };
- // decode payload
- decodePayload(data, this.socket.binaryType).forEach(callback);
- // if an event did not trigger closing
- if ("closed" !== this.readyState) {
- // if we got data we're not polling
- this._polling = false;
- this.emitReserved("pollComplete");
- if ("open" === this.readyState) {
- this._poll();
- }
- else {
- }
- }
- }
- /**
- * For polling, send a close packet.
- *
- * @protected
- */
- doClose() {
- const close = () => {
- this.write([{ type: "close" }]);
- };
- if ("open" === this.readyState) {
- close();
- }
- else {
- // in case we're trying to close while
- // handshaking is in progress (GH-164)
- this.once("open", close);
- }
- }
- /**
- * Writes a packets payload.
- *
- * @param {Array} packets - data packets
- * @protected
- */
- write(packets) {
- this.writable = false;
- encodePayload(packets, (data) => {
- this.doWrite(data, () => {
- this.writable = true;
- this.emitReserved("drain");
- });
- });
- }
- /**
- * Generates uri for connection.
- *
- * @private
- */
- uri() {
- const schema = this.opts.secure ? "https" : "http";
- const query = this.query || {};
- // cache busting is forced
- if (false !== this.opts.timestampRequests) {
- query[this.opts.timestampParam] = randomString();
- }
- if (!this.supportsBinary && !query.sid) {
- query.b64 = 1;
- }
- return this.createUri(schema, query);
- }
- }
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