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RequestQueue

A simple queue for GM_xmlhttpRequests or other async functions

Version vom 03.07.2018. Aktuellste Version

Dieses Skript sollte nicht direkt installiert werden. Es handelt sich hier um eine Bibliothek für andere Skripte, welche über folgenden Befehl in den Metadaten eines Skriptes eingebunden wird // @require https://update.greatest.deepsurf.us/scripts/370011/610040/RequestQueue.js 

// ==UserScript==
// @exclude     *
// ==UserLibrary==
// @name        RequestQueue
// @description A simple queue for GM_xmlhttpRequests or other async functions
// @version     6
// @license     MIT
// ==/UserLibrary==
// @namespace   cuzi
// @homepageURL https://github.com/cvzi/RequestQueue/
// @grant       GM_xmlhttpRequest
// @grant       GM.xmlhttpRequest
// ==/UserScript==

// ==OpenUserJS==
// @author      cuzi
// ==/OpenUserJS==

"use strict";

function RequestQueue(maxParallel,maxTotal) {
  // A simple queue for GM_xmlhttpRequests or other async functions

  maxParallel = parseInt(maxParallel)>0?parseInt(maxParallel):1;
  maxTotal = parseInt(maxTotal)>0?parseInt(maxTotal):Number.POSITIVE_INFINITY;

  var index = 0; // incrementing, used for unique ids
  var finished = 0; // Number of finished requests
  var pending = [];
  var running = [];
  
  
  
  
  var defaultFunction;
  if(typeof GM != "undefined" && "xmlHttpRequest" in GM) {
    defaultFunction = GM.xmlHttpRequest;
  } else {
    defaultFunction = function(a,b,c,d) { return GM_xmlhttpRequest(a,b,c,d);} // Wrap GM_xmlhttpRequest to avoid security exception
  }


  /*
  The internal request Object extended by add(req,fun,thisArg)
  {
    __fun : fun, defaults to GM_xmlhttpRequest
    __thisArg : thisArg, the this object for the above function
    __result : the return value of __fun is saved in this property

    __org_onload : The original event callbacks of req
    __org_onerror
    __org_onabort

    onload : The new event callbacks that wrap the above callbacks
    onerror
    onabort

    ... and all the original properties of the "req" object
  }

  */

  var fire = function() {
    // Check for pending requests and send them.
    if(pending.length > 0 && running.length < maxParallel && finished < maxTotal) {
      var req = pending.shift();
      running.push(req);
      req.__result = req.__fun.call(req.__thisArg,req);
      fire();
    }
  };

  var remove = function(id) {
    // Remove the request with id from the the running array
    for(var i = 0; i < running.length; i++) {
      if(running[i].id == id) {
        running.splice(i, 1);
        finished++;
        fire();
        break;
      }
    }
  };

  this.add = function(req,fun,thisArg) {
    // Schedule a request: add(req[, fun[, thisArg]])
    // fun:      defaults to GM.xmlHttpRequest
    // thisArg:  The value of this provided for the call to fun. Keep strict mode in mind!
    req.id = index++;

    req.__fun = typeof(fun) === 'function'?fun:defaultFunction; 
    req.__thisArg = thisArg;

    // Wrap events that indicate that the request has finished
    req.__org_onload = req.onload;
    req.onload = function(response) {
     if(response.status === 0) { // This is true if a request was aborted. This seems to happen only sporadically
        req.onabort(response);
        return;
      }
      remove(req.id);
      if(req.__org_onload) req.__org_onload(response);
      };

    req.__org_onerror = req.onerror;
    req.onerror = function(response) {
      remove(req.id);
      if(req.__org_onerror) req.__org_onerror(response);
      };

    req.__org_onabort = req.onabort;
    req.onabort = function(response) {
      remove(req.id);
      if(req.__org_onabort) req.__org_onabort(response);
      };

    pending.push(req);
    fire();
  };

  this.abortRunning = function() {
    // For any added function that was already run: result = thisArg.fun(req)
    // it will call result.abort()
    // For GM_xmlhttpRequest this will subsequently fire an onabort event
    for(var i = 0; i < running.length; i++) {
      if(running[i] && typeof running[i].__result.abort === 'function') {
        running[i].__result.abort();
      }
    }
  };

  this.abortPending = function() {
    // Clear the pending list
    pending = [];
  };

  this.abort = function() {
    // Abort both running and pending requests
    this.abortPending();
    this.abortRunning();
  };
  
  this.resetTotal = function() {
    // Reset number of finished requests
    finished = 0;
  }
  
  this.hasReachedTotal = function() {
    // Number of maximum allowed requests reached?
    return finished >= maxTotal;
  }
  
  this.hasRunning = function() {
    // Are there any running requests?
    return running.length > 0;
  }
  
  
}