Initial State

start point

intermediate/monitoring/src/main/webapp/js/jquery.periodicalupdater.js

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+/**
+ * PeriodicalUpdater - jQuery plugin for timed, decaying ajax calls
+ *
+ * http://www.360innovate.co.uk/blog/2009/03/periodicalupdater-for-jquery/
+ * http://enfranchisedmind.com/blog/posts/jquery-periodicalupdater-ajax-polling/
+ *
+ * Copyright (c) 2009 by the following:
+ *  Frank White (http://customcode.info)
+ *  Robert Fischer (http://smokejumperit.com)
+ *  360innovate (http://www.360innovate.co.uk)
+ *
+ * Dual licensed under the MIT and GPL licenses:
+ * http://www.opensource.org/licenses/mit-license.php
+ * http://www.gnu.org/licenses/gpl.html
+ *
+ */
+
+(function($) {
+    var pu_log = function(msg) {
+      try {
+        console.log(msg);
+      } catch(err) {}
+    }
+
+    // Now back to our regularly scheduled work
+    $.PeriodicalUpdater = function(url, options, callback, autoStopCallback){
+      var settings = jQuery.extend(true, {
+          url: url,         // URL of ajax request
+          cache: false,     // By default, don't allow caching
+          method: 'GET',    // method; get or post
+          data: '',         // array of values to be passed to the page - e.g. {name: "John", greeting: "hello"}
+          minTimeout: 1000, // starting value for the timeout in milliseconds
+          maxTimeout: 8000, // maximum length of time between requests
+          multiplier: 2,    // if set to 2, timerInterval will double each time the response hasn't changed (up to maxTimeout)
+          maxCalls: 0,      // maximum number of calls. 0 = no limit.
+          autoStop: 0       // automatically stop requests after this many returns of the same data. 0 = disabled
+        }, options);
+
+        // set some initial values, then begin
+        var timer         = null;
+        var timerInterval = settings.minTimeout;
+        var maxCalls      = settings.maxCalls;
+        var autoStop      = settings.autoStop;
+        var calls         = 0;
+        var noChange      = 0;
+        var originalMaxCalls = maxCalls;
+
+        var reset_timer = function(interval) {
+          if (timer != null) {
+            clearTimeout(timer);
+          }
+          timerInterval = interval;
+          pu_log('resetting timer to '+ timerInterval +'.');
+          timer = setTimeout(getdata, timerInterval);
+        }
+
+        // Function to boost the timer
+        var boostPeriod = function() {
+          if(settings.multiplier >= 1) {
+            before = timerInterval;
+            timerInterval = timerInterval * settings.multiplier;
+
+            if(timerInterval > settings.maxTimeout) {
+              timerInterval = settings.maxTimeout;
+            }
+            after = timerInterval;
+            pu_log('adjusting timer from '+ before +' to '+ after +'.');
+            reset_timer(timerInterval);
+          }
+        };
+
+        // Construct the settings for $.ajax based on settings
+        var ajaxSettings = jQuery.extend(true, {}, settings);
+        if(settings.type && !ajaxSettings.dataType) ajaxSettings.dataType = settings.type;
+        if(settings.sendData) ajaxSettings.data = settings.sendData;
+        ajaxSettings.type = settings.method; // 'type' is used internally for jQuery.  Who knew?
+        ajaxSettings.ifModified = true;
+
+        var handle = {
+                    restart: function() {
+                        maxCalls = originalMaxCalls;
+                        calls = 0;
+                        reset_timer(timerInterval);
+                        return;
+                    },
+          stop: function() {
+            maxCalls = -1;
+            return;
+          }
+        };
+
+        // Create the function to get data
+        // TODO It'd be nice to do the options.data check once (a la boostPeriod)
+        function getdata() {
+          var toSend  = jQuery.extend(true, {}, ajaxSettings); // jQuery screws with what you pass in
+          if(typeof(options.data) == 'function') {
+            toSend.data = options.data();
+            if(toSend.data) {
+              // Handle transformations (only strings and objects are understood)
+              if(typeof(toSend.data) == "number") {
+                toSend.data = toSend.data.toString();
+              }
+            }
+          }
+
+          if(maxCalls == 0) {
+            $.ajax(toSend);
+          } else if(maxCalls > 0 && calls < maxCalls) {
+            $.ajax(toSend);
+            calls++;
+          }
+        }
+
+        // Implement the tricky behind logic
+        var remoteData  = null;
+        var prevData    = null;
+
+        ajaxSettings.success = function(data) {
+          pu_log("Successful run! (In 'success')");
+          remoteData      = data;
+          // timerInterval   = settings.minTimeout;
+        };
+
+        ajaxSettings.complete = function(xhr, success) {
+          //pu_log("Status of call: " + success + " (In 'complete')");
+          if(maxCalls == -1) return;
+          if(success == "success" || success == "notmodified") {
+            var rawData = $.trim(xhr.responseText);
+            if(rawData == 'STOP_AJAX_CALLS') {
+                            handle.stop();
+              return;
+            }
+            if(prevData == rawData) {
+              if(autoStop > 0) {
+                noChange++;
+                if(noChange == autoStop) {
+                                    handle.stop();
+                  if(autoStopCallback) autoStopCallback(noChange);
+                  return;
+                }
+              }
+              boostPeriod();
+            } else {
+              noChange        = 0;
+              reset_timer(settings.minTimeout);
+              prevData        = rawData;
+              if(remoteData == null) remoteData = rawData;
+              // jQuery 1.4+ $.ajax() automatically converts "data" into a JS Object for "type:json" requests now
+              // For compatibility with 1.4+ and pre1.4 jQuery only try to parse actual strings, skip when remoteData is already an Object
+              if((ajaxSettings.dataType === 'json') && (typeof(remoteData) === 'string') && (success == "success")) {
+                remoteData = JSON.parse(remoteData);
+              }
+              if(settings.success) { settings.success(remoteData, success, xhr, handle); }
+              if(callback) callback(remoteData, success, xhr, handle);
+            }
+          }
+          remoteData = null;
+        }
+
+
+        ajaxSettings.error = function (xhr, textStatus) {
+          //pu_log("Error message: " + textStatus + " (In 'error')");
+          if(textStatus != "notmodified") {
+            prevData = null;
+            reset_timer(settings.minTimeout);
+          }
+          if(settings.error) { settings.error(xhr, textStatus); }
+        };
+
+        // Make the first call
+        $(function() { reset_timer(timerInterval); });
+
+        return handle;
+    };
+})(jQuery);