Make pow script be a shared worker

boards/static/js/form.js

@@ -1,132 +1,133 b''
 var ITEM_FILE_SOURCE = 'fileSource';
 
 $('input[name=image]').wrap($('<div class="file_wrap"></div>'));
 
 $('body').on('change', 'input[name=image]', function(event) {
     var file = event.target.files[0];
 
     if(file.type.match('image.*')) {
         var fileReader = new FileReader();
 
         fileReader.addEventListener("load", function(event) {
             var wrapper = $('.file_wrap');
 
             wrapper.find('.file-thumb').remove();
             wrapper.append(
                 $('<div class="file-thumb" style="background-image: url('+event.target.result+')"></div>')
             );
         });
 
         fileReader.readAsDataURL(file);
     }
 });
 
 var form = $('#form');
 $('textarea').keypress(function(event) {
     if (event.which == 13 && event.ctrlKey) {
         form.find('input[type=submit]').click();
     }
 });
 
 $('#preview-button').click(function() {
     var data = {
         raw_text: $('textarea').val()
     }
 
     var diffUrl = '/api/preview/';
 
     $.post(diffUrl,
         data,
         function(data) {
             var previewTextBlock = $('#preview-text');
             previewTextBlock.html(data);
             previewTextBlock.show();
         })
 });
 
 /**
  * Show text in the errors row of the form.
  * @param form
  * @param text
  */
 function showAsErrors(form, text) {
     form.children('.form-errors').remove();
 
     if (text.length > 0) {
         var errorList = $('<div class="form-errors">' + text + '<div>');
         errorList.appendTo(form);
     }
 }
 
 function addHiddenInput(form, name, value) {
     form.find('input[name=' + name + ']').val(value);
 }
 
 function selectFileChoice() {
     var file_input = $('#id_file');
     var url_input = $('#id_file_url');
 
     var file_input_row = file_input.parent().parent();
     var url_input_row = url_input.parent().parent();
 
     file_input_row.toggle();
     url_input_row.toggle();
     url_input.val('');
     file_input.val('');
 
     var source;
     if (file_input_row.is(':visible')) {
         source = 'file';
     } else {
         source = 'url';
     }
     localStorage.setItem(ITEM_FILE_SOURCE, source);
 }
 
 $(document).ready(function() {
     var powDifficulty = parseInt($('body').attr('data-pow-difficulty'));
     if (powDifficulty > 0) {
-        var worker = new Worker($('#powScript').attr('src'));
-        worker.onmessage = function(e) {
+        var worker = new SharedWorker($('#powScript').attr('src'));
+        worker.port.onmessage = function(e) {
             var form = $('#form');
             addHiddenInput(form, 'timestamp', e.data.timestamp);
             addHiddenInput(form, 'iteration', e.data.iteration);
             addHiddenInput(form, 'guess', e.data.guess);
 
             form.submit();
             $('.post-form-w').unblock();
         };
+        worker.port.start();
 
         var form = $('#form');
         var submitButton = form.find('input[type=submit]');
         submitButton.click(function() {
             showAsErrors(form, gettext('Computing PoW...'));
             $('.post-form-w').block({ message: gettext('Computing PoW...') })
 
             var msg = $('textarea').val().trim();
 
             var data = {
                 msg: msg,
                 difficulty: parseInt($('body').attr('data-pow-difficulty')),
                 hasher: $('#sha256Script').attr('src')
             };
-            worker.postMessage(data);
+            worker.port.postMessage(data);
 
             return false;
         });
     }
 
     var source = localStorage.getItem(ITEM_FILE_SOURCE);
     if (source == null) {
         source = 'file';
     }
     if (source == 'file') {
         $('#id_file_url').parent().parent().hide();
     } else {
         $('#id_file').parent().parent().hide();
     }
 
     $('#file-source-button').click(function() {
         selectFileChoice();
     });
 });

boards/static/js/proof_of_work.js

@@ -1,54 +1,63 b''
 var POW_COMPUTING_TIMEOUT = 2;
 var POW_HASH_LENGTH = 16;
 
+var hasher;
 
-function computeHash(iteration, guess, target, payload, timestamp, hasher) {
+
+function computeHash(iteration, guess, target, payload, timestamp, hasher, port) {
     iteration += 1;
     var hash = hasher(payload + iteration).toString();
     guess = hash.substring(0, POW_HASH_LENGTH);
 
     if (guess <= target) {
         //console.log("Iteration: ", iteration);
         //console.log("Guess: ", guess);
         //console.log("Target: ", target);
 
         var data = {
             iteration: iteration,
             timestamp: timestamp,
             guess: guess
         };
-        self.postMessage(data);
+        port.postMessage(data);
     } else {
         //console.log("Iteration: ", iteration);
         //console.log("Guess: ", guess);
         //console.log("Target: ", target);
 
         setTimeout(function() {
-            computeHash(iteration, guess, target, payload, timestamp, hasher);
+            computeHash(iteration, guess, target, payload, timestamp, hasher, port);
         }, POW_COMPUTING_TIMEOUT);
     }
 }
 
-function doWork(message, hasher, difficulty) {
+function doWork(message, hasher, difficulty, port) {
     var timestamp = Date.now();
     var iteration = 0;
     var payload = timestamp + message;
 
     var target = parseInt(Math.pow(2, POW_HASH_LENGTH * 3) / difficulty).toString();
     while (target.length < POW_HASH_LENGTH) {
         target = '0' + target;
     }
 
     var guess = target + '0';
 
     setTimeout(function() {
-        computeHash(iteration, guess, target, payload, timestamp, hasher);
+        computeHash(iteration, guess, target, payload, timestamp, hasher, port);
     }, POW_COMPUTING_TIMEOUT);
 }
 
-self.onmessage = function(e) {
-    var difficulty = e.data.difficulty;
-    importScripts(e.data.hasher);
-    var hasher = CryptoJS.SHA256;
-    self.doWork(e.data.msg, hasher, difficulty);
-};
+onconnect = function(e) {
+    var port = e.ports[0];
+    port.start();
+
+    port.onmessage = function(e) {
+        var difficulty = e.data.difficulty;
+        importScripts(e.data.hasher);
+        var hasher = CryptoJS.SHA256;
+
+        self.doWork(e.data.msg, hasher, difficulty, port);
+    };
+}
+