Improve terminal performance by adding FastForEach

Move the AutoScroll function to an animation frame to prevent layout thrashing and to keep it in sync with fastForEach
Remove the <br> tag from the terminal and use display: block; on span tags to prevent increasing DOM nodes and faster processing of the terminal

src/octoprint/server/util/flask.py

@@ -1278,6 +1278,7 @@ def collect_core_assets(enable_gcodeviewer=True, preferred_stylesheet="css"):
 		'js/app/bindings/popover.js',
 		'js/app/bindings/qrcode.js',
 		'js/app/bindings/slimscrolledforeach.js',
+		'js/app/bindings/fastforeach.js',
 		'js/app/bindings/toggle.js',
 		'js/app/bindings/togglecontent.js',
 		'js/app/bindings/valuewithinit.js',

src/octoprint/static/js/app/bindings/fastforeach.js

@@ -0,0 +1,477 @@
+/*!
+  Knockout Fast Foreach v0.6.0 (2016-07-28T11:02:54.197Z)
+  By: Brian M Hunt (C) 2015 | License: MIT
+
+  Adds `fastForEach` to `ko.bindingHandlers`.
+*/
+(function (root, factory) {
+  if (typeof define === 'function' && define.amd) {
+    define(['knockout'], factory);
+  } else if (typeof exports === 'object') {
+    module.exports = factory(require('knockout'));
+  } else {
+    root.KnockoutFastForeach = factory(root.ko);
+  }
+}(this, function (ko) {
+  "use strict";
+// index.js
+// --------
+// Fast For Each
+//
+// Employing sound techniques to make a faster Knockout foreach binding.
+// --------
+
+//      Utilities
+var MAX_LIST_SIZE = 9007199254740991;
+
+// from https://github.com/jonschlinkert/is-plain-object
+function isPlainObject(o) {
+  return !!o && typeof o === 'object' && o.constructor === Object;
+}
+
+// From knockout/src/virtualElements.js
+var commentNodesHaveTextProperty = document && document.createComment("test").text === "<!--test-->";
+var startCommentRegex = commentNodesHaveTextProperty ? /^<!--\s*ko(?:\s+([\s\S]+))?\s*-->$/ : /^\s*ko(?:\s+([\s\S]+))?\s*$/;
+var supportsDocumentFragment = document && typeof document.createDocumentFragment === "function";
+function isVirtualNode(node) {
+  return (node.nodeType === 8) && startCommentRegex.test(commentNodesHaveTextProperty ? node.text : node.nodeValue);
+}
+
+
+// Get a copy of the (possibly virtual) child nodes of the given element,
+// put them into a container, then empty the given node.
+function makeTemplateNode(sourceNode) {
+  var container = document.createElement("div");
+  var parentNode;
+  if (sourceNode.content) {
+    // For e.g. <template> tags
+    parentNode = sourceNode.content;
+  } else if (sourceNode.tagName === 'SCRIPT') {
+    parentNode = document.createElement("div");
+    parentNode.innerHTML = sourceNode.text;
+  } else {
+    // Anything else e.g. <div>
+    parentNode = sourceNode;
+  }
+  ko.utils.arrayForEach(ko.virtualElements.childNodes(parentNode), function (child) {
+    // FIXME - This cloneNode could be expensive; we may prefer to iterate over the
+    // parentNode children in reverse (so as not to foul the indexes as childNodes are
+    // removed from parentNode when inserted into the container)
+    if (child) {
+      container.insertBefore(child.cloneNode(true), null);
+    }
+  });
+  return container;
+}
+
+// Mimic a KO change item 'add'
+function valueToChangeAddItem(value, index) {
+  return {
+    status: 'added',
+    value: value,
+    index: index
+  };
+}
+
+// KO 3.4 doesn't seem to export this utility function so it's here just to be sure
+function createSymbolOrString(identifier) {
+  return typeof Symbol === 'function' ? Symbol(identifier) : identifier;
+}
+
+// store a symbol for caching the pending delete info index in the data item objects
+var PENDING_DELETE_INDEX_KEY = createSymbolOrString("_ko_ffe_pending_delete_index");
+
+function FastForEach(spec) {
+  this.element = spec.element;
+  this.container = isVirtualNode(this.element) ?
+                   this.element.parentNode : this.element;
+  this.$context = spec.$context;
+  this.data = spec.data;
+  this.as = spec.as;
+  this.noContext = spec.noContext;
+  this.noIndex = spec.noIndex;
+  this.afterAdd = spec.afterAdd;
+  this.beforeRemove = spec.beforeRemove;
+  this.templateNode = makeTemplateNode(
+    spec.templateNode || (spec.name ? document.getElementById(spec.name).cloneNode(true) : spec.element)
+  );
+  this.afterQueueFlush = spec.afterQueueFlush;
+  this.beforeQueueFlush = spec.beforeQueueFlush;
+  this.changeQueue = [];
+  this.firstLastNodesList = [];
+  this.indexesToDelete = [];
+  this.rendering_queued = false;
+  this.pendingDeletes = [];
+
+  // Remove existing content.
+  ko.virtualElements.emptyNode(this.element);
+
+  // Prime content
+  var primeData = ko.unwrap(this.data);
+  if (primeData.map) {
+    this.onArrayChange(primeData.map(valueToChangeAddItem), true);
+  }
+
+  // Watch for changes
+  if (ko.isObservable(this.data)) {
+    if (!this.data.indexOf) {
+      // Make sure the observable is trackable.
+      this.data = this.data.extend({ trackArrayChanges: true });
+    }
+    this.changeSubs = this.data.subscribe(this.onArrayChange, this, 'arrayChange');
+  }
+}
+
+FastForEach.PENDING_DELETE_INDEX_KEY = PENDING_DELETE_INDEX_KEY;
+
+FastForEach.animateFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame ||
+  window.mozRequestAnimationFrame || window.msRequestAnimationFrame ||
+  function (cb) { return window.setTimeout(cb, 1000 / 60); };
+
+
+FastForEach.prototype.dispose = function () {
+  if (this.changeSubs) {
+    this.changeSubs.dispose();
+  }
+  this.flushPendingDeletes();
+};
+
+
+// If the array changes we register the change.
+FastForEach.prototype.onArrayChange = function (changeSet, isInitial) {
+  var self = this;
+  var changeMap = {
+    added: [],
+    deleted: []
+  };
+
+  // knockout array change notification index handling:
+  // - sends the original array indexes for deletes
+  // - sends the new array indexes for adds
+  // - sorts them all by index in ascending order
+  // because of this, when checking for possible batch additions, any delete can be between to adds with neighboring indexes, so only additions should be checked
+  for (var i = 0, len = changeSet.length; i < len; i++) {
+
+    if (changeMap.added.length && changeSet[i].status == 'added') {
+      var lastAdd = changeMap.added[changeMap.added.length - 1];
+      var lastIndex = lastAdd.isBatch ? lastAdd.index + lastAdd.values.length - 1 : lastAdd.index;
+      if (lastIndex + 1 == changeSet[i].index) {
+        if (!lastAdd.isBatch) {
+          // transform the last addition into a batch addition object
+          lastAdd = {
+            isBatch: true,
+            status: 'added',
+            index: lastAdd.index,
+            values: [lastAdd.value]
+          };
+          changeMap.added.splice(changeMap.added.length - 1, 1, lastAdd);
+        }
+        lastAdd.values.push(changeSet[i].value);
+        continue;
+      }
+    }
+
+    changeMap[changeSet[i].status].push(changeSet[i]);
+  }
+
+  if (changeMap.deleted.length > 0) {
+    this.changeQueue.push.apply(this.changeQueue, changeMap.deleted);
+    this.changeQueue.push({ status: 'clearDeletedIndexes' });
+  }
+  this.changeQueue.push.apply(this.changeQueue, changeMap.added);
+  // Once a change is registered, the ticking count-down starts for the processQueue.
+  if (this.changeQueue.length > 0 && !this.rendering_queued) {
+    this.rendering_queued = true;
+    if (isInitial) {
+      self.processQueue();
+    } else {
+      FastForEach.animateFrame.call(window, function () { self.processQueue(); });
+    }
+  }
+};
+
+
+// Reflect all the changes in the queue in the DOM, then wipe the queue.
+FastForEach.prototype.processQueue = function () {
+  var self = this;
+  var lowestIndexChanged = MAX_LIST_SIZE;
+
+  // Callback so folks can do things before the queue flush.
+  if (typeof this.beforeQueueFlush === 'function') {
+    this.beforeQueueFlush(this.changeQueue);
+  }
+
+  ko.utils.arrayForEach(this.changeQueue, function (changeItem) {
+    if (typeof changeItem.index === 'number') {
+      lowestIndexChanged = Math.min(lowestIndexChanged, changeItem.index);
+    }
+    // console.log(self.data(), "CI", JSON.stringify(changeItem, null, 2), JSON.stringify($(self.element).text()))
+    self[changeItem.status](changeItem);
+    // console.log("  ==> ", JSON.stringify($(self.element).text()))
+  });
+  this.flushPendingDeletes();
+  this.rendering_queued = false;
+
+  // Update our indexes.
+  if (!this.noIndex) {
+    this.updateIndexes(lowestIndexChanged);
+  }
+
+  // Callback so folks can do things.
+  if (typeof this.afterQueueFlush === 'function') {
+    this.afterQueueFlush(this.changeQueue);
+  }
+  this.changeQueue = [];
+};
+
+
+function extendWithIndex(context) {
+  context.$index = ko.observable();
+};
+
+
+// Process a changeItem with {status: 'added', ...}
+FastForEach.prototype.added = function (changeItem) {
+  var index = changeItem.index;
+  var valuesToAdd = changeItem.isBatch ? changeItem.values : [changeItem.value];
+  var referenceElement = this.getLastNodeBeforeIndex(index);
+  // gather all childnodes for a possible batch insertion
+  var allChildNodes = [];
+
+  for (var i = 0, len = valuesToAdd.length; i < len; ++i) {
+    var childNodes;
+
+    // we check if we have a pending delete with reusable nodesets for this data, and if yes, we reuse one nodeset
+    var pendingDelete = this.getPendingDeleteFor(valuesToAdd[i]);
+    if (pendingDelete && pendingDelete.nodesets.length) {
+      childNodes = pendingDelete.nodesets.pop();
+    } else {
+      var templateClone = this.templateNode.cloneNode(true);
+      var childContext;
+
+      if (this.noContext) {
+        childContext = this.$context.extend({
+          $item: valuesToAdd[i],
+          $index: this.noIndex ? undefined : ko.observable()
+        });
+      } else {
+        childContext = this.$context.createChildContext(valuesToAdd[i], this.as || null, this.noIndex ? undefined : extendWithIndex);
+      }
+
+      // apply bindings first, and then process child nodes, because bindings can add childnodes
+      ko.applyBindingsToDescendants(childContext, templateClone);
+
+      childNodes = ko.virtualElements.childNodes(templateClone);
+    }
+
+    // Note discussion at https://github.com/angular/angular.js/issues/7851
+    allChildNodes.push.apply(allChildNodes, Array.prototype.slice.call(childNodes));
+    this.firstLastNodesList.splice(index + i, 0, { first: childNodes[0], last: childNodes[childNodes.length - 1] });
+  }
+
+  if (typeof this.afterAdd === 'function') {
+    this.afterAdd({
+      nodeOrArrayInserted: this.insertAllAfter(allChildNodes, referenceElement),
+      foreachInstance: this
+    }
+    );
+  } else {
+    this.insertAllAfter(allChildNodes, referenceElement);
+  }
+};
+
+FastForEach.prototype.getNodesForIndex = function (index) {
+  var result = [],
+    ptr = this.firstLastNodesList[index].first,
+    last = this.firstLastNodesList[index].last;
+  result.push(ptr);
+  while (ptr && ptr !== last) {
+    ptr = ptr.nextSibling;
+    result.push(ptr);
+  }
+  return result;
+};
+
+FastForEach.prototype.getLastNodeBeforeIndex = function (index) {
+  if (index < 1 || index - 1 >= this.firstLastNodesList.length)
+    return null;
+  return this.firstLastNodesList[index - 1].last;
+};
+
+FastForEach.prototype.insertAllAfter = function (nodeOrNodeArrayToInsert, insertAfterNode) {
+  var frag, len, i,
+    containerNode = this.element;
+
+  // poor man's node and array check, should be enough for this
+  if (nodeOrNodeArrayToInsert.nodeType === undefined && nodeOrNodeArrayToInsert.length === undefined) {
+    throw new Error("Expected a single node or a node array");
+  }
+  if (nodeOrNodeArrayToInsert.nodeType !== undefined) {
+    ko.virtualElements.insertAfter(containerNode, nodeOrNodeArrayToInsert, insertAfterNode);
+    return [nodeOrNodeArrayToInsert];
+  } else if (nodeOrNodeArrayToInsert.length === 1) {
+    ko.virtualElements.insertAfter(containerNode, nodeOrNodeArrayToInsert[0], insertAfterNode);
+  } else if (supportsDocumentFragment) {
+    frag = document.createDocumentFragment();
+
+    for (i = 0, len = nodeOrNodeArrayToInsert.length; i !== len; ++i) {
+      frag.appendChild(nodeOrNodeArrayToInsert[i]);
+    }
+    ko.virtualElements.insertAfter(containerNode, frag, insertAfterNode);
+  } else {
+    // Nodes are inserted in reverse order - pushed down immediately after
+    // the last node for the previous item or as the first node of element.
+    for (i = nodeOrNodeArrayToInsert.length - 1; i >= 0; --i) {
+      var child = nodeOrNodeArrayToInsert[i];
+      if (!child) { break; }
+      ko.virtualElements.insertAfter(containerNode, child, insertAfterNode);
+    }
+  }
+  return nodeOrNodeArrayToInsert;
+};
+
+// checks if the deleted data item should be handled with delay for a possible reuse at additions
+FastForEach.prototype.shouldDelayDeletion = function (data) {
+  return data && (typeof data === "object" || typeof data === "function");
+};
+
+// gets the pending deletion info for this data item
+FastForEach.prototype.getPendingDeleteFor = function (data) {
+  var index = data && data[PENDING_DELETE_INDEX_KEY];
+  if (index === undefined) return null;
+  return this.pendingDeletes[index];
+};
+
+// tries to find the existing pending delete info for this data item, and if it can't, it registeres one
+FastForEach.prototype.getOrCreatePendingDeleteFor = function (data) {
+  var pd = this.getPendingDeleteFor(data);
+  if (pd) {
+    return pd;
+  }
+  pd = {
+    data: data,
+    nodesets: []
+  };
+  data[PENDING_DELETE_INDEX_KEY] = this.pendingDeletes.length;
+  this.pendingDeletes.push(pd);
+  return pd;
+};
+
+// Process a changeItem with {status: 'deleted', ...}
+FastForEach.prototype.deleted = function (changeItem) {
+  // if we should delay the deletion of this data, we add the nodeset to the pending delete info object
+  if (this.shouldDelayDeletion(changeItem.value)) {
+    var pd = this.getOrCreatePendingDeleteFor(changeItem.value);
+    pd.nodesets.push(this.getNodesForIndex(changeItem.index));
+  } else { // simple data, just remove the nodes
+    this.removeNodes(this.getNodesForIndex(changeItem.index));
+  }
+  this.indexesToDelete.push(changeItem.index);
+};
+
+// removes a set of nodes from the DOM
+FastForEach.prototype.removeNodes = function (nodes) {
+  if (!nodes.length) { return; }
+
+  var removeFn = function () {
+    var parent = nodes[0].parentNode;
+    for (var i = nodes.length - 1; i >= 0; --i) {
+      ko.cleanNode(nodes[i]);
+      parent.removeChild(nodes[i]);
+    }
+  };
+
+  if (this.beforeRemove) {
+    var beforeRemoveReturn = this.beforeRemove({
+      nodesToRemove: nodes, foreachInstance: this
+    }) || {};
+    // If beforeRemove returns a `then`–able e.g. a Promise, we remove
+    // the nodes when that thenable completes.  We pass any errors to
+    // ko.onError.
+    if (typeof beforeRemoveReturn.then === 'function') {
+      beforeRemoveReturn.then(removeFn, ko.onError ? ko.onError : undefined);
+    }
+  } else {
+    removeFn();
+  }
+};
+
+// flushes the pending delete info store
+// this should be called after queue processing has finished, so that data items and remaining (not reused) nodesets get cleaned up
+// we also call it on dispose not to leave any mess
+FastForEach.prototype.flushPendingDeletes = function () {
+  for (var i = 0, len = this.pendingDeletes.length; i != len; ++i) {
+    var pd = this.pendingDeletes[i];
+    while (pd.nodesets.length) {
+      this.removeNodes(pd.nodesets.pop());
+    }
+    if (pd.data && pd.data[PENDING_DELETE_INDEX_KEY] !== undefined)
+      delete pd.data[PENDING_DELETE_INDEX_KEY];
+  }
+  this.pendingDeletes = [];
+};
+
+// We batch our deletion of item indexes in our parallel array.
+// See brianmhunt/knockout-fast-foreach#6/#8
+FastForEach.prototype.clearDeletedIndexes = function () {
+  // We iterate in reverse on the presumption (following the unit tests) that KO's diff engine
+  // processes diffs (esp. deletes) monotonically ascending i.e. from index 0 -> N.
+  for (var i = this.indexesToDelete.length - 1; i >= 0; --i) {
+    this.firstLastNodesList.splice(this.indexesToDelete[i], 1);
+  }
+  this.indexesToDelete = [];
+};
+
+
+FastForEach.prototype.getContextStartingFrom = function (node) {
+  var ctx;
+  while (node) {
+    ctx = ko.contextFor(node);
+    if (ctx) { return ctx; }
+    node = node.nextSibling;
+  }
+};
+
+
+FastForEach.prototype.updateIndexes = function (fromIndex) {
+  var ctx;
+  for (var i = fromIndex, len = this.firstLastNodesList.length; i < len; ++i) {
+    ctx = this.getContextStartingFrom(this.firstLastNodesList[i].first);
+    if (ctx) { ctx.$index(i); }
+  }
+};
+
+
+ko.bindingHandlers.fastForEach = {
+  // Valid valueAccessors:
+  //    []
+  //    ko.observable([])
+  //    ko.observableArray([])
+  //    ko.computed
+  //    {data: array, name: string, as: string}
+  init: function init(element, valueAccessor, bindings, vm, context) {
+    var ffe, value = valueAccessor();
+    if (isPlainObject(value)) {
+      value.element = value.element || element;
+      value.$context = context;
+      ffe = new FastForEach(value);
+    } else {
+      ffe = new FastForEach({
+        element: element,
+        data: ko.unwrap(context.$rawData) === value ? context.$rawData : value,
+        $context: context
+      });
+    }
+
+    ko.utils.domNodeDisposal.addDisposeCallback(element, function () {
+      ffe.dispose();
+    });
+    return { controlsDescendantBindings: true };
+  },
+
+  // Export for testing, debugging, and overloading.
+  FastForEach: FastForEach
+};
+
+ko.virtualElements.allowedBindings.fastForEach = true;
+}));

src/octoprint/static/js/app/viewmodels/terminal.js

@@ -242,10 +242,12 @@ $(function() {
         };
 
         self.scrollToEnd = function() {
-            var container = self.fancyFunctionality() ? $("#terminal-output") : $("#terminal-output-lowfi");
-            if (container.length) {
-                container.scrollTop(container[0].scrollHeight);
-            }
+            ko.bindingHandlers.fastForEach.FastForEach.animateFrame.call(window, function scrollToEnd() {
+                var container = self.fancyFunctionality() ? $("#terminal-output") : $("#terminal-output-lowfi");
+                if (container.length) {
+                    container.scrollTop(container.prop("scrollHeight"));
+                }
+            });
         };
 
         self.sendCommand = function() {

src/octoprint/static/less/octoprint.less

@@ -757,6 +757,10 @@ ul.dropdown-menu li a {
   #terminal-sendpanel {
     text-align: right;
   }
+  
+  #terminal-output span {
+    display: block;
+  }
 }
 
 #settings_dialog {

src/octoprint/templates/tabs/terminal.jinja2

@@ -1,5 +1,5 @@
 <div class="terminal">
-    <pre id="terminal-output" class="pre-scrollable" data-bind="foreach: displayedLines, visible: fancyFunctionality()"><span data-bind="text: line, css: {muted: type == 'filtered' || type == 'cut'}"></span><br></pre>
+    <pre id="terminal-output" class="pre-scrollable" data-bind="fastForEach: displayedLines, visible: fancyFunctionality()"><span data-bind="text: line, css: {muted: type == 'filtered' || type == 'cut'}"></span></pre>
     <pre id="terminal-output-lowfi" style="display: none" class="pre-scrollable" data-bind="text: plainLogOutput, visible: !fancyFunctionality()"></pre>
     <small class="pull-left" data-bind="visible: fancyFunctionality()"><button class="btn btn-mini" data-bind="click: toggleAutoscroll, css: {active: autoscrollEnabled}">{{ _('Autoscroll') }}</button> <span data-bind="text: lineCount, visible: enableFancyFunctionality"></span></small>
     <small class="pull-right" data-bind="visible: fancyFunctionality()"><a href="#" data-bind="click: scrollToEnd">{{ _("Scroll to end") }}</a>&nbsp;|&nbsp;<a href="#" data-bind="click: selectAll">{{ _("Select all") }}</a></small>