Quelle census-tree-node.js Sprache: JAVA

/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
"use strict";

// CensusTreeNode is an intermediate representation of a census report that
// exists between after a report is generated by taking a census and before the
// report is rendered in the DOM. It must be dead simple to render, with no
// further data processing or massaging needed before rendering DOM nodes. Our
// goal is to do the census report to CensusTreeNode transformation in the
// HeapAnalysesWorker, and ensure that the **only** work that the main thread
// has to do is strictly DOM rendering work.

const {
  Visitor,
  walk,
  basisTotalBytes,
  basisTotalCount,
} = require("resource://devtools/shared/heapsnapshot/CensusUtils.js");

// Monotonically increasing integer for CensusTreeNode `id`s.
let censusTreeNodeIdCounter = 0;

/**
* Return true if the given object is a SavedFrame stack object, false otherwise.
*
* @param {any} obj
* @returns {Boolean}
*/
function isSavedFrame(obj) {
  return Object.prototype.toString.call(obj) === "[object SavedFrame]";
}

/**
* A CensusTreeNodeCache maps from SavedFrames to CensusTreeNodes. It is used when
* aggregating multiple SavedFrame allocation stack keys into a tree of many
* CensusTreeNodes. Each stack may share older frames, and we want to preserve
* this sharing when converting to CensusTreeNode, so before creating a new
* CensusTreeNode, we look for an existing one in one of our CensusTreeNodeCaches.
*/
function CensusTreeNodeCache() {}
CensusTreeNodeCache.prototype = null;

/**
* The value of a single entry stored in a CensusTreeNodeCache. It is a pair of
* the CensusTreeNode for this cache value, and the subsequent
* CensusTreeNodeCache for this node's children.
*
* @param {SavedFrame} frame
*        The frame being cached.
*/
function CensusTreeNodeCacheValue() {
  // The CensusTreeNode for this cache value.
  this.node = undefined;
  // The CensusTreeNodeCache for this frame's children.
  this.children = undefined;
}

CensusTreeNodeCacheValue.prototype = null;

/**
* Create a unique string for the given SavedFrame (ignoring the frame's parent
* chain) that can be used as a hash to key this frame within a CensusTreeNodeCache.
*
* NB: We manually hash rather than using an ES6 Map because we are purposely
* ignoring the parent chain and wish to consider frames with everything the
* same except their parents as the same.
*
* @param {SavedFrame} frame
*        The SavedFrame object we would like to lookup in or insert into a
*        CensusTreeNodeCache.
*
* @returns {String}
*          The unique string that can be used as a key in a CensusTreeNodeCache.
*/
CensusTreeNodeCache.hashFrame = function (frame) {
  // eslint-disable-next-line max-len
  return `FRAME,${frame.functionDisplayName},${frame.source},${frame.line},${frame.column},${frame.asyncCause}`;
};

/**
* Create a unique string for the given CensusTreeNode **with regards to
* siblings at the current depth of the tree, not within the whole tree.** It
* can be used as a hash to key this node within a CensusTreeNodeCache.
*
* @param {CensusTreeNode} node
*        The node we would like to lookup in or insert into a cache.
*
* @returns {String}
*          The unique string that can be used as a key in a CensusTreeNodeCache.
*/
CensusTreeNodeCache.hashNode = function (node) {
  return isSavedFrame(node.name)
    ? CensusTreeNodeCache.hashFrame(node.name)
    : `NODE,${node.name}`;
};

/**
* Insert the given CensusTreeNodeCacheValue whose node.name is a SavedFrame
* object in the given cache.
*
* @param {CensusTreeNodeCache} cache
* @param {CensusTreeNodeCacheValue} value
*/
CensusTreeNodeCache.insertFrame = function (cache, value) {
  cache[CensusTreeNodeCache.hashFrame(value.node.name)] = value;
};

/**
* Insert the given value in the cache.
*
* @param {CensusTreeNodeCache} cache
* @param {CensusTreeNodeCacheValue} value
*/
CensusTreeNodeCache.insertNode = function (cache, value) {
  if (isSavedFrame(value.node.name)) {
    CensusTreeNodeCache.insertFrame(cache, value);
  } else {
    cache[CensusTreeNodeCache.hashNode(value.node)] = value;
  }
};

/**
* Lookup `frame` in `cache` and return its value if it exists.
*
* @param {CensusTreeNodeCache} cache
* @param {SavedFrame} frame
*
* @returns {undefined|CensusTreeNodeCacheValue}
*/
CensusTreeNodeCache.lookupFrame = function (cache, frame) {
  return cache[CensusTreeNodeCache.hashFrame(frame)];
};

/**
* Lookup `node` in `cache` and return its value if it exists.
*
* @param {CensusTreeNodeCache} cache
* @param {CensusTreeNode} node
*
* @returns {undefined|CensusTreeNodeCacheValue}
*/
CensusTreeNodeCache.lookupNode = function (cache, node) {
  return isSavedFrame(node.name)
    ? CensusTreeNodeCache.lookupFrame(cache, node.name)
    : cache[CensusTreeNodeCache.hashNode(node)];
};

/**
* Add `child` to `parent`'s set of children and store the parent ID
* on the child.
*
* @param {CensusTreeNode} parent
* @param {CensusTreeNode} child
*/
function addChild(parent, child) {
  if (!parent.children) {
    parent.children = [];
  }
  child.parent = parent.id;
  parent.children.push(child);
}

/**
* Get an array of each frame in the provided stack.
*
* @param {SavedFrame} stack
* @returns {Array<SavedFrame>}
*/
function getArrayOfFrames(stack) {
  const frames = [];
  let frame = stack;
  while (frame) {
    frames.push(frame);
    frame = frame.parent;
  }
  frames.reverse();
  return frames;
}

/**
* Given an `edge` to a sub-`report` whose structure is described by
* `breakdown`, create a CensusTreeNode tree.
*
* @param {Object} breakdown
*        The breakdown specifying the structure of the given report.
*
* @param {Object} report
*        The census report.
*
* @param {null|String|SavedFrame} edge
*        The edge leading to this report from the parent report.
*
* @param {CensusTreeNodeCache} cache
*        The cache of CensusTreeNodes we have already made for the siblings of
*        the node being created. The existing nodes are reused when possible.
*
* @param {Object} outParams
*        The return values are attached to this object after this function
*        returns. Because we create a CensusTreeNode for each frame in a
*        SavedFrame stack edge, there may multiple nodes per sub-report.
*
*          - top: The deepest node in the CensusTreeNode subtree created.
*
*          - bottom: The shallowest node in the CensusTreeNode subtree created.
*                    This is null if the shallowest node in the subtree was
*                    found in the `cache` and reused.
*
*        Note that top and bottom are not necessarily different. In the case
*        where there is a 1:1 correspondence between an edge in the report and
*        a CensusTreeNode, top and bottom refer to the same node.
*/
function makeCensusTreeNodeSubTree(breakdown, report, edge, cache, outParams) {
  if (!isSavedFrame(edge)) {
    const node = new CensusTreeNode(edge);
    outParams.top = outParams.bottom = node;
    return;
  }

  const frames = getArrayOfFrames(edge);
  let currentCache = cache;
  let prevNode;
  for (let i = 0, length = frames.length; i < length; i++) {
    const frame = frames[i];

    // Get or create the CensusTreeNodeCacheValue for this frame. If we already
    // have a CensusTreeNodeCacheValue (and hence a CensusTreeNode) for this
    // frame, we don't need to add the node to the previous node's children as
    // we have already done that. If we don't have a CensusTreeNodeCacheValue
    // and CensusTreeNode for this frame, then create one and make sure to hook
    // it up as a child of the previous node.
    let isNewNode = false;
    let val = CensusTreeNodeCache.lookupFrame(currentCache, frame);
    if (!val) {
      isNewNode = true;
      val = new CensusTreeNodeCacheValue();
      val.node = new CensusTreeNode(frame);

      CensusTreeNodeCache.insertFrame(currentCache, val);
      if (prevNode) {
        addChild(prevNode, val.node);
      }
    }

    if (i === 0) {
      outParams.bottom = isNewNode ? val.node : null;
    }
    if (i === length - 1) {
      outParams.top = val.node;
    }

    prevNode = val.node;

    if (i !== length - 1 && !val.children) {
      // This is not the last frame and therefore this node will have
      // children, which we must cache.
      val.children = new CensusTreeNodeCache();
    }

    currentCache = val.children;
  }
}

/**
* A Visitor that walks a census report and creates the corresponding
* CensusTreeNode tree.
*/
function CensusTreeNodeVisitor() {
  // The root of the resulting CensusTreeNode tree.
  this._root = null;

  // The stack of CensusTreeNodes that we are in the process of building while
  // walking the census report.
  this._nodeStack = [];

  // To avoid unnecessary allocations, we reuse the same out parameter object
  // passed to `makeCensusTreeNodeSubTree` every time we call it.
  this._outParams = {
    top: null,
    bottom: null,
  };

  // The stack of `CensusTreeNodeCache`s that we use to aggregate many
  // SavedFrame stacks into a single CensusTreeNode tree.
  this._cacheStack = [new CensusTreeNodeCache()];

  // The current index in the DFS of the census report tree.
  this._index = -1;
}

CensusTreeNodeVisitor.prototype = Object.create(Visitor);

/**
* Create the CensusTreeNode subtree for this sub-report and link it to the
* parent CensusTreeNode.
*
* @overrides Visitor.prototype.enter
*/
CensusTreeNodeVisitor.prototype.enter = function (breakdown, report, edge) {
  this._index++;

  const cache = this._cacheStack[this._cacheStack.length - 1];
  makeCensusTreeNodeSubTree(breakdown, report, edge, cache, this._outParams);
  const { top, bottom } = this._outParams;

  if (!this._root) {
    this._root = bottom;
  } else if (bottom) {
    addChild(this._nodeStack[this._nodeStack.length - 1], bottom);
  }

  this._cacheStack.push(new CensusTreeNodeCache());
  this._nodeStack.push(top);
};

function values(cache) {
  return Object.keys(cache).map(k => cache[k]);
}

function isNonEmpty(node) {
  return (
    (node.children !== undefined && node.children.length) ||
    node.bytes !== 0 ||
    node.count !== 0
  );
}

/**
* We have finished adding children to the CensusTreeNode subtree for the
* current sub-report. Make sure that the children are sorted for every node in
* the subtree.
*
* @overrides Visitor.prototype.exit
*/
CensusTreeNodeVisitor.prototype.exit = function () {
  // Ensure all children are sorted and have their counts/bytes aggregated. We
  // only need to consider cache children here, because other children
  // correspond to other sub-reports and we already fixed them up in an earlier
  // invocation of `exit`.

  function dfs(node, childrenCache) {
    if (childrenCache) {
      const childValues = values(childrenCache);
      for (let i = 0, length = childValues.length; i < length; i++) {
        dfs(childValues[i].node, childValues[i].children);
      }
    }

    node.totalCount = node.count;
    node.totalBytes = node.bytes;

    if (node.children) {
      // Prune empty leaves.
      node.children = node.children.filter(isNonEmpty);

      node.children.sort(compareByTotal);

      for (let i = 0, length = node.children.length; i < length; i++) {
        node.totalCount += node.children[i].totalCount;
        node.totalBytes += node.children[i].totalBytes;
      }
    }
  }

  const top = this._nodeStack.pop();
  const cache = this._cacheStack.pop();
  dfs(top, cache);
};

/**
* @overrides Visitor.prototype.count
*/
CensusTreeNodeVisitor.prototype.count = function (breakdown, report) {
  const node = this._nodeStack[this._nodeStack.length - 1];
  node.reportLeafIndex = this._index;

  if (breakdown.count) {
    node.count = report.count;
  }

  if (breakdown.bytes) {
    node.bytes = report.bytes;
  }
};

/**
* Get the root of the resulting CensusTreeNode tree.
*
* @returns {CensusTreeNode}
*/
CensusTreeNodeVisitor.prototype.root = function () {
  if (!this._root) {
    throw new Error(
      "Attempt to get the root before walking the census report!"
    );
  }

  if (this._nodeStack.length) {
    throw new Error("Attempt to get the root while walking the census report!");
  }

  return this._root;
};

/**
* Create a single, uninitialized CensusTreeNode.
*
* @param {null|String|SavedFrame} name
*/
function CensusTreeNode(name) {
  // Display name for this CensusTreeNode. Either null, a string, or a
  // SavedFrame.
  this.name = name;

  // The number of bytes occupied by matching things in the heap snapshot.
  this.bytes = 0;

  // The sum of `this.bytes` and `child.totalBytes` for each child in
  // `this.children`.
  this.totalBytes = 0;

  // The number of things in the heap snapshot that match this node in the
  // census tree.
  this.count = 0;

  // The sum of `this.count` and `child.totalCount` for each child in
  // `this.children`.
  this.totalCount = 0;

  // An array of this node's children, or undefined if it has no children.
  this.children = undefined;

  // The unique ID of this node.
  this.id = ++censusTreeNodeIdCounter;

  // If present, the unique ID of this node's parent. If this node does not have
  // a parent, then undefined.
  this.parent = undefined;

  // The `reportLeafIndex` property allows mapping a CensusTreeNode node back to
  // a leaf in the census report it was generated from. It is always one of the
  // following variants:
  //
  // * A `Number` index pointing a leaf report in a pre-order DFS traversal of
  //   this CensusTreeNode's census report.
  //
  // * A `Set` object containing such indices, when this is part of an inverted
  //   CensusTreeNode tree and multiple leaves in the report map onto this node.
  //
  // * Finally, `undefined` when no leaves in the census report correspond with
  //   this node.
  //
  // The first and third cases are the common cases. The second case is rather
  // uncommon, and to avoid doubling the number of allocations when creating
  // CensusTreeNode trees, and objects that get structured cloned when sending
  // such trees from the HeapAnalysesWorker to the main thread, we only allocate
  // a Set object once a node actually does have multiple leaves it corresponds
  // to.
  this.reportLeafIndex = undefined;
}

CensusTreeNode.prototype = null;

/**
* Compare the given nodes by their `totalBytes` properties, and breaking ties
* with the `totalCount`, `bytes`, and `count` properties (in that order).
*
* @param {CensusTreeNode} node1
* @param {CensusTreeNode} node2
*
* @returns {Number}
*          A number suitable for using with Array.prototype.sort.
*/
function compareByTotal(node1, node2) {
  return (
    Math.abs(node2.totalBytes) - Math.abs(node1.totalBytes) ||
    Math.abs(node2.totalCount) - Math.abs(node1.totalCount) ||
    Math.abs(node2.bytes) - Math.abs(node1.bytes) ||
    Math.abs(node2.count) - Math.abs(node1.count)
  );
}

/**
* Compare the given nodes by their `bytes` properties, and breaking ties with
* the `count`, `totalBytes`, and `totalCount` properties (in that order).
*
* @param {CensusTreeNode} node1
* @param {CensusTreeNode} node2
*
* @returns {Number}
*          A number suitable for using with Array.prototype.sort.
*/
function compareBySelf(node1, node2) {
  return (
    Math.abs(node2.bytes) - Math.abs(node1.bytes) ||
    Math.abs(node2.count) - Math.abs(node1.count) ||
    Math.abs(node2.totalBytes) - Math.abs(node1.totalBytes) ||
    Math.abs(node2.totalCount) - Math.abs(node1.totalCount)
  );
}

/**
* Given a parent cache value from a tree we are building and a child node from
* a tree we are basing the new tree off of, if we already have a corresponding
* node in the parent's children cache, merge this node's counts with
* it. Otherwise, create the corresponding node, add it to the parent's children
* cache, and create the parent->child edge.
*
* @param {CensusTreeNodeCacheValue} parentCachevalue
* @param {CensusTreeNode} node
*
* @returns {CensusTreeNodeCacheValue}
*          The new or extant child node's corresponding cache value.
*/
function insertOrMergeNode(parentCacheValue, node) {
  if (!parentCacheValue.children) {
    parentCacheValue.children = new CensusTreeNodeCache();
  }

  let val = CensusTreeNodeCache.lookupNode(parentCacheValue.children, node);

  if (val) {
    // When inverting, it is possible that multiple leaves in the census report
    // get merged into a single CensusTreeNode node. When this occurs, switch
    // from a single index to a set of indices.
    if (
      val.node.reportLeafIndex !== undefined &&
      val.node.reportLeafIndex !== node.reportLeafIndex
    ) {
      if (typeof val.node.reportLeafIndex === "number") {
        const oldIndex = val.node.reportLeafIndex;
        val.node.reportLeafIndex = new Set();
        val.node.reportLeafIndex.add(oldIndex);
        val.node.reportLeafIndex.add(node.reportLeafIndex);
      } else {
        val.node.reportLeafIndex.add(node.reportLeafIndex);
      }
    }

    val.node.count += node.count;
    val.node.bytes += node.bytes;
  } else {
    val = new CensusTreeNodeCacheValue();

    val.node = new CensusTreeNode(node.name);
    val.node.reportLeafIndex = node.reportLeafIndex;
    val.node.count = node.count;
    val.node.totalCount = node.totalCount;
    val.node.bytes = node.bytes;
    val.node.totalBytes = node.totalBytes;

    addChild(parentCacheValue.node, val.node);
    CensusTreeNodeCache.insertNode(parentCacheValue.children, val);
  }

  return val;
}

/**
* Given an un-inverted CensusTreeNode tree, return the corresponding inverted
* CensusTreeNode tree. The input tree is not modified. The resulting inverted
* tree is sorted by self bytes rather than by total bytes.
*
* @param {CensusTreeNode} tree
*        The un-inverted tree.
*
* @returns {CensusTreeNode}
*          The corresponding inverted tree.
*/
function invert(tree) {
  const inverted = new CensusTreeNodeCacheValue();
  inverted.node = new CensusTreeNode(null);

  // Do a depth-first search of the un-inverted tree. As we reach each leaf,
  // take the path from the old root to the leaf, reverse that path, and add it
  // to the new, inverted tree's root.

  const path = [];
  (function addInvertedPaths(node) {
    path.push(node);

    if (node.children) {
      for (let i = 0, length = node.children.length; i < length; i++) {
        addInvertedPaths(node.children[i]);
      }
    } else {
      // We found a leaf node, add the reverse path to the inverted tree.
      let currentCacheValue = inverted;
      for (let i = path.length - 1; i >= 0; i--) {
        currentCacheValue = insertOrMergeNode(currentCacheValue, path[i]);
      }
    }

    path.pop();
  })(tree);

  // Ensure that the root node always has the totals.
  inverted.node.totalBytes = tree.totalBytes;
  inverted.node.totalCount = tree.totalCount;

  return inverted.node;
}

/**
* Given a CensusTreeNode tree and predicate function, create the tree
* containing only the nodes in any path `(node_0, node_1, ..., node_n-1)` in
* the given tree where `predicate(node_j)` is true for `0 <= j < n`, `node_0`
* is the given tree's root, and `node_n-1` is a leaf in the given tree. The
* given tree is left unmodified.
*
* @param {CensusTreeNode} tree
* @param {Function} predicate
*
* @returns {CensusTreeNode}
*/
function filter(tree, predicate) {
  const filtered = new CensusTreeNodeCacheValue();
  filtered.node = new CensusTreeNode(null);

  // Do a DFS over the given tree. If the predicate returns true for any node,
  // add that node and its whole subtree to the filtered tree.

  const path = [];
  let match = false;

  function addMatchingNodes(node) {
    path.push(node);

    const oldMatch = match;
    if (!match && predicate(node)) {
      match = true;
    }

    if (node.children) {
      for (let i = 0, length = node.children.length; i < length; i++) {
        addMatchingNodes(node.children[i]);
      }
    } else if (match) {
      // We found a matching leaf node, add it to the filtered tree.
      let currentCacheValue = filtered;
      for (let i = 0, length = path.length; i < length; i++) {
        currentCacheValue = insertOrMergeNode(currentCacheValue, path[i]);
      }
    }

    match = oldMatch;
    path.pop();
  }

  if (tree.children) {
    for (let i = 0, length = tree.children.length; i < length; i++) {
      addMatchingNodes(tree.children[i]);
    }
  }

  filtered.node.count = tree.count;
  filtered.node.totalCount = tree.totalCount;
  filtered.node.bytes = tree.bytes;
  filtered.node.totalBytes = tree.totalBytes;

  return filtered.node;
}

/**
* Given a filter string, return a predicate function that takes a node and
* returns true iff the node matches the filter.
*
* @param {String} filterString
* @returns {Function}
*/
function makeFilterPredicate(filterString) {
  return function (node) {
    if (!node.name) {
      return false;
    }

    if (isSavedFrame(node.name)) {
      return (
        node.name.source.includes(filterString) ||
        (node.name.functionDisplayName || "").includes(filterString) ||
        (node.name.asyncCause || "").includes(filterString)
      );
    }

    return String(node.name).includes(filterString);
  };
}

/**
* Takes a report from a census (`dbg.memory.takeCensus()`) and the breakdown
* used to generate the census and returns a structure used to render
* a tree to display the data.
*
* Returns a recursive "CensusTreeNode" object, looking like:
*
* CensusTreeNode = {
*   // `children` if it exists, is sorted by `bytes`, if they are leaf nodes.
*   children: ?[<CensusTreeNode...>],
*   name: <?String>
*   count: <?Number>
*   bytes: <?Number>
*   id: <?Number>
*   parent: <?Number>
* }
*
* @param {Object} breakdown
*        The breakdown used to generate the census report.
*
* @param {Object} report
*        The census report generated with the specified breakdown.
*
* @param {Object} options
*        Configuration options.
*          - invert: Whether to invert the resulting tree or not. Defaults to
*                    false, ie uninverted.
*
* @returns {CensusTreeNode}
*/
exports.censusReportToCensusTreeNode = function (
  breakdown,
  report,
  options = {
    invert: false,
    filter: null,
  }
) {
  // Reset the counter so that turning the same census report into a
  // CensusTreeNode tree repeatedly is idempotent.
  censusTreeNodeIdCounter = 0;

  const visitor = new CensusTreeNodeVisitor();
  walk(breakdown, report, visitor);
  let result = visitor.root();

  if (options.invert) {
    result = invert(result);
  }

  if (typeof options.filter === "string") {
    result = filter(result, makeFilterPredicate(options.filter));
  }

  // If the report is a delta report that was generated by diffing two other
  // reports, make sure to use the basis totals rather than the totals of the
  // difference.
  if (typeof report[basisTotalBytes] === "number") {
    result.totalBytes = report[basisTotalBytes];
    result.totalCount = report[basisTotalCount];
  }

  // Inverting and filtering could have messed up the sort order, so do a
  // depth-first search of the tree and ensure that siblings are sorted.
  const comparator = options.invert ? compareBySelf : compareByTotal;
  (function ensureSorted(node) {
    if (node.children) {
      node.children.sort(comparator);
      for (let i = 0, length = node.children.length; i < length; i++) {
        ensureSorted(node.children[i]);
      }
    }
  })(result);

  return result;
};

quality90%

¤ Dauer der Verarbeitung: 0.17 Sekunden (vorverarbeitet) ¤

Wurzel

Suchen

Beweissystem der NASA

Beweissystem Isabelle

NIST Cobol Testsuite

Cephes Mathematical Library

Wiener Entwicklungsmethode

Haftungshinweis

Die Informationen auf dieser Webseite wurden nach bestem Wissen sorgfältig zusammengestellt. Es wird jedoch weder Vollständigkeit, noch Richtigkeit, noch Qualität der bereit gestellten Informationen zugesichert.

Bemerkung:

Die farbliche Syntaxdarstellung ist noch experimentell.