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+/* 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";
+
+const { flatten } = require("resource://devtools/shared/ThreadSafeDevToolsUtils.js");
+
+/** * Visitor ****************************************************************/
+
+/**
+ * A Visitor visits each node and edge of a census report tree as the census
+ * report is being traversed by `walk`.
+ */
+function Visitor() { }
+exports.Visitor = Visitor;
+
+/**
+ * The `enter` method is called when a new sub-report is entered in traversal.
+ *
+ * @param {Object} breakdown
+ * The breakdown for the sub-report that is being entered by traversal.
+ *
+ * @param {Object} report
+ * The report generated by the given breakdown.
+ *
+ * @param {any} edge
+ * The edge leading to this sub-report. The edge is null if (but not iff!
+ * eg, null allocation stack edges) we are entering the root report.
+ */
+Visitor.prototype.enter = function (breakdown, report, edge) { };
+
+/**
+ * The `exit` method is called when traversal of a sub-report has finished.
+ *
+ * @param {Object} breakdown
+ * The breakdown for the sub-report whose traversal has finished.
+ *
+ * @param {Object} report
+ * The report generated by the given breakdown.
+ *
+ * @param {any} edge
+ * The edge leading to this sub-report. The edge is null if (but not iff!
+ * eg, null allocation stack edges) we are entering the root report.
+ */
+Visitor.prototype.exit = function (breakdown, report, edge) { };
+
+/**
+ * The `count` method is called when leaf nodes (reports whose breakdown is
+ * by: "count") in the report tree are encountered.
+ *
+ * @param {Object} breakdown
+ * The count breakdown for this report.
+ *
+ * @param {Object} report
+ * The report generated by a breakdown by "count".
+ *
+ * @param {any|null} edge
+ * The edge leading to this count report. The edge is null if we are
+ * entering the root report.
+ */
+Visitor.prototype.count = function (breakdown, report, edge) { };
+
+/** * getReportEdges *********************************************************/
+
+const EDGES = Object.create(null);
+
+EDGES.count = function (breakdown, report) {
+ return [];
+};
+
+EDGES.bucket = function (breakdown, report) {
+ return [];
+};
+
+EDGES.internalType = function (breakdown, report) {
+ return Object.keys(report).map(key => ({
+ edge: key,
+ referent: report[key],
+ breakdown: breakdown.then
+ }));
+};
+
+EDGES.objectClass = function (breakdown, report) {
+ return Object.keys(report).map(key => ({
+ edge: key,
+ referent: report[key],
+ breakdown: key === "other" ? breakdown.other : breakdown.then
+ }));
+};
+
+EDGES.coarseType = function (breakdown, report) {
+ return [
+ { edge: "objects", referent: report.objects, breakdown: breakdown.objects },
+ { edge: "scripts", referent: report.scripts, breakdown: breakdown.scripts },
+ { edge: "strings", referent: report.strings, breakdown: breakdown.strings },
+ { edge: "other", referent: report.other, breakdown: breakdown.other },
+ ];
+};
+
+EDGES.allocationStack = function (breakdown, report) {
+ const edges = [];
+ report.forEach((value, key) => {
+ edges.push({
+ edge: key,
+ referent: value,
+ breakdown: key === "noStack" ? breakdown.noStack : breakdown.then
+ });
+ });
+ return edges;
+};
+
+EDGES.filename = function (breakdown, report) {
+ return Object.keys(report).map(key => ({
+ edge: key,
+ referent: report[key],
+ breakdown: key === "noFilename" ? breakdown.noFilename : breakdown.then
+ }));
+};
+
+/**
+ * Get the set of outgoing edges from `report` as specified by the given
+ * breakdown.
+ *
+ * @param {Object} breakdown
+ * The census breakdown.
+ *
+ * @param {Object} report
+ * The census report.
+ */
+function getReportEdges(breakdown, report) {
+ return EDGES[breakdown.by](breakdown, report);
+}
+exports.getReportEdges = getReportEdges;
+
+/** * walk *******************************************************************/
+
+function recursiveWalk(breakdown, edge, report, visitor) {
+ if (breakdown.by === "count") {
+ visitor.enter(breakdown, report, edge);
+ visitor.count(breakdown, report, edge);
+ visitor.exit(breakdown, report, edge);
+ } else {
+ visitor.enter(breakdown, report, edge);
+ for (let { edge, referent, breakdown: subBreakdown } of getReportEdges(breakdown, report)) {
+ recursiveWalk(subBreakdown, edge, referent, visitor);
+ }
+ visitor.exit(breakdown, report, edge);
+ }
+}
+
+/**
+ * Walk the given `report` that was generated by taking a census with the
+ * specified `breakdown`.
+ *
+ * @param {Object} breakdown
+ * The census breakdown.
+ *
+ * @param {Object} report
+ * The census report.
+ *
+ * @param {Visitor} visitor
+ * The Visitor instance to call into while traversing.
+ */
+function walk(breakdown, report, visitor) {
+ recursiveWalk(breakdown, null, report, visitor);
+}
+exports.walk = walk;
+
+/** * diff *******************************************************************/
+
+/**
+ * Return true if the object is a Map, false otherwise. Works with Map objects
+ * from other globals, unlike `instanceof`.
+ *
+ * @returns {Boolean}
+ */
+function isMap(obj) {
+ return Object.prototype.toString.call(obj) === "[object Map]";
+}
+
+/**
+ * A Visitor for computing the difference between the census report being
+ * traversed and the given other census.
+ *
+ * @param {Object} otherCensus
+ * The other census report.
+ */
+function DiffVisitor(otherCensus) {
+ // The other census we are comparing against.
+ this._otherCensus = otherCensus;
+
+ // The total bytes and count of the basis census we are traversing.
+ this._totalBytes = 0;
+ this._totalCount = 0;
+
+ // Stack maintaining the current corresponding sub-report for the other
+ // census we are comparing against.
+ this._otherCensusStack = [];
+
+ // Stack maintaining the set of edges visited at each sub-report.
+ this._edgesVisited = [new Set()];
+
+ // The final delta census. Valid only after traversal.
+ this._results = null;
+
+ // Stack maintaining the results corresponding to each sub-report we are
+ // currently traversing.
+ this._resultsStack = [];
+}
+
+DiffVisitor.prototype = Object.create(Visitor.prototype);
+
+/**
+ * Given a report and an outgoing edge, get the edge's referent.
+ */
+DiffVisitor.prototype._get = function (report, edge) {
+ if (!report) {
+ return undefined;
+ }
+ return isMap(report) ? report.get(edge) : report[edge];
+};
+
+/**
+ * Given a report, an outgoing edge, and a value, set the edge's referent to
+ * the given value.
+ */
+DiffVisitor.prototype._set = function (report, edge, val) {
+ if (isMap(report)) {
+ report.set(edge, val);
+ } else {
+ report[edge] = val;
+ }
+};
+
+/**
+ * @overrides Visitor.prototype.enter
+ */
+DiffVisitor.prototype.enter = function (breakdown, report, edge) {
+ const isFirstTimeEntering = this._results === null;
+
+ const newResults = breakdown.by === "allocationStack" ? new Map() : {};
+ let newOther;
+
+ if (!this._results) {
+ // This is the first time we have entered a sub-report.
+ this._results = newResults;
+ newOther = this._otherCensus;
+ } else {
+ const topResults = this._resultsStack[this._resultsStack.length - 1];
+ this._set(topResults, edge, newResults);
+
+ const topOther = this._otherCensusStack[this._otherCensusStack.length - 1];
+ newOther = this._get(topOther, edge);
+ }
+
+ this._resultsStack.push(newResults);
+ this._otherCensusStack.push(newOther);
+
+ const visited = this._edgesVisited[this._edgesVisited.length - 1];
+ visited.add(edge);
+ this._edgesVisited.push(new Set());
+};
+
+/**
+ * @overrides Visitor.prototype.exit
+ */
+DiffVisitor.prototype.exit = function (breakdown, report, edge) {
+ // Find all the edges in the other census report that were not traversed and
+ // add them to the results directly.
+ const other = this._otherCensusStack[this._otherCensusStack.length - 1];
+ if (other) {
+ const visited = this._edgesVisited[this._edgesVisited.length - 1];
+ const unvisited = getReportEdges(breakdown, other)
+ .map(e => e.edge)
+ .filter(e => !visited.has(e));
+ const results = this._resultsStack[this._resultsStack.length - 1];
+ for (let edge of unvisited) {
+ this._set(results, edge, this._get(other, edge));
+ }
+ }
+
+ this._otherCensusStack.pop();
+ this._resultsStack.pop();
+ this._edgesVisited.pop();
+};
+
+/**
+ * @overrides Visitor.prototype.count
+ */
+DiffVisitor.prototype.count = function (breakdown, report, edge) {
+ const other = this._otherCensusStack[this._otherCensusStack.length - 1];
+ const results = this._resultsStack[this._resultsStack.length - 1];
+
+ if (breakdown.count) {
+ this._totalCount += report.count;
+ }
+ if (breakdown.bytes) {
+ this._totalBytes += report.bytes;
+ }
+
+ if (other) {
+ if (breakdown.count) {
+ results.count = other.count - report.count;
+ }
+ if (breakdown.bytes) {
+ results.bytes = other.bytes - report.bytes;
+ }
+ } else {
+ if (breakdown.count) {
+ results.count = -report.count;
+ }
+ if (breakdown.bytes) {
+ results.bytes = -report.bytes;
+ }
+ }
+};
+
+const basisTotalBytes = exports.basisTotalBytes = Symbol("basisTotalBytes");
+const basisTotalCount = exports.basisTotalCount = Symbol("basisTotalCount");
+
+/**
+ * Get the resulting report of the difference between the traversed census
+ * report and the other census report.
+ *
+ * @returns {Object}
+ * The delta census report.
+ */
+DiffVisitor.prototype.results = function () {
+ if (!this._results) {
+ throw new Error("Attempt to get results before computing diff!");
+ }
+
+ if (this._resultsStack.length) {
+ throw new Error("Attempt to get results while still computing diff!");
+ }
+
+ this._results[basisTotalBytes] = this._totalBytes;
+ this._results[basisTotalCount] = this._totalCount;
+
+ return this._results;
+};
+
+/**
+ * Take the difference between two censuses. The resulting delta report
+ * contains the number/size of things that are in the `endCensus` that are not
+ * in the `startCensus`.
+ *
+ * @param {Object} breakdown
+ * The breakdown used to generate both census reports.
+ *
+ * @param {Object} startCensus
+ * The first census report.
+ *
+ * @param {Object} endCensus
+ * The second census report.
+ *
+ * @returns {Object}
+ * A delta report mirroring the structure of the two census reports (as
+ * specified by the given breakdown). Has two additional properties:
+ * - {Number} basisTotalBytes: the total number of bytes in the start
+ * census.
+ * - {Number} basisTotalCount: the total count in the start census.
+ */
+function diff(breakdown, startCensus, endCensus) {
+ const visitor = new DiffVisitor(endCensus);
+ walk(breakdown, startCensus, visitor);
+ return visitor.results();
+}
+exports.diff = diff;
+
+/**
+ * Creates a hash map mapping node IDs to its parent node.
+ *
+ * @param {CensusTreeNode} node
+ * @param {Object<number, TreeNode>} aggregator
+ *
+ * @return {Object<number, TreeNode>}
+ */
+const createParentMap = exports.createParentMap = function (node,
+ getId = node => node.id,
+ aggregator = Object.create(null)) {
+ if (node.children) {
+ for (let i = 0, length = node.children.length; i < length; i++) {
+ const child = node.children[i];
+ aggregator[getId(child)] = node;
+ createParentMap(child, getId, aggregator);
+ }
+ }
+
+ return aggregator;
+};
+
+const BUCKET = Object.freeze({ by: "bucket" });
+
+/**
+ * Convert a breakdown whose leaves are { by: "count" } to an identical
+ * breakdown, except with { by: "bucket" } leaves.
+ *
+ * @param {Object} breakdown
+ * @returns {Object}
+ */
+exports.countToBucketBreakdown = function (breakdown) {
+ if (typeof breakdown !== "object" || !breakdown) {
+ return breakdown;
+ }
+
+ if (breakdown.by === "count") {
+ return BUCKET;
+ }
+
+ const keys = Object.keys(breakdown);
+ const vals = keys.reduce((vs, k) => {
+ vs.push(exports.countToBucketBreakdown(breakdown[k]));
+ return vs;
+ }, []);
+
+ const result = {};
+ for (let i = 0, length = keys.length; i < length; i++) {
+ result[keys[i]] = vals[i];
+ }
+
+ return Object.freeze(result);
+};
+
+/**
+ * A Visitor for finding report leaves by their DFS index.
+ */
+function GetLeavesVisitor(targetIndices) {
+ this._index = -1;
+ this._targetIndices = targetIndices;
+ this._leaves = [];
+}
+
+GetLeavesVisitor.prototype = Object.create(Visitor.prototype);
+
+/**
+ * @overrides Visitor.prototype.enter
+ */
+GetLeavesVisitor.prototype.enter = function (breakdown, report, edge) {
+ this._index++;
+ if (this._targetIndices.has(this._index)) {
+ this._leaves.push(report);
+ }
+};
+
+/**
+ * Get the accumulated report leaves after traversal.
+ */
+GetLeavesVisitor.prototype.leaves = function () {
+ if (this._index === -1) {
+ throw new Error("Attempt to call `leaves` before traversing report!");
+ }
+ return this._leaves;
+};
+
+/**
+ * Given a set of indices of leaves in a pre-order depth-first traversal of the
+ * given census report, return the leaves.
+ *
+ * @param {Set<Number>} indices
+ * @param {Object} breakdown
+ * @param {Object} report
+ *
+ * @returns {Array<Object>}
+ */
+exports.getReportLeaves = function (indices, breakdown, report) {
+ const visitor = new GetLeavesVisitor(indices);
+ walk(breakdown, report, visitor);
+ return visitor.leaves();
+};
+
+/**
+ * Get a list of the individual node IDs that belong to the census report leaves
+ * of the given indices.
+ *
+ * @param {Set<Number>} indices
+ * @param {Object} breakdown
+ * @param {HeapSnapshot} snapshot
+ *
+ * @returns {Array<NodeId>}
+ */
+exports.getCensusIndividuals = function (indices, countBreakdown, snapshot) {
+ const bucketBreakdown = exports.countToBucketBreakdown(countBreakdown);
+ const bucketReport = snapshot.takeCensus({ breakdown: bucketBreakdown });
+ const buckets = exports.getReportLeaves(indices,
+ bucketBreakdown,
+ bucketReport);
+ return flatten(buckets);
+};