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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";
/**
* Memory leak hunter. Walks a tree of objects looking for DOM nodes.
* Usage:
* leakHunt({
* thing: thing,
* otherthing: otherthing
* });
*/
function leakHunt(root) {
const path = [];
const seen = [];
try {
const output = leakHunt.inner(root, path, seen);
output.forEach(function (line) {
dump(line + "\n");
});
} catch (ex) {
dump(ex + "\n");
}
}
leakHunt.inner = function (root, path, seen) {
const prefix = new Array(path.length).join(" ");
const reply = [];
function log(msg) {
reply.push(msg);
}
let direct;
try {
direct = Object.keys(root);
} catch (ex) {
log(prefix + " Error enumerating: " + ex);
return reply;
}
try {
let index = 0;
for (const data of root) {
const prop = "" + index;
leakHunt.digProperty(prop, data, path, seen, direct, log);
index++;
}
} catch (ex) {
/* Ignore things that are not enumerable */
}
for (const prop in root) {
let data;
try {
data = root[prop];
} catch (ex) {
log(prefix + " " + prop + " = Error: " + ex.toString().substring(0, 30));
continue;
}
leakHunt.digProperty(prop, data, path, seen, direct, log);
}
return reply;
};
leakHunt.hide = [/^string$/, /^number$/, /^boolean$/, /^null/, /^undefined/];
leakHunt.noRecurse = [
/^string$/,
/^number$/,
/^boolean$/,
/^null/,
/^undefined/,
/^Window$/,
/^Document$/,
/^XULElement$/,
/^DOMWindow$/,
/^HTMLDocument$/,
/^HTML.*Element$/,
/^ChromeWindow$/,
];
leakHunt.digProperty = function (prop, data, path, seen, direct, log) {
const newPath = path.slice();
newPath.push(prop);
const prefix = new Array(newPath.length).join(" ");
let recurse = true;
let message = leakHunt.getType(data);
if (leakHunt.matchesAnyPattern(message, leakHunt.hide)) {
return;
}
if (message === "function" && !direct.includes(prop)) {
return;
}
if (message === "string") {
const extra = data.length > 10 ? data.substring(0, 9) + "_" : data;
message += ' "' + extra.replace(/\n/g, "|") + '"';
recurse = false;
} else if (leakHunt.matchesAnyPattern(message, leakHunt.noRecurse)) {
message += " (no recurse)";
recurse = false;
} else if (seen.includes(data)) {
message += " (already seen)";
recurse = false;
}
if (recurse) {
seen.push(data);
const lines = leakHunt.inner(data, newPath, seen);
if (!lines.length) {
if (message !== "function") {
log(prefix + prop + " = " + message + " { }");
}
} else {
log(prefix + prop + " = " + message + " {");
lines.forEach(function (line) {
log(line);
});
log(prefix + "}");
}
} else {
log(prefix + prop + " = " + message);
}
};
leakHunt.matchesAnyPattern = function (str, patterns) {
let match = false;
patterns.forEach(function (pattern) {
if (str.match(pattern)) {
match = true;
}
});
return match;
};
leakHunt.getType = function (data) {
if (data === null) {
return "null";
}
if (data === undefined) {
return "undefined";
}
let type = typeof data;
if (type === "object" || type === "Object") {
type = leakHunt.getCtorName(data);
}
return type;
};
leakHunt.getCtorName = function (obj) {
try {
if (obj.constructor && obj.constructor.name) {
return obj.constructor.name;
}
} catch (ex) {
return "UnknownObject";
}
// If that fails, use Objects toString which sometimes gives something
// better than 'Object', and at least defaults to Object if nothing better
return Object.prototype.toString.call(obj).slice(8, -1);
};
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