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fs: more realpath*() optimizations
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Including:

* Skip URL instance check for common (string) cases

* Avoid regexp on non-Windows platforms when parsing the root of a path

* Skip call to `getOptions()` in common case where no `options` is passed

* Avoid `hasOwnProperty()`

PR-URL: #11665
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
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@mscdex @jasnell
mscdex authored and jasnell committed Mar 15, 2017
1 parent 6a5ab5d commit 7109774
Showing 1 changed file with 56 additions and 40 deletions.
96 changes: 56 additions & 40 deletions lib/fs.js
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,7 @@ const internalUtil = require('internal/util');
const assertEncoding = internalFS.assertEncoding;
const stringToFlags = internalFS.stringToFlags;
const getPathFromURL = internalURL.getPathFromURL;
const { StorageObject } = require('internal/querystring');

Object.defineProperty(exports, 'constants', {
configurable: false,
Expand Down Expand Up @@ -1514,10 +1515,23 @@ fs.unwatchFile = function(filename, listener) {
};


// Regex to find the device root, including trailing slash. E.g. 'c:\\'.
const splitRootRe = isWindows ?
/^(?:[a-zA-Z]:|[\\/]{2}[^\\/]+[\\/][^\\/]+)?[\\/]*/ :
/^[/]*/;
var splitRoot;
if (isWindows) {
// Regex to find the device root on Windows (e.g. 'c:\\'), including trailing
// slash.
const splitRootRe = /^(?:[a-zA-Z]:|[\\/]{2}[^\\/]+[\\/][^\\/]+)?[\\/]*/;
splitRoot = function splitRoot(str) {
return splitRootRe.exec(str)[0];
};
} else {
splitRoot = function splitRoot(str) {
for (var i = 0; i < str.length; ++i) {
if (str.charCodeAt(i) !== 47/*'/'*/)
return str.slice(0, i);
}
return str;
};
}

function encodeRealpathResult(result, options) {
if (!options || !options.encoding || options.encoding === 'utf8')
Expand Down Expand Up @@ -1545,11 +1559,17 @@ if (isWindows) {
nextPart = function nextPart(p, i) { return p.indexOf('/', i); };
}

const emptyObj = new StorageObject();
fs.realpathSync = function realpathSync(p, options) {
options = getOptions(options, {});
handleError((p = getPathFromURL(p)));
if (typeof p !== 'string')
p += '';
if (!options)
options = emptyObj;
else
options = getOptions(options, emptyObj);
if (typeof p !== 'string') {
handleError((p = getPathFromURL(p)));
if (typeof p !== 'string')
p += '';
}
nullCheck(p);
p = pathModule.resolve(p);

Expand All @@ -1559,8 +1579,8 @@ fs.realpathSync = function realpathSync(p, options) {
return maybeCachedResult;
}

const seenLinks = {};
const knownHard = {};
const seenLinks = new StorageObject();
const knownHard = new StorageObject();
const original = p;

// current character position in p
Expand All @@ -1573,10 +1593,8 @@ fs.realpathSync = function realpathSync(p, options) {
var previous;

// Skip over roots
var m = splitRootRe.exec(p);
pos = m[0].length;
current = m[0];
base = m[0];
current = base = splitRoot(p);
pos = current.length;

// On windows, check that the root exists. On unix there is no need.
if (isWindows && !knownHard[base]) {
Expand Down Expand Up @@ -1615,7 +1633,8 @@ fs.realpathSync = function realpathSync(p, options) {
// Use stats array directly to avoid creating an fs.Stats instance just
// for our internal use.

binding.lstat(pathModule._makeLong(base));
var baseLong = pathModule._makeLong(base);
binding.lstat(baseLong);

if ((statValues[1/*mode*/] & S_IFMT) !== S_IFLNK) {
knownHard[base] = true;
Expand All @@ -1631,13 +1650,13 @@ fs.realpathSync = function realpathSync(p, options) {
var dev = statValues[0/*dev*/].toString(32);
var ino = statValues[7/*ino*/].toString(32);
id = `${dev}:${ino}`;
if (seenLinks.hasOwnProperty(id)) {
if (seenLinks[id]) {
linkTarget = seenLinks[id];
}
}
if (linkTarget === null) {
binding.stat(pathModule._makeLong(base));
linkTarget = binding.readlink(pathModule._makeLong(base));
binding.stat(baseLong);
linkTarget = binding.readlink(baseLong);
}
resolvedLink = pathModule.resolve(previous, linkTarget);

Expand All @@ -1649,10 +1668,8 @@ fs.realpathSync = function realpathSync(p, options) {
p = pathModule.resolve(resolvedLink, p.slice(pos));

// Skip over roots
m = splitRootRe.exec(p);
pos = m[0].length;
current = m[0];
base = m[0];
current = base = splitRoot(p);
pos = current.length;

// On windows, check that the root exists. On unix there is no need.
if (isWindows && !knownHard[base]) {
Expand All @@ -1668,17 +1685,22 @@ fs.realpathSync = function realpathSync(p, options) {

fs.realpath = function realpath(p, options, callback) {
callback = maybeCallback(typeof options === 'function' ? options : callback);
options = getOptions(options, {});
if (handleError((p = getPathFromURL(p)), callback))
return;
if (typeof p !== 'string')
p += '';
if (!options)
options = emptyObj;
else
options = getOptions(options, emptyObj);
if (typeof p !== 'string') {
if (handleError((p = getPathFromURL(p)), callback))
return;
if (typeof p !== 'string')
p += '';
}
if (!nullCheck(p, callback))
return;
p = pathModule.resolve(p);

const seenLinks = {};
const knownHard = {};
const seenLinks = new StorageObject();
const knownHard = new StorageObject();

// current character position in p
var pos;
Expand All @@ -1689,11 +1711,8 @@ fs.realpath = function realpath(p, options, callback) {
// the partial path scanned in the previous round, with slash
var previous;

var m = splitRootRe.exec(p);
pos = m[0].length;
current = m[0];
base = m[0];
previous = '';
current = base = splitRoot(p);
pos = current.length;

// On windows, check that the root exists. On unix there is no need.
if (isWindows && !knownHard[base]) {
Expand Down Expand Up @@ -1756,7 +1775,7 @@ fs.realpath = function realpath(p, options, callback) {
var dev = statValues[0/*ino*/].toString(32);
var ino = statValues[7/*ino*/].toString(32);
id = `${dev}:${ino}`;
if (seenLinks.hasOwnProperty(id)) {
if (seenLinks[id]) {
return gotTarget(null, seenLinks[id], base);
}
}
Expand All @@ -1780,11 +1799,8 @@ fs.realpath = function realpath(p, options, callback) {
function gotResolvedLink(resolvedLink) {
// resolve the link, then start over
p = pathModule.resolve(resolvedLink, p.slice(pos));
var m = splitRootRe.exec(p);
pos = m[0].length;
current = m[0];
base = m[0];
previous = '';
current = base = splitRoot(p);
pos = current.length;

// On windows, check that the root exists. On unix there is no need.
if (isWindows && !knownHard[base]) {
Expand Down

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