node-walk
====
| Sponsored by [ppl](https://ppl.family)
nodejs walk implementation.
This is somewhat of a port python's `os.walk`, but using Node.JS conventions.
* EventEmitter
* Asynchronous
* Chronological (optionally)
* Built-in flow-control
* includes Synchronous version (same API as Asynchronous)
As few file descriptors are opened at a time as possible.
This is particularly well suited for single hard disks which are not flash or solid state.
Installation
----
```bash
npm install --save walk
```
Getting Started
====
```javascript
(function () {
"use strict";
var walk = require('walk');
var fs = require('fs');
var walker;
walker = walk.walk("/tmp", options);
walker.on("file", function (root, fileStats, next) {
fs.readFile(fileStats.name, function () {
// doStuff
next();
});
});
walker.on("errors", function (root, nodeStatsArray, next) {
next();
});
walker.on("end", function () {
console.log("all done");
});
}());
```
Common Events
-----
All single event callbacks are in the form of `function (root, stat, next) {}`.
All multiple event callbacks callbacks are in the form of `function (root, stats, next) {}`, except **names** which is an array of strings.
All **error** event callbacks are in the form `function (root, stat/stats, next) {}`.
**`stat.error`** contains the error.
* `names`
* `directory`
* `directories`
* `file`
* `files`
* `end`
* `nodeError` (`stat` failed)
* `directoryError` (`stat` succedded, but `readdir` failed)
* `errors` (a collection of any errors encountered)
A typical `stat` event looks like this:
```javascript
{ dev: 16777223,
mode: 33188,
nlink: 1,
uid: 501,
gid: 20,
rdev: 0,
blksize: 4096,
ino: 49868100,
size: 5617,
blocks: 16,
atime: Mon Jan 05 2015 18:18:10 GMT-0700 (MST),
mtime: Thu Sep 25 2014 21:21:28 GMT-0600 (MDT),
ctime: Thu Sep 25 2014 21:21:28 GMT-0600 (MDT),
birthtime: Thu Sep 25 2014 21:21:28 GMT-0600 (MDT),
name: 'README.md',
type: 'file' }
```
Advanced Example
====
Both Asynchronous and Synchronous versions are provided.
```javascript
(function () {
"use strict";
var walk = require('walk');
var fs = require('fs');
var options;
var walker;
options = {
followLinks: false
// directories with these keys will be skipped
, filters: ["Temp", "_Temp"]
};
walker = walk.walk("/tmp", options);
// OR
// walker = walk.walkSync("/tmp", options);
walker.on("names", function (root, nodeNamesArray) {
nodeNamesArray.sort(function (a, b) {
if (a > b) return 1;
if (a < b) return -1;
return 0;
});
});
walker.on("directories", function (root, dirStatsArray, next) {
// dirStatsArray is an array of `stat` objects with the additional attributes
// * type
// * error
// * name
next();
});
walker.on("file", function (root, fileStats, next) {
fs.readFile(fileStats.name, function () {
// doStuff
next();
});
});
walker.on("errors", function (root, nodeStatsArray, next) {
next();
});
walker.on("end", function () {
console.log("all done");
});
}());
```
### Sync
Note: You **can't use EventEmitter** if you want truly synchronous walker
(although it's synchronous under the hood, it appears not to be due to the use of `process.nextTick()`).
Instead **you must use `options.listeners`** for truly synchronous walker.
Although the sync version uses all of the `fs.readSync`, `fs.readdirSync`, and other sync methods,
I don't think I can prevent the `process.nextTick()` that `EventEmitter` calls.
```javascript
(function () {
"use strict";
var walk = require('walk');
var fs = require('fs');
var options;
var walker;
// To be truly synchronous in the emitter and maintain a compatible api,
// the listeners must be listed before the object is created
options = {
listeners: {
names: function (root, nodeNamesArray) {
nodeNamesArray.sort(function (a, b) {
if (a > b) return 1;
if (a < b) return -1;
return 0;
});
}
, directories: function (root, dirStatsArray, next) {
// dirStatsArray is an array of `stat` objects with the additional attributes
// * type
// * error
// * name
next();
}
, file: function (root, fileStats, next) {
fs.readFile(fileStats.name, function () {
// doStuff
next();
});
}
, errors: function (root, nodeStatsArray, next) {
next();
}
}
};
walker = walk.walkSync("/tmp", options);
console.log("all done");
}());
```
API
====
Emitted Values
* `on('XYZ', function(root, stats, next) {})`
* `root` - the containing the files to be inspected
* *stats[Array]* - a single `stats` object or an array with some added attributes
* type - 'file', 'directory', etc
* error
* name - the name of the file, dir, etc
* next - no more files will be read until this is called
Single Events - fired immediately
* `end` - No files, dirs, etc left to inspect
* `directoryError` - Error when `fstat` succeeded, but reading path failed (Probably due to permissions).
* `nodeError` - Error `fstat` did not succeeded.
* `node` - a `stats` object for a node of any type
* `file` - includes links when `followLinks` is `true`
* `directory` - **NOTE** you could get a recursive loop if `followLinks` and a directory links to its parent
* `symbolicLink` - always empty when `followLinks` is `true`
* `blockDevice`
* `characterDevice`
* `FIFO`
* `socket`
Events with Array Arguments - fired after all files in the dir have been `stat`ed
* `names` - before any `stat` takes place. Useful for sorting and filtering.
* Note: the array is an array of `string`s, not `stat` objects
* Note: the `next` argument is a `noop`
* `errors` - errors encountered by `fs.stat` when reading ndes in a directory
* `nodes` - an array of `stats` of any type
* `files`
* `directories` - modification of this array - sorting, removing, etc - affects traversal
* `symbolicLinks`
* `blockDevices`
* `characterDevices`
* `FIFOs`
* `sockets`
**Warning** beware of infinite loops when `followLinks` is true (using `walk-recurse` varient).
Comparisons
====
Tested on my `/System` containing 59,490 (+ self) directories (and lots of files).
The size of the text output was 6mb.
`find`:
time bash -c "find /System -type d | wc"
59491 97935 6262916
real 2m27.114s
user 0m1.193s
sys 0m14.859s
`find.js`:
Note that `find.js` omits the start directory
time bash -c "node examples/find.js /System -type d | wc"
59490 97934 6262908
# Test 1
real 2m52.273s
user 0m20.374s
sys 0m27.800s
# Test 2
real 2m23.725s
user 0m18.019s
sys 0m23.202s
# Test 3
real 2m50.077s
user 0m17.661s
sys 0m24.008s
In conclusion node.js asynchronous walk is much slower than regular "find".
LICENSE
===
`node-walk` is available under the following licenses:
* MIT
* Apache 2
Copyright 2011 - Present AJ ONeal