refactoring of the fs module.

[drsm]

1. Handle arguments containing path strings in one place:
   1e9f7f5

[drsm]

2. Fixed callback invocations in "fs" module. Fixes fs.readFile should be async #200.
   https://gist.github.com/drsm/3f4567cacbc0f088862b04a0b5d5d7f2 (Ready)

[drsm]

TODO: (in no particular order)

• TypedArrays & ArrayBuffer
• better testsuite
• benchmark
• add more encodings

[xeioex]

Fixed callback invocations in "fs" module. Fixes #200.
https://gist.github.com/drsm/3f4567cacbc0f088862b04a0b5d5d7f2 (Ready)

Thanks, committed with some improvements: cd10a4b.

[drsm]

3. Introduced fs.promises API. / Introduced fs.access and friends.
   https://gist.github.com/drsm/d950402101765c7395c36cb4051576ba (Ready)

@xeioex please take a look.
isn't it broken by design?

[xeioex]

@drsm

isn't it broken by design?

Looks promising. Have no issues with the design.

[drsm]

I've updated the patch above.
The solution is compatible with nodejs except the cases like fs.promises.readFile() (our version will throw).

[xeioex]

@drsm I am on large (Array objects) refactoring now. I plan to merge the patch this or next week.

[drsm]

4. Added fs.symlink(), fs.unlink(), fs.mkdir(), fs.rmdir() and friends.
   https://gist.github.com/drsm/d0b44c1d6252a9c2a0627c15aed97c31 (outdated)

[drsm]

JFF

var fs = require('fs'), fsp = fs.promises;
var current;

Promise.resolve('100k fs.access(/dev/null)')
.then((name) => {
    current = name;
    console.log('start', current);
    console.time(current);
})
.then(() => {
    console.time(current + ' sync');
    for (var i = 0; i < 100000; ++i) {
        fs.accessSync('/dev/null');
    }
    console.timeEnd(current + ' sync');
})
.then(() => {
    console.time(current + ' promise');
    var n = 100000;
    var f = () => {
        if (n--) {
            return fsp.access('/dev/null').then(() => f());
        }
        console.timeEnd(current + ' promise');
        return Promise.resolve();
    };

    return f();
})
/*.then(() => {
    var f = async () => {
        console.time(current + ' async');
        for (var i = 0; i < 100000; ++i) {
            await fsp.access('/dev/null');
        }
        console.timeEnd(current + ' async');
    };

    return f();
})*/
.then(() => {
    return new Promise((resolve, reject) => {
        console.time(current + ' callback');
        var n = 100000;
        var f = (err) => {
            if (err) {
                reject(err);
                return;
            }
            if (n--) {
                fs.access('/dev/null', f);
                return;
            }
            console.timeEnd(current + ' callback');
            resolve();
        };

        f();
    })
})
.then(() => {
    console.timeEnd(current);
    console.log('stop', current);
    current = void 0;
})
.catch((e) => {
    console.log(current, 'failed', e)
});

$ node fs_bench.js 
start 100k fs.access(/dev/null)
100k fs.access(/dev/null) sync: 131.249ms
100k fs.access(/dev/null) promise: 1226.996ms
100k fs.access(/dev/null) callback: 965.285ms
100k fs.access(/dev/null): 2326.356ms
stop 100k fs.access(/dev/null)
$ build/njs fs_bench.js 
start 100k fs.access(/dev/null)
100k fs.access(/dev/null) sync: 123.637338ms
100k fs.access(/dev/null) promise: 426.900264ms
100k fs.access(/dev/null) callback: 151.360074ms
100k fs.access(/dev/null): 781.825911ms
stop 100k fs.access(/dev/null)

[xeioex]

@drsm

Introduced fs.promises API. / Introduced fs.access and friends.
https://gist.github.com/drsm/d950402101765c7395c36cb4051576ba (Ready)

Thanks, committed (096f5aa, d71a881) with some refactoring included.

[drsm]

4. Added fs.symlink(), fs.unlink(), fs.realpath() and friends.
   https://gist.github.com/drsm/3d0402f41dc332b3c87bbe5dfcb7892e