fuse

[frank-dspeed]

BUILDING A FILESYSTEM IN NODE.JS • Use the fuse-bindings github project • https://github.com/mafintosh/fuse-bindings • Implement required filesystem operations • Run your node.js code and mount on an existing directory. • Success?!?!
9. BUILDING A FILESYSTEM IN NODE.JS read(filePath, fd, buf, len, pos, cb) { } write(filePath, fd, buf, len, pos, cb) { } create(filePath, mode, cb) { } open(filePath, flags, cb) { } readdir(filePath, cb) { } Good list for reference: https://www.cs.hmc.edu/~geoff/classes/hmc.cs135.201001/homework/fuse/fuse_doc.html#function-­‐ purposes getattr(filePath, cb) { }
10. BUILDING A FILESYSTEM IN NODE.JS getattr(/) getattr(/cat.jpg) create(/cat.jpg, 33188) getattr(/cat.jpg) write(/cat.jpg, 0, len: 65536, buf.length: 65536, pos: 0 write(/cat.jpg, 0, len: 65536, buf.length: 65536, pos: 65536) // ... getattr(/cat.jpg) release(/cat.jpg, 0) Example: What does a file copy look like?
11. BUILDING A FILESYSTEM IN NODE.JS In-memory virtual filesystem backed by JS array (yikes)
12. BUILDING A FILESYSTEM IN NODE.JS var files = [ { name: 'readme.md', data: new Buffer('# test filen'), } ]; A 'file' is just an item in this array: Buffer()-backed
13. BUILDING A FILESYSTEM IN NODE.JS readdir() { // ... for (var i = 0; i < files.length; i++) { var buffer = files[i].data; var hash = hasha(buffer).substring(0, 12); files[i].name = ${hash}-${files[i].name}; files[i].hasFingerprint = true; } } Let's rename the filename to be a hash!
14. BUILDING A FILESYSTEM IN NODE.JS releaseFile(filePath, fd) { // Buffer is a WritableStream() var buffer = this.files[fileIndex].data.getContents(); zlib.gzip(buffer, function(error, result) { // create file if compression succeeded. }); } Like gzip?
15. BUILDING A FILESYSTEM IN NODE.JS Performance profiling CC A SA www.flickr.com/photos/libertinus/9231731038
16. Benchmarking disk or file system IO performance can be tricky at best. BUILDING A FILESYSTEM IN NODE.JS James Coyle
17. BUILDING A FILESYSTEM IN NODE.JS dd: "The Easy Route" •time sh -c "dd if=/dev/zero of=./in- memory/tst.tmp bs=4k count=1000 && sync" •409600 bytes written 1000 times... •Result: 3 mb/s (node, FuSE fs)