generic-filehandle2

generic-filehandle2

Provides a uniform interface for accessing binary data from local files, remote HTTP resources, and Blob data in the browser.

Usage

import { LocalFile, RemoteFile, BlobFile } from 'generic-filehandle2'

const local = new LocalFile('/some/file/path/file.txt')
const remote = new RemoteFile('http://somesite.com/file.txt')
const blobfile = new BlobFile(new Blob([some_data], { type: 'text/plain' }))

const buf1 = await remote.read(/* length */ 10, /* position */ 10) // range request
const buf2 = await remote.readFile()

If you are reading a remote file through an indexed parser, put @gmod/range-cache-filehandle underneath it. Its RemoteFileWithRangeCache is a drop-in replacement for RemoteFile that caches byte ranges in chunks, so that a query's many small reads turn into a few requests.

API

Every filehandle has the same four methods:

await file.read(length, position, opts) // the bytes at a byte offset
await file.readFile(opts) // the whole file, as bytes or as a string
await file.stat() // the file size, as { size }
await file.close() // close the file descriptor, if one is open

The options they take, the behavior they share, and the seam for extending RemoteFile are all covered in docs/api.md.

LocalFile takes two more options in its constructor, cacheFd and fdIdleTimeoutMs, which control how it manages its file descriptor. docs/local-files.md explains what they do and why they default the way they do.

Docs

• @gmod/range-cache-filehandle is the byte-range cache to put underneath these handles when reading remote files.
• docs/api.md documents every method, option and type, and how to extend RemoteFile.
• docs/optimizations.md explains why reads, requests and buffers work the way they do, and what each of those choices measured.
• docs/local-files.md covers the file descriptor that LocalFile keeps open, and the stub that replaces the class in browser builds.

See also

The original generic-filehandle library: https://github.com/GMOD/generic-filehandle

Publishing

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