random-access-file-promises v0.3.0

random-access-file-promises

This is a TypeScript wrapper of JS random-access-file library that wraps its callback-based API in Promises.

Usage example

import {RandomAccessFile} from 'random-access-file-promises';

const file = new RandomAccessFile('path/to/file');
try {
    const buffer = await file.read(42, 10);
    console.log(buffer);
    await file.write(42, Buffer.from('Hello, world!'));
} finally {
    await file.close();
}

For convenience, there is also a withFile function that automatically closes the file when the callback returns:

import {withFile} from 'random-access-file-promises';

await withFile('path/to/file', async (file) => {
    const buffer = await file.read(42, 10);
    console.log(buffer);
    await file.write(42, Buffer.from('Hello, world!'));
});

API

class RandomAccessFile

constructor(path: string, options?: Options)

Creates a new instance of RandomAccessFile class.

read(offset: number, size: number): Promise<Buffer>

Reads size bytes from the file at the given offset.

write(offset: number, buffer: Buffer): Promise<void>

Writes buffer to the file at the given offset.

stat(): Promise<Stats>

Returns the file stats, currently only size is supported.

truncate(length: number): Promise<void>

Truncates the file to the given length.

del(offset: number, length: number): Promise<void>

Deletes length bytes from the file at the given offset.

close(): Promise<void>

Closes the file.

unlink(): Promise<void>

Unlinks the file, removes the directories up to opts.directory if opts.rmdir is set to true

static createPool(maxSize: number): Pool

Creates a new Pool instance of size maxSize.

withFile(path: string, callback: (file: RandomAccessFile) => Promise<void>, opts?: RandomAccessFileOptions): Promise<void>

Opens the file, calls the callback with the file instance and closes the file when the callback returns or errors out.

interface RandomAccessFileOptions

Options for RandomAccessFile class.

size?: number

Initial size of the file.

truncate?: boolean

Specifies if the file should be truncated if opts.size is not provided.

directory?: string

Directory to resolve the file in. Also acts as root directory if opts.rmdir is set to true.

readable?: boolean

Specifies if the file should be opened in read mode. Both readable and writable set to true results in RW mode. Both readable and writable set to false results in W mode.

writable?: boolean

Specifies if the file should be opened in write mode. Both readable and writable set to true results in RW mode. Both readable and writable set to false results in W mode.

pool?: Pool

Specify the pool to which this file belongs. Pool cam be created with createPool function.

rmdir?: boolean

Specifies if the directory should be removed when the file is unlinked.

lock?: boolean

Specifies if a process-level lock should be acquired on the file. Files open in readonly mode provide a shared flag to flock.

sparse?: boolean

Specifies if the file should be marked as a sparse file. May be required for del operation.

alloc?: (size: number) => Buffer

Buffer allocation function.Buffer.allocUnsafe is used by default.