overleaf/services/history-v1/storage/lib/streams.js
Alf Eaton ee85d948e2 Avoid duplicating a math-closing dollar sign (#11227)
GitOrigin-RevId: ef2ef77e26df59d1af3df6dc664e284d3c70102d
2023-01-16 08:41:42 +00:00

100 lines
2.4 KiB
JavaScript

/**
* Promises are promises and streams are streams, and ne'er the twain shall
* meet.
* @module
*/
'use strict'
const BPromise = require('bluebird')
const zlib = require('zlib')
const stringToStream = require('string-to-stream')
function promiseWriteStreamFinish(writeStream) {
return new BPromise(function (resolve, reject) {
writeStream.on('finish', resolve)
writeStream.on('error', reject)
})
}
function promisePipe(readStream, writeStream) {
readStream.pipe(writeStream)
return promiseWriteStreamFinish(writeStream)
}
/**
* Pipe a read stream to a write stream. The promise resolves when the write
* stream finishes.
*
* @function
* @param {stream.Readable} readStream
* @param {stream.Writable} writeStream
* @return {Promise}
*/
exports.promisePipe = promisePipe
function readStreamToBuffer(readStream) {
return new BPromise(function (resolve, reject) {
const buffers = []
readStream.on('readable', function () {
while (true) {
const buffer = this.read()
if (!buffer) {
break
}
buffers.push(buffer)
}
})
readStream.on('end', function () {
resolve(Buffer.concat(buffers))
})
readStream.on('error', reject)
})
}
/**
* Create a promise for the result of reading a stream to a buffer.
*
* @function
* @param {stream.Readable} readStream
* @return {Promise.<Buffer>}
*/
exports.readStreamToBuffer = readStreamToBuffer
function gunzipStreamToBuffer(readStream) {
const gunzip = zlib.createGunzip()
const gunzipStream = readStream.pipe(gunzip)
return new BPromise(function (resolve, reject) {
const buffers = []
gunzipStream.on('data', function (buffer) {
buffers.push(buffer)
})
gunzipStream.on('end', function () {
resolve(Buffer.concat(buffers))
})
readStream.on('error', reject)
gunzipStream.on('error', reject)
})
}
/**
* Create a promise for the result of un-gzipping a stream to a buffer.
*
* @function
* @param {stream.Readable} readStream
* @return {Promise.<Buffer>}
*/
exports.gunzipStreamToBuffer = gunzipStreamToBuffer
function gzipStringToStream(string) {
const gzip = zlib.createGzip()
return stringToStream(string).pipe(gzip)
}
/**
* Create a write stream that gzips the given string.
*
* @function
* @param {string} string
* @return {stream.Writable}
*/
exports.gzipStringToStream = gzipStringToStream