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multipleRangeDownloader.ts
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multipleRangeDownloader.ts
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import { createHttpError, safeGetHeader } from "builder-util-runtime"
import { IncomingMessage } from "http"
import { Writable } from "stream"
import { copyData, DataSplitter, PartListDataTask } from "./DataSplitter"
import { DifferentialDownloader } from "./DifferentialDownloader"
import { Operation, OperationKind } from "./downloadPlanBuilder"
export function executeTasksUsingMultipleRangeRequests(
differentialDownloader: DifferentialDownloader,
tasks: Array<Operation>,
out: Writable,
oldFileFd: number,
reject: (error: Error) => void
): (taskOffset: number) => void {
const w = (taskOffset: number): void => {
if (taskOffset >= tasks.length) {
if (differentialDownloader.fileMetadataBuffer != null) {
out.write(differentialDownloader.fileMetadataBuffer)
}
out.end()
return
}
const nextOffset = taskOffset + 1000
doExecuteTasks(
differentialDownloader,
{
tasks,
start: taskOffset,
end: Math.min(tasks.length, nextOffset),
oldFileFd,
},
out,
() => w(nextOffset),
reject
)
}
return w
}
function doExecuteTasks(differentialDownloader: DifferentialDownloader, options: PartListDataTask, out: Writable, resolve: () => void, reject: (error: Error) => void): void {
let ranges = "bytes="
let partCount = 0
const partIndexToTaskIndex = new Map<number, number>()
const partIndexToLength: Array<number> = []
for (let i = options.start; i < options.end; i++) {
const task = options.tasks[i]
if (task.kind === OperationKind.DOWNLOAD) {
ranges += `${task.start}-${task.end - 1}, `
partIndexToTaskIndex.set(partCount, i)
partCount++
partIndexToLength.push(task.end - task.start)
}
}
if (partCount <= 1) {
// the only remote range - copy
const w = (index: number): void => {
if (index >= options.end) {
resolve()
return
}
const task = options.tasks[index++]
if (task.kind === OperationKind.COPY) {
copyData(task, out, options.oldFileFd, reject, () => w(index))
} else {
const requestOptions = differentialDownloader.createRequestOptions()
requestOptions.headers!.Range = `bytes=${task.start}-${task.end - 1}`
const request = differentialDownloader.httpExecutor.createRequest(requestOptions, response => {
if (!checkIsRangesSupported(response, reject)) {
return
}
response.pipe(out, {
end: false,
})
response.once("end", () => w(index))
})
differentialDownloader.httpExecutor.addErrorAndTimeoutHandlers(request, reject)
request.end()
}
}
w(options.start)
return
}
const requestOptions = differentialDownloader.createRequestOptions()
requestOptions.headers!.Range = ranges.substring(0, ranges.length - 2)
const request = differentialDownloader.httpExecutor.createRequest(requestOptions, response => {
if (!checkIsRangesSupported(response, reject)) {
return
}
const contentType = safeGetHeader(response, "content-type")
const m = /^multipart\/.+?(?:; boundary=(?:(?:"(.+)")|(?:([^\s]+))))$/i.exec(contentType)
if (m == null) {
reject(new Error(`Content-Type "multipart/byteranges" is expected, but got "${contentType}"`))
return
}
const dicer = new DataSplitter(out, options, partIndexToTaskIndex, m[1] || m[2], partIndexToLength, resolve)
dicer.on("error", reject)
response.pipe(dicer)
response.on("end", () => {
setTimeout(() => {
request.abort()
reject(new Error("Response ends without calling any handlers"))
}, 10000)
})
})
differentialDownloader.httpExecutor.addErrorAndTimeoutHandlers(request, reject)
request.end()
}
export function checkIsRangesSupported(response: IncomingMessage, reject: (error: Error) => void): boolean {
// Electron net handles redirects automatically, our NodeJS test server doesn't use redirects - so, we don't check 3xx codes.
if (response.statusCode! >= 400) {
reject(createHttpError(response))
return false
}
if (response.statusCode !== 206) {
const acceptRanges = safeGetHeader(response, "accept-ranges")
if (acceptRanges == null || acceptRanges === "none") {
reject(new Error(`Server doesn't support Accept-Ranges (response code ${response.statusCode})`))
return false
}
}
return true
}