const assert = require('assert')
const { kRetryHandlerDefaultRetry } = require('../core/symbols')
const { RequestRetryError } = require('../core/errors')
const { isDisturbed, parseHeaders, parseRangeHeader } = require('../core/util')
function calculateRetryAfterHeader (retryAfter) {
const current = Date.now()
const diff = new Date(retryAfter).getTime() - current
return diff
}
class RetryHandler {
constructor (opts, handlers) {
const { retryOptions, ...dispatchOpts } = opts
const {
// Retry scoped
retry: retryFn,
maxRetries,
maxTimeout,
minTimeout,
timeoutFactor,
// Response scoped
methods,
errorCodes,
retryAfter,
statusCodes
} = retryOptions ?? {}
this.dispatch = handlers.dispatch
this.handler = handlers.handler
this.opts = dispatchOpts
this.abort = null
this.aborted = false
this.retryOpts = {
retry: retryFn ?? RetryHandler[kRetryHandlerDefaultRetry],
retryAfter: retryAfter ?? true,
maxTimeout: maxTimeout ?? 30 * 1000, // 30s,
timeout: minTimeout ?? 500, // .5s
timeoutFactor: timeoutFactor ?? 2,
maxRetries: maxRetries ?? 5,
// What errors we should retry
methods: methods ?? ['GET', 'HEAD', 'OPTIONS', 'PUT', 'DELETE', 'TRACE'],
// Indicates which errors to retry
statusCodes: statusCodes ?? [500, 502, 503, 504, 429],
// List of errors to retry
errorCodes: errorCodes ?? [
'ECONNRESET',
'ECONNREFUSED',
'ENOTFOUND',
'ENETDOWN',
'ENETUNREACH',
'EHOSTDOWN',
'EHOSTUNREACH',
'EPIPE'
]
}
this.retryCount = 0
this.start = 0
this.end = null
this.etag = null
this.resume = null
// Handle possible onConnect duplication
this.handler.onConnect(reason => {
this.aborted = true
if (this.abort) {
this.abort(reason)
} else {
this.reason = reason
}
})
}
onRequestSent () {
if (this.handler.onRequestSent) {
this.handler.onRequestSent()
}
}
onUpgrade (statusCode, headers, socket) {
if (this.handler.onUpgrade) {
this.handler.onUpgrade(statusCode, headers, socket)
}
}
onConnect (abort) {
if (this.aborted) {
abort(this.reason)
} else {
this.abort = abort
}
}
onBodySent (chunk) {
if (this.handler.onBodySent) return this.handler.onBodySent(chunk)
}
static [kRetryHandlerDefaultRetry] (err, { state, opts }, cb) {
const { statusCode, code, headers } = err
const { method, retryOptions } = opts
const {
maxRetries,
timeout,
maxTimeout,
timeoutFactor,
statusCodes,
errorCodes,
methods
} = retryOptions
let { counter, currentTimeout } = state
currentTimeout =
currentTimeout != null && currentTimeout > 0 ? currentTimeout : timeout
// Any code that is not a Undici's originated and allowed to retry
if (
code &&
code !== 'UND_ERR_REQ_RETRY' &&
code !== 'UND_ERR_SOCKET' &&
!errorCodes.includes(code)
) {
cb(err)
return
}
// If a set of method are provided and the current method is not in the list
if (Array.isArray(methods) && !methods.includes(method)) {
cb(err)
return
}
// If a set of status code are provided and the current status code is not in the list
if (
statusCode != null &&
Array.isArray(statusCodes) &&
!statusCodes.includes(statusCode)
) {
cb(err)
return
}
// If we reached the max number of retries
if (counter > maxRetries) {
cb(err)
return
}
let retryAfterHeader = headers != null && headers['retry-after']
if (retryAfterHeader) {
retryAfterHeader = Number(retryAfterHeader)
retryAfterHeader = isNaN(retryAfterHeader)
? calculateRetryAfterHeader(retryAfterHeader)
: retryAfterHeader * 1e3 // Retry-After is in seconds
}
const retryTimeout =
retryAfterHeader > 0
? Math.min(retryAfterHeader, maxTimeout)
: Math.min(currentTimeout * timeoutFactor ** counter, maxTimeout)
state.currentTimeout = retryTimeout
setTimeout(() => cb(null), retryTimeout)
}
onHeaders (statusCode, rawHeaders, resume, statusMessage) {
const headers = parseHeaders(rawHeaders)
this.retryCount += 1
if (statusCode >= 300) {
this.abort(
new RequestRetryError('Request failed', statusCode, {
headers,
count: this.retryCount
})
)
return false
}
// Checkpoint for resume from where we left it
if (this.resume != null) {
this.resume = null
if (statusCode !== 206) {
return true
}
const contentRange = parseRangeHeader(headers['content-range'])
// If no content range
if (!contentRange) {
this.abort(
new RequestRetryError('Content-Range mismatch', statusCode, {
headers,
count: this.retryCount
})
)
return false
}
// Let's start with a weak etag check
if (this.etag != null && this.etag !== headers.etag) {
this.abort(
new RequestRetryError('ETag mismatch', statusCode, {
headers,
count: this.retryCount
})
)
return false
}
const { start, size, end = size } = contentRange
assert(this.start === start, 'content-range mismatch')
assert(this.end == null || this.end === end, 'content-range mismatch')
this.resume = resume
return true
}
if (this.end == null) {
if (statusCode === 206) {
// First time we receive 206
const range = parseRangeHeader(headers['content-range'])
if (range == null) {
return this.handler.onHeaders(
statusCode,
rawHeaders,
resume,
statusMessage
)
}
const { start, size, end = size } = range
assert(
start != null && Number.isFinite(start) && this.start !== start,
'content-range mismatch'
)
assert(Number.isFinite(start))
assert(
end != null && Number.isFinite(end) && this.end !== end,
'invalid content-length'
)
this.start = start
this.end = end
}
// We make our best to checkpoint the body for further range headers
if (this.end == null) {
const contentLength = headers['content-length']
this.end = contentLength != null ? Number(contentLength) : null
}
assert(Number.isFinite(this.start))
assert(
this.end == null || Number.isFinite(this.end),
'invalid content-length'
)
this.resume = resume
this.etag = headers.etag != null ? headers.etag : null
return this.handler.onHeaders(
statusCode,
rawHeaders,
resume,
statusMessage
)
}
const err = new RequestRetryError('Request failed', statusCode, {
headers,
count: this.retryCount
})
this.abort(err)
return false
}
onData (chunk) {
this.start += chunk.length
return this.handler.onData(chunk)
}
onComplete (rawTrailers) {
this.retryCount = 0
return this.handler.onComplete(rawTrailers)
}
onError (err) {
if (this.aborted || isDisturbed(this.opts.body)) {
return this.handler.onError(err)
}
this.retryOpts.retry(
err,
{
state: { counter: this.retryCount++, currentTimeout: this.retryAfter },
opts: { retryOptions: this.retryOpts, ...this.opts }
},
onRetry.bind(this)
)
function onRetry (err) {
if (err != null || this.aborted || isDisturbed(this.opts.body)) {
return this.handler.onError(err)
}
if (this.start !== 0) {
this.opts = {
...this.opts,
headers: {
...this.opts.headers,
range: `bytes=${this.start}-${this.end ?? ''}`
}
}
}
try {
this.dispatch(this.opts, this)
} catch (err) {
this.handler.onError(err)
}
}
}
}
module.exports = RetryHandler
