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'use strict'
const {
PoolBase,
kClients,
kNeedDrain,
kAddClient,
kGetDispatcher,
kRemoveClient
} = require('./pool-base')
const Client = require('./client')
const {
InvalidArgumentError
} = require('../core/errors')
const util = require('../core/util')
const { kUrl } = require('../core/symbols')
const buildConnector = require('../core/connect')
const kOptions = Symbol('options')
const kConnections = Symbol('connections')
const kFactory = Symbol('factory')
const kIndex = Symbol('index')
function defaultFactory (origin, opts) {
return new Client(origin, opts)
}
class RoundRobinPool extends PoolBase {
constructor (origin, {
connections,
factory = defaultFactory,
connect,
connectTimeout,
tls,
maxCachedSessions,
socketPath,
autoSelectFamily,
autoSelectFamilyAttemptTimeout,
allowH2,
clientTtl,
...options
} = {}) {
if (connections != null && (!Number.isFinite(connections) || connections < 0)) {
throw new InvalidArgumentError('invalid connections')
}
if (typeof factory !== 'function') {
throw new InvalidArgumentError('factory must be a function.')
}
if (connect != null && typeof connect !== 'function' && typeof connect !== 'object') {
throw new InvalidArgumentError('connect must be a function or an object')
}
if (typeof connect !== 'function') {
connect = buildConnector({
...tls,
maxCachedSessions,
allowH2,
socketPath,
timeout: connectTimeout,
...(typeof autoSelectFamily === 'boolean' ? { autoSelectFamily, autoSelectFamilyAttemptTimeout } : undefined),
...connect
})
}
super()
this[kConnections] = connections || null
this[kUrl] = util.parseOrigin(origin)
this[kOptions] = { ...util.deepClone(options), connect, allowH2, clientTtl }
this[kOptions].interceptors = options.interceptors
? { ...options.interceptors }
: undefined
this[kFactory] = factory
this[kIndex] = -1
this.on('connect', (origin, targets) => {
if (clientTtl != null && clientTtl > 0) {
for (const target of targets) {
Object.assign(target, { ttl: Date.now() })
}
}
})
this.on('connectionError', (origin, targets, error) => {
for (const target of targets) {
const idx = this[kClients].indexOf(target)
if (idx !== -1) {
this[kClients].splice(idx, 1)
}
}
})
}
[kGetDispatcher] () {
const clientTtlOption = this[kOptions].clientTtl
const clientsLength = this[kClients].length
// If we have no clients yet, create one
if (clientsLength === 0) {
const dispatcher = this[kFactory](this[kUrl], this[kOptions])
this[kAddClient](dispatcher)
return dispatcher
}
// Round-robin through existing clients
let checked = 0
while (checked < clientsLength) {
this[kIndex] = (this[kIndex] + 1) % clientsLength
const client = this[kClients][this[kIndex]]
// Check if client is stale (TTL expired)
if (clientTtlOption != null && clientTtlOption > 0 && client.ttl && ((Date.now() - client.ttl) > clientTtlOption)) {
this[kRemoveClient](client)
checked++
continue
}
// Return client if it's not draining
if (!client[kNeedDrain]) {
return client
}
checked++
}
// All clients are busy, create a new one if we haven't reached the limit
if (!this[kConnections] || clientsLength < this[kConnections]) {
const dispatcher = this[kFactory](this[kUrl], this[kOptions])
this[kAddClient](dispatcher)
return dispatcher
}
}
}
module.exports = RoundRobinPool
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