chore: base

node_modules/undici/lib/balanced-pool.js

@@ -0,0 +1,110 @@
+'use strict'
+
+const {
+  BalancedPoolMissingUpstreamError,
+  InvalidArgumentError
+} = require('./core/errors')
+const {
+  PoolBase,
+  kClients,
+  kNeedDrain,
+  kAddClient,
+  kRemoveClient,
+  kGetDispatcher
+} = require('./pool-base')
+const Pool = require('./pool')
+const { kUrl } = require('./core/symbols')
+const { parseOrigin } = require('./core/util')
+const kFactory = Symbol('factory')
+
+const kOptions = Symbol('options')
+
+function defaultFactory (origin, opts) {
+  return new Pool(origin, opts)
+}
+
+class BalancedPool extends PoolBase {
+  constructor (upstreams = [], { factory = defaultFactory, ...opts } = {}) {
+    super()
+
+    this[kOptions] = opts
+
+    if (!Array.isArray(upstreams)) {
+      upstreams = [upstreams]
+    }
+
+    if (typeof factory !== 'function') {
+      throw new InvalidArgumentError('factory must be a function.')
+    }
+
+    this[kFactory] = factory
+
+    for (const upstream of upstreams) {
+      this.addUpstream(upstream)
+    }
+  }
+
+  addUpstream (upstream) {
+    const upstreamOrigin = parseOrigin(upstream).origin
+
+    if (this[kClients].find((pool) => (
+      pool[kUrl].origin === upstreamOrigin &&
+      pool.closed !== true &&
+      pool.destroyed !== true
+    ))) {
+      return this
+    }
+
+    this[kAddClient](this[kFactory](upstreamOrigin, Object.assign({}, this[kOptions])))
+
+    return this
+  }
+
+  removeUpstream (upstream) {
+    const upstreamOrigin = parseOrigin(upstream).origin
+
+    const pool = this[kClients].find((pool) => (
+      pool[kUrl].origin === upstreamOrigin &&
+      pool.closed !== true &&
+      pool.destroyed !== true
+    ))
+
+    if (pool) {
+      this[kRemoveClient](pool)
+    }
+
+    return this
+  }
+
+  get upstreams () {
+    return this[kClients]
+      .filter(dispatcher => dispatcher.closed !== true && dispatcher.destroyed !== true)
+      .map((p) => p[kUrl].origin)
+  }
+
+  [kGetDispatcher] () {
+    // We validate that pools is greater than 0,
+    // otherwise we would have to wait until an upstream
+    // is added, which might never happen.
+    if (this[kClients].length === 0) {
+      throw new BalancedPoolMissingUpstreamError()
+    }
+
+    const dispatcher = this[kClients].find(dispatcher => (
+      !dispatcher[kNeedDrain] &&
+      dispatcher.closed !== true &&
+      dispatcher.destroyed !== true
+    ))
+
+    if (!dispatcher) {
+      return
+    }
+
+    this[kClients].splice(this[kClients].indexOf(dispatcher), 1)
+    this[kClients].push(dispatcher)
+
+    return dispatcher
+  }
+}
+
+module.exports = BalancedPool