1 files changed, 194 insertions, 0 deletions
diff --git a/lib/pool-base.js b/lib/pool-base.js
new file mode 100644
index 0000000..2a909ee
--- /dev/null
+++ b/lib/pool-base.js
@@ -0,0 +1,194 @@
+'use strict'
+
+const DispatcherBase = require('./dispatcher-base')
+const FixedQueue = require('./node/fixed-queue')
+const { kConnected, kSize, kRunning, kPending, kQueued, kBusy, kFree, kUrl, kClose, kDestroy, kDispatch } = require('./core/symbols')
+const PoolStats = require('./pool-stats')
+
+const kClients = Symbol('clients')
+const kNeedDrain = Symbol('needDrain')
+const kQueue = Symbol('queue')
+const kClosedResolve = Symbol('closed resolve')
+const kOnDrain = Symbol('onDrain')
+const kOnConnect = Symbol('onConnect')
+const kOnDisconnect = Symbol('onDisconnect')
+const kOnConnectionError = Symbol('onConnectionError')
+const kGetDispatcher = Symbol('get dispatcher')
+const kAddClient = Symbol('add client')
+const kRemoveClient = Symbol('remove client')
+const kStats = Symbol('stats')
+
+class PoolBase extends DispatcherBase {
+  constructor () {
+    super()
+
+    this[kQueue] = new FixedQueue()
+    this[kClients] = []
+    this[kQueued] = 0
+
+    const pool = this
+
+    this[kOnDrain] = function onDrain (origin, targets) {
+      const queue = pool[kQueue]
+
+      let needDrain = false
+
+      while (!needDrain) {
+        const item = queue.shift()
+        if (!item) {
+          break
+        }
+        pool[kQueued]--
+        needDrain = !this.dispatch(item.opts, item.handler)
+      }
+
+      this[kNeedDrain] = needDrain
+
+      if (!this[kNeedDrain] && pool[kNeedDrain]) {
+        pool[kNeedDrain] = false
+        pool.emit('drain', origin, [pool, ...targets])
+      }
+
+      if (pool[kClosedResolve] && queue.isEmpty()) {
+        Promise
+          .all(pool[kClients].map(c => c.close()))
+          .then(pool[kClosedResolve])
+      }
+    }
+
+    this[kOnConnect] = (origin, targets) => {
+      pool.emit('connect', origin, [pool, ...targets])
+    }
+
+    this[kOnDisconnect] = (origin, targets, err) => {
+      pool.emit('disconnect', origin, [pool, ...targets], err)
+    }
+
+    this[kOnConnectionError] = (origin, targets, err) => {
+      pool.emit('connectionError', origin, [pool, ...targets], err)
+    }
+
+    this[kStats] = new PoolStats(this)
+  }
+
+  get [kBusy] () {
+    return this[kNeedDrain]
+  }
+
+  get [kConnected] () {
+    return this[kClients].filter(client => client[kConnected]).length
+  }
+
+  get [kFree] () {
+    return this[kClients].filter(client => client[kConnected] && !client[kNeedDrain]).length
+  }
+
+  get [kPending] () {
+    let ret = this[kQueued]
+    for (const { [kPending]: pending } of this[kClients]) {
+      ret += pending
+    }
+    return ret
+  }
+
+  get [kRunning] () {
+    let ret = 0
+    for (const { [kRunning]: running } of this[kClients]) {
+      ret += running
+    }
+    return ret
+  }
+
+  get [kSize] () {
+    let ret = this[kQueued]
+    for (const { [kSize]: size } of this[kClients]) {
+      ret += size
+    }
+    return ret
+  }
+
+  get stats () {
+    return this[kStats]
+  }
+
+  async [kClose] () {
+    if (this[kQueue].isEmpty()) {
+      return Promise.all(this[kClients].map(c => c.close()))
+    } else {
+      return new Promise((resolve) => {
+        this[kClosedResolve] = resolve
+      })
+    }
+  }
+
+  async [kDestroy] (err) {
+    while (true) {
+      const item = this[kQueue].shift()
+      if (!item) {
+        break
+      }
+      item.handler.onError(err)
+    }
+
+    return Promise.all(this[kClients].map(c => c.destroy(err)))
+  }
+
+  [kDispatch] (opts, handler) {
+    const dispatcher = this[kGetDispatcher]()
+
+    if (!dispatcher) {
+      this[kNeedDrain] = true
+      this[kQueue].push({ opts, handler })
+      this[kQueued]++
+    } else if (!dispatcher.dispatch(opts, handler)) {
+      dispatcher[kNeedDrain] = true
+      this[kNeedDrain] = !this[kGetDispatcher]()
+    }
+
+    return !this[kNeedDrain]
+  }
+
+  [kAddClient] (client) {
+    client
+      .on('drain', this[kOnDrain])
+      .on('connect', this[kOnConnect])
+      .on('disconnect', this[kOnDisconnect])
+      .on('connectionError', this[kOnConnectionError])
+
+    this[kClients].push(client)
+
+    if (this[kNeedDrain]) {
+      process.nextTick(() => {
+        if (this[kNeedDrain]) {
+          this[kOnDrain](client[kUrl], [this, client])
+        }
+      })
+    }
+
+    return this
+  }
+
+  [kRemoveClient] (client) {
+    client.close(() => {
+      const idx = this[kClients].indexOf(client)
+      if (idx !== -1) {
+        this[kClients].splice(idx, 1)
+      }
+    })
+
+    this[kNeedDrain] = this[kClients].some(dispatcher => (
+      !dispatcher[kNeedDrain] &&
+      dispatcher.closed !== true &&
+      dispatcher.destroyed !== true
+    ))
+  }
+}
+
+module.exports = {
+  PoolBase,
+  kClients,
+  kNeedDrain,
+  kAddClient,
+  kRemoveClient,
+  kGetDispatcher
+}