Improve purge address of the Pool routine (#994)

In Browser environments, the WebSocket release can take seconds to finish.
This behaviour can make LDAP authentication expired take more time then usual.

Purging the connection in parallel speeds up this process.

Author: bigmontz

packages/bolt-connection/src/pool/pool.js

@@ -300,16 +300,18 @@ class Pool {
   async _purgeKey (key) {
     const pool = this._pools[key] || []
     const poolState = this._poolState[key] || new PoolState()
+    const destructionList = []
     while (pool.length) {
       const resource = pool.pop()
       if (this._removeIdleObserver) {
         this._removeIdleObserver(resource)
       }
-      await this._destroy(resource)
+      destructionList.push(this._destroy(resource))
     }
     poolState.close()
     delete this._pools[key]
     delete this._poolState[key]
+    await Promise.all(destructionList)
   }
 
   _processPendingAcquireRequests (address) {

packages/bolt-connection/test/pool/pool.test.js

@@ -923,6 +923,43 @@ describe('#unit Pool', () => {
     expect(resource1.observer).toBeFalsy()
     expect(resource2.observer).toBeFalsy()
   })
+
+  it('should purge resources in parallel', async () => {
+    const address = ServerAddress.fromUrl('bolt://localhost:7687')
+    let resourceCount = 0
+    const resourcesReleased = []
+    let resolveRelease 
+    const releasePromise = new Promise((resolve) => {
+      resolveRelease = resolve
+    })
+
+    const pool = new Pool({
+      create: (server, release) => 
+        Promise.resolve(new Resource(server, resourceCount++, release)),
+      destroy: res => {
+        resourcesReleased.push(res)
+        resourceCount--
+        // Only destroy when the last resource
+        // get destroyed
+        if (resourceCount === 0) {
+          resolveRelease()
+        }
+        return releasePromise
+      },
+      validate: res => true,
+    })
+
+    const resource1 = await pool.acquire(address)
+    const resource2 = await pool.acquire(address)
+    await resource1.close()
+    await resource2.close()
+
+    await pool.purge(address)
+
+    expect(resourcesReleased).toEqual([
+      resource2, resource1
+    ])
+  })
 })
 
 function expectNoPendingAcquisitionRequests (pool) {