WIP: initial prototype

- Added client.close API
- Added resurrect event
- Improved resurrect ping strategy
- Updated types

lib/Connection.d.ts

@@ -46,7 +46,7 @@ export default class Connection {
   _status: string;
   _agent: http.Agent;
   constructor(opts?: ConnectionOptions);
-  request(params: any, callback: (err: Error | null, response: http.IncomingMessage | null) => void): http.ClientRequest;
+  request(params: http.ClientRequestArgs, callback: (err: Error | null, response: http.IncomingMessage | null) => void): http.ClientRequest;
   close(): Connection;
   setRole(role: string, enabled: boolean): Connection;
   status: string;

lib/Connection.js

@@ -64,7 +64,7 @@ class Connection {
         ended = true
         this._openRequests--
         request.abort()
-        callback(new TimeoutError('Request timed out', params))
+        callback(new TimeoutError('Request timed out', params), null)
       }
     })
 
@@ -73,7 +73,7 @@ class Connection {
       if (ended === false) {
         ended = true
         this._openRequests--
-        callback(err)
+        callback(err, null)
       }
     })
 
@@ -95,7 +95,7 @@ class Connection {
         if (err != null && ended === false) {
           ended = true
           this._openRequests--
-          callback(err)
+          callback(err, null)
         }
       })
     } else {
@@ -152,6 +152,7 @@ class Connection {
       pathname: url.pathname,
       path: '',
       href: url.href,
+      origin: url.origin,
       port: url.port,
       headers: this.headers,
       auth: !!url.username === true || !!url.password === true

lib/ConnectionPool.d.ts

@@ -27,6 +27,12 @@ export interface getConnectionOptions {
   selector?: nodeSelectorFn;
 }
 
+export interface ResurrectMeta {
+  strategy: string;
+  isAlive: boolean;
+  connection: Connection;
+}
+
 export default class ConnectionPool {
   static resurrectStrategies: {
     none: number;

lib/ConnectionPool.js

@@ -26,6 +26,7 @@ class ConnectionPool {
     this.randomizeHost = opts.randomizeHost === true
     this.nodeFilter = opts.nodeFilter || defaultNodeFilter
     this.Connection = opts.Connection
+    this.emit = opts.emit || noop
 
     if (typeof opts.nodeSelector === 'function') {
       this.nodeSelector = opts.nodeSelector
@@ -107,6 +108,7 @@ class ConnectionPool {
    */
   resurrect (now = Date.now(), callback = noop) {
     if (this.resurrectStrategy === 0 || this.dead.length === 0) {
+      debug('Nothing to resurrect')
       callback(null, null)
       return
     }
@@ -116,6 +118,7 @@ class ConnectionPool {
     const connection = this.connections.get(this.dead[0])
     if (now < connection.resurrectTimeout) {
       debug('Nothing to resurrect')
+      callback(null, null)
       return
     }
 
@@ -127,9 +130,11 @@ class ConnectionPool {
         method: 'HEAD',
         path: '/',
         timeout: this.pingTimeout
-      }, (err, res) => {
+      }, (err, response) => {
         var isAlive = true
-        if (err != null) {
+        const statusCode = response !== null ? response.statusCode : 0
+        if (err != null ||
+           (statusCode === 502 || statusCode === 503 || statusCode === 504)) {
           debug(`Resurrect: connection '${id}' is still dead`)
           this.markDead(connection)
           isAlive = false
@@ -137,6 +142,7 @@ class ConnectionPool {
           debug(`Resurrect: connection '${id}' is now alive`)
           this.markAlive(connection)
         }
+        this.emit('resurrect', null, { strategy: 'ping', isAlive, connection })
         callback(isAlive, connection)
       })
     // optimistic strategy
@@ -144,6 +150,7 @@ class ConnectionPool {
       debug(`Resurrect: optimistic resurrection for connection '${id}'`)
       this.dead.splice(this.dead.indexOf(id), 1)
       connection.status = Connection.statuses.ALIVE
+      this.emit('resurrect', null, { strategy: 'optimistic', isAlive: true, connection })
       // eslint-disable-next-line standard/no-callback-literal
       callback(true, connection)
     }