From 71a040f5ee98d91e9f388b0d4509adf8d5589bb9 Mon Sep 17 00:00:00 2001
From: Wolfy-J <wolfy.jd@gmail.com>
Date: Sun, 28 Jan 2018 18:57:25 +0300
Subject: Context

---
 pool.go | 42 ++++++++++++++++++++++++++++++++----------
 1 file changed, 32 insertions(+), 10 deletions(-)

(limited to 'pool.go')

diff --git a/pool.go b/pool.go
index c2226420..deb24fd7 100644
--- a/pool.go
+++ b/pool.go
@@ -3,7 +3,6 @@ package roadrunner
 import (
 	"fmt"
 	"github.com/pkg/errors"
-	"log"
 	"os/exec"
 	"sync"
 	"time"
@@ -14,8 +13,22 @@ const (
 	StopRequest = "{\"stop\":true}"
 )
 
+const (
+	// EventCreated thrown when new worker is spawned.
+	EventCreated = iota
+
+	// EventDestruct thrown before worker destruction.
+	EventDestruct
+
+	// EventError thrown any worker related even happen (error passed as context)
+	EventError
+)
+
 // Pool controls worker creation, destruction and task routing.
 type Pool struct {
+	// EventHandler is optional callback to handle worker create/destruct/error events.
+	EventHandler func(event int, w *Worker, ctx interface{})
+
 	// pool behaviour
 	cfg Config
 
@@ -163,14 +176,17 @@ func (p *Pool) allocateWorker() (w *Worker, err error) {
 func (p *Pool) replaceWorker(w *Worker, caused interface{}) {
 	go p.destroyWorker(w)
 
-	nw, _ := p.createWorker()
-
-	// if unable to create, retry ? or report error
-	p.free <- nw
+	if nw, err := p.createWorker(); err != nil {
+		p.throw(EventError, w, err)
+	} else {
+		p.free <- nw
+	}
 }
 
 // destroy and remove worker from the pool.
 func (p *Pool) destroyWorker(w *Worker) {
+	p.throw(EventDestruct, w, nil)
+
 	// detaching
 	p.muw.Lock()
 	for i, wc := range p.workers {
@@ -189,7 +205,7 @@ func (p *Pool) destroyWorker(w *Worker) {
 	case <-time.NewTimer(p.cfg.DestroyTimeout).C:
 		// failed to stop process
 		if err := w.Kill(); err != nil {
-			// todo: handle error
+			p.throw(EventError, w, err)
 		}
 	}
 }
@@ -202,12 +218,11 @@ func (p *Pool) createWorker() (*Worker, error) {
 		return nil, err
 	}
 
+	p.throw(EventCreated, w, nil)
+
 	go func(w *Worker) {
 		if err := w.Wait(); err != nil {
-			// todo: register error
-
-			log.Println(err)
-
+			p.throw(EventError, w, err)
 		}
 	}(w)
 
@@ -218,3 +233,10 @@ func (p *Pool) createWorker() (*Worker, error) {
 
 	return w, nil
 }
+
+// throw invokes event handler if any.
+func (p *Pool) throw(event int, w *Worker, ctx interface{}) {
+	if p.EventHandler != nil {
+		p.EventHandler(event, w, ctx)
+	}
+}
-- 
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