Add leadership election

Signed-off-by: Emile Vauge <emile@vauge.com>

safe/routine.go

@@ -1,6 +1,7 @@
 package safe
 
 import (
+	"golang.org/x/net/context"
 	"log"
 	"runtime/debug"
 	"sync"
@@ -11,11 +12,44 @@ type routine struct {
 	stop      chan bool
 }
 
-// Pool creates a pool of go routines
+type routineCtx func(ctx context.Context)
+
+// Pool is a pool of go routines
 type Pool struct {
-	routines  []routine
-	waitGroup sync.WaitGroup
-	lock      sync.Mutex
+	routines    []routine
+	routinesCtx []routineCtx
+	waitGroup   sync.WaitGroup
+	lock        sync.Mutex
+	baseCtx     context.Context
+	ctx         context.Context
+	cancel      context.CancelFunc
+}
+
+// NewPool creates a Pool
+func NewPool(baseCtx context.Context) *Pool {
+	ctx, cancel := context.WithCancel(baseCtx)
+	return &Pool{
+		ctx:     ctx,
+		cancel:  cancel,
+		baseCtx: baseCtx,
+	}
+}
+
+// Ctx returns main context
+func (p *Pool) Ctx() context.Context {
+	return p.ctx
+}
+
+//GoCtx starts a recoverable goroutine with a context
+func (p *Pool) GoCtx(goroutine routineCtx) {
+	p.lock.Lock()
+	p.routinesCtx = append(p.routinesCtx, goroutine)
+	p.waitGroup.Add(1)
+	Go(func() {
+		goroutine(p.ctx)
+		p.waitGroup.Done()
+	})
+	p.lock.Unlock()
 }
 
 // Go starts a recoverable goroutine, and can be stopped with stop chan
@@ -37,6 +71,7 @@ func (p *Pool) Go(goroutine func(stop chan bool)) {
 // Stop stops all started routines, waiting for their termination
 func (p *Pool) Stop() {
 	p.lock.Lock()
+	p.cancel()
 	for _, routine := range p.routines {
 		routine.stop <- true
 	}
@@ -47,6 +82,29 @@ func (p *Pool) Stop() {
 	p.lock.Unlock()
 }
 
+// Start starts all stoped routines
+func (p *Pool) Start() {
+	p.lock.Lock()
+	p.ctx, p.cancel = context.WithCancel(p.baseCtx)
+	for _, routine := range p.routines {
+		p.waitGroup.Add(1)
+		routine.stop = make(chan bool, 1)
+		Go(func() {
+			routine.goroutine(routine.stop)
+			p.waitGroup.Done()
+		})
+	}
+
+	for _, routine := range p.routinesCtx {
+		p.waitGroup.Add(1)
+		Go(func() {
+			routine(p.ctx)
+			p.waitGroup.Done()
+		})
+	}
+	p.lock.Unlock()
+}
+
 // Go starts a recoverable goroutine
 func Go(goroutine func()) {
 	GoWithRecover(goroutine, defaultRecoverGoroutine)