Merge pull request #3 from heartwilltell/v0.1.4

Add NopChecker

hc.go

@@ -17,28 +17,21 @@ type HealthChecker interface {
 // NewMultiChecker takes several health checkers and performs
 // health checks for each of them concurrently.
 func NewMultiChecker(hcs ...HealthChecker) *MultiChecker {
-	c := MultiChecker{
-		hcs: make([]HealthChecker, 0, len(hcs)),
-	}
+	c := MultiChecker{hcs: make([]HealthChecker, 0, len(hcs))}
 	c.hcs = append(c.hcs, hcs...)
 	return &c
 }
 
-// MultiChecker takes several health checker and performs
+// MultiChecker takes multiple health checker and performs
 // health checks for each of them concurrently.
-type MultiChecker struct {
-	hcs []HealthChecker
-}
+type MultiChecker struct{ hcs []HealthChecker }
 
 // Health takes the context and performs the health check.
 // Returns nil in case of success or an error in case
 // of a failure.
 func (c *MultiChecker) Health(ctx context.Context) error {
 	hctx, cancel := context.WithCancel(ctx)
-
-	s := Synchronizer{
-		cancel: cancel,
-	}
+	s := Synchronizer{cancel: cancel}
 
 	for _, check := range c.hcs {
 		s.Add(1)
@@ -64,6 +57,11 @@ func (c *MultiChecker) Health(ctx context.Context) error {
 // Add appends health HealthChecker to internal slice of HealthCheckers.
 func (c *MultiChecker) Add(hc HealthChecker) { c.hcs = append(c.hcs, hc) }
 
+// NopChecker represents nop health checker.
+type NopChecker struct{}
+
+func (n NopChecker) Health(context.Context) error { return nil }
+
 // Synchronizer holds synchronization mechanics.
 type Synchronizer struct {
 	wg     sync.WaitGroup
@@ -80,7 +78,7 @@ func (s *Synchronizer) Error() string { return s.err.Error() }
 // Uses sync.Once to set error only once.
 func (s *Synchronizer) SetError(err error) { s.so.Do(func() { s.err = err }) }
 
-// Do wraps the sync.Once Do method.
+// Do wrap the sync.Once Do method.
 func (s *Synchronizer) Do(f func()) { s.so.Do(f) }
 
 // Done wraps the sync.WaitGroup Done method.
@@ -92,9 +90,6 @@ func (s *Synchronizer) Add(delta int) { s.wg.Add(delta) }
 // Wait wraps the sync.WaitGroup Wait method.
 func (s *Synchronizer) Wait() { s.wg.Wait() }
 
-// Cancel calls underlying cancel function
-// to cancel context, which passed to all
-// health checks function.
-func (s *Synchronizer) Cancel() {
-	s.cancel()
-}
+// Cancel calls underlying cancel function to cancel context,
+// which passed to all health checks function.
+func (s *Synchronizer) Cancel() { s.cancel() }