opt: calculate the interval for ReleaseTimeout() based on a default count

This PR reverts #325 to some extent.

Author: panjf2000

Diff for: ants.go

@@ -97,8 +97,8 @@ var (
 )
 
 const (
-	nowTimeUpdateInterval  = 500 * time.Millisecond
-	releaseTimeoutInterval = 100 * time.Millisecond
+	nowTimeUpdateInterval = 500 * time.Millisecond
+	releaseTimeoutCount   = 10
 )
 
 // Logger is used for logging formatted messages.

Diff for: pool.go

@@ -299,14 +299,15 @@ func (p *Pool) ReleaseTimeout(timeout time.Duration) error {
 	}
 	p.Release()
 
+	interval := timeout / releaseTimeoutCount
 	endTime := time.Now().Add(timeout)
 	for time.Now().Before(endTime) {
 		if p.Running() == 0 &&
 			(p.options.DisablePurge || atomic.LoadInt32(&p.purgeDone) == 1) &&
 			atomic.LoadInt32(&p.ticktockDone) == 1 {
 			return nil
 		}
-		time.Sleep(releaseTimeoutInterval)
+		time.Sleep(interval)
 	}
 	return ErrTimeout
 }

Diff for: pool_func.go

@@ -304,14 +304,15 @@ func (p *PoolWithFunc) ReleaseTimeout(timeout time.Duration) error {
 	}
 	p.Release()
 
+	interval := timeout / releaseTimeoutCount
 	endTime := time.Now().Add(timeout)
 	for time.Now().Before(endTime) {
 		if p.Running() == 0 &&
 			(p.options.DisablePurge || atomic.LoadInt32(&p.purgeDone) == 1) &&
 			atomic.LoadInt32(&p.ticktockDone) == 1 {
 			return nil
 		}
-		time.Sleep(releaseTimeoutInterval)
+		time.Sleep(interval)
 	}
 	return ErrTimeout
 }