tokenBucket: incorrect count of issued when refill

[Rodrigo Schio]

equalizer/token_bucket.go

Lines 66 to 79 in d5d1ad1

 // refill refills the token bucket. 
 func (tb *tokenBucket) refill() { 
 	issued := atomic.LoadInt32(&tb.issued) 
 	atomic.StoreInt32(&tb.issued, 0) 
 	tb.fillTokenBucket(int(issued)) 
 } 
  
 // Ask requires a permit. 
 // It is a non blocking call, returns true or false. 
 func (tb *TokenBucket) Ask() bool { 
 	select { 
 	case <-tb.t.permits: 
 		atomic.AddInt32(&tb.t.issued, 1) 
 		return true 

A token can be issued between line 68 and 69 and then it will lead to a incorrect issued count and decrease the bucket real capacity.

Example:
refill() and Ask() executes concurrently then:
line 68 executes
line 77 and 78 executes
line 69 and 70 executes

Solution:
issued := atomic.SwapInt32(&tb.issued, 0)

[Eugene R.]

@rschio thanks.