Initialize rate limiter balance with maxBalance

sampler_test.go

@@ -466,7 +466,11 @@ func TestUpdateSampler(t *testing.T) {
 			assert.NotEqual(t, initSampler, sampler.sampler, "Sampler should have been updated")
 			assert.Equal(t, test.defaultProbability, s.defaultSampler.SamplingRate())
 
+			// First call is always sampled
 			sampled, tags := sampler.IsSampled(TraceID{Low: testMaxID + 10}, testOperationName)
+			assert.True(t, sampled)
+
+			sampled, tags = sampler.IsSampled(TraceID{Low: testMaxID + 10}, testOperationName)
 			assert.False(t, sampled)
 			sampled, tags = sampler.IsSampled(TraceID{Low: testMaxID - 10}, testOperationName)
 			assert.True(t, sampled)

utils/rate_limiter.go

@@ -56,7 +56,7 @@ type rateLimiter struct {
 func NewRateLimiter(creditsPerSecond, maxBalance float64) RateLimiter {
 	return &rateLimiter{
 		creditsPerSecond: creditsPerSecond,
-		balance:          creditsPerSecond,
+		balance:          maxBalance,
 		maxBalance:       maxBalance,
 		lastTick:         time.Now(),
 		timeNow:          time.Now}

utils/rate_limiter_test.go

@@ -69,7 +69,8 @@ func TestMaxBalance(t *testing.T) {
 	limiter.(*rateLimiter).timeNow = func() time.Time {
 		return ts
 	}
-	assert.False(t, limiter.CheckCredit(1.0))
+	// on initialization, should have enough credits for 1 message
+	assert.True(t, limiter.CheckCredit(1.0))
 
 	// move time 20s forward, enough to accumulate credits for 2 messages, but it should still be capped at 1
 	limiter.(*rateLimiter).timeNow = func() time.Time {