Fix leaky bucket algo as reported in #77

algorithms.go

@@ -204,7 +204,7 @@ func leakyBucket(s Store, c Cache, r *RateLimitReq) (resp *RateLimitResp, err er
 		}
 
 		if HasBehavior(r.Behavior, Behavior_RESET_REMAINING) {
-			b.Remaining = r.Limit
+			b.Remaining = float64(r.Limit)
 		}
 
 		// Update limit and duration if they changed
@@ -231,18 +231,22 @@ func leakyBucket(s Store, c Cache, r *RateLimitReq) (resp *RateLimitResp, err er
 			duration = expire - (n.UnixNano() / 1000000)
 		}
 
-		// Calculate how much leaked out of the bucket since the last hit
+		// Calculate how much leaked out of the bucket since the last time we leaked a hit
 		elapsed := now - b.UpdatedAt
-		leak := int64(float64(elapsed) / rate)
+		leak := float64(elapsed) / rate
 
-		b.Remaining += leak
-		if b.Remaining > b.Limit {
-			b.Remaining = b.Limit
+		if int64(b.Remaining) > b.Limit {
+			b.Remaining = float64(b.Limit)
+		}
+
+		if int64(leak) > 0 {
+			b.Remaining += leak
+			b.UpdatedAt = now
 		}
 
 		rl := &RateLimitResp{
 			Limit:     b.Limit,
-			Remaining: b.Remaining,
+			Remaining: int64(b.Remaining),
 			Status:    Status_UNDER_LIMIT,
 			ResetTime: now + int64(rate),
 		}
@@ -254,26 +258,21 @@ func leakyBucket(s Store, c Cache, r *RateLimitReq) (resp *RateLimitResp, err er
 		}
 
 		// If we are already at the limit
-		if b.Remaining == 0 {
+		if int64(b.Remaining) == 0 {
 			rl.Status = Status_OVER_LIMIT
 			return rl, nil
 		}
 
-		// Only update the timestamp if client is incrementing the hit
-		if r.Hits != 0 {
-			b.UpdatedAt = now
-		}
-
 		// If requested hits takes the remainder
-		if b.Remaining == r.Hits {
-			b.Remaining = 0
+		if int64(b.Remaining) == r.Hits {
+			b.Remaining -= float64(r.Hits)
 			rl.Remaining = 0
 			return rl, nil
 		}
 
 		// If requested is more than available, then return over the limit
 		// without updating the bucket.
-		if r.Hits > b.Remaining {
+		if r.Hits > int64(b.Remaining) {
 			rl.Status = Status_OVER_LIMIT
 			return rl, nil
 		}
@@ -283,8 +282,8 @@ func leakyBucket(s Store, c Cache, r *RateLimitReq) (resp *RateLimitResp, err er
 			return rl, nil
 		}
 
-		b.Remaining -= r.Hits
-		rl.Remaining = b.Remaining
+		b.Remaining -= float64(r.Hits)
+		rl.Remaining = int64(b.Remaining)
 		c.UpdateExpiration(r.HashKey(), now*duration)
 		return rl, nil
 	}
@@ -303,7 +302,7 @@ func leakyBucket(s Store, c Cache, r *RateLimitReq) (resp *RateLimitResp, err er
 
 	// Create a new leaky bucket
 	b := LeakyBucketItem{
-		Remaining: r.Limit - r.Hits,
+		Remaining: float64(r.Limit - r.Hits),
 		Limit:     r.Limit,
 		Duration:  duration,
 		UpdatedAt: now,
@@ -313,7 +312,7 @@ func leakyBucket(s Store, c Cache, r *RateLimitReq) (resp *RateLimitResp, err er
 		Status:    Status_UNDER_LIMIT,
 		Limit:     r.Limit,
 		Remaining: r.Limit - r.Hits,
-		ResetTime: now + duration / r.Limit,
+		ResetTime: now + duration/r.Limit,
 	}
 
 	// Client could be requesting that we start with the bucket OVER_LIMIT

functional_test.go

@@ -118,7 +118,7 @@ func TestTokenBucket(t *testing.T) {
 		{
 			Remaining: 0,
 			Status:    guber.Status_UNDER_LIMIT,
-			Sleep:     clock.Duration(clock.Millisecond * 100),
+			Sleep:     clock.Millisecond * 100,
 		},
 		{
 			Remaining: 1,
@@ -153,68 +153,243 @@ func TestTokenBucket(t *testing.T) {
 	}
 }
 
+func TestTokenBucketGregorian(t *testing.T) {
+	defer clock.Freeze(clock.Now()).Unfreeze()
+
+	client, errs := guber.DialV1Server(cluster.GetRandomPeer().GRPCAddress, nil)
+	require.Nil(t, errs)
+
+	tests := []struct {
+		Name      string
+		Remaining int64
+		Status    guber.Status
+		Sleep     clock.Duration
+		Hits      int64
+	}{
+		{
+			Name:      "first hit",
+			Hits:      1,
+			Remaining: 59,
+			Status:    guber.Status_UNDER_LIMIT,
+		},
+		{
+			Name:      "second hit",
+			Hits:      1,
+			Remaining: 58,
+			Status:    guber.Status_UNDER_LIMIT,
+		},
+		{
+			Name:      "consume remaining hits",
+			Hits:      58,
+			Remaining: 0,
+			Status:    guber.Status_UNDER_LIMIT,
+		},
+		{
+			Name:      "should be over the limit",
+			Hits:      1,
+			Remaining: 0,
+			Status:    guber.Status_OVER_LIMIT,
+			Sleep:     clock.Second * 61,
+		},
+		{
+			Name:      "should be under the limit",
+			Hits:      0,
+			Remaining: 60,
+			Status:    guber.Status_UNDER_LIMIT,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			resp, err := client.GetRateLimits(context.Background(), &guber.GetRateLimitsReq{
+				Requests: []*guber.RateLimitReq{
+					{
+						Name:      "test_token_bucket_greg",
+						UniqueKey: "account:12345",
+						Behavior:  guber.Behavior_DURATION_IS_GREGORIAN,
+						Algorithm: guber.Algorithm_TOKEN_BUCKET,
+						Duration:  guber.GregorianMinutes,
+						Hits:      test.Hits,
+						Limit:     60,
+					},
+				},
+			})
+			require.Nil(t, err)
+
+			rl := resp.Responses[0]
+
+			assert.Empty(t, rl.Error)
+			assert.Equal(t, test.Status, rl.Status)
+			assert.Equal(t, test.Remaining, rl.Remaining)
+			assert.Equal(t, int64(60), rl.Limit)
+			assert.True(t, rl.ResetTime != 0)
+			clock.Advance(test.Sleep)
+		})
+	}
+}
+
 func TestLeakyBucket(t *testing.T) {
 	defer clock.Freeze(clock.Now()).Unfreeze()
 
 	client, errs := guber.DialV1Server(cluster.PeerAt(0).GRPCAddress, nil)
 	require.Nil(t, errs)
 
 	tests := []struct {
+		Name      string
 		Hits      int64
 		Remaining int64
 		Status    guber.Status
 		Sleep     clock.Duration
 	}{
 		{
-			Hits:      5,
+			Name:      "first hit",
+			Hits:      1,
+			Remaining: 9,
+			Status:    guber.Status_UNDER_LIMIT,
+			Sleep:     clock.Second,
+		},
+		{
+			Name:      "second hit; no leak",
+			Hits:      1,
+			Remaining: 8,
+			Status:    guber.Status_UNDER_LIMIT,
+			Sleep:     clock.Second,
+		},
+		{
+			Name:      "third hit; no leak",
+			Hits:      1,
+			Remaining: 7,
+			Status:    guber.Status_UNDER_LIMIT,
+			Sleep:     clock.Millisecond * 1500,
+		},
+		{
+			Name:      "should leak one hit 3 seconds after first hit",
+			Hits:      0,
+			Remaining: 8,
+			Status:    guber.Status_UNDER_LIMIT,
+			Sleep:     clock.Second * 3,
+		},
+		{
+			Name:      "3 Seconds later we should have leaked another hit",
+			Hits:      0,
+			Remaining: 9,
+			Status:    guber.Status_UNDER_LIMIT,
+			Sleep:     clock.Duration(0),
+		},
+		{
+			Name:      "max out our bucket and sleep for 3 seconds",
+			Hits:      9,
 			Remaining: 0,
 			Status:    guber.Status_UNDER_LIMIT,
 			Sleep:     clock.Duration(0),
 		},
 		{
+			Name:      "should be over the limit",
 			Hits:      1,
 			Remaining: 0,
 			Status:    guber.Status_OVER_LIMIT,
-			Sleep:     clock.Millisecond * 100,
+			Sleep:     clock.Second * 3,
 		},
 		{
+			Name:      "should have leaked 1 hit",
+			Hits:      0,
+			Remaining: 1,
+			Status:    guber.Status_UNDER_LIMIT,
+			Sleep:     clock.Second,
+		},
+	}
+
+	now := clock.Now()
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			resp, err := client.GetRateLimits(context.Background(), &guber.GetRateLimitsReq{
+				Requests: []*guber.RateLimitReq{
+					{
+						Name:      "test_leaky_bucket",
+						UniqueKey: "account:1234",
+						Algorithm: guber.Algorithm_LEAKY_BUCKET,
+						Duration:  guber.Second * 30,
+						Hits:      test.Hits,
+						Limit:     10,
+					},
+				},
+			})
+			clock.Freeze(clock.Now())
+			require.NoError(t, err)
+
+			rl := resp.Responses[0]
+
+			assert.Equal(t, test.Status, rl.Status)
+			assert.Equal(t, test.Remaining, rl.Remaining)
+			assert.Equal(t, int64(10), rl.Limit)
+			assert.True(t, rl.ResetTime > now.Unix())
+			clock.Advance(test.Sleep)
+		})
+	}
+}
+
+func TestLeakyBucketGregorian(t *testing.T) {
+	defer clock.Freeze(clock.Now()).Unfreeze()
+
+	client, errs := guber.DialV1Server(cluster.PeerAt(0).GRPCAddress, nil)
+	require.Nil(t, errs)
+
+	tests := []struct {
+		Name      string
+		Hits      int64
+		Remaining int64
+		Status    guber.Status
+		Sleep     clock.Duration
+	}{
+		{
+			Name:      "first hit",
 			Hits:      1,
-			Remaining: 0,
+			Remaining: 59,
 			Status:    guber.Status_UNDER_LIMIT,
-			Sleep:     clock.Millisecond * 400,
+			Sleep:     clock.Millisecond * 500,
 		},
 		{
+			Name:      "second hit; no leak",
 			Hits:      1,
-			Remaining: 4,
+			Remaining: 58,
+			Status:    guber.Status_UNDER_LIMIT,
+			Sleep:     clock.Second,
+		},
+		{
+			Name:      "third hit; leak one hit",
+			Hits:      1,
+			Remaining: 58,
 			Status:    guber.Status_UNDER_LIMIT,
-			Sleep:     clock.Duration(0),
 		},
 	}
 
 	now := clock.Now()
-	for i, test := range tests {
-		resp, err := client.GetRateLimits(context.Background(), &guber.GetRateLimitsReq{
-			Requests: []*guber.RateLimitReq{
-				{
-					Name:      "test_leaky_bucket",
-					UniqueKey: "account:1234",
-					Algorithm: guber.Algorithm_LEAKY_BUCKET,
-					Duration:  guber.Millisecond * 300,
-					Hits:      test.Hits,
-					Limit:     5,
+	for _, test := range tests {
+		t.Run(test.Name, func(t *testing.T) {
+			resp, err := client.GetRateLimits(context.Background(), &guber.GetRateLimitsReq{
+				Requests: []*guber.RateLimitReq{
+					{
+						Name:      "test_leaky_bucket_greg",
+						UniqueKey: "account:12345",
+						Behavior:  guber.Behavior_DURATION_IS_GREGORIAN,
+						Algorithm: guber.Algorithm_LEAKY_BUCKET,
+						Duration:  guber.GregorianMinutes,
+						Hits:      test.Hits,
+						Limit:     60,
+					},
 				},
-			},
-		})
-		clock.Freeze(clock.Now())
-		require.NoError(t, err)
+			})
+			clock.Freeze(clock.Now())
+			require.NoError(t, err)
 
-		rl := resp.Responses[0]
+			rl := resp.Responses[0]
 
-		assert.Equal(t, test.Status, rl.Status, i)
-		assert.Equal(t, test.Remaining, rl.Remaining, i)
-		assert.Equal(t, int64(5), rl.Limit, i)
-		assert.True(t, rl.ResetTime > now.Unix())
-		clock.Advance(test.Sleep)
+			assert.Equal(t, test.Status, rl.Status)
+			assert.Equal(t, test.Remaining, rl.Remaining)
+			assert.Equal(t, int64(60), rl.Limit)
+			assert.True(t, rl.ResetTime > now.Unix())
+			clock.Advance(test.Sleep)
+		})
 	}
 }
 

store.go

@@ -11,7 +11,7 @@ package gubernator
 type LeakyBucketItem struct {
 	Limit     int64
 	Duration  int64
-	Remaining int64
+	Remaining float64
 	UpdatedAt int64
 }
 

store_test.go

@@ -291,7 +291,7 @@ func getRemaining(item *gubernator.CacheItem) int64 {
 	case gubernator.Algorithm_TOKEN_BUCKET:
 		return item.Value.(*gubernator.TokenBucketItem).Remaining
 	case gubernator.Algorithm_LEAKY_BUCKET:
-		return item.Value.(*gubernator.LeakyBucketItem).Remaining
+		return int64(item.Value.(*gubernator.LeakyBucketItem).Remaining)
 	}
 	return 0
 }