eth/downloader: fix priority queue reset, add throttling test

Godeps/_workspace/src/gopkg.in/karalabe/cookiejar.v2/collections/prque/prque.go

@@ -71,5 +71,5 @@ func (p *Prque) Size() int {
 
 // Clears the contents of the priority queue.
 func (p *Prque) Reset() {
-	p.cont.Reset()
+	*p = *New()
 }

Godeps/_workspace/src/gopkg.in/karalabe/cookiejar.v2/collections/prque/prque_test.go

@@ -61,16 +61,45 @@ func TestPrque(t *testing.T) {
 }
 
 func TestReset(t *testing.T) {
-	// Fill the queue with some random data
+	// Generate a batch of random data and a specific priority order
 	size := 16 * blockSize
-	queue := New()
+	prio := rand.Perm(size)
+	data := make([]int, size)
 	for i := 0; i < size; i++ {
-		queue.Push(rand.Int(), rand.Float32())
+		data[i] = rand.Int()
 	}
-	// Reset and ensure it's empty
-	queue.Reset()
-	if !queue.Empty() {
-		t.Errorf("priority queue not empty after reset: %v", queue)
+	queue := New()
+	for rep := 0; rep < 2; rep++ {
+		// Fill a priority queue with the above data
+		for i := 0; i < size; i++ {
+			queue.Push(data[i], float32(prio[i]))
+			if queue.Size() != i+1 {
+				t.Errorf("queue size mismatch: have %v, want %v.", queue.Size(), i+1)
+			}
+		}
+		// Create a map the values to the priorities for easier verification
+		dict := make(map[float32]int)
+		for i := 0; i < size; i++ {
+			dict[float32(prio[i])] = data[i]
+		}
+		// Pop out half the elements in priority order and verify them
+		prevPrio := float32(size + 1)
+		for i := 0; i < size/2; i++ {
+			val, prio := queue.Pop()
+			if prio > prevPrio {
+				t.Errorf("invalid priority order: %v after %v.", prio, prevPrio)
+			}
+			prevPrio = prio
+			if val != dict[prio] {
+				t.Errorf("push/pop mismatch: have %v, want %v.", val, dict[prio])
+			}
+			delete(dict, prio)
+		}
+		// Reset and ensure it's empty
+		queue.Reset()
+		if !queue.Empty() {
+			t.Errorf("priority queue not empty after reset: %v", queue)
+		}
 	}
 }
 

Godeps/_workspace/src/gopkg.in/karalabe/cookiejar.v2/collections/prque/sstack.go

@@ -88,7 +88,7 @@ func (s *sstack) Less(i, j int) bool {
 	return s.blocks[i/blockSize][i%blockSize].priority > s.blocks[j/blockSize][j%blockSize].priority
 }
 
-// Swapts two elements in the stack. Required by sort.Interface.
+// Swaps two elements in the stack. Required by sort.Interface.
 func (s *sstack) Swap(i, j int) {
 	ib, io, jb, jo := i/blockSize, i%blockSize, j/blockSize, j%blockSize
 	s.blocks[ib][io], s.blocks[jb][jo] = s.blocks[jb][jo], s.blocks[ib][io]
@@ -96,8 +96,5 @@ func (s *sstack) Swap(i, j int) {
 
 // Resets the stack, effectively clearing its contents.
 func (s *sstack) Reset() {
-	s.size = 0
-	s.offset = 0
-	s.active = s.blocks[0]
-	s.capacity = blockSize
+	*s = *newSstack()
 }

Godeps/_workspace/src/gopkg.in/karalabe/cookiejar.v2/collections/prque/sstack_test.go

@@ -79,15 +79,31 @@ func TestSstackSort(t *testing.T) {
 }
 
 func TestSstackReset(t *testing.T) {
-	// Push some stuff onto the stack
+	// Create some initial data
 	size := 16 * blockSize
-	stack := newSstack()
+	data := make([]*item, size)
 	for i := 0; i < size; i++ {
-		stack.Push(&item{i, float32(i)})
+		data[i] = &item{rand.Int(), rand.Float32()}
 	}
-	// Clear and verify
-	stack.Reset()
-	if stack.Len() != 0 {
-		t.Errorf("stack not empty after reset: %v", stack)
+	stack := newSstack()
+	for rep := 0; rep < 2; rep++ {
+		// Push all the data into the stack, pop out every second
+		secs := []*item{}
+		for i := 0; i < size; i++ {
+			stack.Push(data[i])
+			if i%2 == 0 {
+				secs = append(secs, stack.Pop().(*item))
+			}
+		}
+		// Reset and verify both pulled and stack contents
+		stack.Reset()
+		if stack.Len() != 0 {
+			t.Errorf("stack not empty after reset: %v", stack)
+		}
+		for i := 0; i < size; i++ {
+			if i%2 == 0 && data[i] != secs[i/2] {
+				t.Errorf("push/pop mismatch: have %v, want %v.", secs[i/2], data[i])
+			}
+		}
 	}
 }