lnd.xprv/queue/gc_queue_test.go

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package queue_test
import (
"testing"
"time"
"github.com/lightningnetwork/lnd/queue"
)
// mockRecycler implements the queue.Recycler interface using a NOP.
type mockRecycler bool
func (*mockRecycler) Recycle() {}
// TestGCQueueGCCycle asserts that items that are kept in the GCQueue past their
// expiration will be released by a subsequent gc cycle.
func TestGCQueueGCCycle(t *testing.T) {
t.Parallel()
const (
gcInterval = time.Second
expiryInterval = 250 * time.Millisecond
numItems = 6
)
newItem := func() queue.Recycler { return new(mockRecycler) }
bp := queue.NewGCQueue(newItem, 100, gcInterval, expiryInterval)
// Take numItems items from the queue, and immediately return them.
// Returning the items will trigger the gc ticker to start.
itemSet1 := takeN(t, bp, numItems)
returnAll(bp, itemSet1)
// Allow enough time for all expired items to be released by the queue.
<-time.After(gcInterval + expiryInterval)
// Take another set of numItems items from the queue.
itemSet2 := takeN(t, bp, numItems)
// Since the gc ticker should have elapsed, we expect the intersection
// of sets 1 and 2 to be empty.
for item := range itemSet2 {
if _, ok := itemSet1[item]; ok {
t.Fatalf("items taken should not have been reused")
}
}
}
// TestGCQueuePartialGCCycle asserts that the GCQueue will only garbage collect
// the items in its queue that have fully expired. We test this by adding items
// into the queue such that the garbage collection will occur before the items
// expire. Taking items after the gc cycle should return the items that were not
// released by the gc cycle.
func TestGCQueuePartialGCCycle(t *testing.T) {
t.Parallel()
const (
gcInterval = time.Second
expiryInterval = 250 * time.Millisecond
numItems = 6
)
newItem := func() queue.Recycler { return new(mockRecycler) }
bp := queue.NewGCQueue(newItem, 100, gcInterval, expiryInterval)
// Take numItems items from the gc queue.
itemSet1 := takeN(t, bp, numItems)
// Immediately return half of the items, and construct a set of items
// consisting of the half that were not returned.
halfItemSet1 := returnN(t, bp, itemSet1, numItems/2)
// Wait long enough to ensure that adding subsequent items will not be
// released in the next gc cycle.
<-time.After(gcInterval - expiryInterval/2)
// Return the remaining items from itemSet1.
returnAll(bp, halfItemSet1)
// Wait until the gc cycle as done a sweep of the items and released all
// those that have expired.
<-time.After(expiryInterval / 2)
// Retrieve numItems items from the gc queue.
itemSet2 := takeN(t, bp, numItems)
// Tally the number of items returned from Take that are in the second
// half of items returned.
var numReused int
for item := range itemSet2 {
if _, ok := halfItemSet1[item]; ok {
numReused++
}
}
// We expect the number of reused items to be equal to half numItems.
if numReused != numItems/2 {
t.Fatalf("expected %d items to be reused, got %d",
numItems/2, numReused)
}
}
// takeN draws n items from the provided GCQueue. This method also asserts that
// n unique items are drawn, and then returns the resulting set.
func takeN(t *testing.T, q *queue.GCQueue, n int) map[queue.Recycler]struct{} {
t.Helper()
items := make(map[queue.Recycler]struct{})
for i := 0; i < n; i++ {
// Wait a small duration to ensure the tests behave reliable,
// and don't activate the non-blocking case unintentionally.
<-time.After(time.Millisecond)
items[q.Take()] = struct{}{}
}
if len(items) != n {
t.Fatalf("items taken from gc queue should be distinct, "+
"want %d unique items, got %d", n, len(items))
}
return items
}
// returnAll returns the items of the given set back to the GCQueue.
func returnAll(q *queue.GCQueue, items map[queue.Recycler]struct{}) {
for item := range items {
q.Return(item)
// Wait a small duration to ensure the tests behave reliable,
// and don't activate the non-blocking case unintentionally.
<-time.After(time.Millisecond)
}
}
// returnN returns n items at random from the set of items back to the GCQueue.
// This method fails if the set's cardinality is smaller than n.
func returnN(t *testing.T, q *queue.GCQueue,
items map[queue.Recycler]struct{}, n int) map[queue.Recycler]struct{} {
t.Helper()
var remainingItems = make(map[queue.Recycler]struct{})
var numReturned int
for item := range items {
if numReturned < n {
q.Return(item)
numReturned++
// Wait a small duration to ensure the tests behave
// reliable, and don't activate the non-blocking case
// unintentionally.
<-time.After(time.Millisecond)
} else {
remainingItems[item] = struct{}{}
}
}
if numReturned < n {
t.Fatalf("insufficient number of items to return, need %d, "+
"got %d", n, numReturned)
}
return remainingItems
}