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Merge pull request #24164 from sjenning/fix-util-cache 

fix immediate evict in cache
pull/6/head
Robert Bailey 2016-05-06 14:43:53 -07:00
parent 57359e4f2f cf199dbdfa
commit 375d2ad38c
2 changed files with 32 additions and 4 deletions
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7
pkg/util/cache/cache.go vendored
View File

@ -27,6 +27,9 @@ const (
type Cache []*cacheShard type Cache []*cacheShard
func NewCache(maxSize int) Cache { func NewCache(maxSize int) Cache {
if maxSize < shardsCount {
maxSize = shardsCount
}
cache := make(Cache, shardsCount) cache := make(Cache, shardsCount)
for i := 0; i < shardsCount; i++ { for i := 0; i < shardsCount; i++ {
cache[i] = &cacheShard{ cache[i] = &cacheShard{
@ -61,14 +64,14 @@ func (s *cacheShard) add(index uint64, obj interface{}) bool {
s.Lock() s.Lock()
defer s.Unlock() defer s.Unlock()
_, isOverwrite := s.items[index] _, isOverwrite := s.items[index]
s.items[index] = obj if !isOverwrite && len(s.items) >= s.maxSize {
if len(s.items) > s.maxSize {
var randomKey uint64 var randomKey uint64
for randomKey = range s.items { for randomKey = range s.items {
break break
} }
delete(s.items, randomKey) delete(s.items, randomKey)
} }
s.items[index] = obj
return isOverwrite return isOverwrite
} }

29
pkg/util/cache/cache_test.go vendored
View File

@ -24,13 +24,16 @@ const (
maxTestCacheSize int = shardsCount * 2 maxTestCacheSize int = shardsCount * 2
) )
func ExpectEntry(t *testing.T, cache Cache, index uint64, expectedValue interface{}) { func ExpectEntry(t *testing.T, cache Cache, index uint64, expectedValue interface{}) bool {
elem, found := cache.Get(index) elem, found := cache.Get(index)
if !found { if !found {
t.Error("Expected to find entry with key 1") t.Errorf("Expected to find entry with key %d", index)
return false
} else if elem != expectedValue { } else if elem != expectedValue {
t.Errorf("Expected to find %v, got %v", expectedValue, elem) t.Errorf("Expected to find %v, got %v", expectedValue, elem)
return false
} }
return true
} }
func TestBasic(t *testing.T) { func TestBasic(t *testing.T) {
@ -63,3 +66,25 @@ func TestOverwrite(t *testing.T) {
cache.Add(1, "yyy") cache.Add(1, "yyy")
ExpectEntry(t, cache, 1, "yyy") ExpectEntry(t, cache, 1, "yyy")
} }
// TestEvict this test will fail sporatically depending on what add()
// selects for the randomKey to be evicted. Ensure that randomKey
// is never the key we most recently added. Since the chance of failure
// on each evict is 50%, if we do it 7 times, it should catch the problem
// if it exists >99% of the time.
func TestEvict(t *testing.T) {
cache := NewCache(shardsCount)
var found bool
for retry := 0; retry < 7; retry++ {
cache.Add(uint64(shardsCount), "xxx")
found = ExpectEntry(t, cache, uint64(shardsCount), "xxx")
if !found {
break
}
cache.Add(0, "xxx")
found = ExpectEntry(t, cache, 0, "xxx")
if !found {
break
}
}
}