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Add dynamic size to ARC #79

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Add dynamic size to ARC #79

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124 changes: 78 additions & 46 deletions arc.go
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Original file line number Diff line number Diff line change
Expand Up @@ -40,14 +40,17 @@ func (c *ARC) replace(key interface{}) {
}
var old interface{}
if c.t1.Len() > 0 && ((c.b2.Has(key) && c.t1.Len() == c.part) || (c.t1.Len() > c.part)) {
old = c.t1.RemoveTail()
c.b1.PushFront(old)
k, s := c.t1.RemoveTail()
old = k
c.b1.PushFront(k, s)
} else if c.t2.Len() > 0 {
old = c.t2.RemoveTail()
c.b2.PushFront(old)
k, s := c.t2.RemoveTail()
old = k
c.b2.PushFront(k, s)
} else {
old = c.t1.RemoveTail()
c.b1.PushFront(old)
k, s := c.t1.RemoveTail()
old = k
c.b1.PushFront(k, s)
}
item, ok := c.items[old]
if ok {
Expand Down Expand Up @@ -91,11 +94,13 @@ func (c *ARC) set(key, value interface{}) (interface{}, error) {
item, ok := c.items[key]
if ok {
item.value = value
item.size = getSize(value)
} else {
item = &arcItem{
clock: c.clock,
key: key,
value: value,
size: getSize(value),
}
c.items[key] = item
}
Expand All @@ -119,46 +124,48 @@ func (c *ARC) set(key, value interface{}) (interface{}, error) {
c.setPart(minInt(c.size, c.part+maxInt(c.b2.Len()/c.b1.Len(), 1)))
c.replace(key)
c.b1.Remove(key, elt)
c.t2.PushFront(key)
c.t2.PushFront(key, item.size)
return item, nil
}

if elt := c.b2.Lookup(key); elt != nil {
c.setPart(maxInt(0, c.part-maxInt(c.b1.Len()/c.b2.Len(), 1)))
c.replace(key)
c.b2.Remove(key, elt)
c.t2.PushFront(key)
c.t2.PushFront(key, item.size)
return item, nil
}

if c.isCacheFull() && c.t1.Len()+c.b1.Len() == c.size {
if c.t1.Len() < c.size {
c.b1.RemoveTail()
c.replace(key)
} else {
pop := c.t1.RemoveTail()
item, ok := c.items[pop]
if ok {
delete(c.items, pop)
if c.evictedFunc != nil {
c.evictedFunc(item.key, item.value)
for c.isCacheFull() {
if c.t1.Len()+c.b1.Len() >= c.size {
if c.t1.Len() < c.size {
c.b1.RemoveTail()
c.replace(key)
} else {
pop, _ := c.t1.RemoveTail()
item, ok := c.items[pop]
if ok {
delete(c.items, pop)
if c.evictedFunc != nil {
c.evictedFunc(item.key, item.value)
}
}
}
}
} else {
total := c.t1.Len() + c.b1.Len() + c.t2.Len() + c.b2.Len()
if total >= c.size {
if total == (2 * c.size) {
if c.b2.Len() > 0 {
c.b2.RemoveTail()
} else {
c.b1.RemoveTail()
} else {
total := c.t1.Len() + c.b1.Len() + c.t2.Len() + c.b2.Len()
if total >= c.size {
if total >= (2 * c.size) {
if c.b2.Len() > 0 {
c.b2.RemoveTail()
} else {
c.b1.RemoveTail()
}
}
c.replace(key)
}
c.replace(key)
}
}
c.t1.PushFront(key)
c.t1.PushFront(key, item.size)
return item, nil
}

Expand Down Expand Up @@ -200,14 +207,14 @@ func (c *ARC) getValue(key interface{}, onLoad bool) (interface{}, error) {
c.t1.Remove(key, elt)
item := c.items[key]
if !item.IsExpired(nil) {
c.t2.PushFront(key)
c.t2.PushFront(key, item.size)
if !onLoad {
c.stats.IncrHitCount()
}
return item.value, nil
} else {
delete(c.items, key)
c.b1.PushFront(key)
c.b1.PushFront(key, item.size)
if c.evictedFunc != nil {
c.evictedFunc(item.key, item.value)
}
Expand All @@ -224,7 +231,7 @@ func (c *ARC) getValue(key interface{}, onLoad bool) (interface{}, error) {
} else {
delete(c.items, key)
c.t2.Remove(key, elt)
c.b2.PushFront(key)
c.b2.PushFront(key, item.size)
if c.evictedFunc != nil {
c.evictedFunc(item.key, item.value)
}
Expand Down Expand Up @@ -292,7 +299,7 @@ func (c *ARC) remove(key interface{}) bool {
c.t1.Remove(key, elt)
item := c.items[key]
delete(c.items, key)
c.b1.PushFront(key)
c.b1.PushFront(key, item.size)
if c.evictedFunc != nil {
c.evictedFunc(key, item.value)
}
Expand All @@ -303,7 +310,7 @@ func (c *ARC) remove(key interface{}) bool {
c.t2.Remove(key, elt)
item := c.items[key]
delete(c.items, key)
c.b2.PushFront(key)
c.b2.PushFront(key, item.size)
if c.evictedFunc != nil {
c.evictedFunc(key, item.value)
}
Expand Down Expand Up @@ -345,14 +352,16 @@ func (c *ARC) Keys(checkExpired bool) []interface{} {
func (c *ARC) Len(checkExpired bool) int {
c.mu.RLock()
defer c.mu.RUnlock()

if !checkExpired {
return len(c.items)
return c.t1.Len() + c.t2.Len()
}

var length int
now := time.Now()
for k := range c.items {
for k, v := range c.items {
if c.has(k, &now) {
length++
length += v.size
}
}
return length
Expand All @@ -379,7 +388,7 @@ func (c *ARC) setPart(p int) {
}

func (c *ARC) isCacheFull() bool {
return (c.t1.Len() + c.t2.Len()) == c.size
return (c.t1.Len() + c.t2.Len()) >= c.size
}

// IsExpired returns boolean value whether this item is expired or not.
Expand All @@ -394,15 +403,34 @@ func (it *arcItem) IsExpired(now *time.Time) bool {
return it.expiration.Before(*now)
}

type Sizer interface {
Size() int
}

func getSize(v interface{}) int {
s, ok := v.(Sizer)
if !ok {
return 1
}
return s.Size()
}

type arcListItem struct {
key interface{}
size int
}

type arcList struct {
l *list.List
keys map[interface{}]*list.Element
size int
}

type arcItem struct {
clock Clock
key interface{}
value interface{}
size int
expiration *time.Time
}

Expand All @@ -427,30 +455,34 @@ func (al *arcList) MoveToFront(elt *list.Element) {
al.l.MoveToFront(elt)
}

func (al *arcList) PushFront(key interface{}) {
func (al *arcList) PushFront(key interface{}, size int) {
if elt, ok := al.keys[key]; ok {
al.l.MoveToFront(elt)
return
}
elt := al.l.PushFront(key)

elt := al.l.PushFront(arcListItem{key, size})
al.keys[key] = elt
al.size += size
}

func (al *arcList) Remove(key interface{}, elt *list.Element) {
delete(al.keys, key)
al.l.Remove(elt)
al.size -= elt.Value.(arcListItem).size
}

func (al *arcList) RemoveTail() interface{} {
func (al *arcList) RemoveTail() (key interface{}, size int) {
elt := al.l.Back()
al.l.Remove(elt)

key := elt.Value
delete(al.keys, key)
item := elt.Value.(arcListItem)
delete(al.keys, item.key)
al.size -= item.size

return key
return item.key, item.size
}

func (al *arcList) Len() int {
return al.l.Len()
return al.size
}
70 changes: 70 additions & 0 deletions arc_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -112,3 +112,73 @@ func TestARCHas(t *testing.T) {
})
}
}

func TestARCSizer(t *testing.T) {
var evicts int
evict := func(k, v interface{}) {
evicts++
}
c := New(3).ARC().EvictedFunc(evict).Build()

c.Set(1, sizerInt(1))
c.Set(2, sizerInt(2))

v, _ := c.Get(2)
if v != sizerInt(2) {
t.Fatal(v)
}

if evicts != 0 {
t.Fatal(evicts)
}
if l := c.Len(false); l != 3 {
t.Fatal(l)
}

c.Set(3, sizerInt(3))

if evicts != 1 {
t.Fatal(evicts)
}
if l := c.Len(false); l != 5 {
t.Fatal(l)
}

c.Set(4, sizerInt(4))

if evicts != 2 {
t.Fatal(evicts)
}
if l := c.Len(false); l != 6 {
t.Fatal(l)
}

c.Set(6, sizerInt(6))

if evicts != 3 {
t.Fatal(evicts)
}
if l := c.Len(false); l != 8 {
t.Fatal(l)
}

v, _ = c.Get(6)
if v != sizerInt(6) {
t.Fatal(v)
}

c.Set(7, sizerInt(7))

if evicts != 5 {
t.Fatal(evicts)
}
if l := c.Len(false); l != 7 {
t.Fatal(l)
}
}

type sizerInt int

func (s sizerInt) Size() int {
return int(s)
}