From c7ea97b212ee6658feb240dd431247849f368667 Mon Sep 17 00:00:00 2001 From: liqi Date: Thu, 24 Dec 2020 09:29:28 +0800 Subject: [PATCH 1/3] update --- simplelru/list.go | 245 ++++++++++++++++++++++++++++++++++++++++++ simplelru/lru.go | 47 +++++--- simplelru/lru_test.go | 9 ++ 3 files changed, 287 insertions(+), 14 deletions(-) create mode 100644 simplelru/list.go diff --git a/simplelru/list.go b/simplelru/list.go new file mode 100644 index 0000000..8a1938a --- /dev/null +++ b/simplelru/list.go @@ -0,0 +1,245 @@ +// Copyright 2009 The Go Authors. All rights reserved. +// Use of this source code is governed by a BSD-style +// license that can be found in the LICENSE file. + +// Package list implements a doubly linked list. +// +// To iterate over a list (where l is a *List): +// for e := l.Front(); e != nil; e = e.Next() { +// // do something with e.Value +// } +// +package simplelru + +import "fmt" + +// Element is an element of a linked list. +type Element struct { + // Next and previous pointers in the doubly-linked list of elements. + // To simplify the implementation, internally a list l is implemented + // as a ring, such that &l.root is both the next element of the last + // list element (l.Back()) and the previous element of the first list + // element (l.Front()). + next, prev *Element + + // The list to which this element belongs. + list *List + + // The value stored with this element. + Value interface{} +} + +// Next returns the next list element or nil. +func (e *Element) Next() *Element { + if p := e.next; e.list != nil && p != &e.list.root { + return p + } + return nil +} + +// Prev returns the previous list element or nil. +func (e *Element) Prev() *Element { + if p := e.prev; e.list != nil && p != &e.list.root { + return p + } + return nil +} + +// List represents a doubly linked list. +// The zero value for List is an empty list ready to use. +type List struct { + root Element // sentinel list element, only &root, root.prev, and root.next are used + len int // current list length excluding (this) sentinel element +} + +// Init initializes or clears list l. +func (l *List) Init() *List { + l.root.next = &l.root + l.root.prev = &l.root + l.len = 0 + return l +} + +// New returns an initialized list. +func New() *List { return new(List).Init() } + +// Len returns the number of elements of list l. +// The complexity is O(1). +func (l *List) Len() int { return l.len } + +// Front returns the first element of list l or nil if the list is empty. +func (l *List) Front() *Element { + if l.len == 0 { + return nil + } + return l.root.next +} + +// Back returns the last element of list l or nil if the list is empty. +func (l *List) Back() *Element { + if l.len == 0 { + return nil + } + return l.root.prev +} + +// lazyInit lazily initializes a zero List value. +func (l *List) lazyInit() { + if l.root.next == nil { + l.Init() + } +} + +// insert inserts e after at, increments l.len, and returns e. +func (l *List) insert(e, at *Element) *Element { + e.prev = at + e.next = at.next + e.prev.next = e + e.next.prev = e + e.list = l + l.len++ + return e +} + +// insertValue is a convenience wrapper for insert(&Element{Value: v}, at). +func (l *List) insertValue(v interface{}, at *Element) *Element { + return l.insert(&Element{Value: v}, at) +} + +// remove removes e from its list, decrements l.len, and returns e. +func (l *List) remove(e *Element) *Element { + e.prev.next = e.next + e.next.prev = e.prev + e.next = nil // avoid memory leaks + e.prev = nil // avoid memory leaks + e.list = nil + l.len-- + return e +} + +// move moves e to next to at and returns e. +func (l *List) move(e, at *Element) *Element { + if e == at { + return e + } + fmt.Println(e) + e.prev.next = e.next + e.next.prev = e.prev + + e.prev = at + e.next = at.next + e.prev.next = e + e.next.prev = e + + return e +} + +// Remove removes e from l if e is an element of list l. +// It returns the element value e.Value. +// The element must not be nil. +func (l *List) Remove(e *Element) interface{} { + if e.list == l { + // if e.list == l, l must have been initialized when e was inserted + // in l or l == nil (e is a zero Element) and l.remove will crash + l.remove(e) + } + return e.Value +} + +// PushFront inserts a new element e with value v at the front of list l and returns e. +func (l *List) PushFront(v interface{}) *Element { + l.lazyInit() + return l.insertValue(v, &l.root) +} + +func (l *List) PushElementFront(e *Element) *Element { + return l.insert(e, &l.root) +} + +// PushBack inserts a new element e with value v at the back of list l and returns e. +func (l *List) PushBack(v interface{}) *Element { + l.lazyInit() + return l.insertValue(v, l.root.prev) +} + +// InsertBefore inserts a new element e with value v immediately before mark and returns e. +// If mark is not an element of l, the list is not modified. +// The mark must not be nil. +func (l *List) InsertBefore(v interface{}, mark *Element) *Element { + if mark.list != l { + return nil + } + // see comment in List.Remove about initialization of l + return l.insertValue(v, mark.prev) +} + +// InsertAfter inserts a new element e with value v immediately after mark and returns e. +// If mark is not an element of l, the list is not modified. +// The mark must not be nil. +func (l *List) InsertAfter(v interface{}, mark *Element) *Element { + if mark.list != l { + return nil + } + // see comment in List.Remove about initialization of l + return l.insertValue(v, mark) +} + +// MoveToFront moves element e to the front of list l. +// If e is not an element of l, the list is not modified. +// The element must not be nil. +func (l *List) MoveToFront(e *Element) { + if l.root.next == e { + return + } + // see comment in List.Remove about initialization of l + l.move(e, &l.root) +} + +// MoveToBack moves element e to the back of list l. +// If e is not an element of l, the list is not modified. +// The element must not be nil. +func (l *List) MoveToBack(e *Element) { + if l.root.prev == e { + return + } + // see comment in List.Remove about initialization of l + l.move(e, l.root.prev) +} + +// MoveBefore moves element e to its new position before mark. +// If e or mark is not an element of l, or e == mark, the list is not modified. +// The element and mark must not be nil. +func (l *List) MoveBefore(e, mark *Element) { + if e == mark { + return + } + l.move(e, mark.prev) +} + +// MoveAfter moves element e to its new position after mark. +// If e or mark is not an element of l, or e == mark, the list is not modified. +// The element and mark must not be nil. +func (l *List) MoveAfter(e, mark *Element) { + if e == mark { + return + } + l.move(e, mark) +} + +// PushBackList inserts a copy of another list at the back of list l. +// The lists l and other may be the same. They must not be nil. +func (l *List) PushBackList(other *List) { + l.lazyInit() + for i, e := other.Len(), other.Front(); i > 0; i, e = i-1, e.Next() { + l.insertValue(e.Value, l.root.prev) + } +} + +// PushFrontList inserts a copy of another list at the front of list l. +// The lists l and other may be the same. They must not be nil. +func (l *List) PushFrontList(other *List) { + l.lazyInit() + for i, e := other.Len(), other.Back(); i > 0; i, e = i-1, e.Prev() { + l.insertValue(e.Value, &l.root) + } +} diff --git a/simplelru/lru.go b/simplelru/lru.go index ee4fee4..3c8d5a3 100644 --- a/simplelru/lru.go +++ b/simplelru/lru.go @@ -1,7 +1,6 @@ package simplelru import ( - "container/list" "errors" "time" ) @@ -12,8 +11,9 @@ type EvictCallback func(key interface{}, value interface{}) // LRU implements a non-thread safe fixed size LRU cache type LRU struct { size int - evictList *list.List - items map[interface{}]*list.Element + evictList *List + freeList *List + items map[interface{}]*Element expire time.Duration onEvict EvictCallback } @@ -39,11 +39,15 @@ func NewLRU(size int, onEvict EvictCallback) (*LRU, error) { } c := &LRU{ size: size, - evictList: list.New(), - items: make(map[interface{}]*list.Element), + evictList: New(), + freeList: New(), + items: make(map[interface{}]*Element), expire: 0, onEvict: onEvict, } + for i := 0; i < size; i++ { + c.freeList.PushFront(&entry{}) + } return c, nil } @@ -54,11 +58,16 @@ func NewLRUWithExpire(size int, expire time.Duration, onEvict EvictCallback) (*L } c := &LRU{ size: size, - evictList: list.New(), - items: make(map[interface{}]*list.Element), + evictList: New(), + freeList: New(), + items: make(map[interface{}]*Element), expire: expire, onEvict: onEvict, } + for i := 0; i < size; i++ { + c.freeList.PushFront(&entry{}) + } + return c, nil } @@ -71,6 +80,10 @@ func (c *LRU) Purge() { delete(c.items, k) } c.evictList.Init() + c.freeList.Init() + for i := 0; i < c.size; i++ { + c.freeList.PushFront(&entry{}) + } } // Add adds a value to the cache. Returns true if an eviction occurred. @@ -96,16 +109,21 @@ func (c *LRU) AddEx(key, value interface{}, expire time.Duration) bool { return false } - // Add new item - ent := &entry{key: key, value: value, expire: ex} - entry := c.evictList.PushFront(ent) - c.items[key] = entry - - evict := c.evictList.Len() > c.size + evict := c.evictList.Len() >= c.size // Verify size not exceeded if evict { c.removeOldest() } + + // Add new item + ent := c.freeList.Front() + ent.Value.(*entry).key = key + ent.Value.(*entry).value = value + ent.Value.(*entry).expire = ex + c.freeList.Remove(ent) + c.evictList.PushElementFront(ent) + c.items[key] = ent + return evict } @@ -222,8 +240,9 @@ func (c *LRU) removeOldest() { } // removeElement is used to remove a given list element from the cache -func (c *LRU) removeElement(e *list.Element) { +func (c *LRU) removeElement(e *Element) { c.evictList.Remove(e) + c.freeList.PushElementFront(e) kv := e.Value.(*entry) delete(c.items, kv.key) if c.onEvict != nil { diff --git a/simplelru/lru_test.go b/simplelru/lru_test.go index 6ce7095..02ac11b 100644 --- a/simplelru/lru_test.go +++ b/simplelru/lru_test.go @@ -235,3 +235,12 @@ func TestLRU_Resize(t *testing.T) { t.Errorf("Cache should have contained 2 elements") } } + +func BenchmarkAdd(b *testing.B) { + l, _ := NewLRU(1000, nil) + b.ResetTimer() + + for i := 0; i < b.N; i++ { + l.Add(i, true) + } +} From 97985fad43af963640338b321c8b23f76aa65790 Mon Sep 17 00:00:00 2001 From: liqi Date: Thu, 24 Dec 2020 09:39:11 +0800 Subject: [PATCH 2/3] update --- simplelru/list.go | 3 --- simplelru/lru_test.go | 14 +++++++++++--- 2 files changed, 11 insertions(+), 6 deletions(-) diff --git a/simplelru/list.go b/simplelru/list.go index 8a1938a..94b2994 100644 --- a/simplelru/list.go +++ b/simplelru/list.go @@ -11,8 +11,6 @@ // package simplelru -import "fmt" - // Element is an element of a linked list. type Element struct { // Next and previous pointers in the doubly-linked list of elements. @@ -122,7 +120,6 @@ func (l *List) move(e, at *Element) *Element { if e == at { return e } - fmt.Println(e) e.prev.next = e.next e.next.prev = e.prev diff --git a/simplelru/lru_test.go b/simplelru/lru_test.go index 02ac11b..6fc5753 100644 --- a/simplelru/lru_test.go +++ b/simplelru/lru_test.go @@ -240,7 +240,15 @@ func BenchmarkAdd(b *testing.B) { l, _ := NewLRU(1000, nil) b.ResetTimer() - for i := 0; i < b.N; i++ { - l.Add(i, true) - } + b.Run("Add with small keys", func(b *testing.B) { + for i := 0; i < b.N; i++ { + l.Add(i%100, true) + } + }) + + b.Run("Add with large keys", func(b *testing.B) { + for i := 0; i < b.N; i++ { + l.Add(i%10000, true) + } + }) } From 99dbcdc97e405d2c01501af83195fde135d9592c Mon Sep 17 00:00:00 2001 From: liqi Date: Thu, 24 Dec 2020 09:42:09 +0800 Subject: [PATCH 3/3] update --- simplelru/lru_test.go | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/simplelru/lru_test.go b/simplelru/lru_test.go index 6fc5753..2ba0a11 100644 --- a/simplelru/lru_test.go +++ b/simplelru/lru_test.go @@ -242,13 +242,13 @@ func BenchmarkAdd(b *testing.B) { b.Run("Add with small keys", func(b *testing.B) { for i := 0; i < b.N; i++ { - l.Add(i%100, true) + l.Add(i%100, "this is a foo bar") } }) b.Run("Add with large keys", func(b *testing.B) { for i := 0; i < b.N; i++ { - l.Add(i%10000, true) + l.Add(i%10000, "this is a foo bar") } }) }