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https://github.com/1f349/cache.git
synced 2024-09-07 18:56:43 +01:00
Fix cleaner to not get stuck, finish writing test code
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parent
a3aa9e83ed
commit
b262a5f11e
95
cache.go
95
cache.go
@ -18,8 +18,8 @@ func timeUntil(t time.Time) time.Duration { return t.Sub(timeNow()) }
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// actions are completed in the cleaner goroutine to be concurrency safe.
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type Cache[K comparable, V any] struct {
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items sync.Map
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chain *keyed[K] // linked list of to-expire keys
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sched *rescheduler.Rescheduler // TODO: add a mode to have the goroutine running only once after multiple Run calls
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chain *keyed[K] // linked list of to-expire keys
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sched *rescheduler.Rescheduler
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close chan struct{}
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chainAdd chan keyed[K]
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chainDel chan K
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@ -48,7 +48,12 @@ func (c item[T]) HasExpired() bool {
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// New creates a *Cache[K, V] ready to be used by the caller
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func New[K comparable, V any]() *Cache[K, V] {
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c := &Cache[K, V]{}
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c := &Cache[K, V]{
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items: sync.Map{},
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close: make(chan struct{}, 1),
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chainAdd: make(chan keyed[K], 1),
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chainDel: make(chan K, 1),
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}
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c.sched = rescheduler.NewRescheduler(c.cleaner)
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return c
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}
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@ -67,14 +72,26 @@ func (c *Cache[K, V]) Close() {
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// The cleaner is stopped whenever the chain is empty due to there being no chain
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// to manage.
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func (c *Cache[K, V]) cleaner() {
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var t *time.Timer
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if c.chain == nil {
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// fake timer as this select isn't used for an empty chain
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t = &time.Timer{C: make(chan time.Time)}
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} else {
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t = time.NewTimer(timeUntil(c.chain.expires))
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// cleaner is always called from Set or Delete methods with a value sent on chainAdd or chainDel
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select {
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case node := <-c.chainAdd:
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c.chainInsert(node)
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case key := <-c.chainDel:
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c.chainSplice(key)
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default:
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// skip if chainAdd or chainDel isn't ready
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println("Skip first select")
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}
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// at this point if the chain is empty then exit
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if c.chain == nil {
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return
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}
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// create a timer for the next expiry
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t := time.NewTimer(timeUntil(c.chain.expires))
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for {
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select {
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case <-c.close:
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@ -87,21 +104,12 @@ func (c *Cache[K, V]) cleaner() {
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}
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// the chain will not be empty after this insert so no check is required
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c.chainInsert(node)
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t.Reset(timeUntil(c.chain.expires))
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case key := <-c.chainDel:
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// stop the timer safely
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if !t.Stop() {
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<-t.C
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}
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c.chainSplice(key)
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// if there is no chain then kill the expiry scheduler
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if c.chain == nil {
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return
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}
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t.Reset(timeUntil(c.chain.expires))
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case <-t.C:
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// if there is no chain then kill the expiry scheduler
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if c.chain == nil {
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@ -109,18 +117,18 @@ func (c *Cache[K, V]) cleaner() {
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}
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// remove all expired entries
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for c.chain.HasExpired() {
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for c.chain != nil && c.chain.HasExpired() {
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c.items.Delete(c.chain.data)
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c.chain = c.chain.next
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}
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// if there is no chain then kill the expiry scheduler
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if c.chain == nil {
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return
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}
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t.Reset(timeUntil(c.chain.expires))
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}
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// if there is no chain then kill the expiry scheduler
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if c.chain == nil {
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return
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}
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t.Reset(timeUntil(c.chain.expires))
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}
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}
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@ -151,6 +159,11 @@ func (c *Cache[K, V]) chainInsert(node keyed[K]) {
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}
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func (c *Cache[K, V]) chainSplice(key K) {
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// quick path if chain is empty
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if c.chain == nil {
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return
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}
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// quick path if the first node matches
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if c.chain.data == key {
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node := c.chain
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@ -208,6 +221,13 @@ func (c *Cache[K, V]) Get(key K) (V, bool) {
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//
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// If an item is added with the same key then this item with be overwritten.
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func (c *Cache[K, V]) SetPermanent(key K, value V) {
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// if the cache is closed then just return
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select {
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case <-c.close:
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return
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default:
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}
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i := &item[V]{data: value} // expires is not set here
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c.items.Store(key, i)
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}
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@ -216,6 +236,13 @@ func (c *Cache[K, V]) SetPermanent(key K, value V) {
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//
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// If an item is added with the same key then this item with be overwritten.
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func (c *Cache[K, V]) Set(key K, value V, expires time.Time) {
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// if the cache is closed then just return
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select {
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case <-c.close:
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return
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default:
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}
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if expires.Before(timeNow()) {
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return
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}
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@ -226,6 +253,20 @@ func (c *Cache[K, V]) Set(key K, value V, expires time.Time) {
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c.sched.Run()
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}
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// Delete removes an item from the cache.
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func (c *Cache[K, V]) Delete(key K) {
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// if the cache is closed then just return
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select {
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case <-c.close:
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return
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default:
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}
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c.items.Delete(key)
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c.chainDel <- key
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c.sched.Run()
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}
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// Range calls f with every key-value pair, which has not expired, currently
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// stored in the map.
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//
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@ -239,6 +280,6 @@ func (c *Cache[K, V]) Range(f func(key K, value V) bool) {
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return true
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}
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return f(key.(K), value.(V))
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return f(key.(K), item.data)
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})
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}
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118
cache_test.go
118
cache_test.go
@ -6,11 +6,129 @@ import (
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"time"
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)
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var nextYear = time.Now().Year() + 1
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func TestItem_HasExpired(t *testing.T) {
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n := time.Now()
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// date before now is expired
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a := item[string]{expires: n}
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timeNow = func() time.Time { return n.Add(time.Second) }
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assert.True(t, a.HasExpired())
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// date after now is valid
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a = item[string]{expires: n.Add(time.Second * 2)}
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assert.False(t, a.HasExpired())
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// empty date is always valid
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a = item[string]{}
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assert.False(t, a.HasExpired())
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}
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func TestCache_GetExpires(t *testing.T) {
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c := New[string, string]()
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c.items.Store("a", &item[string]{
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data: "b",
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expires: time.Date(nextYear, time.January, 1, 0, 0, 0, 0, time.UTC),
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})
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v, exp, found := c.GetExpires("a")
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assert.Equal(t, "b", v)
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assert.Equal(t, time.Date(nextYear, time.January, 1, 0, 0, 0, 0, time.UTC), exp)
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assert.True(t, found)
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v, exp, found = c.GetExpires("b")
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assert.Equal(t, "", v)
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assert.Equal(t, time.Time{}, exp)
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assert.False(t, found)
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}
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func TestCache_Get(t *testing.T) {
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c := New[string, string]()
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c.items.Store("a", &item[string]{
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data: "b",
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expires: time.Date(nextYear, time.January, 1, 0, 0, 0, 0, time.UTC),
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})
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v, found := c.Get("a")
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assert.Equal(t, "b", v)
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assert.True(t, found)
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v, found = c.Get("b")
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assert.Equal(t, "", v)
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assert.False(t, found)
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}
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func TestCache_SetPermanent(t *testing.T) {
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c := New[string, string]()
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c.SetPermanent("a", "b")
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value, ok := c.items.Load("a")
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v := value.(*item[string])
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assert.Equal(t, item[string]{data: "b"}, *v)
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assert.True(t, ok)
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value, ok = c.items.Load("b")
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assert.False(t, ok)
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}
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func TestCache_Set(t *testing.T) {
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c := New[string, string]()
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c.Set("a", "b", time.Date(nextYear, time.January, 1, 0, 0, 0, 0, time.UTC))
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value, ok := c.items.Load("a")
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v := value.(*item[string])
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assert.Equal(t, item[string]{
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data: "b",
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expires: time.Date(nextYear, time.January, 1, 0, 0, 0, 0, time.UTC),
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}, *v)
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assert.True(t, ok)
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value, ok = c.items.Load("b")
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assert.False(t, ok)
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}
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func TestCache_Delete(t *testing.T) {
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c := New[string, string]()
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c.items.Store("a", &item[string]{data: "b", expires: time.Date(nextYear, time.January, 1, 0, 0, 0, 0, time.UTC)})
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c.chain = &keyed[string]{item: item[string]{data: "a", expires: time.Date(nextYear, time.January, 1, 0, 0, 0, 0, time.UTC)}}
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c.Delete("a")
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// scheduler should finish after deleting the item
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c.sched.Wait()
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assert.Nil(t, c.chain)
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}
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func TestCache_Range(t *testing.T) {
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c := New[string, string]()
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c.items.Store("a", &item[string]{data: "b"})
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c.items.Store("b", &item[string]{data: "c"})
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c.items.Store("c", &item[string]{data: "d"})
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c.items.Store("d", &item[string]{data: "e"})
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c.Range(func(key string, value string) bool {
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assert.Equal(t, string([]byte{[]byte(key)[0] + 1}), value)
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return true
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})
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}
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func TestCache_Cleaner(t *testing.T) {
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timeNow = func() time.Time { return time.Now() }
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n := time.Now().Add(2 * time.Second)
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c := New[string, string]()
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c.Set("a", "b", n)
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// check before expiry
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time.Sleep(time.Second)
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get, b := c.Get("a")
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assert.True(t, b)
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assert.Equal(t, "b", get)
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// check after expiry
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time.Sleep(1001 * time.Millisecond)
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get, b = c.Get("a")
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assert.False(t, b)
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assert.Equal(t, "", get)
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// scheduler should finish after the chain is empty
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c.sched.Wait()
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assert.Nil(t, c.chain)
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}
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2
go.mod
2
go.mod
@ -3,7 +3,7 @@ module github.com/1f349/cache
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go 1.21.1
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require (
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github.com/MrMelon54/rescheduler v0.0.1
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github.com/MrMelon54/rescheduler v0.0.2
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github.com/stretchr/testify v1.8.4
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)
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4
go.sum
4
go.sum
@ -1,5 +1,5 @@
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github.com/MrMelon54/rescheduler v0.0.1 h1:gzNvL8X81M00uYN0i9clFVrXCkG1UuLNYxDcvjKyBqo=
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github.com/MrMelon54/rescheduler v0.0.1/go.mod h1:OQDFtZHdS4/qA/r7rtJUQA22/hbpnZ9MGQCXOPjhC6w=
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github.com/MrMelon54/rescheduler v0.0.2 h1:efrRwr0BYlkaXFucZDjQqRyIawZiMEAnzjea46Bs9Oc=
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github.com/MrMelon54/rescheduler v0.0.2/go.mod h1:OQDFtZHdS4/qA/r7rtJUQA22/hbpnZ9MGQCXOPjhC6w=
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github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
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github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
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github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
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