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Add OptimisticDelete method #170

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079462e
Add OptimisticDelete method
davseby Mar 7, 2025
62e84c4
return boolean indicating a hit
davseby Apr 18, 2025
444697d
Merge branch 'v3' into optimistic-delete
davseby Apr 18, 2025
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25 changes: 20 additions & 5 deletions cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -319,13 +319,15 @@ func (c *Cache[K, V]) evict(reason EvictionReason, elems ...*list.Element) {
// The method is no-op if the item is not found.
// Not safe for concurrent use by multiple goroutines without additional
// locking.
func (c *Cache[K, V]) delete(key K) {
func (c *Cache[K, V]) delete(key K, version *int64) bool {
elem := c.items.values[key]
if elem == nil {
return
if elem == nil || (version != nil && elem.Value.(*Item[K, V]).version != *version) {
return false
}

c.evict(EvictionReasonDeleted, elem)

return true
}

// Set creates a new item from the provided key and value, adds
Expand Down Expand Up @@ -357,7 +359,20 @@ func (c *Cache[K, V]) Delete(key K) {
c.items.mu.Lock()
defer c.items.mu.Unlock()

c.delete(key)
c.delete(key, nil)
}

// OptimisticDelete deletes an item from the cache if the
// provided version matches with the item version. If the
// item associated with the key is not found, the method is no-op.
// In order to use this method and item versions, the cache
// should be initialized using the WithVersion option.
// The return value indicates whether the item was matched and deleted.
func (c *Cache[K, V]) OptimisticDelete(key K, version int64) bool {
c.items.mu.Lock()
defer c.items.mu.Unlock()

return c.delete(key, &version)
}

// Has checks whether the key exists in the cache.
Expand Down Expand Up @@ -422,7 +437,7 @@ func (c *Cache[K, V]) GetAndDelete(key K, opts ...Option[K, V]) (*Item[K, V], bo
return nil, false
}

c.delete(key)
c.delete(key, nil)
c.items.mu.Unlock()

return elem, true
Expand Down
44 changes: 38 additions & 6 deletions cache_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ func TestMain(m *testing.M) {
}

func Test_New(t *testing.T) {
c := New[string, string](
c := New(
WithTTL[string, string](time.Hour),
WithCapacity[string, string](1),
)
Expand Down Expand Up @@ -687,6 +687,34 @@ func Test_Cache_Delete(t *testing.T) {
assert.NotContains(t, cache.items.values, "1")
}

func Test_Cache_OptimisticDelete(t *testing.T) {
var fnsCalls int

cache := prepCache(0, time.Hour, "1", "2", "3", "4")
cache.events.eviction.fns[1] = func(r EvictionReason, item *Item[string, string]) {
assert.Equal(t, EvictionReasonDeleted, r)
fnsCalls++
}
cache.events.eviction.fns[2] = cache.events.eviction.fns[1]

// not found
assert.False(t, cache.OptimisticDelete("1234", 0))
assert.Zero(t, fnsCalls)
assert.Len(t, cache.items.values, 4)

// invalid version
assert.False(t, cache.OptimisticDelete("1", 1))
assert.Zero(t, fnsCalls)
assert.Len(t, cache.items.values, 4)
assert.Contains(t, cache.items.values, "1")

// success
assert.True(t, cache.OptimisticDelete("1", 0))
assert.Equal(t, 2, fnsCalls)
assert.Len(t, cache.items.values, 3)
assert.NotContains(t, cache.items.values, "1")
}

func Test_Cache_Has(t *testing.T) {
cache := prepCache(0, time.Hour, "1")
addToCache(cache, time.Nanosecond, "2")
Expand Down Expand Up @@ -1267,15 +1295,19 @@ func Test_SuppressedLoader_Load(t *testing.T) {
func prepCache(maxCost uint64, ttl time.Duration, keys ...string) *Cache[string, string] {
c := &Cache[string, string]{}
c.options.ttl = ttl
c.options.itemOpts = append(c.options.itemOpts,
withVersionTracking[string, string](false))
c.options.itemOpts = append(
c.options.itemOpts,
withVersionTracking[string, string](true),
)

if maxCost != 0 {
c.options.maxCost = maxCost
c.options.itemOpts = append(c.options.itemOpts,
withCostFunc[string, string](func(item *Item[string, string]) uint64 {
c.options.itemOpts = append(
c.options.itemOpts,
withCostFunc(func(item *Item[string, string]) uint64 {
return uint64(len(item.value))
}))
}),
)
}

c.items.values = make(map[string]*list.Element)
Expand Down
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