README
¶
cache
import "github.com/fufuok/utils/generic/cache"
Package cache provides an implementation of a key-value store with a maximum size. Once the maximum size is reached, the cache uses a least-recently-used policy to evict old entries. The cache is implemented as a combined hashmap and linked list. This ensures all operations are constant-time.
Example
package main
import (
"fmt"
"github.com/fufuok/utils/generic/cache"
)
func main() {
c := cache.New[int, int](2)
c.Put(42, 42)
c.Put(10, 10)
c.Get(42)
c.Put(0, 0) // evicts 10
c.Each(func(key, val int) {
fmt.Println("each", key)
})
c.Resize(3)
fmt.Println("size", c.Size())
fmt.Println("capacity", c.Capacity())
c.SetEvictCallback(func(key, val int) {
fmt.Println("evict", key)
})
c.Put(1, 1)
c.Put(2, 2) // evicts 42
c.Remove(3) // no effect
c.Resize(1) // evicts 0 and 1
c.Each(func(key, val int) {
fmt.Println("each", key)
})
}
Output
each 0
each 42
size 2
capacity 3
evict 42
evict 0
evict 1
each 2
Index
- type Cache
- func New[K comparable, V any](capacity int) *Cache[K, V]
- func (t *Cache[K, V]) Capacity() int
- func (t *Cache[K, V]) Each(fn func(key K, val V))
- func (t *Cache[K, V]) Get(k K) (V, bool)
- func (t *Cache[K, V]) Put(k K, e V)
- func (t *Cache[K, V]) Remove(k K)
- func (t *Cache[K, V]) Resize(capacity int)
- func (t *Cache[K, V]) SetEvictCallback(fn func(key K, val V))
- func (t *Cache[K, V]) Size() int
- type KV
type Cache
A Cache is an LRU cache for keys and values. Each entry is put into the table with an associated key used for looking up the entry. The cache has a maximum size, and uses a least-recently-used eviction policy when there is not space for a new entry.
type Cache[K comparable, V any] struct {
// contains filtered or unexported fields
}
func New
func New[K comparable, V any](capacity int) *Cache[K, V]
New returns a new Cache with the given capacity.
func (*Cache[K, V]) Capacity
func (t *Cache[K, V]) Capacity() int
Capacity returns the maximum capacity of the cache.
func (*Cache[K, V]) Each
func (t *Cache[K, V]) Each(fn func(key K, val V))
Each calls 'fn' on every value in the cache, from most recently used to least recently used.
func (*Cache[K, V]) Get
func (t *Cache[K, V]) Get(k K) (V, bool)
Get returns the entry associated with a given key, and a boolean indicating whether the key exists in the table.
func (*Cache[K, V]) Put
func (t *Cache[K, V]) Put(k K, e V)
Put adds a new key-entry pair to the table.
func (*Cache[K, V]) Remove
func (t *Cache[K, V]) Remove(k K)
Remove causes the entry associated with the given key to be immediately evicted from the cache.
func (*Cache[K, V]) Resize
func (t *Cache[K, V]) Resize(capacity int)
Resize changes the maximum capacity for this cache to 'capacity'.
func (*Cache[K, V]) SetEvictCallback
func (t *Cache[K, V]) SetEvictCallback(fn func(key K, val V))
SetEvictCallback sets a callback to be invoked before an entry is evicted. This replaces any prior callback set by this method.
func (*Cache[K, V]) Size
func (t *Cache[K, V]) Size() int
Size returns the number of active elements in the cache.
type KV
type KV[K comparable, V any] struct {
Key K
Val V
}
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Documentation
¶
Overview ¶
Package cache provides an implementation of a key-value store with a maximum size. Once the maximum size is reached, the cache uses a least-recently-used policy to evict old entries. The cache is implemented as a combined hashmap and linked list. This ensures all operations are constant-time.
Example ¶
package main
import (
"fmt"
"github.com/fufuok/utils/generic/cache"
)
func main() {
c := cache.New[int, int](2)
c.Put(42, 42)
c.Put(10, 10)
c.Get(42)
c.Put(0, 0) // evicts 10
c.Each(func(key, val int) {
fmt.Println("each", key)
})
c.Resize(3)
fmt.Println("size", c.Size())
fmt.Println("capacity", c.Capacity())
c.SetEvictCallback(func(key, val int) {
fmt.Println("evict", key)
})
c.Put(1, 1)
c.Put(2, 2) // evicts 42
c.Remove(3) // no effect
c.Resize(1) // evicts 0 and 1
c.Each(func(key, val int) {
fmt.Println("each", key)
})
}
Output: each 0 each 42 size 2 capacity 3 evict 42 evict 0 evict 1 each 2
Index ¶
- type Cache
- func (t *Cache[K, V]) Capacity() int
- func (t *Cache[K, V]) Each(fn func(key K, val V))
- func (t *Cache[K, V]) Get(k K) (V, bool)
- func (t *Cache[K, V]) Put(k K, e V)
- func (t *Cache[K, V]) Remove(k K)
- func (t *Cache[K, V]) Resize(capacity int)
- func (t *Cache[K, V]) SetEvictCallback(fn func(key K, val V))
- func (t *Cache[K, V]) Size() int
- type KV
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Cache ¶
type Cache[K comparable, V any] struct { // contains filtered or unexported fields }
A Cache is an LRU cache for keys and values. Each entry is put into the table with an associated key used for looking up the entry. The cache has a maximum size, and uses a least-recently-used eviction policy when there is not space for a new entry.
func New ¶
func New[K comparable, V any](capacity int) *Cache[K, V]
New returns a new Cache with the given capacity.
func (*Cache[K, V]) Each ¶
func (t *Cache[K, V]) Each(fn func(key K, val V))
Each calls 'fn' on every value in the cache, from most recently used to least recently used.
func (*Cache[K, V]) Get ¶
Get returns the entry associated with a given key, and a boolean indicating whether the key exists in the table.
func (*Cache[K, V]) Put ¶
func (t *Cache[K, V]) Put(k K, e V)
Put adds a new key-entry pair to the table.
func (*Cache[K, V]) Remove ¶
func (t *Cache[K, V]) Remove(k K)
Remove causes the entry associated with the given key to be immediately evicted from the cache.
func (*Cache[K, V]) SetEvictCallback ¶
func (t *Cache[K, V]) SetEvictCallback(fn func(key K, val V))
SetEvictCallback sets a callback to be invoked before an entry is evicted. This replaces any prior callback set by this method.
type KV ¶
type KV[K comparable, V any] struct { Key K Val V }
Source Files