README
¶
wcache
Implements in-memory cache with write-back strategy
(a cache with expiration).
An expiration callback(expireFn) will be called when record is expired.
Features
- Thread-safe.
- Per-key or global TTL.
- Can trigger a custom callback on key expiration(could be used as Pub/Sub with aggregation).
- Can trigger a custom callback on key collisions(e.g. for aggregating metrics). By default, will overwrite value.
- Graceful shutdown(using context). Will call expiration callback for all records, ignoring they TTL.
Install
go get github.com/vtopc/wcache
TODO
- Optional auto-extending expiration on
Getand/orSet.
Similar projects
Documentation
¶
Overview ¶
Example ¶
package main
import (
"context"
"time"
"github.com/vtopc/wcache"
)
func main() {
c := wcache.New(context.Background(), 100*time.Millisecond, wcache.PrintlnOnExpire)
// put value with custom TTL:
c.SetWithTTL("2", "to expire second", 200*time.Millisecond)
// put value with default TTL:
c.Set("1", "to expire first")
time.Sleep(300 * time.Millisecond)
}
Output: 1: to expire first 2: to expire second
Index ¶
Examples ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func AddInt64 ¶
func AddInt64(old, new interface{}) (result interface{})
AddInt64 a CompareFn typed function that will add new value to the old one and return as result
func MaxInt64 ¶
func MaxInt64(old, new interface{}) (result interface{})
MaxInt64 a CompareFn typed function that will return biggest value as result
func PrintlnOnExpire ¶
func PrintlnOnExpire(key string, value interface{})
PrintOnExpire a dummy ExpireFn that will print key, value when record is expired
Types ¶
type Cache ¶
type Cache struct {
// thread unsafe(TODO):
CompareFn CompareFn
// contains filtered or unexported fields
}
func (*Cache) Done ¶
func (c *Cache) Done() <-chan struct{}
Done returns a channel that will be closed when work done(ExpireFn called for all records). This channel would not be closed if there are no records and context is not canceled(expired, etc.).
Example ¶
package main
import (
"context"
"time"
"github.com/vtopc/wcache"
)
func main() {
ctx, cancel := context.WithCancel(context.Background())
c := wcache.New(ctx, time.Hour, wcache.PrintlnOnExpire)
c.Set("1", "my value") // should expire in an hour
// but will expire after context cancellation
cancel()
<-c.Done()
}
Output: 1: my value
func (*Cache) Get ¶
Get returns the value stored in the map for a key, or nil if no value is present. The found result indicates whether value was found in the cache.
type CompareFn ¶
type CompareFn func(old, new interface{}) (result interface{})
CompareFn compares values on key collisions
Example ¶
package main
import (
"context"
"fmt"
"time"
"github.com/vtopc/wcache"
)
func main() {
const key = "test"
c := wcache.New(context.Background(), time.Hour, wcache.NoopExpire)
c.CompareFn = wcache.MaxInt64
c.Set(key, int64(1))
c.Set(key, int64(2))
v, _ := c.Get(key)
fmt.Println(v)
}
Output: 2
type ExpireFn ¶
type ExpireFn func(key string, value interface{})
ExpireFn a callback that will be called when record is expired
func ChanExpire ¶
ChanExpire returns a ExpireFn that will send key, value to the channel `ch` when record is expired
Source Files