Merge pull request #1 from rjbasitali/add-license-1

Create LICENSE

LICENSE

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2022 Basit Ali
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -0,0 +1,50 @@
+# go-cache
+
+Simple thread safe key/value cache for Go.
+
+## Usage
+
+You can initialize the cache using:
+
+```go
+    cache = gocache.NewCache()
+```
+
+And perform the operations using:
+
+```go
+   // GET a value using key, which returns (value, error)
+   cache.Get(key)
+   
+   // SET a value using key
+   cache.Set(key, value)
+   
+   // REMOVE a key/value pair using key
+   cache.Remove(key)
+   
+   // And FLUSH, which removes all items from the cache
+   cache.Flush()
+```
+
+## Cache Expiration
+
+You can also add an **expiration** to the cache, expired cache will be auto deleted by the `sweeper`.
+
+To initialize a cache using `sweeper` we can use:
+
+```go
+    cache := NewCacheWithSweeper(10 * time.Minute, 10 * time.Minute, decisionFunc, onEviction)
+```
+
+Here, first two parameters are `interval` and `expireAfter`, sweeper will run in the background after specified `interval` to check for expired cache to delete.
+
+The `decisionFunc` and `onEviction` are **optional** functions with the following signature:
+```go
+    decisionFunc func(v interface{}) bool
+    
+    onEviction func(k string, v interface{})
+```
+
+We can use `decisionFunc` as a callback, it will be called by the cache before deleting a key/value, it takes in the value to delete and returns `true` to delete and `false` for not deleting a key/value pair even after expired.
+
+The `onEviction` is a callback which will be called every time a cache is deleted with its key/value as parameters.

cache.go

@@ -4,4 +4,5 @@ type Cache interface {
 	Get(key string) (interface{}, error)
 	Set(key string, data interface{}) error
 	Remove(key string) error
+	Flush()
 }

delete_expired.go

@@ -0,0 +1,21 @@
+package gocache
+
+import "time"
+
+func (cache *myCache) deleteExpired() {
+	cache.mutex.Lock()
+	defer cache.mutex.Unlock()
+
+	now := time.Now().UnixNano()
+	for k, v := range cache.items {
+		if cache.decisionFunc != nil && !cache.decisionFunc(v.data) {
+			continue
+		}
+		if v.expiration > 0 && now > v.expiration {
+			if cache.onEviction != nil {
+				cache.onEviction(k, v.data)
+			}
+			delete(cache.items, k)
+		}
+	}
+}

errors.go

@@ -3,5 +3,5 @@ package gocache
 import "errors"
 
 var (
-	ErrKeyNotFound = errors.New("Key not found")
+	ErrKeyNotFound = errors.New("key not found")
 )

flush.go

@@ -0,0 +1,8 @@
+package gocache
+
+func (cache *myCache) Flush() {
+	cache.mutex.Lock()
+	defer cache.mutex.Unlock()
+
+	cache.items = make(map[string]*value)
+}

get.go

@@ -9,5 +9,5 @@ func (cache *myCache) Get(key string) (interface{}, error) {
 		return nil, ErrKeyNotFound
 	}
 
-	return item, nil
+	return item.data, nil
 }

my_cache.go

@@ -2,11 +2,15 @@ package gocache
 
 import (
 	"sync"
+	"time"
 )
 
 type myCache struct {
-	mutex sync.Mutex
-	items map[string]*value
+	mutex        sync.Mutex
+	items        map[string]*value
+	expireAfter  int64
+	decisionFunc func(v interface{}) bool
+	onEviction   func(k string, v interface{})
 }
 
 func NewCache() Cache {
@@ -14,3 +18,21 @@ func NewCache() Cache {
 		items: make(map[string]*value),
 	}
 }
+
+func NewCacheWithSweeper(interval, expireAfter time.Duration,
+	decisionFunc func(v interface{}) bool, onEviction func(k string, v interface{})) Cache {
+	c := &myCache{
+		items:        make(map[string]*value),
+		expireAfter:  expireAfter.Nanoseconds(),
+		decisionFunc: decisionFunc,
+		onEviction:   onEviction,
+	}
+
+	if interval > 0 && expireAfter > 0 {
+		s := newSweeper(c, interval)
+		// runtime.SetFinalizer(c, s.stopSweeper)
+		go s.run(c)
+	}
+
+	return c
+}

set.go

@@ -1,10 +1,12 @@
 package gocache
 
+import "time"
+
 func (cache *myCache) Set(key string, data interface{}) error {
 	cache.mutex.Lock()
 	defer cache.mutex.Unlock()
 
-	value := newValue(key, data)
+	value := newValue(key, data, time.Now().UnixNano()+cache.expireAfter)
 	cache.items[key] = value
 
 	return nil

sweeper.go

@@ -0,0 +1,32 @@
+package gocache
+
+import "time"
+
+type sweeper struct {
+	Interval time.Duration
+	stop     chan bool
+}
+
+func (s *sweeper) run(c *myCache) {
+	ticker := time.NewTicker(s.Interval)
+	for {
+		select {
+		case <-ticker.C:
+			c.deleteExpired()
+		case <-s.stop:
+			ticker.Stop()
+			return
+		}
+	}
+}
+
+func newSweeper(c *myCache, i time.Duration) *sweeper {
+	return &sweeper{
+		Interval: i,
+		stop:     make(chan bool),
+	}
+}
+
+func (s *sweeper) stopSweeper() {
+	s.stop <- true
+}

value.go

@@ -1,13 +1,15 @@
 package gocache
 
 type value struct {
-	key  string
-	data interface{}
+	key        string
+	data       interface{}
+	expiration int64
 }
 
-func newValue(key string, data interface{}) *value {
+func newValue(key string, data interface{}, expiration int64) *value {
 	return &value{
-		key:  key,
-		data: data,
+		key:        key,
+		data:       data,
+		expiration: expiration,
 	}
 }