cache refactoring for save and load

engine/response_cache.go

@@ -0,0 +1,87 @@
+package engine
+
+import (
+	"errors"
+	"sync"
+	"time"
+
+	"github.com/cgrates/cgrates/utils"
+)
+
+var ErrNotFound = errors.New("NOT_FOUND")
+
+type CacheItem struct {
+	Value interface{}
+	Err   error
+}
+
+type ResponseCache struct {
+	ttl       time.Duration
+	cache     map[string]*CacheItem
+	semaphore map[string]chan bool // used for waiting till the first goroutine processes the response
+	mu        sync.RWMutex
+}
+
+func NewResponseCache(ttl time.Duration) *ResponseCache {
+	return &ResponseCache{
+		ttl:       ttl,
+		cache:     make(map[string]*CacheItem),
+		semaphore: make(map[string]chan bool),
+		mu:        sync.RWMutex{},
+	}
+}
+
+func (rc *ResponseCache) Cache(key string, item *CacheItem) {
+	//utils.Logger.Info("key: " + key)
+	if rc.ttl == 0 {
+		return
+	}
+	rc.mu.Lock()
+	rc.cache[key] = item
+	if _, found := rc.semaphore[key]; found {
+		close(rc.semaphore[key])  // send release signal
+		delete(rc.semaphore, key) // delete key
+	}
+	rc.mu.Unlock()
+	go func() {
+		time.Sleep(rc.ttl)
+		rc.mu.Lock()
+		delete(rc.cache, key)
+		rc.mu.Unlock()
+	}()
+}
+
+func (rc *ResponseCache) Get(key string) (*CacheItem, error) {
+	if rc.ttl == 0 {
+		return nil, utils.ErrNotImplemented
+	}
+	rc.mu.RLock()
+	item, ok := rc.cache[key]
+	rc.mu.RUnlock()
+	if ok {
+		//utils.Logger.Info(",,,,,,,,,,,,,,,,,,,,,Found key: " + key)
+		return item, nil
+	}
+	rc.wait(key) // wait for other goroutine processsing this key
+	rc.mu.RLock()
+	defer rc.mu.RUnlock()
+	item, ok = rc.cache[key]
+	if !ok {
+		return nil, ErrNotFound
+	}
+	//utils.Logger.Info("............................Found key: " + key)
+	return item, nil
+}
+
+func (rc *ResponseCache) wait(key string) {
+	rc.mu.RLock()
+	lockChan, found := rc.semaphore[key]
+	rc.mu.RUnlock()
+	if found {
+		<-lockChan
+	} else {
+		rc.mu.Lock()
+		rc.semaphore[key] = make(chan bool)
+		rc.mu.Unlock()
+	}
+}