Add GetWithExpiration

CONTRIBUTORS

@@ -6,3 +6,4 @@ code was contributed.)
 Dustin Sallings <dustin@spy.net>
 Jason Mooberry <jasonmoo@me.com>
 Sergey Shepelev <temotor@gmail.com>
+Alex Edwards <ajmedwards@gmail.com>

cache.go

@@ -135,6 +135,36 @@ func (c *cache) Get(k string) (interface{}, bool) {
 	return item.Object, true
 }
 
+// GetWithExpiration returns an item and its expiration time from the cache.
+// It returns the item or nil, the expiration time if one is set (if the item
+// never expires a zero value for time.Time is returned), and a bool indicating
+// whether the key was found.
+func (c *cache) GetWithExpiration(k string) (interface{}, time.Time, bool) {
+	c.mu.RLock()
+	// "Inlining" of get and Expired
+	item, found := c.items[k]
+	if !found {
+		c.mu.RUnlock()
+		return nil, time.Time{}, false
+	}
+
+	if item.Expiration > 0 {
+		if time.Now().UnixNano() > item.Expiration {
+			c.mu.RUnlock()
+			return nil, time.Time{}, false
+		}
+
+		// Return the item and the expiration time
+		c.mu.RUnlock()
+		return item.Object, time.Unix(0, item.Expiration), true
+	}
+
+	// If expiration <= 0 (i.e. no expiration time set) then return the item
+	// and a zeroed time.Time
+	c.mu.RUnlock()
+	return item.Object, time.Time{}, true
+}
+
 func (c *cache) get(k string) (interface{}, bool) {
 	item, found := c.items[k]
 	if !found {

cache_test.go

@@ -1676,3 +1676,96 @@ func BenchmarkDeleteExpiredLoop(b *testing.B) {
 		tc.DeleteExpired()
 	}
 }
+
+func TestGetWithExpiration(t *testing.T) {
+	tc := New(DefaultExpiration, 0)
+
+	a, expiration, found := tc.GetWithExpiration("a")
+	if found || a != nil || !expiration.IsZero() {
+		t.Error("Getting A found value that shouldn't exist:", a)
+	}
+
+	b, expiration, found := tc.GetWithExpiration("b")
+	if found || b != nil || !expiration.IsZero() {
+		t.Error("Getting B found value that shouldn't exist:", b)
+	}
+
+	c, expiration, found := tc.GetWithExpiration("c")
+	if found || c != nil || !expiration.IsZero() {
+		t.Error("Getting C found value that shouldn't exist:", c)
+	}
+
+	tc.Set("a", 1, DefaultExpiration)
+	tc.Set("b", "b", DefaultExpiration)
+	tc.Set("c", 3.5, DefaultExpiration)
+	tc.Set("d", 1, NoExpiration)
+	tc.Set("e", 1, 50*time.Millisecond)
+
+	x, expiration, found := tc.GetWithExpiration("a")
+	if !found {
+		t.Error("a was not found while getting a2")
+	}
+	if x == nil {
+		t.Error("x for a is nil")
+	} else if a2 := x.(int); a2+2 != 3 {
+		t.Error("a2 (which should be 1) plus 2 does not equal 3; value:", a2)
+	}
+	if !expiration.IsZero() {
+		t.Error("expiration for a is not a zeroed time")
+	}
+
+	x, expiration, found = tc.GetWithExpiration("b")
+	if !found {
+		t.Error("b was not found while getting b2")
+	}
+	if x == nil {
+		t.Error("x for b is nil")
+	} else if b2 := x.(string); b2+"B" != "bB" {
+		t.Error("b2 (which should be b) plus B does not equal bB; value:", b2)
+	}
+	if !expiration.IsZero() {
+		t.Error("expiration for b is not a zeroed time")
+	}
+
+	x, expiration, found = tc.GetWithExpiration("c")
+	if !found {
+		t.Error("c was not found while getting c2")
+	}
+	if x == nil {
+		t.Error("x for c is nil")
+	} else if c2 := x.(float64); c2+1.2 != 4.7 {
+		t.Error("c2 (which should be 3.5) plus 1.2 does not equal 4.7; value:", c2)
+	}
+	if !expiration.IsZero() {
+		t.Error("expiration for c is not a zeroed time")
+	}
+
+	x, expiration, found = tc.GetWithExpiration("d")
+	if !found {
+		t.Error("d was not found while getting d2")
+	}
+	if x == nil {
+		t.Error("x for d is nil")
+	} else if d2 := x.(int); d2+2 != 3 {
+		t.Error("d (which should be 1) plus 2 does not equal 3; value:", d2)
+	}
+	if !expiration.IsZero() {
+		t.Error("expiration for d is not a zeroed time")
+	}
+
+	x, expiration, found = tc.GetWithExpiration("e")
+	if !found {
+		t.Error("e was not found while getting e2")
+	}
+	if x == nil {
+		t.Error("x for e is nil")
+	} else if e2 := x.(int); e2+2 != 3 {
+		t.Error("e (which should be 1) plus 2 does not equal 3; value:", e2)
+	}
+	if expiration.UnixNano() != tc.items["e"].Expiration {
+		t.Error("expiration for e is not the correct time")
+	}
+	if expiration.UnixNano() < time.Now().UnixNano() {
+		t.Error("expiration for e is in the past")
+	}
+}