Guardian - atomic counters

guardian/guardian.go

@@ -19,6 +19,7 @@ package guardian
 
 import (
 	"sync"
+	"sync/atomic"
 	"time"
 )
 
@@ -32,14 +33,14 @@ func newItemLock(keyID string) *itemLock {
 // itemLock represents one lock with key autodestroy
 type itemLock struct {
 	keyID string // store it so we know what to destroy
-	cnt   int
+	cnt   int64
 	sync.Mutex
 }
 
 // unlock() executes combined lock with autoremoving lock from Guardian
 func (il *itemLock) unlock() {
-	il.cnt--
-	if il.cnt == 0 { // last lock in the queue
+	atomic.AddInt64(&il.cnt, -1)
+	if il.count() == 0 { // last lock in the queue
 		Guardian.Lock()
 		delete(Guardian.locksMap, il.keyID)
 		Guardian.Unlock()
@@ -47,6 +48,10 @@ func (il *itemLock) unlock() {
 	il.Unlock()
 }
 
+func (il *itemLock) count() int64 {
+	return atomic.LoadInt64(&il.cnt)
+}
+
 // GuardianLock is an optimized locking system per locking key
 type GuardianLock struct {
 	locksMap   map[string]*itemLock
@@ -64,7 +69,7 @@ func (guard *GuardianLock) lockItems(lockIDs []string) (itmLocks []*itemLock) {
 			itmLock = newItemLock(lockID)
 			Guardian.locksMap[lockID] = itmLock
 		}
-		itmLock.cnt++
+		atomic.AddInt64(&itmLock.cnt, 1)
 		itmLocks = append(itmLocks, itmLock)
 	}
 	guard.Unlock()

guardian/guardian_test.go

@@ -94,7 +94,7 @@ func TestGuardianGuardIDs(t *testing.T) {
 	for _, lockID := range lockIDs {
 		if itmLock, hasKey := Guardian.locksMap[lockID]; !hasKey {
 			t.Errorf("Cannot find lock for lockID: %s", lockID)
-		} else if itmLock.cnt != 1 {
+		} else if itmLock.count() != 1 {
 			t.Errorf("Unexpected itmLock found: %+v", itmLock)
 		}
 	}
@@ -102,17 +102,17 @@ func TestGuardianGuardIDs(t *testing.T) {
 	time.Sleep(20 * time.Microsecond)                                       // give time for goroutine to lock
 	if itmLock, hasKey := Guardian.locksMap["test1"]; !hasKey {
 		t.Errorf("Cannot find lock for lockID: %s", "test1")
-	} else if itmLock.cnt != 1 {
+	} else if itmLock.count() != 1 {
 		t.Errorf("Unexpected itmLock found: %+v", itmLock)
 	}
 	if itmLock, hasKey := Guardian.locksMap["test2"]; !hasKey {
 		t.Errorf("Cannot find lock for lockID: %s", "test2")
-	} else if itmLock.cnt != 2 {
+	} else if itmLock.count() != 2 {
 		t.Errorf("Unexpected itmLock found: %+v", itmLock)
 	}
 	if itmLock, hasKey := Guardian.locksMap["test3"]; !hasKey {
 		t.Errorf("Cannot find lock for lockID: %s", "test3")
-	} else if itmLock.cnt != 2 {
+	} else if itmLock.count() != 2 {
 		t.Errorf("Unexpected itmLock found: %+v", itmLock)
 	}
 	Guardian.GuardIDs(0, lockIDs...)
@@ -124,15 +124,15 @@ func TestGuardianGuardIDs(t *testing.T) {
 		t.Errorf("locksMap should be have 3 elements, have: %+v", Guardian.locksMap)
 	} else if itmLock, hasKey := Guardian.locksMap["test1"]; !hasKey {
 		t.Errorf("Cannot find lock for lockID: %s", "test1")
-	} else if itmLock.cnt != 1 {
+	} else if itmLock.count() != 1 {
 		t.Errorf("Unexpected itmLock found: %+v", itmLock)
 	} else if itmLock, hasKey := Guardian.locksMap["test2"]; !hasKey {
 		t.Errorf("Cannot find lock for lockID: %s", "test2")
-	} else if itmLock.cnt != 1 {
+	} else if itmLock.count() != 1 {
 		t.Errorf("Unexpected itmLock found: %+v", itmLock)
 	} else if itmLock, hasKey := Guardian.locksMap["test3"]; !hasKey {
 		t.Errorf("Cannot find lock for lockID: %s", "test2")
-	} else if itmLock.cnt != 1 {
+	} else if itmLock.count() != 1 {
 		t.Errorf("Unexpected itmLock found: %+v", itmLock)
 	}
 	Guardian.UnguardIDs(lockIDs...)