added Store.SetFunc method

CHANGELOG.md

@@ -3,12 +3,14 @@
 - ⚠️ Prioritized the user submitted non-empty `createData.email` (_it will be unverified_) when creating the PocketBase user during the first OAuth2 auth.
 
 - Load the request info context during password/OAuth2/OTP authentication ([#6402](https://github.com/pocketbase/pocketbase/issues/6402)).
-    This could be helpful in case you want to target the auth method as part of the MFA and Auth API rules.
+    This could be useful in case you want to target the auth method as part of the MFA and Auth API rules.
     For example, to disable MFA for the OAuth2 auth could be expressed as `@request.context != "oauth2"` MFA rule.
     (@todo docs)
 
 - Added `$os.stat(file)` JSVM helper ([#6407](https://github.com/pocketbase/pocketbase/discussions/6407)).
 
+- Added `Store.SetFunc(key, func(old T) new T)` to set/update a store value with the return result of the callback in a concurrent safe manner.
+
 
 ## v0.25.3
 

tools/store/store.go

@@ -136,7 +136,7 @@ func (s *Store[K, T]) Values() []T {
 	return values
 }
 
-// Set sets (or overwrite if already exist) a new value for key.
+// Set sets (or overwrite if already exists) a new value for key.
 func (s *Store[K, T]) Set(key K, value T) {
 	s.mu.Lock()
 	defer s.mu.Unlock()
@@ -148,6 +148,29 @@ func (s *Store[K, T]) Set(key K, value T) {
 	s.data[key] = value
 }
 
+// SetFunc sets (or overwrite if already exists) a new value resolved
+// from the function callback for the provided key.
+//
+// The function callback receives as argument the old store element value (if exists).
+// If there is no old store element, the argument will be the T zero value.
+//
+// Example:
+//
+//	s := store.New[string, int](nil)
+//	s.SetFunc("count", func(old int) int {
+//	    return old + 1
+//	})
+func (s *Store[K, T]) SetFunc(key K, fn func(old T) T) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	if s.data == nil {
+		s.data = make(map[K]T)
+	}
+
+	s.data[key] = fn(s.data[key])
+}
+
 // GetOrSet retrieves a single existing value for the provided key
 // or stores a new one if it doesn't exist.
 func (s *Store[K, T]) GetOrSet(key K, setFunc func() T) T {

tools/store/store_test.go

@@ -249,6 +249,32 @@ func TestSet(t *testing.T) {
 	}
 }
 
+func TestSetFunc(t *testing.T) {
+	s := store.Store[string, int]{}
+
+	// non existing value
+	s.SetFunc("test", func(old int) int {
+		if old != 0 {
+			t.Fatalf("Expected old value %d, got %d", 0, old)
+		}
+		return old + 2
+	})
+	if v := s.Get("test"); v != 2 {
+		t.Fatalf("Expected the stored value to be %d, got %d", 2, v)
+	}
+
+	// increment existing value
+	s.SetFunc("test", func(old int) int {
+		if old != 2 {
+			t.Fatalf("Expected old value %d, got %d", 2, old)
+		}
+		return old + 1
+	})
+	if v := s.Get("test"); v != 3 {
+		t.Fatalf("Expected the stored value to be %d, got %d", 3, v)
+	}
+}
+
 func TestGetOrSet(t *testing.T) {
 	s := store.New(map[string]int{
 		"test1": 0,