1 files changed, 40 insertions, 0 deletions
diff --git a/sem.go b/sem.go
new file mode 100644
index 0000000..c587e61
--- /dev/null
+++ b/sem.go
@@ -0,0 +1,40 @@
+/*
+ * Additional synchronization routines
+ *
+ * Copyright (C) 2024  Runxi Yu <https://runxiyu.org>
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package main
+
+type usemT struct {
+	_ch (chan struct{})
+}
+
+func (s *usemT) init() {
+	s._ch = make(chan struct{}, 1)
+}
+
+func (s *usemT) set() {
+	select {
+	case s._ch <- struct{}{}:
+	default:
+	}
+}
+
+func (s *usemT) ch() (<- chan struct{}) {
+	return s._ch
+}