chore: import upstream snapshot with attribution

2026-07-13 12:47:05 +08:00
commit 4f3b7da785
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+/* ******************************************************************************
+ *
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Apache License, Version 2.0 which is available at
+ * https://www.apache.org/licenses/LICENSE-2.0.
+ *
+ *  See the NOTICE file distributed with this work for additional
+ *  information regarding copyright ownership.
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations
+ * under the License.
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ ******************************************************************************/
+
+//
+// Created by raver on 8/29/2018.
+//
+
+#ifndef LIBND4J_READWRITELOCK_H
+#define LIBND4J_READWRITELOCK_H
+#include <system/common.h>
+
+#include <atomic>
+#include <mutex>
+
+/**
+ * This class provides PRIMITIVE read-write lock, and should NOT be used outside of GraphServer due to its inefficiency.
+ * However, since GraphServer isn't supposed to have Reads/Writes ration even close to 1.0, it'll work just fine.
+ *
+ * Basic idea: write lock won't be obtained before all read requests served
+ */
+namespace sd {
+class SD_LIB_EXPORT SimpleReadWriteLock {
+ private:
+  std::atomic<unsigned long long int> _read_locks;
+  std::atomic<unsigned long long int> _write_locks;
+  std::mutex _mutex;
+
+ public:
+  explicit SimpleReadWriteLock();
+  SimpleReadWriteLock(const SimpleReadWriteLock& other);
+  ~SimpleReadWriteLock() = default;
+
+  // read lock
+  void lockRead();
+  void unlockRead();
+
+  // write lock
+  void lockWrite();
+  void unlockWrite();
+
+  SimpleReadWriteLock& operator=(const SimpleReadWriteLock& other);
+};
+}  // namespace sd
+
+#endif  // DEV_TESTS_READWRITELOCK_H