first commit

.venv/Lib/site-packages/pyarrow/include/arrow/util/concurrent_map.h

@@ -0,0 +1,68 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// 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.
+
+#pragma once
+
+#include <unordered_map>
+#include <utility>
+
+#include "arrow/util/mutex.h"
+
+namespace arrow {
+namespace util {
+
+template <typename K, typename V>
+class ConcurrentMap {
+ public:
+  void Insert(const K& key, const V& value) {
+    auto lock = mutex_.Lock();
+    map_.insert({key, value});
+  }
+
+  template <typename ValueFunc>
+  V GetOrInsert(const K& key, ValueFunc&& compute_value_func) {
+    auto lock = mutex_.Lock();
+    auto it = map_.find(key);
+    if (it == map_.end()) {
+      auto pair = map_.emplace(key, compute_value_func());
+      it = pair.first;
+    }
+    return it->second;
+  }
+
+  void Erase(const K& key) {
+    auto lock = mutex_.Lock();
+    map_.erase(key);
+  }
+
+  void Clear() {
+    auto lock = mutex_.Lock();
+    map_.clear();
+  }
+
+  size_t size() const {
+    auto lock = mutex_.Lock();
+    return map_.size();
+  }
+
+ private:
+  std::unordered_map<K, V> map_;
+  mutable arrow::util::Mutex mutex_;
+};
+
+}  // namespace util
+}  // namespace arrow