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venv/lib/python3.10/site-packages/pyarrow/include/arrow/util/cancel.h

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+// 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 <functional>
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "arrow/status.h"
+#include "arrow/type_fwd.h"
+#include "arrow/util/macros.h"
+#include "arrow/util/visibility.h"
+
+namespace arrow {
+
+class StopToken;
+
+struct StopSourceImpl;
+
+/// EXPERIMENTAL
+class ARROW_EXPORT StopSource {
+ public:
+  StopSource();
+  ~StopSource();
+
+  // Consumer API (the side that stops)
+  void RequestStop();
+  void RequestStop(Status error);
+  // Async-signal-safe. TODO Deprecate this?
+  void RequestStopFromSignal(int signum);
+
+  StopToken token();
+
+  // For internal use only
+  void Reset();
+
+ protected:
+  std::shared_ptr<StopSourceImpl> impl_;
+};
+
+/// EXPERIMENTAL
+class ARROW_EXPORT StopToken {
+ public:
+  // Public for Cython
+  StopToken() = default;
+
+  explicit StopToken(std::shared_ptr<StopSourceImpl> impl) : impl_(std::move(impl)) {}
+
+  // A trivial token that never propagates any stop request
+  static StopToken Unstoppable() { return StopToken(); }
+
+  /// \brief Check if the stop source has been cancelled.
+  ///
+  /// Producers should call this method, whenever convenient, to check and
+  /// see if they should stop producing early (i.e. have been cancelled).
+  /// Failure to call this method often enough will lead to an unresponsive
+  /// cancellation.
+  ///
+  /// This is part of the producer API (the side that gets asked to stop)
+  /// This method is thread-safe
+  ///
+  /// \return An OK status if the stop source has not been cancelled or a
+  ///         cancel error if the source has been cancelled.
+  Status Poll() const;
+  bool IsStopRequested() const;
+
+ protected:
+  std::shared_ptr<StopSourceImpl> impl_;
+};
+
+/// EXPERIMENTAL: Set a global StopSource that can receive signals
+///
+/// The only allowed order of calls is the following:
+/// - SetSignalStopSource()
+/// - any number of pairs of (RegisterCancellingSignalHandler,
+///   UnregisterCancellingSignalHandler) calls
+/// - ResetSignalStopSource()
+///
+/// Beware that these settings are process-wide.  Typically, only one
+/// thread should call these APIs, even in a multithreaded setting.
+ARROW_EXPORT
+Result<StopSource*> SetSignalStopSource();
+
+/// EXPERIMENTAL: Reset the global signal-receiving StopSource
+///
+/// This will invalidate the pointer returned by SetSignalStopSource.
+ARROW_EXPORT
+void ResetSignalStopSource();
+
+/// EXPERIMENTAL: Register signal handler triggering the signal-receiving StopSource
+///
+/// Note that those handlers are automatically un-registered in a fork()ed process,
+/// therefore the child process will need to call RegisterCancellingSignalHandler()
+/// if desired.
+ARROW_EXPORT
+Status RegisterCancellingSignalHandler(const std::vector<int>& signals);
+
+/// EXPERIMENTAL: Unregister signal handler set up by RegisterCancellingSignalHandler
+ARROW_EXPORT
+void UnregisterCancellingSignalHandler();
+
+}  // namespace arrow