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https://github.com/wpilibsuite/allwpilib
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613d5eda0d
This can be conditionally disabled (for cases like JNI callbacks where the JVM may block callbacks into it during shutdown).
117 lines
3.3 KiB
C++
117 lines
3.3 KiB
C++
/*----------------------------------------------------------------------------*/
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/* Copyright (c) 2015-2018 FIRST. All Rights Reserved. */
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/* Open Source Software - may be modified and shared by FRC teams. The code */
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/* must be accompanied by the FIRST BSD license file in the root directory of */
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/* the project. */
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/*----------------------------------------------------------------------------*/
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#ifndef WPIUTIL_WPI_SAFETHREAD_H_
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#define WPIUTIL_WPI_SAFETHREAD_H_
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#include <atomic>
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#include <memory>
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#include <thread>
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#include <utility>
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#include "wpi/condition_variable.h"
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#include "wpi/mutex.h"
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namespace wpi {
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// Base class for SafeThreadOwner threads.
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class SafeThread {
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public:
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virtual ~SafeThread() = default;
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virtual void Main() = 0;
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mutable wpi::mutex m_mutex;
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std::atomic_bool m_active{true};
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wpi::condition_variable m_cond;
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};
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namespace detail {
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// Non-template proxy base class for common proxy code.
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class SafeThreadProxyBase {
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public:
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explicit SafeThreadProxyBase(std::shared_ptr<SafeThread> thr);
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explicit operator bool() const { return m_thread != nullptr; }
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std::unique_lock<wpi::mutex>& GetLock() { return m_lock; }
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protected:
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std::shared_ptr<SafeThread> m_thread;
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std::unique_lock<wpi::mutex> m_lock;
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};
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// A proxy for SafeThread.
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// Also serves as a scoped lock on SafeThread::m_mutex.
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template <typename T>
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class SafeThreadProxy : public SafeThreadProxyBase {
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public:
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explicit SafeThreadProxy(std::shared_ptr<SafeThread> thr)
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: SafeThreadProxyBase(std::move(thr)) {}
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T& operator*() const { return *static_cast<T*>(m_thread.get()); }
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T* operator->() const { return static_cast<T*>(m_thread.get()); }
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};
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// Non-template owner base class for common owner code.
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class SafeThreadOwnerBase {
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public:
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void Stop();
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void Join();
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SafeThreadOwnerBase() noexcept = default;
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SafeThreadOwnerBase(const SafeThreadOwnerBase&) = delete;
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SafeThreadOwnerBase& operator=(const SafeThreadOwnerBase&) = delete;
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SafeThreadOwnerBase(SafeThreadOwnerBase&& other) noexcept
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: SafeThreadOwnerBase() {
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swap(*this, other);
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}
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SafeThreadOwnerBase& operator=(SafeThreadOwnerBase other) noexcept {
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swap(*this, other);
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return *this;
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}
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~SafeThreadOwnerBase();
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friend void swap(SafeThreadOwnerBase& lhs, SafeThreadOwnerBase& rhs) noexcept;
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explicit operator bool() const;
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std::thread::native_handle_type GetNativeThreadHandle();
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void SetJoinAtExit(bool joinAtExit) { m_joinAtExit = joinAtExit; }
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protected:
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void Start(std::shared_ptr<SafeThread> thr);
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std::shared_ptr<SafeThread> GetThread() const;
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private:
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mutable wpi::mutex m_mutex;
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std::thread m_stdThread;
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std::weak_ptr<SafeThread> m_thread;
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std::atomic_bool m_joinAtExit{true};
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};
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void swap(SafeThreadOwnerBase& lhs, SafeThreadOwnerBase& rhs) noexcept;
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} // namespace detail
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template <typename T>
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class SafeThreadOwner : public detail::SafeThreadOwnerBase {
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public:
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template <typename... Args>
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void Start(Args&&... args) {
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detail::SafeThreadOwnerBase::Start(
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std::make_shared<T>(std::forward<Args>(args)...));
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}
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using Proxy = typename detail::SafeThreadProxy<T>;
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Proxy GetThread() const {
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return Proxy(detail::SafeThreadOwnerBase::GetThread());
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}
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};
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} // namespace wpi
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#endif // WPIUTIL_WPI_SAFETHREAD_H_
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