rippled/modules/beast_basics/threads/beast_InterruptibleThread.h

/*============================================================================*/
/*
  VFLib: https://github.com/vinniefalco/VFLib

  Copyright (C) 2008 by Vinnie Falco <vinnie.falco@gmail.com>

  This library contains portions of other open source products covered by
  separate licenses. Please see the corresponding source files for specific
  terms.

  VFLib is provided under the terms of The MIT License (MIT):

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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  IN THE SOFTWARE.
*/
/*============================================================================*/

#ifndef BEAST_INTERRUPTIBLETHREAD_BEASTHEADER
#define BEAST_INTERRUPTIBLETHREAD_BEASTHEADER

#include "../diagnostic/beast_SafeBool.h"
#include "../functor/beast_Function.h"

//==============================================================================
/**
    A thread with soft interruption support.

    The thread must periodically call interruptionPoint(), which returns `true`
    the first time an interruption has occurred since the last call to
    interruptionPoint().

    To create a thread, derive your class from InterruptibleThread::EntryPoint
    and implement the threadRun() function. Then, call run() with your object.

    @ingroup beast_core
*/
class InterruptibleThread
{
public:
    /** InterruptibleThread entry point.
    */
    class EntryPoint
    {
    public:
        virtual ~EntryPoint () { }

        virtual void threadRun () = 0;
    };

public:
    typedef Thread::ThreadID id;

    /** Construct an interruptible thread.

        The name is used for debugger diagnostics.

        @param name The name of the thread.
    */
    explicit InterruptibleThread (String name);

    /** Destroy the interruptible thread.

        This will signal an interrupt and wait until the thread exits.
    */
    ~InterruptibleThread ();

    /** Start the thread.
    */
    void start (EntryPoint* const entryPoint);

    /** Wait for the thread to exit.
    */
    void join ();

    /** Wait for interrupt or timeout.

        This call blocks until the thread is interrupted, or until the timeout
        expires if milliSeconds is non-negative.

        May only be called by the thread of execution.

        @param milliSeconds The amount of time to wait. Negative values mean
                            no timeout.

        @return `true` if the interrupt occurred, or `false` if the
                       timeout expired.
    */
    bool wait (int milliSeconds = -1);

    /** Interrupt the thread of execution.

        This can be called from any thread.
    */
    void interrupt ();

    /** Determine if an interruption is requested.

        After the function returns `true`, the interrupt status is cleared.
        Subsequent calls will return `false` until another interrupt is requested.

        May only be called by the thread of execution.

        @see CurrentInterruptibleThread::interruptionPoint

        @return `true` if an interrupt was requested.
    */
    bool interruptionPoint ();

    /** Get the ID of the associated thread.

        @return The ID of the thread.
    */
    id getId () const;

    /** Determine if this is the thread of execution.

        @note The return value is undefined if the thread is not running.

        @return `true` if the caller is this thread of execution.
    */
    bool isTheCurrentThread () const;

    /** Adjust the thread priority.

        @note This only affects some platforms.

        @param priority A number from 0..10
    */
    void setPriority (int priority);

    /** Get the InterruptibleThread for the thread of execution.

        This will return `nullptr` when called from the message thread, or from
        a thread of execution that is not an InterruptibleThread.
    */
    static InterruptibleThread* getCurrentThread ();

private:
    class ThreadHelper : public Thread
    {
    public:
        ThreadHelper (String name, InterruptibleThread* owner);

        InterruptibleThread* getOwner () const;

        void run ();

    private:
        InterruptibleThread* const m_owner;
    };

    void run ();

    ThreadHelper m_thread;
    EntryPoint* m_entryPoint;
    Function <void (void)> m_function;
    WaitableEvent m_runEvent;
    id m_threadId;

    enum
    {
        stateRun,
        stateInterrupt,
        stateReturn,
        stateWait
    };

    AtomicState m_state;
};

//------------------------------------------------------------------------------

/** Global operations on the current InterruptibleThread.

    Calling members of the class from a thread of execution which is not an
    InterruptibleThread results in undefined behavior.
*/
class CurrentInterruptibleThread
{
public:
    /** Call the current thread's interrupt point function.
    */
    static bool interruptionPoint ();
};

#endif