ZeroTierOne/osdep/Thread.hpp

/*
 * Copyright (c)2019 ZeroTier, Inc.
 *
 * Use of this software is governed by the Business Source License included
 * in the LICENSE.TXT file in the project's root directory.
 *
 * Change Date: 2026-01-01
 *
 * On the date above, in accordance with the Business Source License, use
 * of this software will be governed by version 2.0 of the Apache License.
 */
/****/

#ifndef ZT_THREAD_HPP
#define ZT_THREAD_HPP

#include "../node/Constants.hpp"

#include <stdexcept>

#ifdef __WINDOWS__

#include "../node/Mutex.hpp"

#include <string.h>
#include <windows.h>
#include <winsock2.h>

namespace ZeroTier {

template <typename C> static DWORD WINAPI ___zt_threadMain(LPVOID lpParam)
{
    try {
        ((C*)lpParam)->threadMain();
    }
    catch (...) {
    }
    return 0;
}

class Thread {
  public:
    Thread()
    {
        _th = NULL;
        _tid = 0;
    }

    template <typename C> static inline Thread start(C* instance)
    {
        Thread t;
        t._th = CreateThread(NULL, 0, &___zt_threadMain<C>, (LPVOID)instance, 0, &t._tid);
        if (t._th == NULL)
            throw std::runtime_error("CreateThread() failed");
        return t;
    }

    static inline void join(const Thread& t)
    {
        if (t._th != NULL) {
            for (;;) {
                DWORD ec = STILL_ACTIVE;
                GetExitCodeThread(t._th, &ec);
                if (ec == STILL_ACTIVE)
                    WaitForSingleObject(t._th, 1000);
                else
                    break;
            }
        }
    }

    static inline void sleep(unsigned long ms)
    {
        Sleep((DWORD)ms);
    }

    // Not available on *nix platforms
    static inline void cancelIO(const Thread& t)
    {
#if ! defined(__MINGW32__) && ! defined(__MINGW64__)   // CancelSynchronousIo not available in MSYS2
        if (t._th != NULL)
            CancelSynchronousIo(t._th);
#endif
    }

    inline operator bool() const
    {
        return (_th != NULL);
    }

  private:
    HANDLE _th;
    DWORD _tid;
};

}   // namespace ZeroTier

#else

#include <pthread.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

namespace ZeroTier {

template <typename C> static void* ___zt_threadMain(void* instance)
{
    try {
        ((C*)instance)->threadMain();
    }
    catch (...) {
    }
    return (void*)0;
}

/**
 * A thread identifier, and static methods to start and join threads
 */
class Thread {
  public:
    Thread()
    {
        memset(this, 0, sizeof(Thread));
    }

    Thread(const Thread& t)
    {
        memcpy(this, &t, sizeof(Thread));
    }

    inline Thread& operator=(const Thread& t)
    {
        memcpy(this, &t, sizeof(Thread));
        return *this;
    }

    /**
     * Start a new thread
     *
     * @param instance Instance whose threadMain() method gets called by new thread
     * @return Thread identifier
     * @throws std::runtime_error Unable to create thread
     * @tparam C Class containing threadMain()
     */
    template <typename C> static inline Thread start(C* instance)
    {
        Thread t;
        pthread_attr_t tattr;
        pthread_attr_init(&tattr);
        // This corrects for systems with abnormally small defaults (musl) and also
        // shrinks the stack on systems with large defaults to save a bit of memory.
        pthread_attr_setstacksize(&tattr, ZT_THREAD_MIN_STACK_SIZE);
        if (pthread_create(&t._tid, &tattr, &___zt_threadMain<C>, instance)) {
            pthread_attr_destroy(&tattr);
            throw std::runtime_error("pthread_create() failed, unable to create thread");
        }
        else {
            t._started = true;
            pthread_attr_destroy(&tattr);
        }
        return t;
    }

    /**
     * Join to a thread, waiting for it to terminate (does nothing on null Thread values)
     *
     * @param t Thread to join
     */
    static inline void join(const Thread& t)
    {
        if (t._started)
            pthread_join(t._tid, (void**)0);
    }

    /**
     * Sleep the current thread
     *
     * @param ms Number of milliseconds to sleep
     */
    static inline void sleep(unsigned long ms)
    {
        usleep(ms * 1000);
    }

    inline operator bool() const
    {
        return (_started);
    }

  private:
    pthread_t _tid;
    volatile bool _started;
};

}   // namespace ZeroTier

#endif   // __WINDOWS__ / !__WINDOWS__

#endif