//

// Threading primitives for CUPS.

//

// Copyright © 2021-2023 by OpenPrinting.

// Copyright © 2009-2018 by Apple Inc.

//

// Licensed under Apache License v2.0.  See the file "LICENSE" for more

// information.

//

#include "cups-private.h"

#include "thread.h"

//

// Windows threading...

//

#if _WIN32

#  include <setjmp.h>

//

// Private structures...

//

struct _cups_thread_s

{

  HANDLE  h;      // Thread handle

  void    *(*func)(void *); // Thread start function

  void    *arg;     // Argument to pass to function

  void    *retval;    // Return value from function

  bool    canceled;   // Is the thread canceled?

  jmp_buf jumpbuf;    // Jump buffer for error recovery

};

//

// Local functions...

//

static cups_thread_t  win32_self(void);

static void   win32_testcancel(void);

static DWORD    win32_tls(void);

static int    win32_wrapper(cups_thread_t thread);

//

// 'cupsCondBroadcast()' - Wake up waiting threads.

//

void

cupsCondBroadcast(cups_cond_t *cond)  // I - Condition variable

{

  if (cond)

    WakeAllConditionVariable(cond);

}

//

// 'cupsCondDestroy()' - Destroy a condition variable.

//

void

cupsCondDestroy(cups_cond_t *cond)  // I - Condition variable

{

  (void)cond;

}

//

// 'cupsCondInit()' - Initialize a condition variable.

//

void

cupsCondInit(cups_cond_t *cond)   // I - Condition variable

{

  if (cond)

    InitializeConditionVariable(cond);

}

//

// 'cupsCondWait()' - Wait for a condition with optional timeout.

//

void

cupsCondWait(cups_cond_t  *cond,  // I - Condition

       cups_mutex_t *mutex, // I - Mutex

       double       timeout)  // I - Timeout in seconds (`0` or negative for none)

{

  win32_testcancel();

  if (cond && mutex)

  {

    if (timeout > 0.0)

      SleepConditionVariableCS(cond, mutex, (int)(1000.0 * timeout));

    else

      SleepConditionVariableCS(cond, mutex, INFINITE);

  }

}

//

// 'cupsMutexDestroy()' - Destroy a mutex.

//

void

cupsMutexDestroy(cups_mutex_t *mutex) // I - Mutex

{

  (void)mutex;

}

//

// 'cupsMutexInit()' - Initialize a mutex.

//

void

cupsMutexInit(cups_mutex_t *mutex)  // I - Mutex

{

  if (mutex)

    InitializeCriticalSection(mutex);

}

//

// 'cupsMutexLock()' - Lock a mutex.

//

void

cupsMutexLock(cups_mutex_t *mutex)  // I - Mutex

{

  if (mutex)

    EnterCriticalSection(mutex);

}

//

// 'cupsMutexUnlock()' - Unlock a mutex.

//

void

cupsMutexUnlock(cups_mutex_t *mutex)  // I - Mutex

{

  if (mutex)

    LeaveCriticalSection(mutex);

}

//

// 'cupsRWDestroy()' - Destroy a reader/writer lock.

//

void

cupsRWDestroy(cups_rwlock_t *rwlock)  // I - Reader/writer lock

{

  (void)rwlock;

}

//

// 'cupsRWInit()' - Initialize a reader/writer lock.

//

void

cupsRWInit(cups_rwlock_t *rwlock) // I - Reader/writer lock

{

  if (rwlock)

    InitializeSRWLock(rwlock);

}

//

// 'cupsRWLockRead()' - Acquire a reader/writer lock for reading.

//

void

cupsRWLockRead(cups_rwlock_t *rwlock) // I - Reader/writer lock

{

  if (rwlock)

    AcquireSRWLockShared(rwlock);

}

//

// 'cupsRWLockWrite()' - Acquire a reader/writer lock for writing.

//

void

cupsRWLockWrite(cups_rwlock_t *rwlock)// I - Reader/writer lock

{

  if (rwlock)

    AcquireSRWLockExclusive(rwlock);

}

//

// 'cupsRWUnlock()' - Release a reader/writer lock.

//

void

cupsRWUnlock(cups_rwlock_t *rwlock) // I - Reader/writer lock

{

  if (rwlock)

  {

    void  *val = *(void **)rwlock;// Lock value

    if (val == (void *)1)

      ReleaseSRWLockExclusive(rwlock);

    else

      ReleaseSRWLockShared(rwlock);

  }

}

//

// 'cupsThreadCancel()' - Cancel (kill) a thread.

//

void

cupsThreadCancel(cups_thread_t thread)// I - Thread ID

{

  if (thread)

    thread->canceled = true;

}

//

// 'cupsThreadCreate()' - Create a thread.

//

cups_thread_t       // O - Thread ID or `CUPS_THREAD_INVALID` on failure

cupsThreadCreate(

    cups_thread_func_t func,    // I - Entry point

    void               *arg)    // I - Entry point context

{

  cups_thread_t thread;     // Thread data

  if (!func)

    return (CUPS_THREAD_INVALID);

  if ((thread = (cups_thread_t)calloc(1, sizeof(struct _cups_thread_s))) == NULL)

    return (CUPS_THREAD_INVALID);

  thread->func = func;

  thread->arg  = arg;

  thread->h    = (HANDLE)_beginthreadex(NULL, 0, (LPTHREAD_START_ROUTINE)win32_wrapper, thread, 0, NULL);

  if (thread->h == 0 || thread->h == (HANDLE)-1)

  {

    free(thread);

    return (CUPS_THREAD_INVALID);

  }

  return (thread);

}

//

// 'cupsThreadDetach()' - Tell the OS that the thread is running independently.

//

void

cupsThreadDetach(cups_thread_t thread)// I - Thread ID

{

  if (thread)

  {

    CloseHandle(thread->h);

    thread->h = 0;

  }

}

//

// 'cupsThreadWait()' - Wait for a thread to exit.

//

void *          // O - Return value

cupsThreadWait(cups_thread_t thread)  // I - Thread ID

{

  void  *retval;      // Return value

  if (!thread)

    return (NULL);

  win32_testcancel();

  if (thread->h)

  {

    WaitForSingleObject(thread->h, INFINITE);

    CloseHandle(thread->h);

  }

  retval = thread->retval;

  free(thread);

  return (retval);

}

//

// 'win32_self()' - Return the current thread.

//

static cups_thread_t      // O - Thread

win32_self(void)

{

  cups_thread_t thread;     // Thread

  if ((thread = TlsGetValue(win32_tls())) == NULL)

  {

    // Main thread, so create the info we need...

    if ((thread = (cups_thread_t)calloc(1, sizeof(struct _cups_thread_s))) != NULL)

    {

      thread->h = GetCurrentThread();

      TlsSetValue(win32_tls(), thread);

      if (setjmp(thread->jumpbuf))

      {

        if (!thread->h)

          free(thread);

        _endthreadex(0);

      }

    }

  }

  return (thread);

}

//

// 'win32_testcancel()' - Mark a safe cancellation point.

//

static void

win32_testcancel(void)

{

  cups_thread_t thread;     // Current thread

  // Go to the thread's exit handler if we've been canceled...

  if ((thread = win32_self()) != NULL && thread->canceled)

    longjmp(thread->jumpbuf, 1);

}

//

// 'win32_tls()' - Get the thread local storage key.

//

static DWORD        // O - Key

win32_tls(void)

{

  static DWORD  tls = 0;    // Thread local storage key

  static CRITICAL_SECTION tls_mutex = { (void*)-1, -1, 0, 0, 0, 0 };

          // Lock for thread local storage access

  EnterCriticalSection(&tls_mutex);

  if (!tls)

  {

    if ((tls = TlsAlloc()) == TLS_OUT_OF_INDEXES)

      abort();

  }

  LeaveCriticalSection(&tls_mutex);

  return (tls);

}

//

// 'win32_wrapper()' - Wrapper function for a POSIX thread.

//

static int        // O - Exit status

win32_wrapper(cups_thread_t thread) // I - Thread

{

  TlsSetValue(win32_tls(), thread);

  if (!setjmp(thread->jumpbuf))

  {

    // Call function in thread...

    thread->retval = (thread->func)(thread->arg);

  }

  // Clean up...

  while (thread->h == (HANDLE)-1)

  {

    // win32_create hasn't finished initializing the handle...

    YieldProcessor();

    _ReadWriteBarrier();

  }

  // Free if detached...

  if (!thread->h)

    free(thread);

  return (0);

}

#else

//

// POSIX threading...

//

//

// 'cupsCondBroadcast()' - Wake up waiting threads.

//

void

cupsCondBroadcast(cups_cond_t *cond)  // I - Condition

{

  pthread_cond_broadcast(cond);

}

//

// 'cupsCondDestroy()' - Destroy a condition variable.

//

void

cupsCondDestroy(cups_cond_t *cond)  // I - Condition

{

  pthread_cond_destroy(cond);

}

//

// 'cupsCondInit()' - Initialize a condition variable.

//

void

cupsCondInit(cups_cond_t *cond)   // I - Condition

{

  pthread_cond_init(cond, NULL);

}

//

// 'cupsCondWait()' - Wait for a condition with optional timeout.

//

void

cupsCondWait(cups_cond_t  *cond,  // I - Condition

       cups_mutex_t *mutex, // I - Mutex

       double       timeout)  // I - Timeout in seconds (`0` or negative for none)

{

  if (timeout > 0.0)

  {

    struct timespec abstime;    // Timeout

    clock_gettime(CLOCK_REALTIME, &abstime);

    abstime.tv_sec  += (long)timeout;

    abstime.tv_nsec += (long)(1000000000 * (timeout - (long)timeout));

    while (abstime.tv_nsec >= 1000000000)

    {

      abstime.tv_nsec -= 1000000000;

      abstime.tv_sec ++;

    };

    (void)pthread_cond_timedwait(cond, mutex, &abstime);

  }

  else

    (void)pthread_cond_wait(cond, mutex);

}

//

// 'cupsMutexDestroy()' - Destroy a mutex.

//

void

cupsMutexDestroy(cups_mutex_t *mutex) // I - Mutex

{

  pthread_mutex_destroy(mutex);

}

//

// 'cupsMutexInit()' - Initialize a mutex.

//

void

cupsMutexInit(cups_mutex_t *mutex)  // I - Mutex

{

  pthread_mutex_init(mutex, NULL);

}

//

// 'cupsMutexLock()' - Lock a mutex.

//

void

cupsMutexLock(cups_mutex_t *mutex)  // I - Mutex

{

  pthread_mutex_lock(mutex);

}

//

// 'cupsMutexUnlock()' - Unlock a mutex.

//

void

cupsMutexUnlock(cups_mutex_t *mutex)  // I - Mutex

{

  pthread_mutex_unlock(mutex);

}

//

// 'cupsRWDestroy()' - Destroy a reader/writer lock.

//

void

cupsRWDestroy(cups_rwlock_t *rwlock)  // I - Reader/writer lock

{

  pthread_rwlock_destroy(rwlock);

}

//

// 'cupsRWInit()' - Initialize a reader/writer lock.

//

void

cupsRWInit(cups_rwlock_t *rwlock) // I - Reader/writer lock

{

  pthread_rwlock_init(rwlock, NULL);

}

//

// 'cupsRWLockRead()' - Acquire a reader/writer lock for reading.

//

void

cupsRWLockRead(cups_rwlock_t *rwlock) // I - Reader/writer lock

{

  pthread_rwlock_rdlock(rwlock);

}

//

// 'cupsRWLockWrite()' - Acquire a reader/writer lock for writing.

//

void

cupsRWLockWrite(cups_rwlock_t *rwlock)// I - Reader/writer lock

{

  pthread_rwlock_wrlock(rwlock);

}

//

// 'cupsRWUnlock()' - Release a reader/writer lock.

//

void

cupsRWUnlock(cups_rwlock_t *rwlock) // I - Reader/writer lock

{

  pthread_rwlock_unlock(rwlock);

}

//

// 'cupsThreadCancel()' - Cancel (kill) a thread.

//

void

cupsThreadCancel(cups_thread_t thread)// I - Thread ID

{

  pthread_cancel(thread);

}

//

// 'cupsThreadCreate()' - Create a thread.

//

cups_thread_t       // O - Thread ID or `CUPS_THREAD_INVALID` on failure

cupsThreadCreate(

    cups_thread_func_t func,    // I - Entry point

    void               *arg)    // I - Entry point context

{

  pthread_t thread;     // Thread

  if (pthread_create(&thread, NULL, (void *(*)(void *))func, arg))

    return (CUPS_THREAD_INVALID);

  else

    return (thread);

}

//

// 'cupsThreadDetach()' - Tell the OS that the thread is running independently.

//

void

cupsThreadDetach(cups_thread_t thread)// I - Thread ID

{

  pthread_detach(thread);

}

//

// 'cupsThreadWait()' - Wait for a thread to exit.

//

void *          // O - Return value

cupsThreadWait(cups_thread_t thread)  // I - Thread ID

{

  void  *ret;       // Return value

  if (pthread_join(thread, &ret))

    return (NULL);

  else

    return (ret);

}

#endif // _WIN32