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Filename : thr_cond.h
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#ifndef THR_COND_INCLUDED
#define THR_COND_INCLUDED

/* Copyright (c) 2014, 2023, Oracle and/or its affiliates.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License, version 2.0,
   as published by the Free Software Foundation.

   This program is also distributed with certain software (including
   but not limited to OpenSSL) that is licensed under separate terms,
   as designated in a particular file or component or in included license
   documentation.  The authors of MySQL hereby grant you an additional
   permission to link the program and your derivative works with the
   separately licensed software that they have included with MySQL.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License, version 2.0, for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */

/**
  MySQL condition variable implementation.

  There are three "layers":
  1) native_cond_*()
       Functions that map directly down to OS primitives.
       Windows    - ConditionVariable
       Other OSes - pthread
  2) my_cond_*()
       Functions that use SAFE_MUTEX (default for debug).
       Otherwise native_cond_*() is used.
  3) mysql_cond*()
       Functions that include Performance Schema instrumentation.
       See include/mysql/psi/mysql_thread.h
*/

#include "my_thread.h"
#include "thr_mutex.h"

C_MODE_START

#ifdef _WIN32
typedef CONDITION_VARIABLE native_cond_t;
#else
typedef pthread_cond_t native_cond_t;
#endif

#ifdef _WIN32
/**
  Convert abstime to milliseconds
*/

static DWORD get_milliseconds(const struct timespec *abstime)
{
#ifndef HAVE_STRUCT_TIMESPEC
  long long millis;
  union ft64 now;

  if (abstime == NULL)
   return INFINITE;

  GetSystemTimeAsFileTime(&now.ft);

  /*
    Calculate time left to abstime
    - subtract start time from current time(values are in 100ns units)
    - convert to millisec by dividing with 10000
  */
  millis= (abstime->tv.i64 - now.i64) / 10000;

  /* Don't allow the timeout to be negative */
  if (millis < 0)
    return 0;

  /*
    Make sure the calculated timeout does not exceed original timeout
    value which could cause "wait for ever" if system time changes
  */
  if (millis > abstime->max_timeout_msec)
    millis= abstime->max_timeout_msec;

  if (millis > UINT_MAX)
    millis= UINT_MAX;

  return (DWORD)millis;
#else
  /*
    Convert timespec to millis and subtract current time.
    my_getsystime() returns time in 100 ns units.
  */
  ulonglong future= abstime->tv_sec * 1000 + abstime->tv_nsec / 1000000;
  ulonglong now= my_getsystime() / 10000;
  /* Don't allow the timeout to be negative. */
  if (future < now)
    return 0;
  return (DWORD)(future - now);
#endif
}
#endif /* _WIN32 */

static inline int native_cond_init(native_cond_t *cond)
{
#ifdef _WIN32
  InitializeConditionVariable(cond);
  return 0;
#else
  /* pthread_condattr_t is not used in MySQL */
  return pthread_cond_init(cond, NULL);
#endif
}

static inline int native_cond_destroy(native_cond_t *cond)
{
#ifdef _WIN32
  return 0; /* no destroy function */
#else
  return pthread_cond_destroy(cond);
#endif
}

static inline int native_cond_timedwait(native_cond_t *cond,
                                        native_mutex_t *mutex,
                                        const struct timespec *abstime)
{
#ifdef _WIN32
  DWORD timeout= get_milliseconds(abstime);
  if (!SleepConditionVariableCS(cond, mutex, timeout))
    return ETIMEDOUT;
  return 0;
#else
  return pthread_cond_timedwait(cond, mutex, abstime);
#endif
}

static inline int native_cond_wait(native_cond_t *cond, native_mutex_t *mutex)
{
#ifdef _WIN32
  if (!SleepConditionVariableCS(cond, mutex, INFINITE))
    return ETIMEDOUT;
  return 0;
#else
  return pthread_cond_wait(cond, mutex);
#endif
}

static inline int native_cond_signal(native_cond_t *cond)
{
#ifdef _WIN32
  WakeConditionVariable(cond);
  return 0;
#else
  return pthread_cond_signal(cond);
#endif
}

static inline int native_cond_broadcast(native_cond_t *cond)
{
#ifdef _WIN32
  WakeAllConditionVariable(cond);
  return 0;
#else
  return pthread_cond_broadcast(cond);
#endif
}

#ifdef SAFE_MUTEX
int safe_cond_wait(native_cond_t *cond, my_mutex_t *mp,
                   const char *file, uint line);
int safe_cond_timedwait(native_cond_t *cond, my_mutex_t *mp,
                        const struct timespec *abstime,
                        const char *file, uint line);
#endif

static inline int my_cond_timedwait(native_cond_t *cond, my_mutex_t *mp,
                                    const struct timespec *abstime
#ifdef SAFE_MUTEX
                                    , const char *file, uint line
#endif
                                    )
{
#ifdef SAFE_MUTEX
  return safe_cond_timedwait(cond, mp, abstime, file, line);
#else
  return native_cond_timedwait(cond, mp, abstime);
#endif
}

static inline int my_cond_wait(native_cond_t *cond, my_mutex_t *mp
#ifdef SAFE_MUTEX
                               , const char *file, uint line
#endif
                               )
{
#ifdef SAFE_MUTEX
  return safe_cond_wait(cond, mp, file, line);
#else
  return native_cond_wait(cond, mp);
#endif
}

C_MODE_END

#endif /* THR_COND_INCLUDED */