/*

 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "precompiled/precompiled.hpp"

#include "semaphore_bsd.hpp"

#include "utilities/debug.hpp"

#include <semaphore.h>

#ifdef __APPLE__

// OS X doesn't support unamed POSIX semaphores, so the implementation in os_posix.cpp can't be used.

static const char* sem_init_strerror(kern_return_t value) {

  switch (value) {

    case KERN_INVALID_ARGUMENT:  return "Invalid argument";

    case KERN_RESOURCE_SHORTAGE: return "Resource shortage";

    default:                     return "Unknown";

  }

}

OSXSemaphore::OSXSemaphore(uint value) {

  kern_return_t ret = semaphore_create(mach_task_self(), &_semaphore, SYNC_POLICY_FIFO, value);

  guarantee(ret == KERN_SUCCESS, "Failed to create semaphore: %s", sem_init_strerror(ret));

}

OSXSemaphore::~OSXSemaphore() {

  semaphore_destroy(mach_task_self(), _semaphore);

}

void OSXSemaphore::signal(uint count) {

  for (uint i = 0; i < count; i++) {

    kern_return_t ret = semaphore_signal(_semaphore);

    assert(ret == KERN_SUCCESS, "Failed to signal semaphore");

  }

}

void OSXSemaphore::wait() {

  kern_return_t ret;

  while ((ret = semaphore_wait(_semaphore)) == KERN_ABORTED) {

    // Semaphore was interrupted. Retry.

  }

  assert(ret == KERN_SUCCESS, "Failed to wait on semaphore");

}

int64_t OSXSemaphore::currenttime() {

  struct timeval tv;

  gettimeofday(&tv, NULL);

  return (tv.tv_sec * NANOSECS_PER_SEC) + (tv.tv_usec * 1000);

}

bool OSXSemaphore::trywait() {

  return timedwait(0, 0);

}

bool OSXSemaphore::timedwait(unsigned int sec, int nsec) {

  kern_return_t kr = KERN_ABORTED;

  mach_timespec_t waitspec;

  waitspec.tv_sec = sec;

  waitspec.tv_nsec = nsec;

  int64_t starttime = currenttime();

  kr = semaphore_timedwait(_semaphore, waitspec);

  while (kr == KERN_ABORTED) {

    int64_t totalwait = (sec * NANOSECS_PER_SEC) + nsec;

    int64_t current = currenttime();

    int64_t passedtime = current - starttime;

    if (passedtime >= totalwait) {

      waitspec.tv_sec = 0;

      waitspec.tv_nsec = 0;

    } else {

      int64_t waittime = totalwait - (current - starttime);

      waitspec.tv_sec = waittime / NANOSECS_PER_SEC;

      waitspec.tv_nsec = waittime % NANOSECS_PER_SEC;

    }

    kr = semaphore_timedwait(_semaphore, waitspec);

  }

  return kr == KERN_SUCCESS;

}

#endif // __APPLE__