#include "bingo_lock.h"

DatabaseLockData::DatabaseLockData() : writers_count(0), readers_count(0)
{
   osSemaphoreCreate(&rc_sem, 1, 1);
   osSemaphoreCreate(&wc_sem, 1, 1);
   osSemaphoreCreate(&w_sem, 1, 1);
   osSemaphoreCreate(&r_sem, 1, 1);
}

ReadLock::ReadLock(DatabaseLockData &data) : _data(data)
{
   osSemaphoreWait(&_data.r_sem);
   osSemaphoreWait(&_data.rc_sem);
   _data.readers_count++;
   if (_data.readers_count == 1)
      osSemaphoreWait(&_data.w_sem);
   osSemaphorePost(&_data.rc_sem);
   osSemaphorePost(&_data.r_sem);
}

ReadLock::~ReadLock()
{
   osSemaphoreWait(&_data.rc_sem);
   _data.readers_count--;
   if (_data.readers_count == 0)
      osSemaphorePost(&_data.w_sem);
   osSemaphorePost(&_data.rc_sem);
}

WriteLock::WriteLock(DatabaseLockData &data) : _data(data)
{
   osSemaphoreWait(&_data.wc_sem);
   _data.writers_count++;
   if (_data.writers_count == 1)
      osSemaphoreWait(&_data.r_sem);
   osSemaphorePost(&_data.wc_sem);

   osSemaphoreWait(&_data.w_sem);
}

WriteLock::~WriteLock()
{
   osSemaphorePost(&_data.w_sem);

   osSemaphoreWait(&_data.wc_sem);
   _data.writers_count--;
   if (_data.writers_count == 0)
      osSemaphorePost(&_data.r_sem);
   osSemaphorePost(&_data.wc_sem);
}