Condition.cpp

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#include "blocxx/BLOCXX_config.h"
#include "blocxx/Condition.hpp"
#include "blocxx/NonRecursiveMutexLock.hpp"
#include "blocxx/ExceptionIds.hpp"
#include "blocxx/Timeout.hpp"
#include "blocxx/TimeoutTimer.hpp"
#include "blocxx/ThreadImpl.hpp"

#include <cassert>
#include <cerrno>
#include <limits>
#ifdef BLOCXX_HAVE_SYS_TIME_H
#include <sys/time.h>
#endif

namespace BLOCXX_NAMESPACE
{

BLOCXX_DEFINE_EXCEPTION_WITH_ID(ConditionLock);
BLOCXX_DEFINE_EXCEPTION_WITH_ID(ConditionResource);
#if defined(BLOCXX_USE_PTHREAD)
Condition::Condition()
{
   int res = pthread_cond_init(&m_condition, PTHREAD_COND_ATTR_DEFAULT);
   if (res != 0)
   {
      BLOCXX_THROW(ConditionResourceException, "Failed initializing condition variable");
   }
}
Condition::~Condition()
{
   int res = pthread_cond_destroy(&m_condition);
   assert(res == 0);
}
void
Condition::notifyOne()
{
   int res = pthread_cond_signal(&m_condition);
   assert(res == 0);
}
void
Condition::notifyAll()
{
   int res = pthread_cond_broadcast(&m_condition);
   assert(res == 0);
}
void
Condition::doWait(NonRecursiveMutex& mutex)
{
   ThreadImpl::testCancel();
   int res;
   NonRecursiveMutexLockState state;
   mutex.conditionPreWait(state);
   res = pthread_cond_wait(&m_condition, state.pmutex);
   mutex.conditionPostWait(state);
   assert(res == 0 || res == EINTR);
   if (res == EINTR)
   {
      ThreadImpl::testCancel();
   }
}
namespace
{
   inline 
   bool timespec_less(struct timespec const & x, struct timespec const & y)
   {
      return x.tv_sec < y.tv_sec ||
         x.tv_sec == y.tv_sec && x.tv_nsec < y.tv_nsec;
   }

   int check_timedwait(
      int rc, pthread_cond_t * cond, pthread_mutex_t * mtx,
      struct timespec const * abstime
   )
   {
#ifdef BLOCXX_NCR
      if (rc == -1 && errno == EAGAIN)
      {
         return ETIMEDOUT;
      }
#endif
      if (rc != EINVAL)
      {
         return rc;
      }
      // Solaris won't let you wait more than 10 ** 8 seconds.
      time_t const max_future = 99999999;
      time_t const max_time = std::numeric_limits<time_t>::max();
      time_t now_sec = DateTime::getCurrent().get();
      struct timespec new_abstime;
      new_abstime.tv_sec = (
         now_sec <= max_time - max_future
         ? now_sec + max_future
         : max_time
      );
      new_abstime.tv_nsec = 0;
      bool early = timespec_less(new_abstime, *abstime);
      if (!early)
      {
         new_abstime = *abstime;
      }
      int newrc = pthread_cond_timedwait(cond, mtx, &new_abstime);
      return (newrc == ETIMEDOUT && early ? EINTR : newrc);
   }
}

bool
Condition::doTimedWait(NonRecursiveMutex& mutex, const Timeout& timeout)
{
   ThreadImpl::testCancel();
   int res;
   NonRecursiveMutexLockState state;
   mutex.conditionPreWait(state);
   bool ret = false;

   timespec ts;
   TimeoutTimer timer(timeout);

   res = pthread_cond_timedwait(&m_condition, state.pmutex, timer.asTimespec(ts));
   res = check_timedwait(res, &m_condition, state.pmutex, &ts);
   mutex.conditionPostWait(state);
   assert(res == 0 || res == ETIMEDOUT || res == EINTR);
   if (res == EINTR)
   {
      ThreadImpl::testCancel();
   }
   ret = res != ETIMEDOUT;
   return ret;
}
#elif defined (BLOCXX_WIN32)
Condition::Condition()
   : m_condition(new ConditionInfo_t)
{
   m_condition->waitersCount = 0;
   m_condition->wasBroadcast = false;
   m_condition->queue = ::CreateSemaphore(
      NULL,    // No security
      0,       // initially 0
      0x7fffffff, // max count
      NULL);      // Unnamed
   ::InitializeCriticalSection(&m_condition->waitersCountLock);
   m_condition->waitersDone = ::CreateEvent(
      NULL,    // No security
      false,      // auto-reset
      false,      // non-signaled initially
      NULL);      // Unnamed
}
Condition::~Condition()
{
   ::CloseHandle(m_condition->queue);
   ::DeleteCriticalSection(&m_condition->waitersCountLock);
   ::CloseHandle(m_condition->waitersDone);
   delete m_condition;
}
void
Condition::notifyOne()
{
   ::EnterCriticalSection(&m_condition->waitersCountLock);
   bool haveWaiters = m_condition->waitersCount > 0;
   ::LeaveCriticalSection(&m_condition->waitersCountLock);

   // If no threads waiting, then this is a no-op
   if (haveWaiters)
   {
      ::ReleaseSemaphore(m_condition->queue, 1, 0);
   }
}
void
Condition::notifyAll()
{
   ::EnterCriticalSection(&m_condition->waitersCountLock);
   bool haveWaiters = false;
   if (m_condition->waitersCount > 0)
   {
      // It's gonna be a broadcast, even if there's only one waiting thread.
      haveWaiters = m_condition->wasBroadcast = true;
   }

   if (haveWaiters)
   {
      // Wake up all the waiting threads atomically
      ::ReleaseSemaphore(m_condition->queue, m_condition->waitersCount, 0);
      ::LeaveCriticalSection(&m_condition->waitersCountLock);

      // Wait for all the threads to acquire the counting semaphore
      ::WaitForSingleObject(m_condition->waitersDone, INFINITE);
      m_condition->wasBroadcast = false;
   }
   else
   {
      ::LeaveCriticalSection(&m_condition->waitersCountLock);
   }
}
void
Condition::doWait(NonRecursiveMutex& mutex)
{
  doTimedWait(mutex, Timeout::infinite);
}
bool
//Condition::doTimedWait(NonRecursiveMutex& mutex, UInt32 sTimeout, UInt32 usTimeout)
Condition::doTimedWait(NonRecursiveMutex& mutex, const Timeout& timeout)
{
   ThreadImpl::testCancel();
   bool cc = true;
   NonRecursiveMutexLockState state;
   mutex.conditionPreWait(state);

   ::EnterCriticalSection(&m_condition->waitersCountLock);
   m_condition->waitersCount++;
   ::LeaveCriticalSection(&m_condition->waitersCountLock);

   TimeoutTimer timer(timeout);
   // Atomically release the mutex and wait on the
   // queue until signal/broadcast.
   if (::SignalObjectAndWait(mutex.m_mutex, m_condition->queue, timer.asDWORDMs(),
      false) == WAIT_TIMEOUT)
   {
      cc = false;
   }

   ::EnterCriticalSection(&m_condition->waitersCountLock);
   m_condition->waitersCount--;

   // Check to see if we're the last waiter after the broadcast
   bool isLastWaiter = (m_condition->wasBroadcast && m_condition->waitersCount == 0
      && cc == true);

   ::LeaveCriticalSection(&m_condition->waitersCountLock);

   // If this is the last thread waiting for this broadcast, then let all the
   // other threads proceed.
   if (isLastWaiter)
   {
      // Atomically signal the waitersDone event and wait to acquire
      // the external mutex. Enusres fairness
      ::SignalObjectAndWait(m_condition->waitersDone, mutex.m_mutex,
         INFINITE, false);
   }
   else
   {
      // Re-gain ownership of the external mutex
      ::WaitForSingleObject(mutex.m_mutex, INFINITE);
   }
   mutex.conditionPostWait(state);
   return cc;
}
#else
#error "port me!"
#endif
void
Condition::wait(NonRecursiveMutexLock& lock)
{
   if (!lock.isLocked())
   {
      BLOCXX_THROW(ConditionLockException, "Lock must be locked");
   }
   doWait(*(lock.m_mutex));
}
bool
Condition::timedWait(NonRecursiveMutexLock& lock, UInt32 sTimeout, UInt32 usTimeout)
{
   return timedWait(lock, Timeout::relative(sTimeout + static_cast<float>(usTimeout) / 1000000.0));
}

bool
Condition::timedWait(NonRecursiveMutexLock& lock, const Timeout& timeout)
{
   if (!lock.isLocked())
   {
      BLOCXX_THROW(ConditionLockException, "Lock must be locked");
   }
   return doTimedWait(*(lock.m_mutex), timeout);
}

} // end namespace BLOCXX_NAMESPACE