G4MTBarrier.cc

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//
// G4MTBarrier class implementation
//
// Author: A.Dotti (SLAC), 10 February 2016
// Revision: J.Madsen (NERSC), 09 February 2018
// --------------------------------------------------------------------
 
#include "G4MTBarrier.hh"
#include "G4AutoLock.hh"
 
// --------------------------------------------------------------------
G4MTBarrier::G4MTBarrier(unsigned int numThreads)
  : m_numActiveThreads(numThreads)
{}
 
// --------------------------------------------------------------------
void G4MTBarrier::ThisWorkerReady()
{
  // Step-1: Worker acquires lock on shared resource (the counter)
  G4AutoLock lock(&m_mutex);
  // Step-2: Worker increases counter
  ++m_counter;
  // Step-3: Worker broadcasts that the counter has changed
  G4CONDITIONBROADCAST(&m_counterChanged);
  // Step-4: Worker waits on condition to continue
  G4CONDITIONWAIT(&m_continue, &lock);
}
 
// --------------------------------------------------------------------
void G4MTBarrier::Wait()
{
  while(true)
  {
    // Step-2: Acquires lock on shared resource (the counter)
    G4AutoLock lock(&m_mutex);
    // If the counter equals active threads, all threads are ready, exit the
    // loop
    if(m_counter == m_numActiveThreads)
    {
      break;
    }
    // Step-3: Not all workers are ready, wait for the number to change
    // before repeating the check
    G4CONDITIONWAIT(&m_counterChanged, &lock);
  }
}
 
// --------------------------------------------------------------------
void G4MTBarrier::ReleaseBarrier()
{
  // Step-4: re-aquire lock and re-set shared resource for future re-use
  G4AutoLock lock(&m_mutex);
  m_counter = 0;
  G4CONDITIONBROADCAST(&m_continue);
}
 
// --------------------------------------------------------------------
void G4MTBarrier::WaitForReadyWorkers()
{
  // Step-1: Master enters a loop to wait all workers to be ready
  Wait();
  // Done, all workers are ready, broadcast a continue signal
  ReleaseBarrier();
}
 
// --------------------------------------------------------------------
void G4MTBarrier::ResetCounter()
{
  G4AutoLock l(&m_mutex);
  m_counter = 0;
}
 
// --------------------------------------------------------------------
unsigned int G4MTBarrier::GetCounter()
{
  G4AutoLock l(&m_mutex);
  const unsigned int result = m_counter;
  return result;
}