RobustMutex.cpp

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#include "uhallibs/ipc/RobustMutex.hpp"
 
#include "uhal/log/log.hpp"
#include <cstring>
 
namespace uhallibs {
namespace ipc {
 
RobustMutex::RobustMutex()
  : mCount(0)
  , mSessionActive(false)
{
  pthread_mutexattr_t lAttr;
 
  int s = pthread_mutexattr_init(&lAttr);
  if (s != 0) {
    exception::MutexError lExc;
    log(lExc, "Error code ", uhal::Integer(s), " (", strerror(s), ") returned in mutex attr initialisation");
    throw lExc;
  }
 
  s = pthread_mutexattr_setpshared(&lAttr, PTHREAD_PROCESS_SHARED);
  if (s != 0) {
    exception::MutexError lExc;
    log(lExc, "Error code ", uhal::Integer(s), " (", strerror(s), ") returned by pthread_mutexattr_setpshared");
    throw lExc;
  }
 
  s = pthread_mutexattr_setrobust(&lAttr, PTHREAD_MUTEX_ROBUST);
  if (s != 0) {
    exception::MutexError lExc;
    log(lExc, "Error code ", uhal::Integer(s), " (", strerror(s), ") returned by pthread_mutexattr_setrobust");
    throw lExc;
  }
 
  s = pthread_mutex_init(&mMutex, &lAttr);
  if (s != 0) {
    exception::MutexError lExc;
    log(lExc, "Error code ", uhal::Integer(s), " (", strerror(s), ") returned in mutex initialisation");
    throw lExc;
  }
}
 
RobustMutex::~RobustMutex() {}
 
void
RobustMutex::lock()
{
  int s = pthread_mutex_lock(&mMutex);
  bool lLastOwnerDied = (s == EOWNERDEAD);
  if (lLastOwnerDied)
    s = pthread_mutex_consistent(&mMutex);
 
  if (s != 0) {
    exception::MutexError lExc;
    log(lExc,
        "Error code ",
        uhal::Integer(s),
        " (",
        strerror(s),
        ") returned when ",
        lLastOwnerDied ? "making mutex state consistent" : "locking mutex");
    throw lExc;
  }
}
 
void
RobustMutex::unlock()
{
  int s = pthread_mutex_unlock(&mMutex);
  if (s != 0)
    log(uhal::Error(), "Error code ", uhal::Integer(s), " (", strerror(s), ") returned when unlocking mutex");
}
 
uint64_t
RobustMutex::getCounter() const
{
  return mCount;
}
 
bool
RobustMutex::isActive() const
{
  return mSessionActive;
}
 
void
RobustMutex::startSession()
{
  mCount++;
  mSessionActive = true;
}
 
void
RobustMutex::endSession()
{
  mSessionActive = false;
}
 
} // namespace ipc
} // namespace uhal