FIFOConnection.cpp

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// DUNE DAQ modification notice:
// This file has been modified from the original ATLAS system source for the DUNE DAQ project.
// Fork baseline commit: system-00-00-20 (2020-09-25).
// Renamed since fork: yes (from src/FIFOConnection.cxx to src/FIFOConnection.cpp).
 
/*
 *  FIFOConnection.cxx
 *  OksSystem
 *
 *  Created by Matthias Wiesmann on 07.04.05.
 *  Copyright 2005 CERN. All rights reserved.
 *
 */
 
#include <fcntl.h>
 
#include "ers/ers.hpp"
 
#include "okssystem/FIFOConnection.hpp"
#include "okssystem/exceptions.hpp"
 
const unsigned int OksSystem::FIFOConnection::MAX_MESSAGE_LEN = 512;

 
OksSystem::FIFOConnection::FIFOConnection(const std::string& name)
  : OksSystem::File(name)
{
  m_fifo_fd = 0;
  m_is_blocking = true;
}

 
OksSystem::FIFOConnection::FIFOConnection(const File& file)
  : OksSystem::File(file)
{
  m_fifo_fd = 0;
  m_is_blocking = true;
}
 
OksSystem::FIFOConnection::~FIFOConnection()
{
  delete m_fifo_fd;
}
 
void
OksSystem::FIFOConnection::make(mode_t perm) const
{
  File::make_fifo(perm);
} // make

 
std::string
OksSystem::FIFOConnection::read_message() const
{
  ERS_ASSERT_MSG(exists(), "FIFO " << c_full_name() << " does not exist.");
  if (!is_fifo()) {
    ers::warning(OksSystem::Exception(ERS_HERE, std::string(c_full_name()) + std::string(" is not a FIFO")));
  } // should probably be FIFO
  OksSystem::Descriptor connection_fd(this, O_RDONLY, 0);
  char buffer[MAX_MESSAGE_LEN];
  while (true) {
    const int status = connection_fd.read(buffer, sizeof(buffer) - 1);
    if (status > 0) {
      ERS_ASSERT(status < (int)sizeof(buffer));
      buffer[status] = '\0'; // we make sure we have a C-string
      return std::string(buffer);
    } // if
    usleep(100000);
  } // while
} // read_message
 
void
OksSystem::FIFOConnection::send_message(const std::string& message) const
{
  ERS_ASSERT_MSG(exists(), "FIFO " << c_full_name() << " does not exist. Cannot put " << message << " into FIFO.");
  if (!is_fifo()) {
    ers::warning(OksSystem::Exception(ERS_HERE, std::string(c_full_name()) + std::string(" is not a FIFO")));
  } // should probably be FIFO
  const unsigned int l = message.size();
  ERS_RANGE_CHECK(1, l, MAX_MESSAGE_LEN);
  OksSystem::Descriptor connection_fd(this, O_WRONLY, 0);
  connection_fd.write(message.data(), l);
} // send_message

 
void
OksSystem::FIFOConnection::send(const std::string& message) const
{
  ERS_ASSERT(m_fifo_fd);
  const unsigned int l = message.size();
  ERS_RANGE_CHECK(1, l, MAX_MESSAGE_LEN);
  m_fifo_fd->write(message.data(), l);
} // send

 
std::string
OksSystem::FIFOConnection::read() const
{
  ERS_ASSERT(m_fifo_fd);
  char buffer[MAX_MESSAGE_LEN];
  while (true) {
    const int status = m_fifo_fd->read(buffer, sizeof(buffer) - 1);
    if (status > 0) {
      ERS_ASSERT(status < (int)sizeof(buffer));
      buffer[status] = '\0'; // we make sure we have a C-string
      return std::string(buffer);
    } // if
    if (m_is_blocking == false && status == 0)
      return std::string("");
    usleep(100000); // Slow down the loop
  } // while
} // read

 
OksSystem::Descriptor*
OksSystem::FIFOConnection::open_r(bool block)
{
 
  ERS_ASSERT(!m_fifo_fd);
 
  int flags = O_RDONLY;
 
  if (block == false) {
    flags = O_RDONLY | O_NONBLOCK;
    m_is_blocking = false;
  }
 
  try {
    m_fifo_fd = new OksSystem::Descriptor(this, flags, 0);
  } catch (OksSystem::OpenFileIssue& ex) {
    delete m_fifo_fd;
    m_fifo_fd = 0;
    throw;
  }
 
  return m_fifo_fd;
}

 
OksSystem::Descriptor*
OksSystem::FIFOConnection::open_w(bool block)
{
 
  ERS_ASSERT(!m_fifo_fd);
 
  int flags = O_WRONLY;
 
  if (block == false) {
    flags = O_WRONLY | O_NONBLOCK;
    m_is_blocking = false;
  }
 
  try {
    m_fifo_fd = new OksSystem::Descriptor(this, flags, 0);
  } catch (OksSystem::OpenFileIssue& ex) {
    delete m_fifo_fd;
    m_fifo_fd = 0;
    throw;
  }
 
  return m_fifo_fd;
}

 
OksSystem::Descriptor*
OksSystem::FIFOConnection::open_rw(bool block)
{
 
  ERS_ASSERT(!m_fifo_fd);
 
  int flags = O_RDWR;
 
  if (block == false) {
    flags = O_RDWR | O_NONBLOCK;
    m_is_blocking = false;
  }
 
  try {
    m_fifo_fd = new OksSystem::Descriptor(this, flags, 0);
  } catch (OksSystem::OpenFileIssue& ex) {
    delete m_fifo_fd;
    m_fifo_fd = 0;
    throw;
  }
 
  return m_fifo_fd;
}

 
void
OksSystem::FIFOConnection::close()
{
 
  delete m_fifo_fd;
  m_fifo_fd = 0;
}

 
int
OksSystem::FIFOConnection::fd() const
{
 
  ERS_ASSERT(m_fifo_fd);
  return m_fifo_fd->fd();
}