#include <FIFOConnection.hpp>

Inheritance diagram for OksSystem::FIFOConnection:

Collaboration diagram for OksSystem::FIFOConnection:

Public Member Functions
	FIFOConnection (const std::string &name)
	FIFOConnection (const File &file)
	~FIFOConnection ()
void	make (mode_t perm=0622) const
std::string	read_message () const
void	send_message (const std::string &message) const
OksSystem::Descriptor *	open_r (bool block=true)
	It opens the FIFO in read-only mode.
OksSystem::Descriptor *	open_w (bool block=true)
	It opens the FIFO in write-only mode.
OksSystem::Descriptor *	open_rw (bool block=true)
	It opens the FIFO in read and write mode.
void	send (const std::string &message) const
	It writes a message to a FIFO.
std::string	read () const
	It reads a single message (string) from a FIFO.
int	fd () const
	It gets the FIFO file descriptor.
void	close ()
	It closes the FIFO file descriptor.
Public Member Functions inherited from OksSystem::File
	File (const std::string &name)
	File (const char *name)
	File (const File &other)
virtual	~File ()
	operator std::string () const throw ()
	operator const char * () const throw ()
	operator bool () const throw ()
bool	equals (const File &other) const throw ()
	compare two files *‍/
	operator size_t () const
const std::string &	full_name () const throw ()
	full name for file *‍/
const char *	c_full_name () const throw ()
std::string	short_name () const throw ()
	short name for file *‍/
std::string	parent_name () const throw ()
	path of directory containing file *‍/
std::string	extension () const throw ()
	extension for file *‍/
int	depth () const throw ()
	depth of the file *‍/
OksSystem::File	parent () const
	parent of the current file *‍/
OksSystem::File	child (const std::string &name) const
	named child of the current directory *‍/
OksSystem::File	temporary (const std::string &prefix) const
bool	exists () const throw ()
	does the file exist *‍/
mode_t	permissions () const
	permissions for the file *‍/
std::string	pretty_permissions () const
	pretty permissions for the file *‍/
size_t	size () const
	size of file *‍/
uid_t	owner_id () const
	owner id of file *‍/
User	owner () const
	owner of the file *‍/
gid_t	group () const
	group of file *‍/
bool	is_regular () const
	is the file a directory *‍/
bool	is_directory () const
	is the file a regular file *‍/
bool	is_fifo () const
	is the file a named pipe *‍/
std::string	file_type () const
	type of the file *‍/
file_list_t	directory () const
	list of file in directory *‍/
void	unlink () const
	deletes (unlinks) file *‍/
void	rmdir () const
	deletes directory *‍/
void	remove () const
	recursively delete files and directories *‍/
void	rename (const File &other) const
	rename or moves the file *‍/
void	permissions (mode_t permissions) const
	sets the type of the file *‍/
void	make_dir (mode_t permissions) const
	creates a directory *‍/
void	make_path (mode_t permissions) const
	creates a full path *‍/
void	make_fifo (mode_t permissions) const
	creates a FIFO (named pipe) *‍/
void	ensure_path (mode_t permissions) const
	creates the parent path *‍/
std::istream *	input () const
	returns an input stream from the file*‍/
std::ostream *	output (bool append=false) const
	returns an output stream to the file*‍/

Static Public Attributes
static const unsigned int	MAX_MESSAGE_LEN = 512
Static Public Attributes inherited from OksSystem::File
static const char *const	FILE_FLAG_STR = "-rwxS"
	column headers for display of permissions *‍/
static const char *const	FILE_PROTOCOL = "file"
	string for the file protocol *‍/

Private Attributes
OksSystem::Descriptor *	m_fifo_fd
bool	m_is_blocking

Additional Inherited Members
Public Types inherited from OksSystem::File
typedef std::vector< OksSystem::File >	file_list_t
Static Public Member Functions inherited from OksSystem::File
static std::string	protocol (const std::string &url) throw ()
	extracts the protocol part of an url *‍/
static std::string	extension (const std::string &url) throw ()
	extracts the extension of a path or an url *‍/
static std::string	uri (const std::string &url) throw ()
	extracts the local path of an url *‍/
static std::string	short_name (const std::string &url) throw ()
	extracts the short file name of an url *‍/
static int	depth (const std::string &path) throw ()
	calculates depth of a path *‍/
static std::string	first_line (const std::string &text)
	extracts the first line of a text *‍/
static File	from_url (const std::string &url)
	build a file out of an URL *‍/
static std::string	working_directory ()
	current directory of process *‍/
static void	working_directory (const File &dir)
	set working directory of process *‍/
static std::string	expand_home (const std::string path)
	resolve home directory *‍/
static std::string	pretty_permissions (mode_t permissions)
	pretty prints permissions *‍/
static std::string	to_string (mode_t permissions) throw ()
	converts permission to string *‍/
static std::string	pretty_open_flag (int flags)
	pretty prints open flags *‍/
static std::string	pretty_size (size_t size, bool cut_small)
	pretty prints a file size *‍/
Protected Member Functions inherited from OksSystem::File
void	set_name (const std::string &name)
	sets the name of the file *‍/
mode_t	get_mode () const
	get mode associated with file (permission + type) *‍/
Static Protected Member Functions inherited from OksSystem::File
static int	unit (int u)
	calculates the value of a computer unit of order n (i.e KB,GB, etc *‍/
Protected Attributes inherited from OksSystem::File
std::string	m_full_name
	full name (path) of the file *‍/
Static Protected Attributes inherited from OksSystem::File
static const char *const	HUMAN_SIZE_STR [] = { "B", "KB", "MB", "GB" }
	strings for pretty printing file sizes *‍/
static const char *const	HUMAN_OPEN_STR []
	strings for pretty printing open flags *‍/
static const int	KILOBYTE = 1024
	number of bytes in a kilobyte *‍/
static const char *const	FILE_COMMAND_PATH = "/usr/bin/file"

Detailed Description

This class offers some basic tool to communicate simple messages using a filesystem based FIFO (named pipe).

Author: Matthias Wiesmann

Version: 1.0

Definition at line 29 of file FIFOConnection.hpp.

Constructor & Destructor Documentation

◆ FIFOConnection() [1/2]

OksSystem::FIFOConnection::FIFOConnection ( const std::string & name )

Constructor, does not actually create the named pipe in the file okssystem. To create it, use the make method

Parameters

name	the name (full path) of the named pipe

Definition at line 29 of file FIFOConnection.cpp.

  : OksSystem::File(name)
{
  m_fifo_fd = 0;
  m_is_blocking = true;
}

◆ FIFOConnection() [2/2]

OksSystem::FIFOConnection::FIFOConnection ( const File & file )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 38 of file FIFOConnection.cpp.

  : OksSystem::File(file)
{
  m_fifo_fd = 0;
  m_is_blocking = true;
}

◆ ~FIFOConnection()

OksSystem::FIFOConnection::~FIFOConnection ( )

Definition at line 45 of file FIFOConnection.cpp.

{
  delete m_fifo_fd;
}

Member Function Documentation

◆ close()

void OksSystem::FIFOConnection::close ( )

It closes the FIFO file descriptor.

Note: This method has to be used to close the FIFO file descriptor only when it is opened using one of the open_r(), open_w() or open_wr() methods.

Definition at line 238 of file FIFOConnection.cpp.

{
 
  delete m_fifo_fd;
  m_fifo_fd = 0;
}

◆ fd()

int OksSystem::FIFOConnection::fd ( ) const

It gets the FIFO file descriptor.

Note: This method can to be used only when the FIFO is opened using the open_r(), open_w() or open_rw() methods.

Returns: The FIFO file descriptor.

Definition at line 253 of file FIFOConnection.cpp.

{
 
  ERS_ASSERT(m_fifo_fd);
  return m_fifo_fd->fd();
}

◆ make()

void OksSystem::FIFOConnection::make ( mode_t perm = 0622 ) const

Definition at line 51 of file FIFOConnection.cpp.

{
  File::make_fifo(perm);
} // make

◆ open_r()

OksSystem::Descriptor * OksSystem::FIFOConnection::open_r ( bool block = true )

It opens the FIFO in read-only mode.

Returns: A pointer to a OksSystem::Descriptor object holding the FIFO file descriptor.

Parameters

block If TRUE the FIFO will be opened in blocking mode.

Definition at line 148 of file FIFOConnection.cpp.

{
 
  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;
}

◆ open_rw()

OksSystem::Descriptor * OksSystem::FIFOConnection::open_rw ( bool block = true )

It opens the FIFO in read and write mode.

Returns: A pointer to a OksSystem::Descriptor object holding the FIFO file descriptor.

Parameters

block If TRUE the FIFO will be opened in blocking mode.

Definition at line 208 of file FIFOConnection.cpp.

{
 
  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;
}

◆ open_w()

OksSystem::Descriptor * OksSystem::FIFOConnection::open_w ( bool block = true )

It opens the FIFO in write-only mode.

Returns: A pointer to a OksSystem::Descriptor object holding the FIFO file descriptor.

Parameters

block If TRUE the FIFO will be opened in blocking mode.

Definition at line 178 of file FIFOConnection.cpp.

{
 
  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;
}

◆ read()

std::string OksSystem::FIFOConnection::read ( ) const

It reads a single message (string) from a FIFO.

Returns: The actual message.

Note

The maximum message length is MAX_MESSAGE_LEN-1 bytes.
This method does not take care of opening the FIFO (as it happens in read_message()), and should be used only when the FIFO is opened using one of the open_r() or open_wr() methods (see linux "open", "fifo" and "read" man/info pages for more details).
This method will block or not depending on the way the FIFO has been opened.

Definition at line 124 of file FIFOConnection.cpp.

{
  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

◆ read_message()

std::string OksSystem::FIFOConnection::read_message ( ) const

Blocking read of a single message (string) from a FIFO

Returns: the actual message

Note: maximum message length is MAX_MESSAGE_LEN-1 bytes

Definition at line 62 of file FIFOConnection.cpp.

{
  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

◆ send()

void OksSystem::FIFOConnection::send ( const std::string & message ) const

It writes a message to a FIFO.

Parameters

message The message to write into the FIFO.

Note

The maximum message length is MAX_MESSAGE_LEN-1 bytes.
This method does not take care of opening the FIFO (as it happens in send_message()), and should be used only when the FIFO is opened using one of the open_w() or open_wr() methods (see linux "open", "fifo" and "write" man/info pages for more details).
This method will block or not depending on the way the FIFO has been opened.

Definition at line 105 of file FIFOConnection.cpp.

{
  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

◆ send_message()

void OksSystem::FIFOConnection::send_message ( const std::string & message ) const

Definition at line 82 of file FIFOConnection.cpp.

{
  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

Member Data Documentation

◆ m_fifo_fd

OksSystem::Descriptor* OksSystem::FIFOConnection::m_fifo_fd

private

Definition at line 54 of file FIFOConnection.hpp.

◆ m_is_blocking

bool OksSystem::FIFOConnection::m_is_blocking

private

Definition at line 55 of file FIFOConnection.hpp.

◆ MAX_MESSAGE_LEN

const unsigned int OksSystem::FIFOConnection::MAX_MESSAGE_LEN = 512

static

Definition at line 33 of file FIFOConnection.hpp.

The documentation for this class was generated from the following files:

/github/workspace/dunedaq/sourcecode/okssystem/include/okssystem/FIFOConnection.hpp
/github/workspace/dunedaq/sourcecode/okssystem/src/FIFOConnection.cpp

Public Member Functions

Static Public Attributes

Private Attributes

Additional Inherited Members

Detailed Description

Constructor & Destructor Documentation

◆ FIFOConnection() [1/2]

◆ FIFOConnection() [2/2]

◆ ~FIFOConnection()

Member Function Documentation

◆ close()

◆ fd()

◆ make()

◆ open_r()

◆ open_rw()

◆ open_w()

◆ read()

◆ read_message()

◆ send()

◆ send_message()

Member Data Documentation

◆ m_fifo_fd

◆ m_is_blocking

◆ MAX_MESSAGE_LEN