SH::DiskWriterXRD Class Reference

an implementation of DiskWriter for the XRD protocol More...

#include <DiskWriterXRD.h>

Inheritance diagram for SH::DiskWriterXRD:

Collaboration diagram for SH::DiskWriterXRD:

Public Member Functions
void	testInvariant () const
	test the invariant of this object
	DiskWriterXRD (const std::string &val_path)
	standard constructor
	~DiskWriterXRD ()
	standard destructor
std::string	path () const
	the path where this file can be accessed or the empty string if it is not known (yet).
TFile *	file ()
	the file we are writing to
void	close ()
	closes the file we are writing to

Private Member Functions
virtual std::string	getPath () const override
	the path where this file can be accessed or the empty string if it is not known (yet).
virtual TFile *	getFile () override
	the file we are writing to
virtual void	doClose () override
	closes the file we are writing to

Private Attributes
std::string	m_tmp
	the temporary path being used
std::string	m_path
	the path being used
std::unique_ptr< TFile >	m_file
	the actual file object

Detailed Description

an implementation of DiskWriter for the XRD protocol

See also

DiskOutputXRD

Definition at line 21 of file DiskWriterXRD.h.

Constructor & Destructor Documentation

DiskWriterXRD()

SH::DiskWriterXRD::DiskWriterXRD

(

const std::string &

val_path

)

standard constructor

Guarantee

strong

Failures

out of memory I

Precondition

val_path.find ("root://") == 0

Definition at line 42 of file DiskWriterXRD.cxx.

    : m_path (val_path)
  {
    RCU_REQUIRE (val_path.find ("root://") == 0);
 
    const char *tmpdir = getenv ("TMPDIR");
    std::size_t hash {0};
    boost::hash_combine (hash, std::hash<pid_t>() (getpid()));
    std::size_t tries = 0;
    while (m_file == nullptr || !m_file->IsOpen())
    {
      if (++ tries == 10)
        throw std::runtime_error ("infinite loop trying to create tempory file for DiskWriterXRD");
 
      auto time = std::chrono::duration_cast<std::chrono::microseconds>(std::chrono::system_clock::now().time_since_epoch()).count();
      boost::hash_combine (hash, std::hash<decltype(time)>() (time));
      std::size_t hash16 {hash};
      while (hash16 > 0xffff)
        hash16 = (hash16&0xffff) ^ (hash16 >> 16);
 
      std::ostringstream str;
      if (tmpdir)
    str << tmpdir;
      else
    str << "/tmp";
      str << "/SH-XRD-" << m_path.substr (m_path.rfind ("/")+1)
          << "-" << std::format("{:04x}", hash16);
      m_tmp = str.str();
      if (gSystem->AccessPathName (m_tmp.c_str()) != 0)
    m_file.reset (TFile::Open (m_tmp.c_str(), "CREATE"));
    }
 
    RCU_NEW_INVARIANT (this);
  }

~DiskWriterXRD()

SH::DiskWriterXRD::~DiskWriterXRD

(

)

standard destructor

Guarantee

no-fail

Definition at line 80 of file DiskWriterXRD.cxx.

  {
    RCU_DESTROY_INVARIANT (this);
 
    if (m_file != nullptr)
    {
      try
      {
    close ();
      } catch (std::exception& e)
      {
    std::cerr << "exception closing file " << m_path << ": "
          << e.what() << std::endl;
    
      } catch (...)
      {
    std::cerr << "unknown exception closing file " << m_path << std::endl;
      }
    }
  }

Member Function Documentation

close()

void SH::DiskWriter::close ( )

inherited

closes the file we are writing to

Guarantee

basic

Failures

i/o errors
file already closed

Definition at line 66 of file DiskWriter.cxx.

  {
    RCU_CHANGE_INVARIANT (this);
 
    doClose ();
  }

doClose()

void SH::DiskWriterXRD::doClose ( )

overrideprivatevirtual

closes the file we are writing to

Guarantee

basic

Failures

i/o errors
file already closed

Rationale

the virtual part of DiskWriter::close

Implements SH::DiskWriter.

Definition at line 123 of file DiskWriterXRD.cxx.

  {
    RCU_CHANGE_INVARIANT (this);
    RCU_REQUIRE2_SOFT (m_file != nullptr, "file already closed");
 
    if (m_file->IsOpen())
    {
      if (m_file->Write () < 0)
    RCU_THROW_MSG ("failed to write to file: " + m_path);
      m_file->Close ();
    }
 
    std::random_device rd;
    std::mt19937 gen (rd());
    bool success = false;
    unsigned tries = 0u;
    while (!success)
    {
      try
      {
        // using the -f flag, because if this copy failed previously
        // we need to force an overwrite.  note that there would be no
        // point in leaving this out on the first try (even though
        // there should be no file there), because it would just fail
        // and retry with the flag set.
        RCU::Shell::exec ("xrdcp -f " + RCU::Shell::quote (m_tmp) + " " + RCU::Shell::quote (m_path));
        success = true;
      } catch (...)
      {
        std::cerr << "encountered error copying files to XRD path: \"" << m_path << "\"" << std::endl;
        if (tries < 10u)
        {
          tries += 1;
          // sleeping for a random period of time, to reduce the
          // chance that the problem is that multiple jobs finishing
          // at the same time keep overloading the server by
          // repeatedly hitting it at the same time.
          unsigned seconds = std::uniform_int_distribution<>(30,60) (gen);
          std::cerr << "sleeping for " << seconds << " seconds before retrying" << std::endl;
          std::this_thread::sleep_for (std::chrono::seconds(seconds));
        } else
        {
          std::cerr << "giving up, leaving file at " << m_tmp << std::endl;
          throw std::runtime_error ("failed to copy file to XRD");
        }
      }
    }
    RCU::Shell::exec ("rm " + RCU::Shell::quote (m_tmp));
    m_file.reset ();
  }

file()

TFile * SH::DiskWriter::file ( )

inherited

the file we are writing to

Guarantee

strong

Failures

file already closed

Postcondition

result != 0

Definition at line 54 of file DiskWriter.cxx.

  {
    RCU_CHANGE_INVARIANT (this);
 
    TFile *result = getFile ();
    RCU_REQUIRE (result != 0);
    return result;
  }

getFile()

TFile * SH::DiskWriterXRD::getFile ( )

overrideprivatevirtual

the file we are writing to

Guarantee

strong

Failures

file already closed

Postcondition

result != 0

Rationale

the virtual part of DiskWriter::file

Implements SH::DiskWriter.

Definition at line 113 of file DiskWriterXRD.cxx.

  {
    RCU_CHANGE_INVARIANT (this);
    RCU_REQUIRE2_SOFT (m_file != nullptr, "file already closed");
    return m_file.get();
  }

getPath()

std::string SH::DiskWriterXRD::getPath ( ) const

overrideprivatevirtual

the path where this file can be accessed or the empty string if it is not known (yet).

Rationale

while it is not guaranteed that every writer will know how to handle this, most writers will, and it can be useful. however, not every writer will know this until after the file is closed.

Rationale

the virtual part of DiskWriter::path

Implements SH::DiskWriter.

Definition at line 104 of file DiskWriterXRD.cxx.

  {
    RCU_READ_INVARIANT (this);
    return m_path;
  }

path()

std::string SH::DiskWriter::path ( ) const

inherited

the path where this file can be accessed or the empty string if it is not known (yet).

Rationale

while it is not guaranteed that every writer will know how to handle this, most writers will, and it can be useful. however, not every writer will know this until after the file is closed.

Definition at line 45 of file DiskWriter.cxx.

  {
    RCU_READ_INVARIANT (this);
    return getPath ();
  }

testInvariant()

void SH::DiskWriterXRD::testInvariant

(

)

const

test the invariant of this object

Guarantee

no-fail

Definition at line 35 of file DiskWriterXRD.cxx.

  {
  }

Member Data Documentation

m_file

std::unique_ptr<TFile> SH::DiskWriterXRD::m_file

private

the actual file object

Definition at line 86 of file DiskWriterXRD.h.

m_path

std::string SH::DiskWriterXRD::m_path

private

the path being used

Definition at line 82 of file DiskWriterXRD.h.

m_tmp

std::string SH::DiskWriterXRD::m_tmp

private

the temporary path being used

Definition at line 78 of file DiskWriterXRD.h.

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

• DiskWriterXRD.h
• DiskWriterXRD.cxx