DCacheFile.cc

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#include "Utilities/DCacheAdaptor/interface/DCacheFile.h"
#include "FWCore/Utilities/interface/Exception.h"
#include "FWCore/Utilities/interface/EDMException.h"
#include "FWCore/MessageLogger/interface/MessageLogger.h"
#include <cassert>
#include <vector>
#include <unistd.h>
#include <fcntl.h>
#include <dcap.h>
 
DCacheFile::DCacheFile(void) : m_fd(EDM_IOFD_INVALID), m_close(false) {}
 
DCacheFile::DCacheFile(IOFD fd) : m_fd(fd), m_close(true) {}
 
DCacheFile::DCacheFile(const char *name, int flags /* = IOFlags::OpenRead */, int perms /* = 066 */)
    : m_fd(EDM_IOFD_INVALID), m_close(false) {
  open(name, flags, perms);
}
 
DCacheFile::DCacheFile(const std::string &name, int flags /* = IOFlags::OpenRead */, int perms /* = 066 */)
    : m_fd(EDM_IOFD_INVALID), m_close(false) {
  open(name.c_str(), flags, perms);
}
 
DCacheFile::~DCacheFile(void) {
  if (m_close)
    edm::LogError("DCacheFileError") << "Destructor called on dCache file '" << m_name
                                     << "' but the file is still open";
}
 
void DCacheFile::create(const char *name, bool exclusive /* = false */, int perms /* = 066 */) {
  open(name,
       (IOFlags::OpenCreate | IOFlags::OpenWrite | IOFlags::OpenTruncate | (exclusive ? IOFlags::OpenExclusive : 0)),
       perms);
}
 
void DCacheFile::create(const std::string &name, bool exclusive /* = false */, int perms /* = 066 */) {
  open(name.c_str(),
       (IOFlags::OpenCreate | IOFlags::OpenWrite | IOFlags::OpenTruncate | (exclusive ? IOFlags::OpenExclusive : 0)),
       perms);
}
 
void DCacheFile::open(const std::string &name, int flags /* = IOFlags::OpenRead */, int perms /* = 066 */) {
  open(name.c_str(), flags, perms);
}
 
void DCacheFile::open(const char *name, int flags /* = IOFlags::OpenRead */, int perms /* = 066 */) {
  // Actual open
  if ((name == nullptr) || (*name == 0)) {
    edm::Exception ex(edm::errors::FileOpenError);
    ex << "Cannot open a file without a name";
    ex.addContext("Calling DCacheFile::open()");
    throw ex;
  }
 
  if ((flags & (IOFlags::OpenRead | IOFlags::OpenWrite)) == 0) {
    edm::Exception ex(edm::errors::FileOpenError);
    ex << "Must open file '" << name << "' at least for read or write";
    ex.addContext("Calling DCacheFile::open()");
    throw ex;
  }
 
  // If I am already open, close old file first
  if (m_fd != EDM_IOFD_INVALID && m_close)
    close();
 
  // Translate our flags to system flags
  int openflags = 0;
 
  if ((flags & IOFlags::OpenRead) && (flags & IOFlags::OpenWrite))
    openflags |= O_RDWR;
  else if (flags & IOFlags::OpenRead)
    openflags |= O_RDONLY;
  else if (flags & IOFlags::OpenWrite)
    openflags |= O_WRONLY;
 
  if (flags & IOFlags::OpenNonBlock)
    openflags |= O_NONBLOCK;
 
  if (flags & IOFlags::OpenAppend)
    openflags |= O_APPEND;
 
  if (flags & IOFlags::OpenCreate)
    openflags |= O_CREAT;
 
  if (flags & IOFlags::OpenExclusive)
    openflags |= O_EXCL;
 
  if (flags & IOFlags::OpenTruncate)
    openflags |= O_TRUNC;
 
  IOFD newfd = EDM_IOFD_INVALID;
  dc_errno = 0;
  if ((newfd = dc_open(name, openflags, perms)) == -1) {
    edm::Exception ex(edm::errors::FileOpenError);
    ex << "dc_open(name='" << name << "', flags=0x" << std::hex << openflags << ", permissions=0" << std::oct << perms
       << std::dec << ") => error '" << dc_strerror(dc_errno) << "' (dc_errno=" << dc_errno << ")";
    ex.addContext("Calling DCacheFile::open()");
    throw ex;
  }
 
  m_name = name;
  m_fd = newfd;
 
  // Turn off read-ahead, or adjust read-ahead size depending on
  // whether buffering has been requested.  This is a very tricky
  // balance here.  Without read-ahead data processing appears to
  // become exceedingly slow, and with default (1MB) read-ahead
  // it appears to saturate disk servers and network.  Try tread
  // reasonable middle ground here.
  if (flags & IOFlags::OpenUnbuffered)
    dc_noBuffering(m_fd);
  else
    dc_setBufferSize(m_fd, 64000);
 
  m_close = true;
 
  edm::LogInfo("DCacheFileInfo") << "Opened " << m_name;
}
 
void DCacheFile::close(void) {
  if (m_fd == EDM_IOFD_INVALID) {
    edm::LogError("DCacheFileError") << "DCacheFile::close(name='" << m_name << "') called but the file is not open";
    m_close = false;
    return;
  }
 
  dc_errno = 0;
  if (dc_close(m_fd) == -1)
    edm::LogWarning("DCacheFileWarning") << "dc_close(name='" << m_name << "') failed with error '"
                                         << dc_strerror(dc_errno) << "' (dc_errno=" << dc_errno << ")";
 
  m_close = false;
  m_fd = EDM_IOFD_INVALID;
 
  // Caused hang.  Will be added back after problem is fixed.
  // edm::LogInfo("DCacheFileInfo") << "Closed " << m_name;
}
 
void DCacheFile::abort(void) {
  if (m_fd != EDM_IOFD_INVALID)
    dc_close(m_fd);
 
  m_close = false;
  m_fd = EDM_IOFD_INVALID;
}
 
static const int BUGLINE = __LINE__ + 1;
// Apparently dc_read can return short reads; I don't know if dc_write
// will also return short writes.  This is a bug in dCache.  POSIX,
// apparently contrary to the understanding of dCache authors, does
// not allow reads from files to return short, and in fact no network
// file system returns short reads.  For more details please refer to
// http://www.opengroup.org/onlinepubs/000095399/functions/read.html:
//    The value returned may be less than nbyte if the number of
//    bytes left in the file is less than nbyte, if the read()
//    request was interrupted by a signal, or if the file is a
//    pipe or FIFO or special file and has fewer than nbyte bytes
//    immediately available for reading.
// (In other words, barring signals (which should use SA_RESTART and
// in any case should not affect dCache) the only way a read from a
// file can return short is when there is nothing left to read.)
IOSize DCacheFile::read(void *into, IOSize n) {
  IOSize done = 0;
  while (done < n) {
    dc_errno = 0;
    ssize_t s = dc_read(m_fd, (char *)into + done, n - done);
    if (s == -1) {
      edm::Exception ex(edm::errors::FileReadError);
      ex << "dc_read(name='" << m_name << "', n=" << (n - done) << ") failed with error '" << dc_strerror(dc_errno)
         << "' (dc_errno=" << dc_errno << ")";
      ex.addContext("Calling DCacheFile::read()");
      throw ex;
    } else if (s == 0)
      // end of file
      break;
    else if (s < ssize_t(n - done))
      edm::LogInfo("DCacheFileWarning") << "dc_read(name='" << m_name << "', n=" << (n - done)
                                        << ") returned a short read of " << s << " bytes; "
                                        << "please report a bug in dCache referencing the "
                                        << "comment on line " << BUGLINE << " of " << __FILE__;
    done += s;
  }
 
  return done;
}
 
IOSize DCacheFile::write(const void *from, IOSize n) {
  IOSize done = 0;
  while (done < n) {
    dc_errno = 0;
    ssize_t s = dc_write(m_fd, (const char *)from + done, n - done);
    if (s == -1) {
      edm::Exception ex(edm::errors::FileWriteError);
      ex << "dc_write(name='" << m_name << "', n=" << (n - done) << ") failed with error '" << dc_strerror(dc_errno)
         << "' (dc_errno=" << dc_errno << ")";
      ex.addContext("Calling DCacheFile::write()");
      throw ex;
    } else if (s < ssize_t(n - done))
      edm::LogInfo("DCacheFileWarning") << "dc_write(name='" << m_name << "', n=" << (n - done)
                                        << ") returned a short write of " << s << " bytes; "
                                        << "please report a bug in dCache referencing the "
                                        << "comment on line " << BUGLINE << " of " << __FILE__;
    done += s;
  }
 
  return done;
}
 
IOSize DCacheFile::readv(IOBuffer *into, IOSize buffers) {
  assert(!buffers || into);
 
  // readv may not support zero buffers.
  if (!buffers)
    return 0;
 
  // Convert the buffers to system format.
  std::vector<iovec> bufs(buffers);
  for (IOSize i = 0; i < buffers; ++i) {
    bufs[i].iov_len = into[i].size();
    bufs[i].iov_base = (caddr_t)into[i].data();
  }
 
  // Read as long as signals cancel the read before doing anything.
  dc_errno = 0;
  ssize_t n = dc_readv(m_fd, &bufs[0], buffers);
 
  // If it was serious error, throw it.
  if (n == -1) {
    edm::Exception ex(edm::errors::FileReadError);
    ex << "dc_readv(name='" << m_name << "', iov[" << buffers << "]) failed with error '" << dc_strerror(dc_errno)
       << "' (dc_errno=" << dc_errno << ")";
    ex.addContext("Calling DCacheFile::readv()");
    throw ex;
  }
 
  // Return the number of bytes actually read.
  return n;
}
 
IOSize DCacheFile::readv(IOPosBuffer *into, IOSize buffers) {
  assert(!buffers || into);
 
  // readv may not support zero buffers.
  if (!buffers)
    return 0;
 
  // Convert the buffers to system format.
  std::vector<iovec2> bufs(buffers);
  IOSize total = 0;
  for (IOSize i = 0; i < buffers; ++i) {
    bufs[i].offset = into[i].offset();
    bufs[i].len = into[i].size();
    bufs[i].buf = (char *)into[i].data();
    total += into[i].size();
  }
 
  // Read as long as signals cancel the read before doing anything.
  dc_errno = 0;
  ssize_t n = dc_readv2(m_fd, &bufs[0], buffers);
 
  // If it was serious error, throw it.
  if (n == -1) {
    edm::Exception ex(edm::errors::FileReadError);
    ex << "dc_readv2(name='" << m_name << "', iov2[" << buffers << "]) failed with error '" << dc_strerror(dc_errno)
       << "' (dc_errno=" << dc_errno << ")";
    ex.addContext("Calling DCacheFile::readv()");
    throw ex;
  }
  // dc_readv2 returns 0 on success.
  return (n == 0) ? total : 0;
}
 
IOOffset DCacheFile::position(IOOffset offset, Relative whence /* = SET */) {
  if (m_fd == EDM_IOFD_INVALID) {
    cms::Exception ex("FilePositionError");
    ex << "DCacheFile::position() called on a closed file";
    throw ex;
  }
  if (whence != CURRENT && whence != SET && whence != END) {
    cms::Exception ex("FilePositionError");
    ex << "DCacheFile::position() called with incorrect 'whence' parameter";
    throw ex;
  }
  IOOffset result;
  int mywhence = (whence == SET ? SEEK_SET : whence == CURRENT ? SEEK_CUR : SEEK_END);
 
  dc_errno = 0;
  if ((result = dc_lseek64(m_fd, offset, mywhence)) == -1) {
    cms::Exception ex("FilePositionError");
    ex << "dc_lseek64(name='" << m_name << "', offset=" << offset << ", whence=" << mywhence << ") failed with error '"
       << dc_strerror(dc_errno) << "' (dc_errno=" << dc_errno << ")";
    ex.addContext("Calling DCacheFile::position()");
    throw ex;
  }
  // FIXME: dCache returns incorrect value on SEEK_END.
  // Remove this hack when dcap has been fixed.
  if (whence == SEEK_END && (result = dc_lseek64(m_fd, result, SEEK_SET)) == -1) {
    cms::Exception ex("FilePositionError");
    ex << "dc_lseek64(name='" << m_name << "', offset=" << offset << ", whence=" << SEEK_SET << ") failed with error '"
       << dc_strerror(dc_errno) << "' (dc_errno=" << dc_errno << ")";
    ex.addContext("Calling DCacheFile::position()");
    throw ex;
  }
  return result;
}
 
void DCacheFile::resize(IOOffset /* size */) {
  cms::Exception ex("FileResizeError");
  ex << "DCacheFile::resize(name='" << m_name << "') not implemented";
  throw ex;
}