MMap::MMap (const FileDescriptor& fd, bool const sequential)
:
size (fd.size()),
ptr (mmap (NULL, size, PROT_READ|PROT_WRITE,
MAP_SHARED|MAP_NORESERVE, fd.get(), 0)),
mapped (ptr != GU_MAP_FAILED)
{
if (!mapped)
{
gu_throw_error(errno) << "mmap() on '" << fd.name()
<< "' failed";
}
#if !defined(__sun__) && !defined(__APPLE__) && !defined(__FreeBSD__)
/* Solaris, Darwin, and FreeBSD do not have MADV_DONTFORK */
if (posix_madvise (ptr, size, MADV_DONTFORK))
{
int const err(errno);
log_warn << "Failed to set MADV_DONTFORK on " << fd.name()
<< ": " << err << " (" << strerror(err) << ")";
}
#endif
/* benefits are questionable */
if (sequential && posix_madvise (ptr, size, MADV_SEQUENTIAL))
{
int const err(errno);
log_warn << "Failed to set MADV_SEQUENTIAL on " << fd.name()
<< ": " << err << " (" << strerror(err) << ")";
}
log_debug << "Memory mapped: " << ptr << " (" << size << " bytes)";
}
