Re: [Bug-wget] Remove set_windows_fd_as_blocking_socket()?

[Ray Satiro]

On 8/5/2014 4:48 PM, Gisle Vanem wrote:
> A little study of why calling the function 
> 'set_windows_fd_as_blocking_socket()' is needed, reveals that on 
> downloading a big file (400MByte using ftp), the Winsock functions 
> 'WSASetLastError()' and 'WSAGetLastError()' are called approx. 277.000 
> times!!  IMHO this is a terrible waste of CPU-time.

How many times is select called?

> I failed to find a Gnulib reference/changelog where this bug was fixed 
> (after 2011), but reading some sources failed to find any place where 
> a network-socket is set to blocking in Gnulib's select() or poll().
> Hence I request that the call to 'set_windows_fd_as_blocking_socket()'
> should be removed.

The function should only be called on a non-blocking socket to set it 
blocking. It was needed because gnulib's select called WSAEventSelect() 
which turns blocking sockets into non-blocking. After every select call 
in wget the socket had to be turned back into blocking because wget used 
blocking sockets. Assuming both those things are still true and the wget 
team is not going back to MS select() then the code is needed. A cursory 
check of select.c and I see WSAEventSelect() is still used for sockets:
http://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=blob;f=lib/select.c;h=acb67a0e7041766daae1d1a90ac0e502f5811754;hb=HEAD#l377

The WSASetLastError()/WSAGetLastError() in 
set_windows_fd_as_blocking_socket() are unfortunately necessary to wait 
until the socket is converted back to blocking. I could not ascertain 
that the winsock last error code would be set during the ioctl in all 
cases so I zeroed it beforehand using WSASetLastError(), then wait until 
the socket went back to blocking using WSAGetLastError(). Excessive CPU 
time for just those calls my gut says no but you may best me on that. I 
know that GetLastError()/SetLastError() just read/write a variable that 
isn't exposed and I'm pretty sure WSAGetLastError()/WSASetLastError() do 
the same.

Jay