• Charma (19/19) May 30 2007 hello,
• Paul Findlay (14/25) May 30 2007 Output buffering? Since server.accept() blocks you have to wait for the ...
• Charma (2/33) May 30 2007 i do know that accept blocks... but it is called AFTER the writef... so ...
• Regan Heath (4/40) May 30 2007 I am fairly sure it is output buffering (as Paul suggested). Change wri...
• Charma (3/46) May 30 2007 ok, i got it now!

Charma <Motoko_Kusanagi web.de> writes:

hello,
I have a very strange problem with the accept function of TpcSocket. I
programmed a mini-server who is waiting for a user and does something as soon a
user has connected(this has no concern) anyway, i got this part of code:

...
scope TcpSocket server = new TcpSocket( );
Socket user;
server.blocking(true);
server.bind( addr );
server.listen( 10 );

...
while(!killServer)
{
writef( "Waiting for user..." ); // **
user = server.accept( );
writef("[OK]")
...
}

Now my problem is that the line marked with ** is only displayed when a user
connects... which is very strange... i can't figure out the problem, since i
tell him to FIRST write that line and THEN wait for a user...

Any ideas?
thanks

Paul Findlay <r.lph50+d gmail.com> writes:

 while(!killServer)
 {
 writef( "Waiting for user..." ); // **
 user = server.accept( );
 writef("[OK]")
 ...
 }

 Now my problem is that the line marked with ** is only displayed when a
 user connects... which is very strange... i can't figure out the problem,
 since i tell him to FIRST write that line and THEN wait for a user...
 Any ideas?

Output buffering? Since server.accept() blocks you have to wait for the user
to connect until writef next called, whereupon the buffered output may be
flushed?

Maybe try something like the following instead

import std.c.stdio;

// ...
while(/*...*/)
{
    writef( "Waiting for user..." );
    fflush(stdout); // or flushall();
    // ...
}

Yes, I am just guessing. Perhaps best to ask in digitalmars.D.learn

 - Paul

Charma <Motoko_Kusanagi web.de> writes:

Paul Findlay Wrote:

 while(!killServer)
 {
 writef( "Waiting for user..." ); // **
 user = server.accept( );
 writef("[OK]")
 ...
 }

 
 Now my problem is that the line marked with ** is only displayed when a
 user connects... which is very strange... i can't figure out the problem,
 since i tell him to FIRST write that line and THEN wait for a user...
 Any ideas?

 Output buffering? Since server.accept() blocks you have to wait for the user
 to connect until writef next called, whereupon the buffered output may be
 flushed?
 
 Maybe try something like the following instead
 
 import std.c.stdio;
 
 // ...
 while(/*...*/)
 {
     writef( "Waiting for user..." );
     fflush(stdout); // or flushall();
     // ...
 }
 
 Yes, I am just guessing. Perhaps best to ask in digitalmars.D.learn
 
  - Paul


i do know that accept blocks... but it is called AFTER the writef... so it
should black AFTER it... i still don't get it...

Regan Heath <regan netmail.co.nz> writes:

Charma Wrote:
 Paul Findlay Wrote:
 
 while(!killServer)
 {
 writef( "Waiting for user..." ); // **
 user = server.accept( );
 writef("[OK]")
 ...
 }

 
 Now my problem is that the line marked with ** is only displayed when a
 user connects... which is very strange... i can't figure out the problem,
 since i tell him to FIRST write that line and THEN wait for a user...
 Any ideas?

 Output buffering? Since server.accept() blocks you have to wait for the user
 to connect until writef next called, whereupon the buffered output may be
 flushed?
 
 Maybe try something like the following instead
 
 import std.c.stdio;
 
 // ...
 while(/*...*/)
 {
     writef( "Waiting for user..." );
     fflush(stdout); // or flushall();
     // ...
 }
 
 Yes, I am just guessing. Perhaps best to ask in digitalmars.D.learn
 
  - Paul

 
 
 i do know that accept blocks... but it is called AFTER the writef... so it
should black AFTER it... i still don't get it...

I am fairly sure it is output buffering (as Paul suggested).  Change writef to
writefln (I believe the output code flushes itself when a newline is sent). 
Failing that manually flushing as Paul mentioned should fix it.

To explain, you call writef, it puts that in the output buffer but does not
flush that to the screen.  You call accept, this waits for a connection, a
connection arrives and (for some reason) the output buffer gets flushed,
perhaps because the socket code flushes all handles at some stage?

Regan

Charma <Motoko_Kusanagi web.de> writes:

Regan Heath Wrote:

 Charma Wrote:
 Paul Findlay Wrote:
 
 while(!killServer)
 {
 writef( "Waiting for user..." ); // **
 user = server.accept( );
 writef("[OK]")
 ...
 }

 
 Now my problem is that the line marked with ** is only displayed when a
 user connects... which is very strange... i can't figure out the problem,
 since i tell him to FIRST write that line and THEN wait for a user...
 Any ideas?

 Output buffering? Since server.accept() blocks you have to wait for the user
 to connect until writef next called, whereupon the buffered output may be
 flushed?
 
 Maybe try something like the following instead
 
 import std.c.stdio;
 
 // ...
 while(/*...*/)
 {
     writef( "Waiting for user..." );
     fflush(stdout); // or flushall();
     // ...
 }
 
 Yes, I am just guessing. Perhaps best to ask in digitalmars.D.learn
 
  - Paul

 
 
 i do know that accept blocks... but it is called AFTER the writef... so it
should black AFTER it... i still don't get it...

 
 I am fairly sure it is output buffering (as Paul suggested).  Change writef to
writefln (I believe the output code flushes itself when a newline is sent). 
Failing that manually flushing as Paul mentioned should fix it.
 
 To explain, you call writef, it puts that in the output buffer but does not
flush that to the screen.  You call accept, this waits for a connection, a
connection arrives and (for some reason) the output buffer gets flushed,
perhaps because the socket code flushes all handles at some stage?
 
 Regan

ok, i got it now!

fflush fixed it, thanks a lot!