Re: [boost] Asio formal review - vc8.0 debug

From: Victor A. Wagner Jr. (vawjr_at_[hidden])
Date: 2005-12-27 01:54:26

At 11:59 2005-12-24, simon meiklejohn wrote:
>running a debug build of one of your examples in 
>vc8.0 (visual studio beta 2) asserts "list iterators incompatible"
>from a calling location in hash_map.hpp
>// Insert a new entry into the map.
>std::pair<iterator, bool> insert(const value_type& v)
>{
>   size_t bucket = boost::hash_value(v.first) % num_buckets;
>   iterator it = buckets_[bucket].first;
>   if (it == values_.end() )  <--- asserts
>
>Probably just "Safe" C++ library getting in the way. Anyone
>know a way to disable this checking?

you may be pleased to know that with the 
"release" vs2005 there is no assert (debug), but 
I'm concerned about the program itself.
I get different outputs from release and debug
release:
Successful accept
Successful connect
Successful receive
hello therePress any key to continue . . .
.....long pause before the last line.

debug:
Successful accept
Successful connect
Successful receive
hello 
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any key to continue . . .
......significant pause before the "Press any....."

ok, this intrigued me some....so I put 
breakpoints before the output of  "Successful........" and looked at  buf_
when in release, there was a '\0' after the 
"hello there", in debug, there wasn't.
I then looked up   readsome  for I/O streams in 
"The C++ Standard Library" Nicolai Josuttis... his documentation says
readsome() returns a std::streamsize (so you know 
how many characters are actually in the biffer) 
AND explicitly says there will be NO '\0' put into the buffer.

I haven't started my formal review of asio yet, 
but something is clearly amiss from looking at 
your program (and the signature for read_some()).

from 27.6.13 of the standard:
streamsize readsome(char_type* s, streamsize n);
30 Effects: Behaves as an unformatted input 
function (as described in 27.6.1.3, paragraph 1). After constructing
a sentry object, if !good() calls 
setstate(failbit) which may throw an exception, and
return. Otherwise extracts characters and stores 
them into successive locations of an array whose first
element is designated by s. If 
rdbuf()->in_avail() == -1, calls setstate(eofbit)
(which may throw ios_base::failure (27.4.4.3)), and extracts no characters;
— If rdbuf()->in_avail() == 0, extracts no characters
— If rdbuf()->in_avail() > 0, extracts min(rdbuf()->in_avail(),n)).
31 Returns: The number of characters extracted.

I guess it's spelled differently in asio than the 
function in the standard streams because there is 
no way to tell how much data we have.
I note there is no  .gcount() const   function either.

>Simon
>
>
>
>
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Victor A. Wagner Jr.      http://rudbek.com
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