Re: 1.30.0 - problem with filesystem lib

From: Russell Hind (yg-boost-users_at_[hidden])
Date: 2003-03-21 04:00:16

Russ Wood wrote:
> Hi,
> 
> When using the filesystem lib in the 1.30.0 release, I experience hangs
> when incrementing the directory iterator.
> 
> The compiler I've been using is MinGW, an example that exhibits the
> behaviour on my machine is included below.
> 
> The hang only occurs when -mthreads is used.
> 
> The hang occurs on the increment when there are no more files in the
> directory.
> 

I had the same problem with C++Builder 6 when first using the filesystem 
library.  The default builds for filesystem are single threaded.  If 
your application is multi-threaded, then you need to re-build the 
filesystem library with multi-threading (it uses mutexes somewhere (I 
think from smart_ptr but can't remember)).  If you use the 
single-threaded library, then you don't get the mutex, but the 
++operator is inlined and tries to lock it.  This causes a hang as the 
win32 light-weight mutex is stored as just an integer (long maybe), so 
the program just hangs waiting for it to be cleared.

I have built four versions of the library

libboost_filesystem.lib    - release, single-threaded
libboost_filesystemd.lib   - debug, single-threaded
libboost_filesystemmt.lib  - release, multi-threaded
libboost_filesystemmtd.lib - debug, multi-threaded

I use a #pragma int the code to link the appropriate lib depending on 
Borland's __MT__ define (and also if I want debugging or not)

HTH

Russell