Re: CRT fd limitation in Squid NT port

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Serassio Guido wrote:
> Hi Andrey,
>
> At 21.22 05/07/2005, Andrey Shorin wrote:
>
>> Hello Guido,
>>
>> I've been thinking about the problem for a while. Here is what comes
>> to mind.
>>
>> The only way to leave out CRT fd number limitation is to give up CRT
>> use for files and sockets operations. On the other hand, code change
>> to the source tree should be minimal.
>
>
> I agree: MS CRT is too limited and the impact in the source code should
> be minimal.
>
>> Say, add one or two headers
>> and a .cc file. From that, here is an idea:
>>
>> We could implement a class, say, FileDescriptor. Then we derive FDfile,
>> FDtcp, FDpipe & FDudp from it (or whatever fd kind is needed).
>> FileDescriptor class should have pure virtual methods for write,
>> read, open, connect etc. Then we have functions like
>>
>> __inline int
>> write(FileDescriptor& fd, const void *buffer, unsigned int count) {
>> return fd.write(buffer, count);
>> }
>>
>> int FDtcp::write(const void *buffer, unsigned int count)
>> {
>> return ::send(fh /* member of FileDescriptor */,
>> buffer, count, 0);
>> }
>>
>> int FDfile::write(const void *buffer, unsigned int count)
>> {
>> DWORD cbWritten;
>>
>> if ( WriteFile(fh, buffer, count, &cbWritten, NULL ) {
>> return cbWritten;
>> } else {
>> ...
>> }
>> }
>>
>> This way, the source tree would remain mostly unchanged and squid
>> won't have that 2048 fd limitation.
>
>
> I think that changes should be deeper: My opinion is that we should
> remove any direct reference to FD concept creating a virtualized
> interface between Squid and the OS.
> And this isn't a so simple thing to do ... :-(
>
>> I haven't write something in C++ for quite a while. So I'm not sure
>> if the idea would work at all ;) May be template thing should be
>> used, which I'm not too familar with :) (but will read about it).
>
>
> My C++ knowledge is very limited too. I'm still looking, without success
> for now, for someone that could help me on this work.

You might look for inspiration at the ACE (Adaptive Communication
Environment) project, which is full of useful patterns for C++
programming around / across the "systems programmming" spectrum:

 http://www.cs.wustl.edu/~schmidt/ACE.html

The library includes abstractions which cross the POSIX / Win32 API
boundaries for all sorts of interesting problems.

Tres.
- --
===================================================================
Tres Seaver +1 202-558-7113 tseaver@palladion.com
Palladion Software "Excellence by Design" http://palladion.com
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Received on Tue Jul 05 2005 - 14:32:39 MDT