Re: Introduction

On Fri, 29 Apr 2005 11:16:23 +0200
  Serassio Guido <guido.serassio@acmeconsulting.it> wrote:
> Hi Evgeny,
>
> At 09.52 29/04/2005, Evgeny Kotsuba wrote:
>>>FD_READ_METHOD/FD_WRITE_METHOD macros should be more efficient.
>>>Look here:
>>>http://cvs.sourceforge.net/viewcvs.py/squid/squid/src/fd.c?rev=1.7.16.9&only_with_tag=nt-2_5&view=auto
>>I don't understand why macros may be more efficient.
>>I use things like
>>int squid_fde::read(char *buf, int len)
>>{ int rc=-1;
>> switch(type)
>> { case FD_SOCKET:
>> if(fh < 0)
>> { debug(91, 0) ("squid_fde::read WARNING: fh=%i\n",fh);
>> rc = -1;
>> break;
>> }
>> rc = recv(fh, buf, len, 0 /* MSG_DONTWAIT ? */);
>> break;
>> case FD_NONE:
>> fatalf("Attempt to Read with FD_NONE type handle %i
>>bytes",
>> len);
>> return -1;
>> case FD_PIPE:
>> case FD_PIPE_READ:
>> rc = ::read(fh, buf, len);
>> break;
>> default:
>> rc = ::read(fh, buf, len);
>> }
>> if(rc>0) bytes_read += rc;
>> return rc;
>>}
>
> Your code is more bigger and long, for any I/O you do:
>
> - a function call with stack and context switch (your function seems
>to be not inlined)
> - a fd_table lookup
> - a decision
> - call to the correct I/O function.
>
> Macros are defined in squid.h as:
>
> #define FD_READ_METHOD(fd, buf, len) (*fd_table[fd].read_method)(fd,
>buf, len)
> #define FD_WRITE_METHOD(fd, buf, len)
>(*fd_table[fd].write_method)(fd, buf, len)
>
> read_method and write_method pointers are initialized during fd_open
>
> Everywher in the 2.5 and 3.0 source code you find already only the
> FD_READ_METHOD/FD_WRITE_METHOD macros instead of read() and write().
>
> Whith macros for any I/O we do:
> - a fd_table lookup for the function pointer
> - call to the correct I/O function with the previous pointer
>
> More faster.
>
You make me laugh. squid2.5 use read/write/send/recv/ etc. as well
as FD_READ_METHOD/FD_WRITE_METHOD.
It seems the same things are in squid3.
With classes we have only read/write/open/close to any handle and
 can control it in single place.
Why you don't see "bytes_read += rc;" that is fd_bytes() and that
is one more function call etc. ?

  
SY,
Evgeny Kotsuba
Received on Fri Apr 29 2005 - 16:40:16 MDT