Re: [AOLSERVER] Thread safe version of Ns_ConnReturnOpenFd()?

[Jim Davidson]

Fred,

I was sitting on a bunch of code changes so I added routines to  
support this and checked it in.  Routine is Ns_ConnReturnOpenFdEx  
which includes an offset arg and uses a pread via new  
Ns_ConnSendFdEx.  Seems to work on a simple test I tried.

I'll send a separate note about the other code changes including some  
routines to get at the uploaded files in C....

-Jim






On Jul 18, 2005, at 5:11 PM, Fred Cox wrote:

--- Jim Davidson <[EMAIL PROTECTED]> wrote:


Hi,

You're right -- it's not thread safe.  Two options:

1.  Add the offset & length parameters and have the
server use pread
as you suggest (not sure about the equivalent on
win32).  I suppose
this would technically not be backward compatible in
case someone was
expecting the current seek position to change as a
result of the call
so perhaps a new API such as Ns_ConnReturnSharedFd
may make more sense.

2. Mmap the file and allow multiple threads to use
Ns_ConnReturnData.  You should be able to do this in
user code now.



Unfortunately, the files I'm using are quite large, so
under 32 bit OSes, I don't have the address space to
mmap the whole file.

A new API would work best for my particular
application.

If you like, I can do the coding and send you diffs
from 4.0.10 and/or the current CVS trunk.

Windows does suck in not having pread, but if people
want the functionality under Windows, I suppose it
could be done by mmap()ing the portion of the file to
sent, temporarily.

Not being a Windows coder (voluntarily), I'm not sure
if there's something special you have to do to use
large files.

Presumably, the right thing to do is have configure
check for pread, and fall back to mmap()ing the
portion of the file.

Fred



-Jim




On Jul 12, 2005, at 1:05 AM, Fred Cox wrote:


If multiple threads have the same file open, and

would

like to send portions of it back to the clients,
Ns_ConnReturnOpenFd() is close to being useful,

but it

fails because a seek() must be done before before
calling the API.  Also, the documentation

incorrectly

states that the full file will be sent, ignoring

the

length parameter.

A version that ultimately uses pread() instead of
read() would be useful in this case, but I suppose

it

doesn't fit the FILE * paradigm.  I don't know

about

Tcl channels, so I can't say whether it makes from
that perspective.

For now, I'm working around this by reading the
portion of the file into a buffer on the stack and
doing Ns_ConnReturnData().

Would it be worth while to append an offset

parameter

just for the FD case?

Fred





____________________________________________________

Sell on Yahoo! Auctions – no fees. Bid on great

items.

http://auctions.yahoo.com/


--
AOLserver - http://www.aolserver.com/

To Remove yourself from this list, simply send an

email to

<[EMAIL PROTECTED]> with the
body of "SIGNOFF AOLSERVER" in the email message.

You can leave the

Subject: field of your email blank.




--
AOLserver - http://www.aolserver.com/

To Remove yourself from this list, simply send an
email to <[EMAIL PROTECTED]> with the
body of "SIGNOFF AOLSERVER" in the email message.
You can leave the Subject: field of your email
blank.




__________________________________________________
Do You Yahoo!?
Tired of spam?  Yahoo! Mail has the best spam protection around
http://mail.yahoo.com


--
AOLserver - http://www.aolserver.com/

To Remove yourself from this list, simply send an email to  
<[EMAIL PROTECTED]> with the
body of "SIGNOFF AOLSERVER" in the email message. You can leave the  
Subject: field of your email blank.



--
AOLserver - http://www.aolserver.com/

To Remove yourself from this list, simply send an email to <[EMAIL PROTECTED]> 
with the
body of "SIGNOFF AOLSERVER" in the email message. You can leave the Subject: 
field of your email blank.