Den 17-08-2011 15:51, Steven Schveighoffer skrev:
On Wed, 17 Aug 2011 05:43:00 -0400, Jonas Drewsen <jdrew...@nospam.com>
wrote:
On 17/08/11 00.21, Jonathan M Davis wrote:
On Tuesday, August 16, 2011 12:32 Martin Nowak wrote:
On Tue, 16 Aug 2011 20:48:51 +0200, jdrewsen<jdrew...@nospam.com>
wrote:
Den 16-08-2011 18:55, Martin Nowak skrev:
On Tue, 16 Aug 2011 15:13:40 +0200, dsimcha<dsim...@yahoo.com> wrote:
On 8/16/2011 7:48 AM, Jonas Drewsen wrote:
Hi all,
This is a review request for the curl wrapper. Please read the
"known
issues" in the top of the source file and if possible suggest a
solution.
We also need somebody for running the review process. Anyone?
Code:
https://github.com/jcd/phobos/blob/curl-wrapper/etc/curl.d
Docs:
http://freeze.steamwinter.com/D/web/phobos/etc_curl.html
Demolish!
/Jonas
From a quick look, this looks very well thought out. I'll review it
more thoroughly when I have more time. A few questions/comments
from a
quick look at the docs:
Does the async stuff use D threads, or does Curl have its own async
API?
In your examples for postData, you have onReceive a ubyte[] and
write
it out to console. Did you mean to cast this to some kind of string?
For onReceive, what's the purpose of the return value?
If/when this module makes it into Phobos, are we going to start
including a libcurl binary with DMD distributions so that std.curl
feels truly **standard** and requires zero extra configuration?
I was also wondering about the async handling. In the long-term
I'd like
to see a bigger picture for async handling in phobos (offering
some kind
of futures, maybe event-loops etc.).
Though this is not a requirement for the curl wrapper now.
std.parallelism also has some kind of this stuff and file reading
would
benefit from it too.
This has been discussed before and I also think this is very
important.
But before that I think some kind of package management should be
prioritized (A DIP11 implementaion or a more traditional solution).
One thing I spotted at a quick glance, sending to be filled
buffers to
another thread should not be done by casting to shared not immutable.
I'm not entirely sure what you mean. There is no use of shared buffers
in the wrapper. I do cast the buffer between mutable/immutable because
only immutable or by value data can be passed using std.concurrency.
Since the buffers are only used by the thread that currently has the
buffer this is safe. I've previously asked for a non-cast solution
(ie.
some kind of move between threads semantic for std.concurrency) but
was
advised that this was the way to do it.
martin
Pardon the typo. What I meant is that AFAIK casting from immutable to
mutable has undefined behavior.
The intended method for sending a uint[] buffer to another thread is to
cast that
buffer to shared (cast(shared(uint[])) and casting away the shared
on the
receiving side.
It is allowed to send shared data using std.concurrency.
Casting away immutability and then altering data is undefined. Actually
casting it away is defined. So, if you have data in one thread that
you know
is unique, you can cast it to immutable (or
std.exception.assumeUnique to do
it) and then send it to another thread. On that thread, you can then
cast it
to mutable and alter it.
However, you're circumventing the type system when you do this. So,
you have
to be very careful. You're throwing away the guarantees that the
compiler
makes with regards to const and immutable. It _is_ guaranteed to work
though.
And I'm not sure that there's really any difference between casting
to shared
and back and casting to immutable and back. In both cases, you're
circumventing the type system. The main difference would be that if you
screwed up with immutable and cast away immutable on something that
really was
immutable rather than something that you cast to immutable just to
send it to
another thread, then you could a segfault when you tried to alter it,
since it
could be in ROM.
- Jonathan M Davis
Yeah I know you have to be careful when doing these kind of things. I
ran into the problem of sending buffers between threads (using
std.concurrency) so that they could be reused. There isn't any "move
ownership" support in place so Andrei suggested I could do it by
casting immutable.
If anyone knows of a cleaner way to do this please tell.
casting to shared and back. Passing shared data should be supported by
std.concurrency, and casting away shared is defined as long as you know
only one thread owns the data after casting.
-Steve
Why is this cleaner than casting to immutable and back?
/Jonas
