Re: [Evolution-hackers] Loading really large E-mails on devices with not enough Vm

[Philip Van Hoof <spam pvanhoof be>]

Looks like the GByteArray is still being created.

(gdb) break camel-mime-part-utils.c:82
Breakpoint 2 at 0xb6dd541e: file camel-mime-part-utils.c, line 82.
(gdb) delete 1
(gdb) cont
Continuing.

Breakpoint 2, simple_data_wrapper_construct_from_parser (dw=0xb3f02800, mp=0x827bcd0) at camel-mime-part-utils.c:82
82                      if (buffer != NULL) {
(gdb) print buffer
$1 = (GByteArray *) 0x80e4dc0
(gdb) 


Breakpoint 1, camel_mime_parser_step (parser=0x827bcd0, databuffer=0xb4882f3c, datalength=0xb4882f40) at camel-mime-parser.c:610
610             struct _header_scan_state *s = _PRIVATE (parser);
(gdb) bt
#0  camel_mime_parser_step (parser=0x827bcd0, databuffer=0xb4882f3c, datalength=0xb4882f40) at camel-mime-parser.c:610
#1  0xb6dd5456 in simple_data_wrapper_construct_from_parser (dw=0xb3f02800, mp=0x827bcd0) at camel-mime-part-utils.c:81
#2  0xb6dd55e9 in camel_mime_part_construct_content_from_parser (dw=0x824e8c8, mp=0x827bcd0) at camel-mime-part-utils.c:127
#3  0xb6dd6ff1 in construct_from_parser (mime_part=0x824e8c8, mp=0x827bcd0) at camel-mime-part.c:968
#4  0xb6dd70af in camel_mime_part_construct_from_parser (mime_part=0x824e8c8, mp=0x827bcd0) at camel-mime-part.c:996
#5  0xb6de1aab in construct_from_parser (multipart=0x8246f80, mp=0x827bcd0) at camel-multipart.c:577
#6  0xb6de1bea in camel_multipart_construct_from_parser (multipart=0x8246f80, mp=0x827bcd0) at camel-multipart.c:609
#7  0xb6dd5681 in camel_mime_part_construct_content_from_parser (dw=0x8254570, mp=0x827bcd0) at camel-mime-part-utils.c:144
#8  0xb6dd6ff1 in construct_from_parser (mime_part=0x8254570, mp=0x827bcd0) at camel-mime-part.c:968
#9  0xb6dd1de4 in construct_from_parser (dw=0x8254570, mp=0x827bcd0) at camel-mime-message.c:597
#10 0xb6dd70af in camel_mime_part_construct_from_parser (mime_part=0x8254570, mp=0x827bcd0) at camel-mime-part.c:996
#11 0xb6dd7122 in construct_from_stream (dw=0x8254570, s=0x826ab10) at camel-mime-part.c:1012
#12 0xb6dc2f63 in camel_data_wrapper_construct_from_stream (data_wrapper=0x8254570, stream=0x826ab10) at camel-data-wrapper.c:270
#13 0xb60fbd97 in maildir_get_message (folder=0x80def28, uid=0x8269dd0 "1192085835.11467_1.evergrey", 
    ........

pvanhoof schtrumpf:~/Current/mailtests/md/spam1/cur$ ls -alh 1192085835.11467_1.evergrey\!2\,SH 
-rw-r--r-- 1 pvanhoof pvanhoof 401M 2008-01-27 13:28 1192085835.11467_1.evergrey!2,SH
pvanhoof schtrumpf:~/Current/mailtests/md/spam1/cur$ 



On Sat, 2008-01-26 at 23:22 -0500, Jeffrey Stedfast wrote:
> Something like the attached patch might work, tho it is untested.
> 
> If this doesn't work, then I suspect the problem is that the seek
> position might get changed out from under the mime parser (assuming it
> is using either a CamelStreamFs or an fd).
> 
> Note that camel_stream_fs_new_with_fd[_and_bounds]() calls lseek() on
> the fd passed in.
> 
> >From the dup() man page:
> 
>        After  a  successful  return from dup() or dup2(), the old and new file
>        descriptors may be used interchangeably.  They refer to the  same  open
>        file description (see open(2)) and thus share file offset and file sta‐
>        tus flags; for example,  if  the  file  offset  is  modified  by  using
>        lseek(2)  on one of the descriptors, the offset is also changed for the
>        other.
> 
> So my guess is that this will break the parser :(
> 
> It might break in the stream case as well, you'd have to follow the code
> paths a bit to know for sure. For instance, even if creating the
> seekable substream doesn't perform an underlying seek on the original
> stream, setting it in a data wrapper might call camel_stream_reset()
> which /might/ do an lseek() on the source fs stream.
> 
> Not an insurmountable problem to solve, but it does make things a little
> more difficult and possibly touchy.
> 
> Jeff
> 
> 
> 
> On Sat, 2008-01-26 at 22:48 -0500, Jeffrey Stedfast wrote:
> > On Sat, 2008-01-26 at 22:12 -0500, Jeffrey Stedfast wrote:
> > > On Sat, 2008-01-26 at 13:44 +0100, Philip Van Hoof wrote:
> > > > This is what happens if you try to open a truly large E-mail on a device
> > > > that has not as much memory available:
> > > > 
> > > > Is there something we can do about this? Can we change the MIME parsing
> > > > algorithm to be less memory demanding for example?
> > > > 
> > > > Note that GArray is not really very sparse with memory once you start
> > > > having a really large array. Perhaps we can in stead change this to a
> > > > normal pointer array of a fixed size (do we know the size before we
> > > > start parsing, so that we can allocate an exact size in stead, perhaps?)
> > > 
> > > eh, why would you change it to a GPtrArray? It doesn't hold pointers, it
> > > holds message part content.
> > > 
> > > Unfortunately we don't know the size ahead of time.
> > > 
> > > I suppose you could use a custom byte array allocator so that you can
> > > force it to grow by larger chunks or something, dunno.
> > >
> > >
> > > The way GMime handles this is by not loading content into RAM, but 
> > > that may be harder to do with Camel, especially in the mbox case.
> > 
> > er, I should probably explain this:
> > 
> > - writing the code should be relatively easy to do, but in the mbox
> > case, the mbox may end up getting expunged or rewritten for some other
> > reason which may cause problems, not sure how that would work.
> > 
> > I think in Maildir, as long as the fd remains open, the file won't
> > actually disappear after an unlink() until the fd gets closed, so that
> > might work out ok assuming you can spare the fd (which might be the
> > other problem with Evolution?).
> > 
> > Jeff
> > 
> > 
> > _______________________________________________
> > Evolution-hackers mailing list
> > Evolution-hackers gnome org
> > http://mail.gnome.org/mailman/listinfo/evolution-hackers
> _______________________________________________
> Evolution-hackers mailing list
> Evolution-hackers gnome org
> http://mail.gnome.org/mailman/listinfo/evolution-hackers
-- 
Philip Van Hoof, freelance software developer
home: me at pvanhoof dot be 
gnome: pvanhoof at gnome dot org 
http://pvanhoof.be/blog
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