Re: [naviserver-devel] Upload Progress

[Vlad S. <vl...@cr...>]

I did very simple test, replaced write with aio_write and at the end 
checked aio_error/aio_return, they all returned 0 so mmap should work 
because file is synced. when i was doing aio_write i used aio_offset, so 
each aio_write would put data into separate region on the file.

Unfortunately i removed modified driver.c by accident, so i will have to 
do it again but something is not right in simply replacing write with 
aio_write and mmap. Without mmap, GetForm will have to read the file 
manually and parse it, it makes it more complicated and still, if writes 
are not complete we may get SIGBUS again.

The problem i see here i cannot be sure that all writes are completed, 
aio_error/aio_return are used to check only one last operation, not the 
batch of writes.

Zoran Vasiljevic wrote:
> 
> Am 02.01.2006 um 12:06 schrieb Zoran Vasiljevic:
> 
>>
>> Am 02.01.2006 um 04:43 schrieb Vlad Seryakov:
>>
>>> Tried it, nsd started crashing and i am guessing that the problem  is 
>>> combination of aio_write and mmap.
>>> When is start spooling, i just submit aio_write and return  
>>> immediately, so there are a lot of quick aio_write calls. By the  
>>> time i reach mmap, it looks like it's always ahead of actual  
>>> writing, so even when i am trying to check aio_error/aio_fsync in  
>>> the NsGetRequest, i still get SIGBUS/SIGSEGV when i access reqPtr- 
>>> >content, looks like mmap and aio_write are out of sync. And there  
>>> is no way to wait until all file buffers will be flushed, so  manual 
>>> separate thread implementation could be the only portable  solution. 
>>> Or i just do not understand aio_xxx things completely.
>>
>>
>> Hm... the idea is to mmap the file when all is read from the client.
>> So you'd have to aio_write into the file until all is received, then
>> at some point check the aio_status of the write (non-blocking) and
>> when it's done, revert to mmap the file. I do not believe you can
>> mix the aio_ with mmap.
> 
> 
> What I still do not know is: if you are allowed to issue multiple
> outstanding aio_writes one after another... It might be that you
> need to check wether the first aio_write is done before you attempt
> the next one.
> 
> Zoran
> 
> 
> 
> 
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-- 
Vlad Seryakov
571 262-8608 office
vl...@cr...
http://www.crystalballinc.com/vlad/