[reSIProcate] AbstractFifo bug?

Tue May 24 08:47:25 CDT 2005

I’ve noticed this problem too.   I’m pretty sure it’s Windows specific.
There is relatively new code in the Condition class for Windows.  Also
AbstractFifo.getNext(timeout) with a timeout hasn’t been used much inside
the stack itself.

Note:  The while (mFifo.empty()) line you are referencing is from getNext()
with no parameters – but the assertion happens in getNext(timeout).

The temporary fix I’ve been using is to change line 44 from 

If (mFifo.empty())  to

While (mFifo.empty())     

This more closely matches what getNext() without a timeout is doing.
Although I’m not entirely sure why getNext is even using a while statement.
Can anyone explain that?

My best guess it that there is a bug a with the windows Condition – such
that it will signal, even though nothing has been added to the Fifo.

I plan to look at this closer this week.

Note:  The mSize counter is always adjusted within a Mutex – so its value
should be properly maintained and protected.

Scott

  _____  

From: Micky Kaufmann [mailto:micky at proxy.co.il] 
Sent: Sunday, May 22, 2005 5:16 AM
To: Derek MacDonald; resiprocate-devel at list.sipfoundry.org
Subject: RE: [reSIProcate] AbstractFifo bug?

I’m working on windows, visual studio 7.1   (Maybe the problem is with the
Mutex being recursive?)

Still what troubles me in the AbstractFifo is the fact that the while
condition is ‘ while (mFifo.empty()) ’ but the assert is not on mFifo. So it
seems that the while condition should be ‘ while (mSize!=0) ’.

The bug appears when a client tries to reach a non registered contact - the
server tries to skip remaining stages of a transaction and terminate it but
it fails...

Here’s the stack trace:

>          repro.exe!_NMSG_WRITE(int rterrnum=10)  Line 195      C

            repro.exe!abort()  Line 44 + 0x7  C

            repro.exe!_assert(const char * expr=0x00a652b0, const char *
filename=0x00a65298, unsigned int lineno=57)  Line 306           C

            repro.exe!resip::AbstractFifo::getNext(int ms=100)  Line 57 +
0x1a            C++

            repro.exe!resip::TimeLimitFifo<resip::Message>::getNext(int
ms=100)  Line 143 + 0xc            C++

            repro.exe!repro::Proxy::thread()  Line 67 + 0xd    C++

            repro.exe!threadWrapper(void * threadParm=0x000e06dc)  Line 34 +
0xd C++

            kernel32.dll!7c80b50b() 

            ntdll.dll!7c96e0d4()         

            kernel32.dll!7c8399f3()   

And here is the debug info produces by repro:

INFO | 20050522-110727.926 | c:\sip\repro\Debug\repro.exe | REPRO:APP | 1724
| proxy.cxx:133 | Inserting new RequestContext
tid=28CA0A6D1F57474F96CCF80478461139 -> RequestContext:  identity=
candidates=[] count=1 final=0

INFO | 20050522-110727.941 | c:\sip\repro\Debug\repro.exe | REPRO:APP | 1724
| locationserver.cxx:50 | LocationServer monkey : no registered target for
sip:33 at mickyxp.proxy.local send 480

INFO | 20050522-110732.705 | c:\sip\repro\Debug\repro.exe |
RESIP:TRANSACTION | 3356 | TransactionState.cxx:357 | discarding stray
response: SipResp: 200 tid=c0a800190131c9b142904bd40000751c0000000a
cseq=OPTIONS / 10 from(wire)

INFO | 20050522-110732.986 | c:\sip\repro\Debug\repro.exe | REPRO:APP | 1724
| requestcontext.cxx:49 | RequestContext::process(TransactionTerminated)
28CA0A6D1F57474F96CCF80478461139 : RequestContext:  identity= candidates=[]
count=1 final=1

Assertion failed: mSize != 0, file .\os\AbstractFifo.cxx, line 57

INFO | 20050522-110752.699 | c:\sip\repro\Debug\repro.exe |
RESIP:TRANSACTION | 3356 | TransactionState.cxx:357 | discarding stray
response: SipResp: 200 tid=c0a800190131c9b142904be800006a170000000b
cseq=OPTIONS / 11 from(wire)

INFO | 20050522-110812.724 | c:\sip\repro\Debug\repro.exe |
RESIP:TRANSACTION | 3356 | TransactionState.cxx:357 | discarding stray
response: SipResp: 200 tid=c0a800190131c9b142904bfc000056860000000c
cseq=OPTIONS / 12 from(wire)

  _____  

From: Derek MacDonald [mailto:derek at xten.com] 
Sent: ה 19 מאי 2005 20:20
To: Micky Kaufmann; resiprocate-devel at list.sipfoundry.org
Subject: RE: [reSIProcate] AbstractFifo bug?

Can you get a stack trace this? AbstractFifo is used a lot in resip, but it
does have several subclasses.  The size is incremeneted in the add methods
of the subclasses, which lock before adding. 

Also, run resiprocate/test/testFifo.cxx on your configuration.

--Derek

PS -- What is your platform/compiler?

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From: resiprocate-devel-bounces at list.sipfoundry.org
[mailto:resiprocate-devel-bounces at list.sipfoundry.org] On Behalf Of Micky
Kaufmann
Sent: Thursday, May 19, 2005 6:31 AM
To: resiprocate-devel at list.sipfoundry.org
Subject: [reSIProcate] AbstractFifo bug?

Hi. All

While running repro I go an assert error from the AbstractFifo::getNext
method:

void* AbstractFifo::getNext() {

   Lock lock(mMutex); (void)lock;

   while (mFifo.empty())

   {

      mCondition.wait(mMutex);

   }

   void* firstMessage = mFifo.front();

   mFifo.pop_front();

   assert(mSize != 0);

   mSize--;

   return firstMessage;

}

As I see it the problem is caused probably because non thread safe adding of
elements to the Fifo. Meaning mSize++ is missing somewhere and from what I
investigated the only reason for using mSize instead of using
std::deque::size is because we want to make sure that mSize < mMaxSize.

Is there another reason?

Is it ok to replace the lines:

   assert(mSize != 0);

   mSize--;

with

   mSize = mFifo.size();

Is it ok to replace the line:

   while (mFifo.empty())

with

   while (mSize==0)  //this.empty()

Any other solution?

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