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Re: [RSPlib-Discusssion] fail-over problems


Chronological Thread 
  • From: Thomas Dreibholz <dreibh AT irmgard.exp-math.uni-essen.de>
  • To: "Marjan Bozinovski" <marjanb AT cpk.auc.dk>, "Thomas Dreibholz" <dreibh AT exp-math.uni-essen.de>, <rsplib-discussion AT sctp.de>
  • Subject: Re: [RSPlib-Discusssion] fail-over problems
  • Date: Wed Oct 2 14:32:02 2002
  • List-id: RSPlib Discussions <rsplib-discussion.sctp.de>
  • Organization: University of Essen, Institute for Experimental Mathematics
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On Dienstag, 1. Oktober 2002 15:21, Marjan Bozinovski wrote:
> Hi Thomas,
>
> I am sorry to be so delayed, from 21st of September until yesterday I was
> out of office and I was not able to check my e-mail. Now, I am back and I
> did according to the suggestions in your last mail. And here is what I've
> got.
>
> First, I set timeout.tv_sec to 20 seconds and realized that it is
> definitely the select timeout that wakes up the ext_select because the
> debug line "select: wake-up" shows up immediately after its expiration.
>
> Second, I recompiled the libraries as you described and this is the debug
> output I get:
>
> -----------------
> select: adding FD 0 (0) with mask $0003
> select: registering user callback for socket 0...
> Sending Break via break pipe...
> F0008: User Callback, mask=$1
> Break via break pipe received
> Break Pipe: 1 calls
> select: adding FD 1020 for read
> select: adding FD 1020 for except
> select: adding FD 1021 for read
> select: waiting...
> A0003 S00: Data Arrive Notification, Length = 392
> broadcast: SCTPAssociation::InQueue
> broadcast: SCTPAssociation::ReadUpdateCondition

The last 2 lines are caused by Condition::broadcast(), which is called for
the
associaton's input queue. Then, since it has the parent
SCTPAssociation::ReadUpdateCondition, Condition::broadcast() is called for
Condition::broadcast().
But here, SCTPAssociation::ReadUpdateCondition should have another parent
which is set in sctpsocketwrapper.cc, collectSCTP_FDs() by the following
code:
if(tdSocket->Socket.SCTPSocketDesc.SCTPAssociationPtr != NULL) {
selectData.ConditionArray[selectData.Conditions] =
tdSocket->Socket.SCTPSocketDesc.SCTPAssociationPtr->getUpdateCondition(type);

The pointer to the condition (SCTPAssociation::ReadUpdateCondition) is
obtained from the SCTPAssociation object.

#ifdef PRINT_SELECT
if(selectData.ConditionArray[selectData.Conditions]->peekFired()) {
cout << "collectSCTP_FDs: condition already fired" << endl;
}
#endif

selectData.ParentConditionArray[selectData.Conditions] = &condition;
selectData.ConditionArray[selectData.Conditions]->addParent(selectData.ParentConditionArray[selectData.Conditions]);

A new parent is set for SCTPAssociation::ReadUpdateCondition is set, here:
selectData.ReadCondition (named "ext_select::ReadCondition").
selectData.ReadCondition itself has the parent seletData.GlobalCondition
(named "ext_select::GlobalCondition").

selectData.ConditionFD[selectData.Conditions] = fd;
selectData.ConditionType[selectData.Conditions] = type;
selectData.Conditions++;
return(0);
}

seletData.GlobalCondition finally is the condition ext_select waits for. When
SCTPAssociation::InQueue is fired, SCTPAssociation::ReadUpdateCondition is
fired. This should fire ext_select::ReadCondition and this
ext_select::GlobalCondition. Therefore, it seems that there is somewhere a
problem with the condition's parent setting. To locate this problem, go to
condition.cc, Condition::addParent() and add the following line:
printf("adding parent %p (%s) to %p
(%s)",(void*)parent,parent->getName(),(void*)this,this->getName);
Go to Condition::removeParent() and add the following line:
printf("removing parent %p (%s) to %p
(%s)",(void*)parent,parent->getName(),(void*)this,this->getName);
Go to condition.icc, Condition::broadcast() and add the following 3 lines at
the specified position:
set<Condition*>::iterator iterator = ParentSet.begin();
// -------- Add this:
if(iterator == ParentSet.end()) {
cout << "No parents!" << endl;
}
// --------
while(iterator != ParentSet.end()) {

Go to sctpsocketwrapper.cc, collectSCTP_FDs() and add the following lines at
the specified position:
selectData.UserCallbackFD[selectData.UserCallbacks] = fd;
if(tdSocket->Socket.SCTPSocketDesc.SCTPAssociationPtr != NULL) {
selectData.ConditionArray[selectData.Conditions] =
tdSocket->Socket.SCTPSocketDesc.SCTPAssociationPtr->getUpdateCondition(type);
// -------- Add this:
printf("Condition for FD %d, type %d is
%p\n",(int)fd,(int)type,(void*)selectData.ConditionArray[selectData.Conditions]);
// --------

Please note the FreeBSD/pthread comments below, recompile and reinstall the
socketapi (with gmake clean, to ensure complete recompilation!), recompile
rsplib (also with gmake clean) and try your program again.



> select: wake-up
> Condition 0 (Type 1020, FD 134880283) not fired
> Condition 2 (Type 1020, FD 134880283) not fired
> Condition 0 (Type 1021, FD 134880283) not fired
> -----------------
>
> What confuses me is actually the fact that my client application is
> essentially very similar to the program examplepu.c. It uses the same
> sequence of functions:
> -------
> connectToPoolElement();
> sendToPoolElement(buffer);
> rspSelect();
> -------
>
> The difference is that mine is an external application with respect to the
> rsplib and socketapi.


Make sure, that *all* your sources are compiled with the options
"-D_REENTRANT -D_THREAD_SAFE" and that you also set the compiler option
- -pthread for FreeBSD. Do not link your program with a pthread library, it
is
already included in the libc for FreeBSD.


Best regards
- --
=======================================================================
Dipl.-Inform. Thomas Dreibholz
Molbachweg 7
D-51674 Wiehl-Forst Mail:
dreibh AT exp-math.uni-essen.de
Germany WWW: http://www.exp-math.uni-essen.de/~dreibh
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