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Bugzilla – Full Text Bug Listing |
| Summary: | RttEstimator doesn't set the m_currentEstimatedRtt to m_initialEstimatedRtt on creation | ||
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| Product: | ns-3 | Reporter: | Tommaso Pecorella <tommaso.pecorella> |
| Component: | internet | Assignee: | George Riley <riley> |
| Status: | RESOLVED FIXED | ||
| Severity: | critical | CC: | bswenson3, ns-bugs |
| Priority: | P5 | ||
| Version: | ns-3-dev | ||
| Hardware: | All | ||
| OS: | All | ||
| Attachments: |
Patch fixing the bug
new patch |
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Forget about it. I have the solution. And it's damn simple. And stupid. And undocumented. Tomorrow I'll post it. T. Created attachment 1532 [details]
Patch fixing the bug
Patch fixing the bug
Ok, the bug is this.
The ObjectBase::ConstructSelf (AttributeConstructionList ()) function will call
GetInstanceTypeId, which usually is a virtual function, inherited from Object.
The function should call GetTypeId, which is static to the class.
On the other hand, inside the constructor the object is still not fully
created, hence its virtual inherited stuff is kinda... strange.
To make a long story short. This will work *only* if the object is actually
implementing a GetInstanceTypeId function.
The patch does this and it clarifies the manual about this point.
T.
Created attachment 1534 [details]
new patch
Also the derived classes must implement GetInstanceTypeId
changeset: 9698:9d91a3c643b2 tag: tip user: Tommaso Pecorella <tommaso.pecorella@unifi.it> date: Fri Apr 19 12:18:00 2013 -0400 summary: Bug 1601 RttEstimator doesn't set m_currentEstimatedRtt fix Updated RELEASE_NOTES |
This bug is quite puzzling me. Not the bug itself, the problem is on how to fix it. Now, RttEstimator's constructor is something like: { ObjectBase::ConstructSelf (AttributeConstructionList ()); m_currentEstimatedRtt = m_initialEstimatedRtt; } whereas m_initialEstimatedRtt is set by an attribute. The problem (huge one) is this: the attribute default value is 1.0 sec, but m_currentEstimatedRtt is set to ZERO. The calls traces are: RttEstimator:RttEstimator(0x7ff2c1c87de0) Initialize m_currentEstimatedRtt to 0 sec. Initialize m_initialEstimatedRtt to 0 sec. RttEstimator:RttMeanDeviation(0x7ff2c1c87de0) RttEstimator:SetInitialEstimatedRtt(0x7ff2c1c87de0, +1000000000.0ns) RttEstimator:SetMinRto(0x7ff2c1c87de0, +200000000.0ns) Mind that I added an explicit setter and getter for InitialEstimatedRtt. How this is possible? Top ranked guess (I'm not an attribute wizard): - the ObjectBase::ConstructSelf (AttributeConstructionList ()) call is not doing what's supposed to do. Maybe because the TypeId is the one of the derived class ? How can we force the base class attributes to be read ? Another solution is to use the DoStart() method, however the RttEstimator is *not* aggregated to the node, it's just built on-the-fly when a socket is created. The only (ugly) solution I found is to add another *public* function DoStart (DoStart is protected usually) and call it explicitly when the RttEstimator is created. Of course we can call it in a different way, but the idea is still ugly, no matter how we call the function. Any better solution ? T.