Bug 2589 – Binary search in LteMiErrorModel::GetTbDecodificationStats is incorrect

Bug 2589 - Binary search in LteMiErrorModel::GetTbDecodificationStats is incorrect


Summary:	Binary search in LteMiErrorModel::GetTbDecodificationStats is incorrect

Status:	PATCH PENDING

Product:	ns-3
Classification:	Unclassified
Component:	lte
Version:	ns-3-dev
Hardware:	All All

Importance:	P3 normal
Assigned To:	Biljana Bojović

URL:
Keywords:

Depends on:
Blocks:
	Show dependency tree / graph

Reported:	2016-12-15 15:58 EST by Alexander Krotov
Modified:	2017-01-04 00:16 EST (History)
CC List:	3 users (show)

See Also:

Attachments
Patch 1/2 (1.41 KB, text/plain) 2016-12-15 15:58 EST, Alexander Krotov	Details
Patch 1/2 (1.41 KB, patch) 2016-12-15 15:58 EST, Alexander Krotov	Details \| Diff
Patch 2/2 (actual fix, apply on top of the first) (2.69 KB, patch) 2016-12-15 16:04 EST, Alexander Krotov	Details \| Diff
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Description Alexander Krotov 2016-12-15 15:58:00 EST

Created attachment 2702 [details]
Patch 1/2

Binary search at http://code.nsnam.org/ns-3-dev/file/f883d71c975e/src/lte/model/lte-mi-error-model.cc#l613 is incorrect. It does not give the intended result. At least the result is not the same as what commented code gives: http://code.nsnam.org/ns-3-dev/file/f883d71c975e/src/lte/model/lte-mi-error-model.cc#l604

I split the fix in two patches. First one uncomments the simple but slow version of code and moves it inside "#ifdef NS3_BUILD_PROFILE_DEBUG" to show that it indeed results in assertion failures during tests.

The second patch replaces the algorithm with the standard std::lower_bound. It follows in the next message.

Comment 1 Alexander Krotov 2016-12-15 15:58:46 EST

Created attachment 2703 [details]
Patch 1/2

Reuploaded first patch as patch.

Comment 2 Alexander Krotov 2016-12-15 16:04:11 EST

Created attachment 2704 [details]
Patch 2/2 (actual fix, apply on top of the first)

Here I wrapped cbSizeTable into std::array to use std::lower_bound. According to tests (no assertion failures) the code corresponds to the simple version of code.

I think we never discussed limits of C++11 usage in NS-3 code since switch, but I decided that using "auto" for iterator and lambda for a one-line comparison function is sane in this case.