NFD » ndn-cxx

#1872 is changing the API of OnDataValidationFailed.
It's recommended to wait until #1872 closes, in order to avoid code conflicts.

I would pose this issue in a slightly different terms. Why don't we plug in Validator (require Validator instance to be passed) into the fetcher, instead of callbacks?

We are using SegmentFetcher to implement an application that retrieves NLSR status dataset. This feature is very important for our implementation.

I'm not against adding an overload, but what if we simply change fetch signature to accept shared_ptr<Valiator>? Would there be any negative consequences?

Answer to note-13:

Only accepting shared_ptr<Validator> forces the caller to create Validator with make_shared, which is undesirable.

Many classes have been accepting Validator& as a constructor parameter, and .shared_from_this() imposes additional requirements on the caller.

There are four kinds of nack.

if (nack == NONE) {
    reexpress the interest;
}
else if (nack == CONGESTION) {
    reexpress the interest after waiting a while;
}
else if (nack == DUPLICATE) {
    wait for timeout/data;
}
else if (nack == NO_ROUTE) {
     error;
}

note-15 design is incomplete:

• "NONE" is not a NackReason. It indicates a Nack with no reason.
• Application SHOULD treat unrecognized NackReason as a Nack with no reason.
• After DUPLICATE, neither timeout nor Data would come back.

Recommendation:

switch (nack.getReason()) {
case DUPLICATE:
  re-express without delay, up to 3 times;
  break;
case CONGESTION:
  re-express with exponential back-off, up to 3 times;
  break;
default:
  fail;
}

How do we coordinate this commit to be merged?

This is a breaking change, so it requires a 5-day notice to ndn-lib mailing list.

Also, prepare patches for NFD, NLSR, and other projects.

ndn-cxx-breaks can help with this process.

• Link of the result of the build of all NDN projects (except ChronoChat): https://travis-ci.org/yoursunny/ndn-cxx-breaks/builds/90789119
• Link to the notice in ndn-lib archive: http://www.lists.cs.ucla.edu/pipermail/ndn-lib/2015-November/000314.html
• Link to affected projects changes in Gerrit:
  • ChronoChat: http://gerrit.named-data.net/#/c/2584/
  • NFD: http://gerrit.named-data.net/#/c/2433/
  • NLSR: http://gerrit.named-data.net/#/c/2422/

I can confirm that ChronoChat (http://gerrit.named-data.net/#/c/2584/2) compiles with this ndn-cxx patch (http://gerrit.named-data.net/#/c/2418/26).

laptop:ndn-cxx vince$ grep BUILD_STRING /usr/local/include/ndn-cxx/version.hpp | tail -n 1
#define NDN_CXX_VERSION_BUILD_STRING "0.1.0-371-gf9f5dc1"
…
laptop:ChronoChat vince$ git rev-parse HEAD
5119f3d84a8abcd7c538f9216587a12ea65b48b9
…
laptop:ChronoChat vince$ ./waf
…
[73/75] Linking build/ChronoChat
[74/75] Compiling build/ChronoChat
[75/75] Creating build/ChronoChat.app/Contents/Info.plist
'build' finished successfully (44.015s)

Test duration comparison:

http://jenkins.named-data.net/job/ndn-cxx/3596/OS=Ubuntu-14.04-64bit/consoleText -> http://jenkins.named-data.net/job/ndn-cxx/3599/OS=Ubuntu-14.04-64bit/consoleText