[PWGUD] Modification of global track selection in UPCCandidateProducer

[diana0x0f]

Modification of global track selection in UPCCandidateProduceR:

• check the correct number of tracks before finding the corresponding MCH-MID tracks
• check whether both global tracks are in the MFT acceptance and handle the four cases separately

[rolavick]

Hi Diana, it seems to me a bit redundant to define variables on line 1608, 1633 and 1634. They are used basically only once on line 1610, 1636 and 1639. Could you please use directly the pointers? It saves just a little bit of memory, but in global it can play a role.
Also, in lines 1631, 1632, use const auto&, also for the computing performance reason. It should speed up the compiler, so your O2Physics build will finish a little bit sooner :)
Last thing, could you please add some comment for the createCandidatesFwdGlobal function, to describe what it does and how it differ from createCandidatesFwd? It seems createCandidatesFwdGlobal is quite specialized.

[diana0x0f]

Hi @rolavick , thanks a lot for your review! I have pushed the changes as you requested.