|Message: Re: G4Cache vs static G4ThreadLocal when there is only one class instance||Not Logged In (login)|
Click on the Forum title, e.g. on the "Forums by Category" page, to read a sequence of postings to the Forum and its threads all in one page. If you are only interested in one thread or the thread following a specific posting, click the thread or the posting, which takes you to a smaller page, which contains only the part you are interested in and may be easier to navigate.
Messages are "chained" if there are only replies at the first level, i.e. 1/1.html, 1/1/1.html etc. In case of "chained" messages the message number is replaced by the icon and there is no indentation.
Inline: Display the subject line only or also the text of the posting(s); for the choice "All" the "Outline" choices are switched off.
|1||0||1||no text / full text of posting|
|2||1||All||text for level 1 only / text for All postings|
Outline: Choose the depth of the posting thread, successive toggle controls provide increasing detail.
|1||2||1||2 levels / 1 level (original posting)|
|2||3||2||3 levels / 2 levels|
|3||3||All||3 levels / all levels (all postings)|
in the specific case of detector construction, since only one instance of it exists at any given time, cases F and H from the twiki are the same. So one could use either of static G4ThreadLocal or G4Cache<>.
The latter has a very small performance penalty (only relevant for cases in which one access the underlying object in the event loop).
The difference between the two is that the G4Cache<> should be used when one wants to give, to a thread-shared object, a data field that has the behavior of thread- and instance-private (case H).
The examples just show how to use the two, but in this particular case they are equivalent.
To summarize: while for this specific case G4ThreadLocal and G4Cache<> are equivalent, they are not in the general case and they serve very different purposes.
Hope this helps, Andrea