[tor-bugs] #22141 [Metrics/metrics-lib]: Deprecate `DescriptorFile` and add relevant information to `Descriptor`

[Tor Bug Tracker & Wiki]

#22141: Deprecate `DescriptorFile` and add relevant information to `Descriptor`
---------------------------------+-----------------------------------
 Reporter:  karsten              |          Owner:  metrics-team
     Type:  enhancement          |         Status:  needs_review
 Priority:  Medium               |      Milestone:  metrics-lib 1.9.0
Component:  Metrics/metrics-lib  |        Version:
 Severity:  Normal               |     Resolution:
 Keywords:                       |  Actual Points:
Parent ID:                       |         Points:
 Reviewer:                       |        Sponsor:
---------------------------------+-----------------------------------

Comment (by iwakeh):

 DescriptorReaderImpl became more readable.  Maybe use Files.walkFileTree
 and an extension of SimpleFileVisitor to simplify the code which currently
 is in "readDescriptorFiles"?

 Regarding `Descriptor.getException`:  The use case here is to determine,
 if the Descriptor object is valid and decide whether to use it or drop it?
 Then, why not add a `Descriptor.valid` method returning true or false?
 The detailed logging of exceptions could be configured if wanted in
 metrics-lib as an extra logging channel for parse exceptions (this code
 would need to be added still).

 About parsing "future or not" I have more questions than suggestions as it
 depends highly on the implementation.
 What do you have in mind?
 It would also introduce some overhead regarding the cancelling, how should
 that be handled?
 How should a client deal with the Futures it receives?

 BTW DescriptorImpl: The `NoSuchAlgorithmException` should be escalated as
 runtime exceptions, b/c this is a problem with the jdk/jvm and shouldn't
 be hidden away.  I'd suggest using a private method for the two digest
 calls (please find a suggestion [https://gitweb.torproject.org/user/iwakeh
 /metrics-
 lib.git/commit/?h=task-22141&id=31a2f15bdc5933cc1f240cff107e01e0fce69a8d
 here]).

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22141#comment:7>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online