[tor-bugs] #20440 [Metrics/metrics-lib]: endless wait in BlockingIteratorImpl

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#20440: endless wait in BlockingIteratorImpl
---------------------------------+-----------------------------------
 Reporter:  iwakeh               |          Owner:  iwakeh
     Type:  defect               |         Status:  merge_ready
 Priority:  High                 |      Milestone:  metrics-lib 1.6.0
Component:  Metrics/metrics-lib  |        Version:
 Severity:  Normal               |     Resolution:
 Keywords:                       |  Actual Points:
Parent ID:                       |         Points:
 Reviewer:                       |        Sponsor:
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Changes (by iwakeh):

 * status:  needs_review => merge_ready


Comment:

 Replying to [comment:15 karsten]:
 > Thanks for pointing me to that email from October.  I was able to
 reproduce the issue!
 >
 > Here's what happens: Onionoo reads descriptors from `in/archive/` and
 finds descriptor types in there that it does not recognize, including
 votes, microdescs, and certs.  It decides (for whatever reason!) that it
 should stop reading from that directory, ...

 Oh, good to know.

 >
 > This means we have two bugs here:
 >
 >  - metrics-lib should allow the application to stop reading descriptors
 for whatever reason.  Therefore, turning the reader thread into a daemon
 thread seems like the right fix.  Please review my
 [https://gitweb.torproject.org/user/karsten/metrics-
 lib.git/log/?h=task-20440 task-20440 branch] with your cherry-picked
 commit and a change log entry.

 Yes, this looks fine.  Ready for merge.

 >
 >  - Onionoo should be a little more robust against unexpected data in the
 `in/archive/` directory.  It could simply skip the unrecognized descriptor
 and carry on with the next descriptor.  That's `s/break/continue/` in
 [https://gitweb.torproject.org/onionoo.git/tree/src/main/java/org/torproject/onionoo/updater/DescriptorSource.java#n213
 this line].  Happy to discuss that further in an Onionoo ticket, or happy
 to just make this change.

 Yes, this is a new ticket #21370, but rather an enhancement ;-)

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20440#comment:16>
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