[tor-bugs] #26155 [Core Tor/Tor]: Bandwidth file Timestamp is the latest scanner result, not the file creation time

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#26155: Bandwidth file Timestamp is the latest scanner result, not the file
creation time
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 Reporter:  teor                  |          Owner:  teor
     Type:  defect                |         Status:  needs_revision
 Priority:  Medium                |      Milestone:  Tor: 0.3.5.x-final
Component:  Core Tor/Tor          |        Version:
 Severity:  Normal                |     Resolution:
 Keywords:  tor-spec, tor-bwauth  |  Actual Points:
Parent ID:  #25925                |         Points:
 Reviewer:                        |        Sponsor:
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Comment (by teor):

 Replying to [comment:12 juga]:
 > Replying to [comment:11 teor]:
 >
 > > Can you tell me what you decided to do about these issues:
 >
 > > > 2. don't generate the file, delete any existing file - tor will warn
 that the file is missing
 >
 > This is what i decided. In the code is in https://github.com/pastly
 /simple-bw-scanner/pull/175/files#diff-
 5d572187bd8e5853f29b5e173a4fa8efR119.
 >
 > However, i don't delete any existing files because i don't understand
 the logic.
 > If previous files were generated by the same code, they will have the
 correct timestamp of previous results.

 Yes, you're right. So it is ok to leave the old file as it is.

 > > > I suggest that we say that generators SHOULD NOT generate a file,
 >
 > i say MUST NOT: https://github.com/torproject/torspec/pull/10/files
 #diff-824f4c7404328d8aa1101d74ba36884dR132
 >
 > > and SHOULD delete any existing file, because it is the least confusing
 option.
 >
 > but not this because of what commented above.

 Ok.

 > > > If you want, you can also say that:
 > > > * generators SHOULD wait until enough relays are measured before
 generating the file (option 2)
 > > > * generators MAY use a placeholder timestamp (option 1j, but the
 time MUST be at least 5 days in the past to avoid silent failures.
 > > > * generators MUST NOT generate an empty file (option 3), because it
 triggers a bug in tor.
 >
 > i say "MUST NOT generate the file", though i don't mention "empty" nor
 that it triggers a bug. Is it needed?.

 I'm not sure. The current version is ok.

 > > > The earliest_bandwidth and latest_bandwidth are optional.
 >
 > Optional is implicit by "zero or one time":
 https://github.com/torproject/torspec/pull/10/files#diff-
 824f4c7404328d8aa1101d74ba36884dR173

 That is good..

 > > > If there is no valid value for these lines, the generator SHOULD
 leave them out.
 >
 > If file is not created when there are not results (no
 "latest_bandwidth"), then "file_created" won't exist. Same for
 "latest_bandwidth". Is it needed to say so?

 That is good.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/26155#comment:13>
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