[tor-bugs] #20224 [Metrics/CollecTor]: Fix `BridgeDescriptorMappingsLimit` config option

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#20224: Fix `BridgeDescriptorMappingsLimit` config option
-----------------------------------+-----------------
     Reporter:  karsten            |      Owner:
         Type:  defect             |     Status:  new
     Priority:  Low                |  Milestone:
    Component:  Metrics/CollecTor  |    Version:
     Severity:  Normal             |   Keywords:
Actual Points:                     |  Parent ID:
       Points:                     |   Reviewer:
      Sponsor:                     |
-----------------------------------+-----------------
 The `BridgeDescriptorMappingsLimit` option doesn't work as expected with
 its default value `inf` or with other sufficiently large values.  Here's
 where that configuration value is used
 (https://gitweb.torproject.org/collector.git/tree/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java#n183):

 {{{
       this.bridgeSanitizingCutOffTimestamp = formatter.format(
           System.currentTimeMillis() - 24L * 60L * 60L * 1000L
           * limitBridgeSanitizingInterval);
 }}}

 For `limitBridgeSanitizingInterval = Integer.MAX_VALUE`, we'd try to
 format `1474617184667 - 86400000 * 2147483647 = -1.855E+017` milliseconds
 since the epoch.  In theory, that large negative value should still fit
 into the `long`, but somehow it gets formatted as `5877475-11-25
 07:53:04`, which is in the future rather than in the past.

 Anyway, I stopped digging what the exact bug might be, and instead suggest
 this possible fix:

 {{{
 diff --git
 a/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java
 b/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java
 index b61cd30..b8674a3 100644
 ---
 a/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java
 +++
 b/src/main/java/org/torproject/collector/bridgedescs/SanitizedBridgesWriter.java
 @@ -180,9 +180,9 @@ public class SanitizedBridgesWriter extends
 CollecTorMain {
        SimpleDateFormat formatter = new SimpleDateFormat(
            "yyyy-MM-dd HH:mm:ss");
        formatter.setTimeZone(TimeZone.getTimeZone("UTC"));
 -      this.bridgeSanitizingCutOffTimestamp = formatter.format(
 +      this.bridgeSanitizingCutOffTimestamp =
 formatter.format(Math.max(-1L,
            System.currentTimeMillis() - 24L * 60L * 60L * 1000L
 -          * limitBridgeSanitizingInterval);
 +          * limitBridgeSanitizingInterval));
      } else {
        this.bridgeSanitizingCutOffTimestamp = "1999-12-31 23:59:59";
      }
 }}}

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/20224>
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