Nlog: Archiving of logs whose file name depends on MDC

[kerams]

Type:

• Bug

NLog version: 4.3.10

Platform: .Net 4.6.1

Current NLog config (xml or C#, if relevant)

<nlog>
    <targets>
      <target
        name="f1"
        type="File"
        layout="${longdate} | ${level} | ${message}"
        fileName="${basedir}/Log/log_${mdc:item=clientId}.txt"
        archiveEvery="Minute"
        archiveFileName="${basedir}/Log/archive/log_${mdc:item=clientId}.{#}.txt"
        archiveNumbering="DateAndSequence"
        archiveAboveSize="1000"
        archiveDateFormat="yyyy-MM-dd" />
    </targets>
    <rules>
      <logger name="PerClientLogger" minLevel="Trace" writeTo="f1" final="true" />
    </rules>
  </nlog>

• What is the current result?
  Let's say that I use PerClientLogger and MappedDiagnosticsContext.Set("clientId", "First") with the config above and fill the log log_First.txt to 999 bytes. If I then switch to MappedDiagnosticsContext.Set("clientId", "Second") and log another message, log_First.txt is archived as log_Second.2016-11-02.0.txt (notice the wrong name!) and log_Second.txt is created. The same thing happens when log_First.txt is older than a minute and I log a message that should go to log_Second.txt.

• What is the expected result?
  Writing to log_Second.txt should not trigger the archiving of log_First.txt at all, let alone use a wrong name for it.

[304NotModified]

archived as log_Second.2016-11-02.0.txt (notice the wrong name!

Well that is bit difficult, as we don't have the previous value of ${mdc:item=clientId} anymore.

IMO this is expected, as it could be also:

    fileName="${basedir}/Log/log_${mdc:item=myfilename}.txt"
    archiveEvery="Minute"
    archiveFileName="${basedir}/Log/archive/log_${mdc:item=myarchivename}.{#}.txt"

Writing to log_Second.txt should not trigger the archiving of log_First.txt at all, let alone use a wrong name for it.

There is only 1 filetarget here and so it's sharing the properties. For this case you need a second FileTarget.

[kerams]

So in other words, it is impossible to write to logs with arbitrary names determined at runtime while archiving each file separately?

[304NotModified]

write to logs with arbitrary names determined at runtime

that's possible

archiving each file separately?

Currently not

[snakefoot]

PR #1993 will make it possible to perform correct archive cleanup, as the rendering of the archive-cleanup-filemask is delayed until having an actual LogEvent (with all details).