FreeAndNil commented on code in PR #336:
URL: https://github.com/apache/logging-log4net/pull/336#discussion_r4242713038
##########
src/log4net/Appender/RollingFileAppender.cs:
##########
@@ -1000,6 +1012,37 @@ public void InitializeRollBackups(string baseFile,
IList<string> arrayFiles)
}
}
+ /// <summary>
+ /// With a static name, a date that formats as a dot and up to four digits
(<c>.dd</c> writes
+ /// <c>.10</c>) is also the name of backup 10. Counting down to a limit
below the smallest such
+ /// name never reaches it.
+ /// </summary>
+ private bool DoesDatePatternCollideWithBackupNames()
+ {
+ if (DatePattern is not string datePattern || !IsBaseFileRolledByDate() ||
!HasNumberedBackups())
+ {
+ return false;
+ }
+
+ string sample = _sDate1970.ToString(datePattern,
DateTimeFormatInfo.InvariantInfo);
+ return IsDotAndUpToFourDigits(sample) && CanBackupNumberEqualDate(sample);
Review Comment:
The 1970 sample is the narrowest formatting of every numeric field except
12-hour `h`, which is unusable without `tt`. `.Md` over-reports a count-down
limit of exactly 10, accepted for an ambiguous pattern. The five-digit
threshold is where `IsDateSuffix` stops counting dated files as backups, so
detection and counting agree. The advice now names a separator only, see
8590be00.
##########
src/changelog/3.5.1/335-short-date-pattern-collides-with-backup-names.xml:
##########
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<entry xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance";
+ xmlns="https://logging.apache.org/xml/ns";
+ xsi:schemaLocation="https://logging.apache.org/xml/ns
https://logging.apache.org/xml/ns/log4j-changelog-0.xsd";
+ type="fixed">
+ <issue id="335" link="https://github.com/apache/logging-log4net/issues/335"/>
+ <description format="asciidoc">With `StaticLogFileName` a `DatePattern` such
as `.dd` named dated
+ files like numbered backups, so a roll could overwrite one with the other.
Such an appender is now
+ reported when activated and uses the dated file name as with
`StaticLogFileName` false, so its
+ backups are numbered after the date, and an existing static file is left
untouched, including
+ its numbered backups. Use a
+ `DatePattern` with a separator or at least five digits to keep the static
name (reported by
Review Comment:
Changed to recommend a separator, with the default `.yyyy-MM-dd` as the
example, see 8590be00.
##########
src/site/antora/modules/ROOT/pages/manual/configuration/appenders/rollingfileappender.adoc:
##########
@@ -88,6 +88,13 @@ For each day only the last 10 files of 1MB will be kept.
</appender>
----
+[NOTE]
+====
+With `staticLogFileName` a `datePattern` that formats as a dot and up to four
digits, such as `.dd`, names dated files like numbered backups.
+Such an appender is reported when activated and uses the dated file name as
with `staticLogFileName` false, so its backups are numbered after the date.
+Use a pattern with a separator or at least five digits to keep the static name.
Review Comment:
Changed to recommend a separator, with the default `.yyyy-MM-dd` as the
example, see 8590be00.
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