Gitea #561 ("production writes a 0-byte log") is closed as not-a-defect. The
production log on wonder-app-vd03 listed as 0 bytes with LastWriteTime ==
CreationTime; opening it showed 4,658,893 bytes of correct output, written
continuously since service start.
On Windows the directory entry's size and last-write time are not refreshed while
the writing process holds the file open, so Get-ChildItem, dir and FileInfo.Length
all report size-at-open for the life of the handle. A live, healthy log is
indistinguishable from a dead sink by metadata alone — which is what made the
false reading survive six weeks of investigation.
That same trap was in the 29a202f5 instrumentation: CheckFileSinkGrowth measured
with FileInfo.Length, so it would have reported "self-check FAILED: the sink did
not grow" at every boot on a perfectly healthy Windows service — and a
self-check's false positive reads as confirmation of the very bug it was added to
find. MeasureFamilyBytes now reads Length through an opened FileStream:
FileShare.ReadWrite to open it at all while the sink holds its write handle, and
FileShare.Delete so the probe never blocks a roll or retention delete.
Both instruments are kept. A sink that cannot write its file is still a real and
otherwise-invisible failure — a sibling repo reproduced it via handle contention,
where RollingFileSink logs the lock-out to SelfLog and falls through to _001. Only
the two doc claims that are now false are corrected: the class summary's
"production ran that way for six weeks" and the warning text's "#561 failure mode".
Tests: A_working_file_sink_passes already measured while Serilog held the file
open — precisely the broken case — and passed throughout, because it only ever ran
on macOS, where the length is honest. That platform blindness is now recorded in
the class summary, alongside two tests pinning the sharing contract the fix
depends on.
Joseph Doherty
c8b5c997b2