From b54d5fdc8d8693e8d31050bca5f66f8eab4760d0 Mon Sep 17 00:00:00 2001
From: Bryan Call <bcall@apache.org>
Date: Thu, 19 Feb 2026 14:46:34 -0800
Subject: [PATCH 1/2] Fix: msdms log fields emit "-" instead of "-1" for unset
 milestones

Add unmarshal_milestone_diff() which outputs a single "-" character
when the marshalled value is negative (milestone was unset), instead
of the literal string "-1". This makes log parsing cleaner -- parsers
can distinguish between "0 ms" (a valid timing) and "not applicable"
without checking for a magic integer value.

The MSDMS container now uses this new unmarshal function instead of
the generic unmarshal_int_to_str.
---
 include/proxy/logging/LogAccess.h |  1 +
 src/proxy/logging/LogAccess.cc    | 35 +++++++++++++++++++++++++++++++
 src/proxy/logging/LogField.cc     |  2 +-
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/include/proxy/logging/LogAccess.h b/include/proxy/logging/LogAccess.h
index 7cdf8ed48be..1d8d6974e24 100644
--- a/include/proxy/logging/LogAccess.h
+++ b/include/proxy/logging/LogAccess.h
@@ -316,6 +316,7 @@ class LogAccess
   static int     unmarshal_itox(int64_t val, char *dest, int field_width = 0, char leading_char = ' ');
   static int     unmarshal_int_to_str(char **buf, char *dest, int len);
   static int     unmarshal_int_to_str_hex(char **buf, char *dest, int len);
+  static int     unmarshal_milestone_diff(char **buf, char *dest, int len);
   static int     unmarshal_str(char **buf, char *dest, int len, LogSlice *slice, LogEscapeType escape_type);
   static int     unmarshal_ttmsf(char **buf, char *dest, int len);
   static int     unmarshal_int_to_date_str(char **buf, char *dest, int len);
diff --git a/src/proxy/logging/LogAccess.cc b/src/proxy/logging/LogAccess.cc
index 908ec8c22ff..c5faa13d99e 100644
--- a/src/proxy/logging/LogAccess.cc
+++ b/src/proxy/logging/LogAccess.cc
@@ -626,6 +626,41 @@ LogAccess::unmarshal_int_to_str(char **buf, char *dest, int len)
   return -1;
 }
 
+/*-------------------------------------------------------------------------
+  LogAccess::unmarshal_milestone_diff
+
+  Unmarshal a milestone difference value.  Returns "-" when the
+  marshalled value is negative (milestone was unset), otherwise
+  the decimal string representation.
+  -------------------------------------------------------------------------*/
+
+int
+LogAccess::unmarshal_milestone_diff(char **buf, char *dest, int len)
+{
+  ink_assert(buf != nullptr);
+  ink_assert(*buf != nullptr);
+  ink_assert(dest != nullptr);
+
+  int64_t val = unmarshal_int(buf);
+  if (val < 0) {
+    if (len >= 1) {
+      dest[0] = '-';
+      return 1;
+    }
+    DBG_UNMARSHAL_DEST_OVERRUN
+    return -1;
+  }
+
+  char val_buf[128];
+  int  val_len = unmarshal_itoa(val, val_buf + 127);
+  if (val_len < len) {
+    memcpy(dest, val_buf + 128 - val_len, val_len);
+    return val_len;
+  }
+  DBG_UNMARSHAL_DEST_OVERRUN
+  return -1;
+}
+
 /*-------------------------------------------------------------------------
   LogAccess::unmarshal_int_to_str_hex
 
diff --git a/src/proxy/logging/LogField.cc b/src/proxy/logging/LogField.cc
index f7dcbbd067a..039aca32a74 100644
--- a/src/proxy/logging/LogField.cc
+++ b/src/proxy/logging/LogField.cc
@@ -388,7 +388,7 @@ LogField::LogField(const char *field, Container container)
     if (0 != rv) {
       Note("Invalid milestone range in LogField ctor: %s", m_name);
     }
-    m_unmarshal_func = &(LogAccess::unmarshal_int_to_str);
+    m_unmarshal_func = &(LogAccess::unmarshal_milestone_diff);
     m_type           = LogField::sINT;
     break;
   }

From 4181d0b1f9558bf74c37b11bb180a11774ee77fa Mon Sep 17 00:00:00 2001
From: Bryan Call <bcall@apache.org>
Date: Thu, 19 Feb 2026 15:26:35 -0800
Subject: [PATCH 2/2] Address review: only map -1 sentinel to dash, not all
 negatives

Copilot correctly noted that val < 0 would also catch reversed
milestone pairs (end < start), hiding potentially useful debug
info.  Tighten to val == -1 which is the specific "missing"
sentinel returned by difference_msec() when a milestone is unset.
---
 src/proxy/logging/LogAccess.cc | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/proxy/logging/LogAccess.cc b/src/proxy/logging/LogAccess.cc
index c5faa13d99e..3f5d6868564 100644
--- a/src/proxy/logging/LogAccess.cc
+++ b/src/proxy/logging/LogAccess.cc
@@ -630,8 +630,10 @@ LogAccess::unmarshal_int_to_str(char **buf, char *dest, int len)
   LogAccess::unmarshal_milestone_diff
 
   Unmarshal a milestone difference value.  Returns "-" when the
-  marshalled value is negative (milestone was unset), otherwise
-  the decimal string representation.
+  marshalled value is -1 (the "missing" sentinel from difference_msec,
+  meaning one or both milestones were unset).  Other negative values
+  (reversed milestone order) are preserved as numeric output for
+  debugging.
   -------------------------------------------------------------------------*/
 
 int
@@ -642,7 +644,7 @@ LogAccess::unmarshal_milestone_diff(char **buf, char *dest, int len)
   ink_assert(dest != nullptr);
 
   int64_t val = unmarshal_int(buf);
-  if (val < 0) {
+  if (val == -1) {
     if (len >= 1) {
       dest[0] = '-';
       return 1;