From 9e308f5dd00d31273e3a515b11943d28d3bfc088 Mon Sep 17 00:00:00 2001
From: Raghu Udiyar <raghusiddarth@gmail.com>
Date: Sun, 17 Jan 2021 19:55:25 +0530
Subject: [PATCH] Do not emit backlog metric if its unsupported

---
 gunicorn/arbiter.py | 6 +++++-
 gunicorn/sock.py    | 8 +++++---
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/gunicorn/arbiter.py b/gunicorn/arbiter.py
index 635826d5a..341844811 100644
--- a/gunicorn/arbiter.py
+++ b/gunicorn/arbiter.py
@@ -584,7 +584,11 @@ def manage_workers(self):
                                   "value": active_worker_count,
                                   "mtype": "gauge"})
 
-        backlog = sum([sock.get_backlog() for sock in self.LISTENERS])
+        backlog = sum([
+            sock.get_backlog()
+            for sock in self.LISTENERS
+                if sock.get_backlog() is not None
+        ])
         if backlog:
             self.log.debug("socket backlog: {0}".format(backlog),
                            extra={"metric": "gunicorn.backlog",
diff --git a/gunicorn/sock.py b/gunicorn/sock.py
index 628e27e1b..747199d1c 100644
--- a/gunicorn/sock.py
+++ b/gunicorn/sock.py
@@ -74,7 +74,7 @@ def close(self):
         self.sock = None
 
     def get_backlog(self):
-        return 0
+        return None
 
 
 class TCPSocket(BaseSocket):
@@ -100,12 +100,14 @@ def get_backlog(self):
             fmt = 'B'*8+'I'*24
             try:
                 tcp_info_struct = self.sock.getsockopt(socket.IPPROTO_TCP,
-                                                      socket.TCP_INFO, 104)
+                                                       socket.TCP_INFO, 104)
                 # 12 is tcpi_unacked
                 return struct.unpack(fmt, tcp_info_struct)[12]
             except AttributeError:
                 pass
-        return 0
+
+        return None
+
 
 class TCP6Socket(TCPSocket):