From: Steinar H. Gunderson <sgunderson@bigfoot.com>
Date: Wed, 22 Jul 2015 00:12:37 +0000 (+0200)
Subject: Replace an assert with a small hack.
X-Git-Tag: 1.2.0~20
X-Git-Url: https://git.sesse.net/?p=cubemap;a=commitdiff_plain;h=ce7802e5d5291c414883efbad93a9d165c03f40c

Replace an assert with a small hack.

Instead of checking that connect times are monotonic, explicitly make them
so if they're not. This seems safest, in case the monotonic clock goes
backwards a small bit (e.g. when changing CPUs). We don't need it for the
serialized case since we explicitly sort those by time; the assert can stay.
---

diff --git a/server.cpp b/server.cpp
index 01ed0ff..079b629 100644
--- a/server.cpp
+++ b/server.cpp
@@ -217,9 +217,15 @@ void Server::add_client(int sock)
 	assert(ret.second == true);  // Should not already exist.
 	Client *client_ptr = &ret.first->second;
 
-	// Connection timestamps must be nondecreasing.
-	assert(clients_ordered_by_connect_time.empty() ||
-	       !is_earlier(client_ptr->connect_time, clients_ordered_by_connect_time.back().first));
+	// Connection timestamps must be nondecreasing. I can't find any guarantee
+	// that even the monotonic clock can't go backwards by a small amount
+	// (think switching between CPUs with non-synchronized TSCs), so if
+	// this actually should happen, we hack around it by fudging
+	// connect_time.
+	if (!clients_ordered_by_connect_time.empty() &&
+	    is_earlier(client_ptr->connect_time, clients_ordered_by_connect_time.back().first)) {
+		client_ptr->connect_time = clients_ordered_by_connect_time.back().first;
+	}
 	clients_ordered_by_connect_time.push(make_pair(client_ptr->connect_time, sock));
 
 	// Start listening on data from this socket.