[master] 0c823a89e an attempt to clarify req.grace/req.ttl

Nils Goroll nils.goroll at uplex.de
Mon Sep 17 08:21:08 UTC 2018


commit 0c823a89e5303ce8b2aeb264cacc6b040401ef6d
Author: Nils Goroll <nils.goroll at uplex.de>
Date:   Mon Sep 17 10:19:58 2018 +0200

    an attempt to clarify req.grace/req.ttl

diff --git a/doc/sphinx/whats-new/upgrading-6.1.rst b/doc/sphinx/whats-new/upgrading-6.1.rst
index f78ed855d..3a0f8452a 100644
--- a/doc/sphinx/whats-new/upgrading-6.1.rst
+++ b/doc/sphinx/whats-new/upgrading-6.1.rst
@@ -49,11 +49,13 @@ VCL variables
 since there are use cases that cannot be solved without it. Similarly,
 ``req.ttl`` used to be deprecated and is now fully supported again.
 
-``req.ttl`` and ``req.grace`` set upper bounds on the TTL and grace
-times that are permitted for the current request -- if these variables
-are set and the TTL/grace of a cache object is longer than their
-settings, then a new response is fetched from the backend, despite the
-presence of an otherwise fresh cache object.
+``req.ttl`` and ``req.grace`` limit the ttl and grace times that are
+permitted for the current request. If ``req.ttl`` is set, it requires
+cache objects to have that minimum remaining ttl to be considered
+fresh. Likewise, ``req.grace`` sets an upper bound on the time an
+object has spent in grace to be considered eligible for grace mode
+(which is to deliver this object and fetch a fresh copy in the
+background).
 
 A common application is to set shorter TTLs when the backend is known
 to be healthy, so that responses are fresher when all is well. But if


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