Hi,
Attached is an updated patch for s-w-r support that I originally sent in
June 23.
I've kept the code outside RFC2616_Ttl but still adding it into
rfc2616_cache.c.
It might be worth merging it and/or moving this into rfc5861_cache.c.
Before this turns into another bike-shedding, a few things worth clarifying:
It only implements stale-while-revalidate as the subject says.
Implementing stale-if-error requires more changes to Varnish and while it
might be implemented in the future is not in the scope of this patch.
I rather have something that people can use now that nothing at all for a
longer period (this diff was sent over 2 months ago).
If ttl is equal or lower than 0 this implementation will ignore the
stale-while-revalidate value. There are 2 reasons for this that are not
related to this diff but to Varnish itself: 1. Varnish won't cache an
object with a 0 ttl and 2. a ttl of -1 indicates that either the response
status was uncacheable (as per RFC2616_Ttl) or that the content already
expired (again based on RFC2616_Ttl).
Should the situation in Varnish change it's as simple of modifying the
check to be `expp->ttl < 0.' so I'd prefer to have that discussion
decoupled from this patch.
Thanks.
bin/varnishd/cache/cache.h | 1 +
bin/varnishd/cache/cache_rfc2616.c | 32 +++++++++++++++++++++++++++++
bin/varnishtest/tests/b00043.vtc | 41 ++++++++++++++++++++++++++++++++++++++
3 files changed, 74 insertions(+)
diff --git a/bin/varnishd/cache/cache.h b/bin/varnishd/cache/cache.h
index 08e8714..e94745c 100644
--- a/bin/varnishd/cache/cache.h
+++ b/bin/varnishd/cache/cache.h
@@ -1243,6 +1243,7 @@ unsigned RFC2616_Req_Gzip(const struct http *);
int RFC2616_Do_Cond(const struct req *sp);
void RFC2616_Weaken_Etag(struct http *hp);
void RFC2616_Vary_AE(struct http *hp);
+void RFC5861_Stale(struct busyobj *);
/* stevedore.c */
int STV_NewObject(struct busyobj *, const char *hint, unsigned len);
diff --git a/bin/varnishd/cache/cache_rfc2616.c b/bin/varnishd/cache/cache_rfc2616.c
index b7737bc..4a8957f 100644
--- a/bin/varnishd/cache/cache_rfc2616.c
+++ b/bin/varnishd/cache/cache_rfc2616.c
@@ -404,3 +404,35 @@ RFC2616_Vary_AE(struct http *hp)
http_SetHeader(hp, "Vary: Accept-Encoding");
}
}
+
+/*
+ * RFC5861 outlines a way to control the use of stale responses.
+ * We use this to initialize the grace period.
+ */
+
+void
+RFC5861_Stale(struct busyobj *bo)
+{
+ char *p;
+ const struct http *hp;
+ struct exp *expp;
+
+ expp = &bo->fetch_objcore->exp;
+
+ /*
+ * If we are not meant to cache this ignore any potential
+ * stale-while-revalidate values.
+ */
+ if (expp->ttl <= 0.)
+ return;
+
+ hp = bo->beresp;
+
+ if (http_GetHdrField(hp, H_Cache_Control,
+ "stale-while-revalidate", &p) && p != NULL) {
+ if (*p == '-')
+ expp->grace = 0;
+ else
+ expp->grace = strtoul(p, NULL, 0);
+ }
+}
diff --git a/bin/varnishtest/tests/b00043.vtc b/bin/varnishtest/tests/b00043.vtc
new file mode 100644
index 0000000..19140f6
--- /dev/null
+++ b/bin/varnishtest/tests/b00043.vtc
@@ -0,0 +1,41 @@
+varnishtest "Test stale-while-revalidate"
+
+server s1 {
+ rxreq
+ txresp -hdr "Cache-Control: max-age=30, stale-while-revalidate=30"
+ rxreq
+ txresp -hdr "Cache-Control: max-age=0, stale-while-revalidate=30"
+ rxreq
+ txresp -hdr "Cache-Control: max-age=30, stale-while-revalidate=30" -hdr "Age: 40"
+ rxreq
+ txresp -status 500 -hdr "Cache-Control: max-age=30, stale-while-revalidate=30"
+} -start
+
+varnish v1 -vcl+backend {
+ sub vcl_backend_response {
+ set beresp.http.grace = beresp.grace;
+ set beresp.http.ttl = beresp.ttl;
+ }
+} -start
+
+client c1 {
+ txreq -url /1
+ rxresp
+ expect resp.http.grace == 30.000
+ expect resp.http.ttl == 30.000
+
+ txreq -url /2
+ rxresp
+ expect resp.http.grace == 10.000
+ expect resp.http.ttl == 0.000
+
+ txreq -url /3
+ rxresp
+ expect resp.http.grace == 30.000
+ expect resp.http.ttl == 30.000
+
+ txreq -url /4
+ rxresp
+ expect resp.http.grace == 10.000
+ expect resp.http.ttl == 0.000
+} -run
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