r305 - trunk/varnish-cache/bin/varnishd
phk at projects.linpro.no
phk at projects.linpro.no
Wed Jul 5 00:08:33 CEST 2006
Author: phk
Date: 2006-07-05 00:08:33 +0200 (Wed, 05 Jul 2006)
New Revision: 305
Modified:
trunk/varnish-cache/bin/varnishd/rfc2616.c
Log:
Implement our TTL calculation.
A first quick check against the weird timestamps from the VG frontend
squids indicates sensible behaviour.
Modified: trunk/varnish-cache/bin/varnishd/rfc2616.c
===================================================================
--- trunk/varnish-cache/bin/varnishd/rfc2616.c 2006-07-04 21:34:39 UTC (rev 304)
+++ trunk/varnish-cache/bin/varnishd/rfc2616.c 2006-07-04 22:08:33 UTC (rev 305)
@@ -5,7 +5,9 @@
#include <stdio.h>
#include <stdlib.h>
#include <pthread.h>
+#include <limits.h>
+#include "shmlog.h"
#include "cache.h"
#include "libvarnish.h"
#include "heritage.h"
@@ -35,124 +37,88 @@
* that talks about how a cache should react to a clockless origin server,
* and more or uses the inverse logic for the opposite relationship.
*
- * /* Marker for no retirement age determined */
- * retirement_age = INT_MAX
- *
- * /* If we have a max-age directive, respect it */
- * if (max-age)
- * retirement_age = max(0,min(retirement_age, max-age - Age:))
- *
- * /* If we have no Date: and Expires: looks sensible, use it */
- * if (!date && expires > our_clock) {
- * ttd = min(our_clock + retirement_age, Expires:)
- *
- * /* If Date: is in the past, and Expires: looks sensible, use it */
- * } else if (date < our_clock && expires > our_clock) {
- * ttd = min(date + retirement_age, Expires:)
- *
- * /* Otherwise we have clock-skew */
- * } else {
- * /* If we have both date and expires, infer max-age */
- * if (date && expires)
- * retirement_age =
- * max(0, min(retirement_age, Expires: - Date:)
- *
- * /* Apply default_ttl if nothing better found */
- * if (retirement_age == INT_MAX)
- * retirement_age = default_ttl
- *
- * /* Apply the max-age we can up with */
- * ttd = our_clock + retirement_age
- * }
- *
- * /* Apply hard limits */
- * ttd = max(ttd, our_clock + hard_lower_ttl)
- * ttd = min(ttd, our_clock + hard_upper_ttl)
*/
-/*--------------------------------------------------------------------
- * From RFC2616, 13.2.3 Age Calculations
- *
- * age_value
- * is the value of Age: header received by the cache with
- * this response.
- * date_value
- * is the value of the origin server's Date: header
- * request_time
- * is the (local) time when the cache made the request
- * that resulted in this cached response
- * response_time
- * is the (local) time when the cache received the response
- * now
- * is the current (local) time
- *
- * apparent_age = max(0, response_time - date_value);
- * corrected_received_age = max(apparent_age, age_value);
- * response_delay = response_time - request_time;
- * corrected_initial_age = corrected_received_age + response_delay;
- * resident_time = now - response_time;
- * current_age = corrected_initial_age + resident_time;
- *
- */
+#if PSEUDO_CODE
+ /* Marker for no retirement age determined */
+ retirement_age = INT_MAX
+ /* If we have a max-age directive, respect it */
+ if (max-age)
+ retirement_age = max(0,min(retirement_age, max-age - Age:))
+
+ /* If Date: is not in future and Expires: looks sensible, use it */
+ if ((!date || date < our_clock) && expires > our_clock) {
+ ttd = min(our_clock + retirement_age, Expires:)
+
+ /* Otherwise we have clock-skew */
+ } else {
+ /* If we have both date and expires, infer max-age */
+ if (date && expires)
+ retirement_age =
+ max(0, min(retirement_age, Expires: - Date:)
+
+ /* Apply default_ttl if nothing better found */
+ if (retirement_age == INT_MAX)
+ retirement_age = default_ttl
+
+ /* Apply the max-age we can up with */
+ ttd = our_clock + retirement_age
+ }
+
+ /* Apply hard limits */
+ ttd = max(ttd, our_clock + hard_lower_ttl)
+ ttd = min(ttd, our_clock + hard_upper_ttl)
+#endif
+
static time_t
RFC2616_Ttl(struct http *hp, time_t t_req, time_t t_resp)
{
- time_t h_date = 0, h_expires = 0, h_age = 0;
- time_t apparent_age = 0, corrected_received_age;
- time_t response_delay, corrected_initial_age;
- time_t max_age = -1, ttl;
- time_t fudge;
+ int retirement_age;
+ unsigned u1, u2;
+ time_t h_date, h_expires, ttd;
char *p;
+
+ retirement_age = INT_MAX;
- if (http_GetHdrField(hp, "Cache-Control", "max-age", &p))
- max_age = strtoul(p, NULL, 0);
+ u1 = u2 = 0;
+ if (http_GetHdrField(hp, "Cache-Control", "max-age", &p)) {
+ u1 = strtoul(p, NULL, 0);
+ u2 = 0;
+ if (http_GetHdr(hp, "Age", &p))
+ u2 = strtoul(p, NULL, 0);
+ if (u2 <= u1)
+ retirement_age = u1 - u2;
+ }
+ h_date = 0;
if (http_GetHdr(hp, "Date", &p))
h_date = TIM_parse(p);
- if (h_date + 3600 < t_resp) {
- fudge = t_resp - h_date;
- h_date += fudge;
- } else
- fudge = 0;
+ h_expires = 0;
+ if (http_GetHdr(hp, "Expires", &p))
+ h_expires = TIM_parse(p);
- if (h_date < t_resp)
- apparent_age = t_resp - h_date;
+ if (h_date < t_req && h_expires > t_req) {
+ ttd = h_expires;
+ if (retirement_age != INT_MAX && t_req + retirement_age < ttd)
+ ttd = t_req + retirement_age;
+ } else {
+ if (h_date != 0 && h_expires != 0) {
+ if (h_date < h_expires &&
+ h_expires - h_date < retirement_age)
+ retirement_age = h_expires - h_date;
+ }
+ if (retirement_age == INT_MAX)
+ retirement_age = heritage.default_ttl;
- if (http_GetHdr(hp, "Age", &p))
- h_age = strtoul(p, NULL, 0);
-
- if (h_age > apparent_age)
- corrected_received_age = h_age;
- else
- corrected_received_age = apparent_age;
-
- response_delay = t_resp - t_req;
- corrected_initial_age = corrected_received_age + response_delay;
-
- if (http_GetHdr(hp, "Expires", &p)) {
- h_expires = TIM_parse(p) + fudge;
+ ttd = t_req + retirement_age;
}
-
- printf("Date: %d\n", h_date);
- printf("Recv: %d\n", t_resp);
- printf("Expires: %d\n", h_expires);
- printf("Age: %d\n", h_age);
- printf("CIAge: %d\n", corrected_initial_age);
- printf("Max-Age: %d\n", max_age);
- ttl = 0;
- if (max_age >= 0)
- ttl = t_resp + max_age - corrected_initial_age;
- if (h_expires && h_expires < ttl)
- ttl = h_expires;
- if (ttl == 0)
- ttl = t_resp + heritage.default_ttl;
- printf("TTL: %d (%+d)\n", ttl, ttl - t_resp);
- if (ttl < t_resp)
- return (0);
-
- return (ttl);
+ VSL(SLT_Debug, 0,
+ "TTD: max-age %u Age: %u Date: %d (%d) Expires %d (%d) our_clock %d"
+ " -> ttd %d (%d)",
+ u1, u2, h_date, h_date - t_req, h_expires, h_expires - t_req, t_req, ttd, ttd - t_req);
+ return (ttd);
}
int
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