Add consistent hash test.

P value is calculated as following:
when we add/remove M upstreams from the list, the probability of hash
miss should be close to the relation N / (N + M), where N is the size of
the previous upstreams list.

So far, the algorithm described in http://arxiv.org/abs/1406.2294 shows
p value more than 0.99.

diff --git a/test/rspamd_upstream_test.c b/test/rspamd_upstream_test.c
index 5c25f120d5e2d9f1cfa03300b32baa812444a9be..fa81aecd97dcae16b54290fbf5c0f0e3940933cb 100644 (file)
--- a/test/rspamd_upstream_test.c
+++ b/test/rspamd_upstream_test.c
@@ -26,9 +26,11 @@
 #include "config.h"
 #include "main.h"
 #include "upstream.h"
+#include "ottery.h"
 
 const char *test_upstream_list = "microsoft.com:443:1,google.com:80:2,kernel.org:443:3";
-
+const char *new_upstream_list = "freebsd.org:80";
+char test_key[32];
 
 static void
 rspamd_upstream_test_method (struct upstream_list *ls,
@@ -36,18 +38,29 @@ rspamd_upstream_test_method (struct upstream_list *ls,
 {
        struct upstream *up;
 
-       up = rspamd_upstream_get (ls, rot);
-       g_assert (up != NULL);
-       g_assert (strcmp (rspamd_upstream_name (up), expected) == 0);
+       if (rot != RSPAMD_UPSTREAM_HASHED) {
+               up = rspamd_upstream_get (ls, rot);
+               g_assert (up != NULL);
+               g_assert (strcmp (rspamd_upstream_name (up), expected) == 0);
+       }
+       else {
+               up = rspamd_upstream_get (ls, RSPAMD_UPSTREAM_HASHED, test_key,
+                                       sizeof (test_key));
+               g_assert (up != NULL);
+               g_assert (strcmp (rspamd_upstream_name (up), expected) == 0);
+       }
 }
 
 void
 rspamd_upstream_test_func (void)
 {
-       struct upstream_list *ls;
+       struct upstream_list *ls, *nls;
+       struct upstream *up, *upn;
        struct event_base *ev_base = event_init ();
        struct rspamd_dns_resolver *resolver;
        struct rspamd_config *cfg;
+       gint i, success = 0;
+       const gint assumptions = 100500;
 
        cfg = (struct rspamd_config *)g_malloc (sizeof (struct rspamd_config));
        bzero (cfg, sizeof (struct rspamd_config));
@@ -73,4 +86,29 @@ rspamd_upstream_test_func (void)
        rspamd_upstream_test_method (ls, RSPAMD_UPSTREAM_ROUND_ROBIN, "microsoft.com");
        rspamd_upstream_test_method (ls, RSPAMD_UPSTREAM_ROUND_ROBIN, "google.com");
        rspamd_upstream_test_method (ls, RSPAMD_UPSTREAM_ROUND_ROBIN, "kernel.org");
+
+       /* Test stable hashing */
+       nls = rspamd_upstreams_create ();
+       g_assert (rspamd_upstreams_parse_line (nls, test_upstream_list, 443, NULL));
+       g_assert (rspamd_upstreams_parse_line (nls, new_upstream_list, 443, NULL));
+       for (i = 0; i < assumptions; i ++) {
+               ottery_rand_bytes (test_key, sizeof (test_key));
+               up = rspamd_upstream_get (ls, RSPAMD_UPSTREAM_HASHED, test_key,
+                       sizeof (test_key));
+               upn = rspamd_upstream_get (nls, RSPAMD_UPSTREAM_HASHED, test_key,
+                       sizeof (test_key));
+
+               if (strcmp (rspamd_upstream_name (up), rspamd_upstream_name (upn)) == 0) {
+                       success ++;
+               }
+       }
+
+       /*
+        * P value is calculated as following:
+        * when we add/remove M upstreams from the list, the probability of hash
+        * miss should be close to the relation N / (N + M), where N is the size of
+        * the previous upstreams list.
+        */
+       msg_info ("p value for hash consistency: %.6f", 1.0 - fabs ((3.0 / 4.0 -
+                       (gdouble)success / (gdouble)assumptions)));
 }