Mailing List Archive

Author: phk
Date: 2008-08-26 21:26:46 +0200 (Tue, 26 Aug 2008)
New Revision: 3134

Modified:
trunk/varnish-cache/bin/varnishd/cache_dir_random.c
trunk/varnish-cache/bin/varnishd/cache_dir_round_robin.c
Log:
Make the random and round-robin directors avoid backends which are
polled as unhealty.

This technically makes Varnish 2.0 "feature complete", but some further
polishing is to be expected.



Modified: trunk/varnish-cache/bin/varnishd/cache_dir_random.c
===================================================================
--- trunk/varnish-cache/bin/varnishd/cache_dir_random.c 2008-08-26 13:09:27 UTC (rev 3133)
+++ trunk/varnish-cache/bin/varnishd/cache_dir_random.c 2008-08-26 19:26:46 UTC (rev 3134)
@@ -50,7 +50,7 @@

struct vdi_random_host {
struct backend *backend;
- unsigned weight;
+ double weight;
};

struct vdi_random {
@@ -61,25 +61,60 @@
unsigned nhosts;
};

-
static struct vbe_conn *
vdi_random_getfd(struct sess *sp)
{
- int i;
+ int i, j, k;
struct vdi_random *vs;
- uint32_t r;
- struct vdi_random_host *vh;
+ double r, s1, s2;
+ struct vbe_conn *vbe;

CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
CHECK_OBJ_NOTNULL(sp->director, DIRECTOR_MAGIC);
CAST_OBJ_NOTNULL(vs, sp->director->priv, VDI_RANDOM_MAGIC);
- r = random();
- r &= 0x7fffffff;

- for (i = 0, vh = vs->hosts; i < vs->nhosts; vh++)
- if (r < vh->weight)
- return (VBE_GetVbe(sp, vh->backend));
- assert(0 == __LINE__);
+ k = 0;
+ for (k = 0; k < 4; ) { /* XXX: 4 is arbitrary */
+
+ r = random() / 2147483648.0; /* 2^31 */
+ assert(r >= 0.0 && r < 1.0);
+
+ s1 = 0.0;
+ j = 0;
+ for (i = 0; i < vs->nhosts; i++) {
+ if (!vs->hosts[i].backend->healthy)
+ continue;
+ s1 += vs->hosts[i].weight;
+ j++;
+ }
+
+ if (j == 0) /* No healthy hosts */
+ return (NULL);
+
+ r *= s1;
+
+ s2 = 0;
+ j = 0;
+ for (i = 0; i < vs->nhosts; i++) {
+ if (!vs->hosts[i].backend->healthy)
+ continue;
+ s2 += vs->hosts[i].weight;
+ if (r > s2)
+ j = i + 1;
+ }
+ if (s2 != s1) {
+ /*
+ * Health bit changed in an unusable way while we
+ * worked the problem. Usable changes are any that
+ * result in the same sum we prepared for.
+ */
+ continue;
+ }
+ vbe = VBE_GetVbe(sp, vs->hosts[j].backend);
+ if (vbe != NULL)
+ return (vbe);
+ k++;
+ }
return (NULL);
}

@@ -108,8 +143,7 @@
struct vdi_random *vs;
const struct vrt_dir_random_entry *te;
struct vdi_random_host *vh;
- double s, a, b;
- unsigned v;
+ double s;
int i;

(void)cli;
@@ -130,24 +164,9 @@
te = t->members;
for (i = 0; i < t->nmember; i++, vh++, te++) {
assert(te->weight > 0.0);
- s += te->weight;
+ vh->weight = te->weight;
vh->backend = VBE_AddBackend(cli, te->host);
}
vs->nhosts = t->nmember;
-
- /* Normalize weights */
- i = 0;
- a = 0.0;
- assert(s > 0.0);
- for (te = t->members; i < t->nmember; te++, i++) {
- /* First normalize the specified weight in FP */
- b = te->weight / s; /*lint !e795 not zero division */
- /* Then accumulate to eliminate rounding errors */
- a += b;
- /* Convert to unsigned in random() range */
- v = (unsigned)((1U<<31) * a);
- vs->hosts[i].weight = v;
- }
- assert(vs->hosts[t->nmember - 1].weight > 0x7fffffff);
*bp = &vs->dir;
}

Modified: trunk/varnish-cache/bin/varnishd/cache_dir_round_robin.c
===================================================================
--- trunk/varnish-cache/bin/varnishd/cache_dir_round_robin.c 2008-08-26 13:09:27 UTC (rev 3133)
+++ trunk/varnish-cache/bin/varnishd/cache_dir_round_robin.c 2008-08-26 19:26:46 UTC (rev 3134)
@@ -47,32 +47,41 @@
/*--------------------------------------------------------------------*/

struct vdi_round_robin_host {
- struct backend *backend;
+ struct backend *backend;
};

struct vdi_round_robin {
- unsigned magic;
-#define VDI_ROUND_ROBIN_MAGIC 0x2114a178
- struct director dir;
+ unsigned magic;
+#define VDI_ROUND_ROBIN_MAGIC 0x2114a178
+ struct director dir;
struct vdi_round_robin_host *hosts;
- unsigned nhosts;
- unsigned next_host;
+ unsigned nhosts;
+ unsigned next_host;
};

static struct vbe_conn *
vdi_round_robin_getfd(struct sess *sp)
{
+ int i;
struct vdi_round_robin *vs;
struct backend *backend;
+ struct vbe_conn *vbe;

CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
CHECK_OBJ_NOTNULL(sp->director, DIRECTOR_MAGIC);
CAST_OBJ_NOTNULL(vs, sp->director->priv, VDI_ROUND_ROBIN_MAGIC);

- backend = vs->hosts[ vs->next_host ].backend;
- vs->next_host = (vs->next_host + 1) % vs->nhosts;
+ for (i = 0; i < vs->nhosts; i++) {
+ backend = vs->hosts[vs->next_host].backend;
+ vs->next_host = (vs->next_host + 1) % vs->nhosts;
+ if (!backend->healthy)
+ continue;
+ vbe = VBE_GetVbe(sp, backend);
+ if (vbe != NULL)
+ return (vbe);
+ }

- return (VBE_GetVbe(sp, backend));
+ return (NULL);
}

/*lint -e{818} not const-able */