[Feature] Allow exception when choosing upstream

src/libutil/upstream.c

@@ -1310,18 +1310,30 @@ rspamd_upstream_restore_cb (gpointer elt, gpointer ls)
 }
 
 static struct upstream*
-rspamd_upstream_get_random (struct upstream_list *ups)
+rspamd_upstream_get_random (struct upstream_list *ups,
+							struct upstream *except)
 {
-	guint idx = ottery_rand_range (ups->alive->len - 1);
+	for (;;) {
+		guint idx = ottery_rand_range (ups->alive->len - 1);
+		struct upstream *up;
 
-	return g_ptr_array_index (ups->alive, idx);
+		up = g_ptr_array_index (ups->alive, idx);
+
+		if (except && up == except) {
+			continue;
+		}
+
+		return up;
+	}
 }
 
 static struct upstream*
-rspamd_upstream_get_round_robin (struct upstream_list *ups, gboolean use_cur)
+rspamd_upstream_get_round_robin (struct upstream_list *ups,
+								 struct upstream *except,
+								 gboolean use_cur)
 {
 	guint max_weight = 0, min_checked = G_MAXUINT;
-	struct upstream *up, *selected = NULL, *min_checked_sel = NULL;
+	struct upstream *up = NULL, *selected = NULL, *min_checked_sel = NULL;
 	guint i;
 
 	/* Select upstream with the maximum cur_weight */
@@ -1329,6 +1341,11 @@ rspamd_upstream_get_round_robin (struct upstream_list *ups, gboolean use_cur)
 
 	for (i = 0; i < ups->alive->len; i ++) {
 		up = g_ptr_array_index (ups->alive, i);
+
+		if (except != NULL && up == except) {
+			continue;
+		}
+
 		if (use_cur) {
 			if (up->cur_weight > max_weight) {
 				selected = up;
@@ -1396,18 +1413,15 @@ rspamd_consistent_hash (guint64 key, guint32 nbuckets)
 }
 
 static struct upstream*
-rspamd_upstream_get_hashed (struct upstream_list *ups, const guint8 *key, guint keylen)
+rspamd_upstream_get_hashed (struct upstream_list *ups,
+							struct upstream *except,
+							const guint8 *key, guint keylen)
 {
 	guint64 k;
 	guint32 idx;
 	static const guint max_tries = 20;
 	struct upstream *up = NULL;
 
-	if (ups->alive->len == 1) {
-		/* Fast path */
-		return g_ptr_array_index (ups->alive, 0);
-	}
-
 	/* Generate 64 bits input key */
 	k = rspamd_cryptobox_fast_hash_specific (RSPAMD_CRYPTOBOX_XXHASH64,
 			key, keylen, ups->hash_seed);
@@ -1420,8 +1434,8 @@ rspamd_upstream_get_hashed (struct upstream_list *ups, const guint8 *key, guint
 		idx = rspamd_consistent_hash (k, ups->ups->len);
 		up = g_ptr_array_index (ups->ups, idx);
 
-		if (up->active_idx < 0) {
-			/* Found inactive upstream */
+		if (up->active_idx < 0 || (except != NULL && up == except)) {
+			/* Found inactive or excluded upstream */
 			k = mum_hash_step (k, ups->hash_seed);
 		}
 		else {
@@ -1435,7 +1449,7 @@ rspamd_upstream_get_hashed (struct upstream_list *ups, const guint8 *key, guint
 	}
 
 	/* We failed to find any active upstream */
-	up = rspamd_upstream_get_random (ups);
+	up = rspamd_upstream_get_random (ups, except);
 	msg_info ("failed to find hashed upstream for %s, fallback to random: %s",
 			ups->ups_line, up->name);
 
@@ -1444,8 +1458,10 @@ rspamd_upstream_get_hashed (struct upstream_list *ups, const guint8 *key, guint
 
 static struct upstream*
 rspamd_upstream_get_common (struct upstream_list *ups,
-		enum rspamd_upstream_rotation default_type,
-		const guchar *key, gsize keylen, gboolean forced)
+							struct upstream* except,
+							enum rspamd_upstream_rotation default_type,
+							const guchar *key, gsize keylen,
+							gboolean forced)
 {
 	enum rspamd_upstream_rotation type;
 	struct upstream *up = NULL;
@@ -1459,6 +1475,12 @@ rspamd_upstream_get_common (struct upstream_list *ups,
 	}
 	RSPAMD_UPSTREAM_UNLOCK (ups);
 
+	if (ups->alive->len == 1) {
+		/* Fast path */
+		up =  g_ptr_array_index (ups->alive, 0);
+		goto end;
+	}
+
 	if (!forced) {
 		type = ups->rot_alg != RSPAMD_UPSTREAM_UNDEF ? ups->rot_alg : default_type;
 	}
@@ -1474,16 +1496,16 @@ rspamd_upstream_get_common (struct upstream_list *ups,
 	switch (type) {
 	default:
 	case RSPAMD_UPSTREAM_RANDOM:
-		up = rspamd_upstream_get_random (ups);
+		up = rspamd_upstream_get_random (ups, except);
 		break;
 	case RSPAMD_UPSTREAM_HASHED:
-		up = rspamd_upstream_get_hashed (ups, key, keylen);
+		up = rspamd_upstream_get_hashed (ups, except, key, keylen);
 		break;
 	case RSPAMD_UPSTREAM_ROUND_ROBIN:
-		up = rspamd_upstream_get_round_robin (ups, TRUE);
+		up = rspamd_upstream_get_round_robin (ups, except, TRUE);
 		break;
 	case RSPAMD_UPSTREAM_MASTER_SLAVE:
-		up = rspamd_upstream_get_round_robin (ups, FALSE);
+		up = rspamd_upstream_get_round_robin (ups, except, FALSE);
 		break;
 	case RSPAMD_UPSTREAM_SEQUENTIAL:
 		if (ups->cur_elt >= ups->alive->len) {
@@ -1495,6 +1517,7 @@ rspamd_upstream_get_common (struct upstream_list *ups,
 		break;
 	}
 
+end:
 	if (up) {
 		up->checked ++;
 	}
@@ -1507,7 +1530,7 @@ rspamd_upstream_get (struct upstream_list *ups,
 		enum rspamd_upstream_rotation default_type,
 		const guchar *key, gsize keylen)
 {
-	return rspamd_upstream_get_common (ups, default_type, key, keylen, FALSE);
+	return rspamd_upstream_get_common (ups, NULL, default_type, key, keylen, FALSE);
 }
 
 struct upstream*
@@ -1515,7 +1538,15 @@ rspamd_upstream_get_forced (struct upstream_list *ups,
 		enum rspamd_upstream_rotation forced_type,
 		const guchar *key, gsize keylen)
 {
-	return rspamd_upstream_get_common (ups, forced_type, key, keylen, TRUE);
+	return rspamd_upstream_get_common (ups, NULL, forced_type, key, keylen, TRUE);
+}
+
+struct upstream *rspamd_upstream_get_except (struct upstream_list *ups,
+											 struct upstream *except,
+											 enum rspamd_upstream_rotation default_type,
+											 const guchar *key, gsize keylen)
+{
+	return rspamd_upstream_get_common (ups, except, default_type, key, keylen, FALSE);
 }
 
 void

src/libutil/upstream.h

@@ -283,6 +283,17 @@ struct upstream *rspamd_upstream_get_forced (struct upstream_list *ups,
 											 enum rspamd_upstream_rotation forced_type,
 											 const guchar *key, gsize keylen);
 
+/**
+ * Get new upstream from the list excepting the upstream specified
+ * @param ups upstream list
+ * @param type type of rotation algorithm, for `RSPAMD_UPSTREAM_HASHED` it is required to specify `key` and `keylen` as arguments
+ * @return
+ */
+struct upstream *rspamd_upstream_get_except (struct upstream_list *ups,
+											 struct upstream *except,
+											 enum rspamd_upstream_rotation default_type,
+											 const guchar *key, gsize keylen);
+
 /**
  * Re-resolve addresses for all upstreams registered
  */