Only reconnect clients when there is room for them on the new proxy, tagging the rest and recruiting as needed

src/stratifier.c

@@ -1141,11 +1141,14 @@ static int64_t current_headroom(sdata_t *sdata, proxy_t **proxy)
 
 	mutex_lock(&sdata->proxy_lock);
 	*proxy = sdata->proxy;
+	if (!*proxy)
+		goto out_unlock;
 	HASH_ITER(sh, (*proxy)->subproxies, subproxy, tmp) {
 		if (subproxy->dead)
 			continue;
 		headroom += subproxy->max_clients - subproxy->clients;
 	}
+out_unlock:
 	mutex_unlock(&sdata->proxy_lock);
 
 	return headroom;
@@ -1170,6 +1173,8 @@ static void reconnect_clients(sdata_t *sdata)
 	proxy_t *proxy;
 
 	headroom = current_headroom(sdata, &proxy);
+	if (!proxy)
+		return;
 
 	ck_rlock(&sdata->instance_lock);
 	HASH_ITER(hh, sdata->stratum_instances, client, tmpclient) {
@@ -1192,7 +1197,7 @@ static void reconnect_clients(sdata_t *sdata)
 			  flagged, proxy->id);
 	}
 	if (flagged)
-		generator_recruit(client->ckp);
+		generator_recruit(sdata->ckp);
 }
 
 static proxy_t *current_proxy(sdata_t *sdata)
@@ -2121,6 +2126,12 @@ static void reconnect_client(sdata_t *sdata, stratum_instance_t *client)
 {
 	json_t *json_msg;
 
+	/* Already requested? */
+	if (client->reconnect_request) {
+		connector_drop_client(sdata->ckp, client->id);
+		client->dropped = true;
+		return;
+	}
 	client->reconnect = false;
 	client->reconnect_request = time(NULL);
 	JSON_CPACK(json_msg, "{sosss[]}", "id", json_null(), "method", "client.reconnect",
@@ -2151,7 +2162,9 @@ static void set_proxy(sdata_t *sdata, const char *buf)
 static void dead_proxy(sdata_t *sdata, const char *buf)
 {
 	stratum_instance_t *client, *tmp;
+	int reconnects = 0, flagged = 0;
 	int id = 0, subid = 0;
+	int64_t headroom;
 	proxy_t *proxy;
 
 	sscanf(buf, "deadproxy=%d:%d", &id, &subid);
@@ -2159,13 +2172,54 @@ static void dead_proxy(sdata_t *sdata, const char *buf)
 	if (proxy)
 		proxy->dead = true;
 	LOGNOTICE("Stratifier dropping clients from proxy %d:%d", id, subid);
+	headroom = current_headroom(sdata, &proxy);
+	if (!proxy)
+		return;
 
 	ck_rlock(&sdata->instance_lock);
 	HASH_ITER(hh, sdata->stratum_instances, client, tmp) {
-		if (client->proxyid == id && client->subproxyid == subid)
+		if (client->proxyid != id || client->subproxyid != subid)
+			continue;
+		if (reconnects >= headroom) {
+			if (!client->reconnect) {
+				client->reconnect = true;
+				flagged++;
+			}
+			continue;
+		}
+		client->reconnect = true;
+		reconnects++;
 		reconnect_client(sdata, client);
 	}
 	ck_runlock(&sdata->instance_lock);
+
+	if (reconnects || flagged) {
+		LOGNOTICE("Reconnected %d clients, flagged %d from dead proxy %d:%d", reconnects,
+			  flagged, id, subid);
+	}
+	if (flagged)
+		generator_recruit(sdata->ckp);
+}
+
+/* Must hold a reference */
+static void lazy_reconnect_client(sdata_t *sdata, stratum_instance_t *client)
+{
+	int64_t headroom;
+	proxy_t *proxy;
+
+	headroom = current_headroom(sdata, &proxy);
+	if (!proxy)
+		return;
+	if (headroom > 0) {
+		LOGNOTICE("Reconnecting client %"PRId64, client->id);
+		reconnect_client(sdata, client);
+	} else {
+		generator_recruit(sdata->ckp);
+		if (!client->reconnect) {
+			LOGNOTICE("Flagging client %"PRId64, client->id);
+			client->reconnect = true;
+		}
+	}
 }
 
 static void reconnect_client_id(sdata_t *sdata, const int64_t client_id)
@@ -2177,8 +2231,7 @@ static void reconnect_client_id(sdata_t *sdata, const int64_t client_id)
 		LOGINFO("reconnect_client_id failed to find client %"PRId64, client_id);
 		return;
 	}
-	LOGNOTICE("Reconnecting client %"PRId64, client_id);
-	reconnect_client(sdata, client);
+	lazy_reconnect_client(sdata, client);
 	dec_instance_ref(sdata, client);
 }
 
@@ -4079,7 +4132,7 @@ static void srecv_process(ckpool_t *ckp, char *buf)
 	/* The client is still active but has been issued a reconnect request
 	 * so use this opportunity to send it a reconnect message */
 	if (unlikely(client->reconnect))
-		reconnect_client(sdata, client);
+		lazy_reconnect_client(sdata, client);
 	dec_instance_ref(sdata, client);
 out:
 	free(buf);