From 2b0aea70c275e08c1e312db91653eef880b4f725 Mon Sep 17 00:00:00 2001
From: cbdev <cb@cbcdn.com>
Date: Sat, 19 Dec 2020 17:25:19 +0100
Subject: Reconnect MQTT instances during maintenance

---
 backends/mqtt.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 57 insertions(+), 3 deletions(-)

diff --git a/backends/mqtt.c b/backends/mqtt.c
index 8c4a9fd..72046df 100644
--- a/backends/mqtt.c
+++ b/backends/mqtt.c
@@ -290,15 +290,69 @@ static int mqtt_set(instance* inst, size_t num, channel** c, channel_value* v){
 	return 0;
 }
 
+static int mqtt_maintenance(){
+	size_t n, u;
+	instance** inst = NULL;
+	mqtt_instance_data* data = NULL;
+
+	if(mm_backend_instances(BACKEND_NAME, &n, &inst)){
+		LOG("Failed to fetch instance list");
+		return 1;
+	}
+
+	DBGPF("Running maintenance operations on %" PRIsize_t " instances", n);
+	for(u = 0; u < n; u++){
+       		data = (mqtt_instance_data*) inst[u]->impl;
+		if(data->fd <= 0){
+			if(mqtt_reconnect(inst[u]) >= 2){
+				LOGPF("Failed to reconnect instance %s, terminating", inst[u]->name);
+				free(inst);
+				return 1;
+			}
+		}
+	}
+
+	free(inst);
+	return 0;
+}
+
+static int mqtt_handle_fd(instance* inst){
+	mqtt_instance_data* data = (mqtt_instance_data*) inst->impl;
+	ssize_t bytes_read = 0, bytes_left = sizeof(data->receive_buffer) - data->receive_offset;
+
+	bytes_read = recv(data->fd, data->receive_buffer + data->receive_offset, bytes_left, 0);
+	if(bytes_read < 0){
+		LOGPF("Failed to receive data on instance %s: %s", inst->name, mmbackend_socket_strerror(errno));
+		return 1;
+	}
+	else if(bytes_read == 0){
+		//disconnected, try to reconnect
+		LOGPF("Instance %s disconnected, reconnection queued", inst->name);
+		mqtt_disconnect(inst);
+		return 1;
+	}
+
+	DBGPF("Instance %s, offset %" PRIsize_t ", read %" PRIsize_t " bytes", inst->name, data->receive_offset, bytes_read);
+
+	return 0;
+}
+
 static int mqtt_handle(size_t num, managed_fd* fds){
 	size_t n = 0;
+	int rv = 0;
 
-	//for(n = 0; n < num; n++){
-	//}
+	for(n = 0; n < num; n++){
+		if(mqtt_handle_fd((instance*) fds[n].impl) >= 2){
+			//propagate critical failures
+			return 1;
+		}
+	}
 
 	//keepalive/reconnect processing
 	if(last_maintenance && mm_timestamp() - last_maintenance >= MQTT_KEEPALIVE * 1000){
-		//TODO run reconnects
+		if(mqtt_maintenance()){
+			return 1;
+		}
 		last_maintenance = mm_timestamp();
 	}
 
-- 
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