From d96d3b27d22b27079728a84862fdc7531aaf5ba3 Mon Sep 17 00:00:00 2001
From: Grant Limberg <grant.limberg@zerotier.com>
Date: Mon, 22 Sep 2025 10:52:06 -0700
Subject: [PATCH] try making the controller attach to an existing pubsub
 subscription if it already exists

---
 nonfree/controller/PubSubListener.cpp | 33 ++++++++++++++++-----------
 nonfree/controller/PubSubListener.hpp |  2 +-
 2 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/nonfree/controller/PubSubListener.cpp b/nonfree/controller/PubSubListener.cpp
index 0d87ff47c..b1a7187f6 100644
--- a/nonfree/controller/PubSubListener.cpp
+++ b/nonfree/controller/PubSubListener.cpp
@@ -30,12 +30,13 @@ PubSubListener::PubSubListener(std::string controller_id, std::string project, s
 	: _controller_id(controller_id)
 	, _project(project)
 	, _topic(topic)
-	, _subscription_id("sub-" + controller_id + "-" + topic)
+	, _subscription_id()
 	, _run(false)
 	, _adminClient(pubsub_admin::MakeSubscriptionAdminConnection())
-	, _subscription(pubsub::Subscription(_project, _subscription_id))
+	, _subscription(nullptr)
 {
-	_subscription_id = _subscription_id + "-" + random_hex_string(8);
+	_subscription_id = "sub-" + controller_id + "-" + topic;   // + "-" + random_hex_string(8);
+	_subscription = new pubsub::Subscription(_project, _subscription_id);
 	fprintf(
 		stderr, "PubSubListener for controller %s project %s topic %s subscription %s\n", controller_id.c_str(),
 		project.c_str(), topic.c_str(), _subscription_id.c_str());
@@ -48,21 +49,22 @@ PubSubListener::PubSubListener(std::string controller_id, std::string project, s
 	}
 
 	google::pubsub::v1::Subscription request;
-	request.set_name(_subscription.FullName());
+	request.set_name(_subscription->FullName());
 	request.set_topic(pubsub::Topic(project, topic).FullName());
 	request.set_filter("(attributes.controller_id=\"" + _controller_id + "\")");
 	auto sub = _adminClient.CreateSubscription(request);
 	if (! sub.ok()) {
-		fprintf(stderr, "Failed to create subscription: %s\n", sub.status().message().c_str());
-		throw std::runtime_error("Failed to create subscription");
+		if (sub.status().code() == google::cloud::StatusCode::kAlreadyExists) {
+			fprintf(stderr, "Subscription already exists.  Attaching to it\n");
+			// throw std::runtime_error("Subscription already exists");
+		}
+		else {
+			fprintf(stderr, "Failed to create subscription: %s\n", sub.status().message().c_str());
+			throw std::runtime_error("Failed to create subscription");
+		}
 	}
 
-	if (sub.status().code() == google::cloud::StatusCode::kAlreadyExists) {
-		fprintf(stderr, "Subscription already exists\n");
-		throw std::runtime_error("Subscription already exists");
-	}
-
-	_subscriber = std::make_shared<pubsub::Subscriber>(pubsub::MakeSubscriberConnection(_subscription));
+	_subscriber = std::make_shared<pubsub::Subscriber>(pubsub::MakeSubscriberConnection(*_subscription));
 
 	_run = true;
 	_subscriberThread = std::thread(&PubSubListener::subscribe, this);
@@ -75,10 +77,15 @@ PubSubListener::~PubSubListener()
 		_subscriberThread.join();
 	}
 
-	auto status = _adminClient.DeleteSubscription(_subscription.FullName());
+	auto status = _adminClient.DeleteSubscription(_subscription->FullName());
 	if (! status.ok()) {
 		fprintf(stderr, "Failed to delete subscription: %s\n", status.message().c_str());
 	}
+
+	if (_subscription) {
+		delete _subscription;
+		_subscription = nullptr;
+	}
 }
 
 void PubSubListener::subscribe()
diff --git a/nonfree/controller/PubSubListener.hpp b/nonfree/controller/PubSubListener.hpp
index 6e7f17c64..2efe8c819 100644
--- a/nonfree/controller/PubSubListener.hpp
+++ b/nonfree/controller/PubSubListener.hpp
@@ -35,7 +35,7 @@ class PubSubListener : public NotificationListener {
 	void subscribe();
 	bool _run = false;
 	google::cloud::pubsub_admin::SubscriptionAdminClient _adminClient;
-	google::cloud::pubsub::Subscription _subscription;
+	google::cloud::pubsub::Subscription* _subscription;
 	std::shared_ptr<google::cloud::pubsub::Subscriber> _subscriber;
 	std::thread _subscriberThread;
 };