Retry connecting to bitcoin core if not available

In some setups, namely when deploying sv2-tp alongside an unsynced
bitcoin node, we want to wait for the node to fully sync before we are
able to connect to it. Otherwise the deployment process would be two
steps instead of one. This commit adds a retry mechanism when connection
to a bitcoin core node every 10 seconds.

Author: jbesraa

src/sv2-tp.cpp

@@ -160,18 +160,24 @@ MAIN_FUNCTION
         options.fee_check_interval = std::chrono::seconds(args.GetIntArg("-sv2interval", 0));
     }
 
-    // Connect to existing bitcoin-node process or spawn new one.
+    // Connect to bitcoin-node via IPC
+    //
+    // If the node is not available, keep retrying in a loop every 10 seconds.
     std::unique_ptr<interfaces::Init> mine_init{interfaces::MakeBasicInit("sv2-tp", argc > 0 ? argv[0] : "")};
     assert(mine_init);
     std::unique_ptr<interfaces::Init> node_init;
-    try {
-        std::string address{args.GetArg("-ipcconnect", "unix")};
-        node_init = mine_init->ipc()->connectAddress(address);
-    } catch (const std::exception& exception) {
-        tfm::format(std::cerr, "Error: %s\n", exception.what());
-        tfm::format(std::cerr, "Probably bitcoin-node is not running or not listening on a unix socket. Can be started with:\n\n");
-        tfm::format(std::cerr, "    bitcoin-node -chain=%s -ipcbind=unix\n", args.GetChainTypeString());
-        return EXIT_FAILURE;
+    std::string address{args.GetArg("-ipcconnect", "unix")};
+    while (true) {
+        try {
+            node_init = mine_init->ipc()->connectAddress(address);
+            break;  // Success: break out of the loop
+        } catch (const std::exception& exception) {
+            tfm::format(std::cerr, "IPC connection failed: %s\n", exception.what());
+            tfm::format(std::cerr, "bitcoin-node might not be running or listening on a UNIX socket.\n");
+            tfm::format(std::cerr, "Retrying in 10 seconds...\n\n");
+
+            std::this_thread::sleep_for(std::chrono::seconds(10));
+        }
     }
     assert(node_init);
     tfm::format(std::cout, "Connected to bitcoin-node\n");