Allow multiple editor instances to use different ports

Previously if more than one Godot editor was running then the debugger of one editor would not work because both editors were trying to connect on the same port.
This commit attempts to fix this by allowing the debugger to change the port at runtime in such cases.

editor/editor_node.cpp

@@ -2029,16 +2029,16 @@ void EditorNode::_run(bool p_current, const String &p_custom) {
 
 	args = ProjectSettings::get_singleton()->get("editor/main_run_args");
 	skip_breakpoints = ScriptEditor::get_singleton()->get_debugger()->is_skip_breakpoints();
+	emit_signal("play_pressed");
 
 	Error error = editor_run.run(run_filename, args, breakpoints, skip_breakpoints);
 
 	if (error != OK) {
-
+		emit_signal("stop_pressed");
 		show_accept(TTR("Could not start subprocess!"), TTR("OK"));
 		return;
 	}
 
-	emit_signal("play_pressed");
 	if (p_current) {
 		play_scene_button->set_pressed(true);
 		play_scene_button->set_icon(gui_base->get_icon("Reload", "EditorIcons"));

editor/editor_run.cpp

@@ -30,6 +30,9 @@
 
 #include "editor_run.h"
 
+#include "plugins/script_editor_plugin.h"
+#include "script_editor_debugger.h"
+
 #include "core/project_settings.h"
 #include "editor_settings.h"
 
@@ -43,8 +46,6 @@ Error EditorRun::run(const String &p_scene, const String &p_custom_args, const L
 	List<String> args;
 
 	String resource_path = ProjectSettings::get_singleton()->get_resource_path();
-	String remote_host = EditorSettings::get_singleton()->get("network/debug/remote_host");
-	int remote_port = (int)EditorSettings::get_singleton()->get("network/debug/remote_port");
 
 	if (resource_path != "") {
 		args.push_back("--path");
@@ -52,8 +53,15 @@ Error EditorRun::run(const String &p_scene, const String &p_custom_args, const L
 	}
 
 	args.push_back("--remote-debug");
-	args.push_back(remote_host + ":" + String::num(remote_port));
 
+	const String conn_string = ScriptEditor::get_singleton()->get_debugger()->get_connection_string();
+	if (!conn_string.empty()) {
+		args.push_back(ScriptEditor::get_singleton()->get_debugger()->get_connection_string());
+	} else { // Try anyway with default settings
+		const String remote_host = EditorSettings::get_singleton()->get("network/debug/remote_host");
+		const int remote_port = (int)EditorSettings::get_singleton()->get("network/debug/remote_port");
+		args.push_back(remote_host + ":" + String::num(remote_port));
+	}
 	args.push_back("--allow_focus_steal_pid");
 	args.push_back(itos(OS::get_singleton()->get_process_id()));
 

editor/script_editor_debugger.cpp

@@ -29,8 +29,8 @@
 /*************************************************************************/
 
 #include "script_editor_debugger.h"
-
 #include "core/io/marshalls.h"
+#include "core/os/os.h"
 #include "core/project_settings.h"
 #include "core/ustring.h"
 #include "editor/plugins/canvas_item_editor_plugin.h"
@@ -1476,13 +1476,25 @@ void ScriptEditorDebugger::start() {
 		perf_max.write[i] = 0;
 	}
 
-	int remote_port = (int)EditorSettings::get_singleton()->get("network/debug/remote_port");
-	if (server->listen(remote_port) != OK) {
-		EditorNode::get_log()->add_message(String("Error listening on port ") + itos(remote_port), EditorLog::MSG_TYPE_ERROR);
-		return;
+	const int max_tries = 6;
+	remote_port = (int)EditorSettings::get_singleton()->get("network/debug/remote_port");
+	int current_try = 0;
+	// Find first available port.
+	Error err = server->listen(remote_port);
+	while (err != OK && current_try < max_tries) {
+		EditorNode::get_log()->add_message(String("Remote debugger failed listening on port: ") + itos(remote_port) + String(" Retrying on new port: " + itos(remote_port + 1)), EditorLog::MSG_TYPE_WARNING);
+		current_try++;
+		remote_port++;
+		OS::get_singleton()->delay_usec(1000);
+		err = server->listen(remote_port);
+	}
+	// No suitable port found.
+	if (err != OK) {
+		EditorNode::get_log()->add_message(String("Error listening on port ") + itos(remote_port), EditorLog::MSG_TYPE_ERROR);
+		EditorNode::get_log()->add_message(String("Remote debugger error listening for connections. No free port"), EditorLog::MSG_TYPE_ERROR);
 	}
-
 	EditorNode::get_singleton()->get_scene_tree_dock()->show_tab_buttons();
+
 	auto_switch_remote_scene_tree = (bool)EditorSettings::get_singleton()->get("debugger/auto_switch_to_remote_scene_tree");
 	if (auto_switch_remote_scene_tree) {
 		EditorNode::get_singleton()->get_scene_tree_dock()->show_remote_tree();
@@ -1517,6 +1529,7 @@ void ScriptEditorDebugger::stop() {
 		reason->set_tooltip("");
 	}
 
+	remote_port = 0;
 	pending_in_queue = 0;
 	message.clear();
 
@@ -2059,6 +2072,11 @@ bool ScriptEditorDebugger::get_debug_with_external_editor() const {
 	return enable_external_editor;
 }
 
+String ScriptEditorDebugger::get_connection_string() const {
+	String remote_host = EditorSettings::get_singleton()->get("network/debug/remote_host");
+	return remote_port ? remote_host + ":" + itos(remote_port) : "";
+}
+
 void ScriptEditorDebugger::set_debug_with_external_editor(bool p_enabled) {
 
 	enable_external_editor = p_enabled;
@@ -2625,6 +2643,7 @@ ScriptEditorDebugger::ScriptEditorDebugger(EditorNode *p_editor) {
 	enable_external_editor = false;
 	last_error_count = 0;
 	last_warning_count = 0;
+	remote_port = 0;
 
 	EditorNode::get_singleton()->get_pause_button()->connect("pressed", this, "_paused");
 }

editor/script_editor_debugger.h

@@ -121,6 +121,7 @@ private:
 	int last_warning_count;
 
 	bool hide_on_stop;
+	int remote_port;
 	bool enable_external_editor;
 
 	bool skip_breakpoints_value = false;
@@ -275,6 +276,7 @@ public:
 	void set_hide_on_stop(bool p_hide);
 
 	bool get_debug_with_external_editor() const;
+	String get_connection_string() const;
 	void set_debug_with_external_editor(bool p_enabled);
 
 	Ref<Script> get_dump_stack_script() const;