ipc: Add callbacks and unify main functions

Part-of: <https://gitlab.freedesktop.org/monado/monado/-/merge_requests/2467>

src/xrt/ipc/server/ipc_server_interface.h

···
  * @ingroup ipc_server
  */
 
-#include "xrt/xrt_compiler.h"
+#pragma once
+
 #include "xrt/xrt_config_os.h"
+#include "xrt/xrt_results.h"
 
-#ifndef XRT_OS_ANDROID
 #include "util/u_debug_gui.h"
-#endif
 
 
 #ifdef __cplusplus
···
 #endif
 
 
-#ifndef XRT_OS_ANDROID
+struct xrt_instance;
+struct ipc_server;
 
 /*!
  * Information passed into the IPC server main function, used for customization
···
 };
 
 /*!
- * Main entrypoint to the compositor process.
+ *
+ * @ingroup ipc_server
+ */
+struct ipc_server_callbacks
+{
+	/*!
+	 * The IPC server failed to init.
+	 *
+	 * @param[in] xret The error code generated during init.
+	 * @param[in] data User data given passed into the main function.
+	 */
+	void (*init_failed)(xrt_result_t xret, void *data);
+
+	/*!
+	 * The service has completed init and is entering its mainloop.
+	 *
+	 * @param[in] s     The IPC server.
+	 * @param[in] xinst Instance that was created by the IPC server.
+	 * @param[in] data  User data given passed into the main function.
+	 */
+	void (*mainloop_entering)(struct ipc_server *s, struct xrt_instance *xinst, void *data);
+
+	/*!
+	 * The service is leaving the mainloop, after this callback returns the
+	 * IPC server will destroy all resources created.
+	 *
+	 * @param[in] s     The IPC server.
+	 * @param[in] xinst Instance that was created by the IPC server.
+	 * @param[in] data  User data given passed into the main function.
+	 */
+	void (*mainloop_leaving)(struct ipc_server *s, struct xrt_instance *xinst, void *data);
+};
+
+/*!
+ * Common main function for starting the IPC service.
  *
  * @ingroup ipc_server
  */
 int
-ipc_server_main(int argc, char **argv, const struct ipc_server_main_info *ismi);
-
-#endif
+ipc_server_main_common(const struct ipc_server_main_info *ismi, const struct ipc_server_callbacks *iscb, void *data);
 
 
-#ifdef XRT_OS_ANDROID
+#ifndef XRT_OS_ANDROID
 
 /*!
- * Main entrypoint to the server process.
- *
- * @param ps Pointer to populate with the server struct.
- * @param startup_complete_callback Function to call upon completing startup
- *                                  and populating *ps, but before entering
- *                                  the mainloop.
- * @param data user data to pass to your callback.
+ * Main entrypoint to the compositor process.
  *
  * @ingroup ipc_server
  */
 int
-ipc_server_main_android(struct ipc_server **ps, void (*startup_complete_callback)(void *data), void *data);
+ipc_server_main(int argc, char **argv, const struct ipc_server_main_info *ismi);
 
 #endif
 

src/xrt/ipc/server/ipc_server_process.c

···
 	return XRT_SUCCESS;
 }
 
-#ifndef XRT_OS_ANDROID
 int
-ipc_server_main(int argc, char **argv, const struct ipc_server_main_info *ismi)
+ipc_server_main_common(const struct ipc_server_main_info *ismi,
+                       const struct ipc_server_callbacks *callbacks,
+                       void *data)
 {
 	xrt_result_t xret = XRT_SUCCESS;
 	int ret = -1;
···
 	xret = init_all(s, log_level);
 	U_LOG_CHK_ONLY_PRINT(log_level, xret, "init_all");
 	if (xret != XRT_SUCCESS) {
-#ifdef XRT_OS_LINUX
-		// Print information how to debug issues.
-		print_linux_end_user_failed_information(log_level);
-#endif
-
+		// Propegate the failure.
+		callbacks->init_failed(xret, data);
 		u_debug_gui_stop(&s->debug_gui);
 		free(s);
 		return -1;
···
 	// Start the debug UI now (if enabled).
 	u_debug_gui_start(s->debug_gui, s->xinst, s->xsysd);
 
-#ifdef XRT_OS_LINUX
-	// Print a very clear service started message.
-	print_linux_end_user_started_information(log_level);
-#endif
+	// Tell the callbacks we are entering the main-loop.
+	callbacks->mainloop_entering(s, s->xinst, data);
+
 	// Main loop.
 	ret = main_loop(s);
 
+	// Tell the callbacks we are leaving the main-loop.
+	callbacks->mainloop_leaving(s, s->xinst, data);
+
 	// Stop the UI before tearing everything down.
 	u_debug_gui_stop(&s->debug_gui);
 
···
 	return ret;
 }
 
-#endif // !XRT_OS_ANDROID
 
-#ifdef XRT_OS_ANDROID
-int
-ipc_server_main_android(struct ipc_server **ps, void (*startup_complete_callback)(void *data), void *data)
-{
-	xrt_result_t xret = XRT_SUCCESS;
-	int ret = -1;
-
-	// Get log level first.
-	enum u_logging_level log_level = debug_get_log_option_ipc_log();
-
-	struct ipc_server *s = U_TYPED_CALLOC(struct ipc_server);
-	U_LOG_D("Created IPC server!");
-
-	xret = init_all(s, log_level);
-	U_LOG_CHK_ONLY_PRINT(log_level, xret, "init_all");
-	if (xret != XRT_SUCCESS) {
-		free(s);
-		startup_complete_callback(data);
-		return -1;
-	}
+#ifndef XRT_OS_ANDROID
 
-	*ps = s;
-	startup_complete_callback(data);
+static void
+init_failed(xrt_result_t xret, void *data)
+{
+#ifdef XRT_OS_LINUX
+	// Print information how to debug issues.
+	print_linux_end_user_failed_information(debug_get_log_option_ipc_log());
+#endif
+}
 
-	ret = main_loop(s);
+static void
+mainloop_entering(struct ipc_server *s, struct xrt_instance *xinst, void *data)
+{
+#ifdef XRT_OS_LINUX
+	// Print a very clear service started message.
+	print_linux_end_user_started_information(s->log_level);
+#endif
+}
 
-	teardown_all(s);
-	free(s);
+static void
+mainloop_leaving(struct ipc_server *s, struct xrt_instance *xinst, void *data)
+{
+	// No-op
+}
 
-	U_LOG_I("Server exiting '%i'!", ret);
+int
+ipc_server_main(int argc, char **argv, const struct ipc_server_main_info *ismi)
+{
+	const struct ipc_server_callbacks callbacks = {
+	    .init_failed = init_failed,
+	    .mainloop_entering = mainloop_entering,
+	    .mainloop_leaving = mainloop_leaving,
+	};
 
-	return ret;
+	return ipc_server_main_common(ismi, &callbacks, NULL);
 }
-#endif // XRT_OS_ANDROID
+
+#endif // !XRT_OS_ANDROID

src/xrt/targets/service-lib/service_target.cpp

···
 // Copyright 2020, Collabora, Ltd.
+// Copyright 2024-2025, NVIDIA CORPORATION.
 // SPDX-License-Identifier: BSL-1.0
 /*!
  * @file
···
 	}
 
 	void
-	signalStartupComplete()
+	signalStartupComplete(ipc_server *s)
 	{
 		std::unique_lock<std::mutex> lock{server_mutex};
 		startup_complete = true;
+		server = s;
 		startup_cond.notify_all();
 	}
 
···
 	{
 		std::unique_lock lock(server_mutex);
 		if (!server && !server_thread) {
-			server_thread = std::make_unique<std::thread>(
-			    [&]() { ipc_server_main_android(&server, signalStartupCompleteTrampoline, this); });
+			server_thread =
+			    std::make_unique<std::thread>([&]() { ipc_server_main_common(&ismi, &callbacks, this); });
 		}
 	}
 
 	static void
-	signalStartupCompleteTrampoline(void *data)
+	signalInitFailed(xrt_result_t xret, void *data)
 	{
-		static_cast<IpcServerHelper *>(data)->signalStartupComplete();
+		static_cast<IpcServerHelper *>(data)->signalStartupComplete(nullptr);
+	}
+
+	static void
+	signalStartupCompleteTrampoline(ipc_server *s, xrt_instance *xsint, void *data)
+	{
+		static_cast<IpcServerHelper *>(data)->signalStartupComplete(s);
+	}
+
+	static void
+	signalShuttingDownTrampoline(ipc_server *s, xrt_instance *xsint, void *data)
+	{
+		// No-op
 	}
 
 	int32_t
···
 		}
 		return server && completed;
 	}
+
+	const struct ipc_server_main_info ismi = {
+	    .udgci =
+	        {
+	            .window_title = "Monado Android Service",
+	            .open = U_DEBUG_GUI_OPEN_NEVER,
+	        },
+	};
+
+	const struct ipc_server_callbacks callbacks = {
+	    .init_failed = signalInitFailed,
+	    .mainloop_entering = signalStartupCompleteTrampoline,
+	    .mainloop_leaving = signalShuttingDownTrampoline,
+	};
 
 	//! Reference to the ipc_server, managed by ipc_server_process
 	struct ipc_server *server = NULL;