RADService

RADService contains deployment-oriented helpers for running RADLib programs as long-lived services: systemd unit generation, watchdog/ready notifications, single-instance locks, and Unix daemonization. These helpers are useful for embedded appliances and desktop background tools that need reproducible service metadata.

A ServiceUnit describes a systemd service: its name, description, execStart command, optional workingDirectory, environment map, user, and wantedBy target. The restart policy is a RestartPolicy (No, OnFailure, or Always), and watchdogSec enables WatchdogSec when non-zero.

ServiceManager exposes the static helpers. generateSystemdUnit() serializes a ServiceUnit to unit-file text, and writeSystemdUnit() writes it into a target directory. restartPolicyName() converts a policy to its systemd token. For runtime supervision, notify() sends an sd_notify-compatible message to NOTIFY_SOCKET without linking libsystemd, with notifyReady() sending READY=1 and notifyWatchdog() sending WATCHDOG=1. daemonize() performs a Unix double-fork when supported.

SingleInstanceLock guards against concurrent instances using a RADCore::RADLockFile. Construct it with a lock path, call tryLock(), and check isLocked(); the lock is released in the destructor.

Core features:

• systemd unit generation and writing from a ServiceUnit.
• sd_notify-compatible ready/watchdog messages without libsystemd.
• Single-instance process locks via RADCore::RADLockFile.
• Optional Unix double-fork daemonization.

Example:

RADService::SingleInstanceLock lock("/run/radappd.lock");
if (!lock.tryLock()) {
    return 1; // Another instance is already running.
}
 
RADService::ServiceUnit unit;
unit.name = "radappd";
unit.description = "RAD appliance daemon";
unit.execStart = "/usr/bin/radappd";
unit.restart = RADService::RestartPolicy::OnFailure;
unit.watchdogSec = 30;
RADService::ServiceManager::writeSystemdUnit(unit, "/etc/systemd/system");
 
RADService::ServiceManager::notifyReady();