RGWRados factory with dependency injection

rgw_rados.cc

RGWRados *RGWStoreManager::init_storage_provider(CephContext *cct, bool use_cache)
{
	// service factory functions return unique_ptr and take dependencies as raw pointers,
	// or as unique_ptr&& to transfer ownership. errors are thrown as std::system_errors
	try {
		auto rados = create_rados(cct);
		auto core = create_sysobj_core(cct, rados.get());
		auto sysobj = create_sysobj(cct, rados.get(), core.get());

		auto sync = create_sync_modules(cct);
		auto zone = create_zone(cct, rados.get(), sync.get());
		auto zoneutils = create_zone_utils(cct, rados.get(), zone.get());

		auto quota = create_quota(cct, zone.default_bucket_quota(), zone.default_user_quota());

		std::unique_ptr<RGWSI_SysObj_Cache> cache;
		if (use_cache) {
			auto finisher = create_finisher(cct);
			auto notify = create_notify(cct, rados.get(), std::move(finisher), zone.get_control_pool());
			cache = create_sysobj_cache(cct, core.get(), std::move(notify));
		}

		// transfer ownership to RGWRados
		auto store = new RGWRados(cct, std::move(rados), std::move(core), std::move(sysobj),
			std::move(sync), std::move(zone), std::move(zoneutils),
			std::move(quota), std::move(cache)));
		if (!store->initialize()) {
			delete store;
			return nullptr;
		}
		return store;
	} catch (const std::exception &e) {
		return nullptr;
	}
}

// example service factory
std::unique_ptr<RGWSI_Zone> create_zone(CephContext *cct, RGWSI_RADOS *rados, RGWSI_SyncModules *sync)
{
	auto zone = std::make_unique<RGWSI_Zone>(cct, rados, sync);
	int r = zone->init();
	if (r < 0) {
		lderr(cct) << "failed to init zone: " << r << dendl;
		throw std::system_error(-r, std::system_category());
	}
	return zone;
}