Expand description
RSM
RSM = Realtime Software Middleware Introduction
Realtime system is defined as a system that can response the external request in certain deterministic time. To achieve this goal in generic computer systems, we must adopt a realtime shcedule policy on the software system, and keep from some time-consuming operation such as synchronous I/O operation, memory garbage collection and lock.
RSM is a lightweight realtime middleware implementation written in rust, support event-driven, message oriented lock-free programming principle. in RSM, every software module is a component, which is normally a Finite State Machine, mainly proccess event loop. Each component can be instantiated to several tasks, and each task mapped to a dedicated OS thread and has its own message queue.
Developer can set the task’s schedule priority and their message queue length respectively,usually based on the service model and performance & latency requirements.
RSM is suitable for the following applications:
- network device control plane, e.g. routing protocol, service control
- embedded system application
- remote control system
- realtime telemetry and instrumentation
Programming
Concept
each RSM component must implement the rsm::Runnable trait and provides a task creation Callback function.
the code in main.rs is a sample RSM application implementation.
pub trait Runnable {
fn on_init(&mut self,cid:&rsm_component_t);
fn on_timer(&mut self,cid:&rsm_component_t,timer_id:rsm_timer_id_t,timer_data:usize);
fn on_message(&mut self,cid:&rsm_component_t,msg_id:rsm_message_id_t,msg:&rsm_message_t);
fn on_close(&mut self,cid:&rsm_component_t);}
type rsm_new_task=fn(cid:&rsm_component_t)->&’static mut dyn Runnable
Initialize the RSM
using rsm_init function to init the rsm system, then the applicaition can register their components to RSM.
rsm_init_cfg_t is the RSM’s configuration file, which is in json format. rsm_init(conf:&config::rsm_init_cfg_t)->errcode::RESULT
pub fn registry_component(cid:u32,attrs:&component_attrs_t,callback:rsm_new_task)->errcode::RESULT
After the component registration is finished, the start_rsm() function should be called to running the system.
Runtime
every running task can be identified uniquely by rsm_component_t
task can send message to each other, with normal message or a high priority message pub fn send_asyn_msg(dst:&rsm_component_t,msg:rsm_message_t)->errcode::RESUL
pub fn send_asyn_priority_msg(dst:&rsm_component_t,msg:rsm_message_t)->errcode::RESULT
for the receiver side, the application use msg.decode::
RSM also provides a timer service, application can set timer simply by calling set_timer function, once the timer is set and expired, rsm task will receive a on_timer event, which is defined in the Runnable trait.
pub fn set_timer(dur_msec:u64,loop_count:u64,timer_data:usize)->Option<rsm_timer_id_t> pub fn kill_timer_by_id(timer_id:rsm_timer_id_t)->errcode::RESULT
Diagnostic
Developer and user can use rest api get running status and statistics
Built in api
help,curl http://127.0.0.1:12000/rsm/help get task running status, curl http://127.0.0.1:12000/rsm/task?1:2 get component configuration,curl http://127.0.0.1:12000/rsm/component?1
Application defined OAM API
application Module must implement OamReqCallBack function, and invoke RegisterOamModule to register self OamReqCallBack=fn(op:E_RSM_OAM_OP,url:&String,param:&String)->oam_cmd_resp_t
register a module callback, urls is a list of rest api url, the prefix /rsm and id following a “?” are not included RegisterOamModule(urls:&String, callback:OamReqCallBack)
Other service& lib function
xlog service
xlog service is based on client/server architecture, the client side simple send log message to the server which responsible for log file manipulation, keeping from write disk under the application’s context, which is very important for the realtime application.
let log = rsm::new_xlog(module_name:&str)->xlog::xlogger_t;
log.Errorf(postion, err, logDesc);
Other thread safe algorithm and data structure
- spin_lock_t, Atomic operation based lock.
- AtomicQueue, based on spin_lock
- TsIdAllocator, thread safe Id allocator
- bitmap
- ethernet packet parser
- Ip routing table
- several other network function and object wrapper