exper-fsm-0
A experiment with state machine. I ran into a problem with exper-fsm-1 which uses traits. That version doesn't compile becasuse there ends up to be two mutable references. So this is an attempt without using traits.
I've tried two techniques one where current_state: States and States is
and enum. And the other where current_state: &'a dyn Fn(&mut Self, &Protocol1).
Using the Fn Pointer, is "easier" no enum needs to be created and the
dispatch routine doesn't need a match statement. I created a benchmark
and they are basically the same speed. Although this is quite contrived.
Using Enum:
pub mod state_machine_current_state_enum {
pub enum Protocol1 {
Add { f1: i32 },
Sub { f1: i32 },
Mul { f1: i32 },
}
pub enum States {
StateAdd,
StateSub,
StateMul,
StateAny,
}
pub struct StateMachine {
pub current_state: States,
pub data1: i32,
}
impl StateMachine {
pub fn new(initial_state: States) -> Self {
StateMachine {
current_state: initial_state,
data1: 0,
}
}
pub fn dispatch_msg(&mut self, msg: &Protocol1) {
match self.current_state {
States::StateAdd => {
self.state_add_process_msg(msg);
}
States::StateSub => {
self.state_sub_process_msg(msg);
}
States::StateMul => {
self.state_mul_process_msg(msg);
}
States::StateAny => {
self.state_any_process_msg(msg);
}
}
}
pub fn state_any_process_msg(&mut self, msg: &Protocol1) {
match *msg {
Protocol1::Add { f1 } => {
self.data1 += f1;
}
Protocol1::Sub { f1 } => {
self.data1 -= f1;
}
Protocol1::Mul { f1 } => {
self.data1 *= f1;
}
}
... More States ...
}
}
}
Using Fn Pointer:
pub mod state_machine_current_state_fn_ptr {
pub enum Protocol1 {
Add { f1: i32 },
Sub { f1: i32 },
Mul { f1: i32 },
}
pub struct StateMachine<'a> {
pub current_state: &'a dyn Fn(&mut Self, &Protocol1),
pub data1: i32,
}
impl<'a> StateMachine<'a> {
pub fn new(initial_state: &'a dyn Fn(&mut Self, &Protocol1)) -> Self {
StateMachine {
current_state: initial_state,
data1: 0,
}
}
pub fn dispatch_msg(&mut self, msg: &Protocol1) {
(self.current_state)(self, msg);
}
pub fn state_any_process_msg(&mut self, msg: &Protocol1) {
match *msg {
Protocol1::Add { f1 } => {
self.data1 += f1;
}
Protocol1::Sub { f1 } => {
self.data1 -= f1;
}
Protocol1::Mul { f1 } => {
self.data1 *= f1;
}
}
}
... More States ...
}
}
The main I used is:
fn main() {
{
println!("state_machine_current_state_enum");
use expr_fsm_0::state_machine_current_state_enum::{StateMachine, Protocol1, States};
// Create state machine with its initial state
let initial_state = States::StateAdd;
let mut sm = StateMachine::new(initial_state);
// Create a message and dispatch it to the state machine
let msg = Protocol1::Add { f1: 123 };
sm.dispatch_msg(&msg);
println!("sm.data1={}", sm.data1);
sm.dispatch_msg(&msg);
println!("sm.data1={}", sm.data1);
}
{
println!("state_machine_current_state_fn_ptr");
use expr_fsm_0::state_machine_current_state_fn_ptr::{StateMachine, Protocol1};
// Create state machine with its initial state
let initial_state = StateMachine::state_add_process_msg;
let mut sm = StateMachine::new(& initial_state);
// Create a message and dispatch it to the state machine
let msg = Protocol1::Add { f1: 123 };
sm.dispatch_msg(&msg);
println!("sm.data1={}", sm.data1);
sm.dispatch_msg(&msg);
println!("sm.data1={}", sm.data1);
}
}
Building and running
wink@3900x 22-05-11T21:43:45.987Z:~/prgs/rust/myrepos/exper-fsm-0 (main)
$ cargo run
Compiling exper-fsm-0 v0.1.0 (/home/wink/prgs/rust/myrepos/exper-fsm-0)
Finished dev [unoptimized + debuginfo] target(s) in 0.22s
Running `target/debug/exper-fsm-0`
state_machine_current_state_enum
sm.data1=123
sm.data1=246
state_machine_current_state_fn_ptr
sm.data1=123
sm.data1=246
wink@3900x 22-05-11T22:08:20.604Z:~/prgs/rust/myrepos/exper-fsm-0 (main)
Test
TODO
Benchmark
wink@3900x 22-05-11T21:24:19.704Z:~/prgs/rust/myrepos/exper-fsm-0 (main)
$ cargo criterion
Compiling exper-fsm-0 v0.1.0 (/home/wink/prgs/rust/myrepos/exper-fsm-0)
Finished bench [optimized] target(s) in 1.25s
Gnuplot not found, using plotters backend
dispatch_add_msg_to_state_add_current_state_enum
time: [1.7430 ns 1.7441 ns 1.7454 ns]
change: [-6.6180% -5.4456% -4.5977%] (p = 0.00 < 0.05)
Performance has improved.
dispatch_add_msg_to_state_any_current_state_enum
time: [1.8240 ns 1.8246 ns 1.8254 ns]
change: [+2.5249% +2.6857% +2.8421%] (p = 0.00 < 0.05)
Performance has regressed.
dispatch_mul_msg_to_state_mul_current_state_enum
time: [2.1922 ns 2.2015 ns 2.2132 ns]
change: [+0.9558% +1.4504% +1.8852%] (p = 0.00 < 0.05)
Change within noise threshold.
dispatch_mul_msg_to_state_any_current_state_enum
time: [2.2081 ns 2.2199 ns 2.2337 ns]
change: [-2.1118% -1.7525% -1.3912%] (p = 0.00 < 0.05)
Performance has improved.
Gnuplot not found, using plotters backend
dispatch_add_msg_to_state_add_current_state_fn_ptr
time: [1.9494 ns 1.9797 ns 2.0117 ns]
change: [+2.1136% +3.5381% +4.8978%] (p = 0.00 < 0.05)
Performance has regressed.
dispatch_add_msg_to_state_any_current_state_fn_ptr
time: [1.8330 ns 1.8350 ns 1.8380 ns]
change: [-4.2148% -3.0492% -1.8726%] (p = 0.00 < 0.05)
Performance has improved.
dispatch_mul_msg_to_state_mul_current_state_fn_ptr
time: [2.3117 ns 2.3191 ns 2.3267 ns]
change: [-2.8740% -2.3532% -1.8451%] (p = 0.00 < 0.05)
Performance has improved.
dispatch_mul_msg_to_state_any_current_state_fn_ptr
time: [2.2650 ns 2.2658 ns 2.2668 ns]
change: [+2.9005% +3.2917% +3.8221%] (p = 0.00 < 0.05)
Performance has regressed.
running 0 tests
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s
License
Licensed under either of
- Apache License, Version 2.0 (LICENSE-APACHE or http://apache.org/licenses/LICENSE-2.0)
- MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)
Contribution
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.