README

sm_retry_logic_1

Demonstrates a state reactor (SrEventCountdown) defined in a superstate. The reactor counts failures across inner state transitions, implementing a 3-attempt retry limit before giving up. This pattern answers the question: can a parent state accumulate event history that persists while its inner states cycle? The answer is yes — and this machine shows how.

What it demonstrates

SrEventCountdown(3) lives in SsAttemptTask (a superstate), not in any leaf state.
The reactor counts timer timeouts and explicit ‘f’ keypresses as failures.
The failure count persists across StIdle ↔ StAttempting inner transitions — it is not reset when the inner states change.
After 3 total failures (any combination), the superstate transitions to StExhausted.
Pressing s at any point during an attempt — or while waiting in StIdle — transitions immediately to StSuccess.

State hierarchy

SmRetryLogic1
├── OrTimer    (ClRos2Timer)
└── OrKeyboard (ClKeyboard)

SmRetryLogic1
├── SsAttemptTask  ←  superstate; owns SrEventCountdown(3)
│   │              Reactor input events: EvTimer, EvKeyPressF
│   │              Reactor output event: EvCountdownEnd → StExhausted
│   │              Also reacts: EvKeyPressS → StSuccess
│   │
│   ├── StIdle       (initial)  — waiting for 'n' to start an attempt
│   └── StAttempting            — attempt in progress; 10s timeout
│
├── StSuccess    — reached by pressing 's' at any time
└── StExhausted  — reached after 3 total failures

Build

cd /home/brettpac/workspaces/isaac_ros-dev
colcon build --packages-select sm_retry_logic_1
source install/setup.bash

Launch

ros2 launch sm_retry_logic_1 sm_retry_logic_1.launch.py

This opens two konsole terminals: the state machine node and the keyboard server.

Keyboard controls

Key	Effect	Active in
`n`	Start an attempt (`StIdle → StAttempting`)	StIdle
`f`	Manually fail the current attempt (`StAttempting → StIdle`, counts as 1 failure)	StAttempting
`s`	Succeed immediately (`→ StSuccess`)	StIdle or StAttempting
(timer)	10-second timeout = auto-fail (`StAttempting → StIdle`, counts as 1 failure)	StAttempting

Send keystrokes via ROS 2 topic (if not using the konsole keyboard server):

ros2 topic pub /keyboard_unicode std_msgs/msg/UInt16 "data: 110" --once  # n
ros2 topic pub /keyboard_unicode std_msgs/msg/UInt16 "data: 102" --once  # f
ros2 topic pub /keyboard_unicode std_msgs/msg/UInt16 "data: 115" --once  # s

Example walkthroughs

Reach StExhausted via 3 manual failures

Start → StIdle
  → press n → StAttempting
  → press f → StIdle          (failure count: 2 remaining)
  → press n → StAttempting
  → press f → StIdle          (failure count: 1 remaining)
  → press n → StAttempting
  → press f → StExhausted     (failure count: 0, EvCountdownEnd fires)

Reach StExhausted via 3 timer timeouts

Start → StIdle
  → press n → StAttempting → wait 10s → StIdle   (failure count: 2 remaining)
  → press n → StAttempting → wait 10s → StIdle   (failure count: 1 remaining)
  → press n → StAttempting → wait 10s → StExhausted

Reach StSuccess after 2 failures

Start → StIdle
  → press n → StAttempting
  → press f → StIdle          (failure count: 2 remaining)
  → press n → StAttempting
  → press f → StIdle          (failure count: 1 remaining)
  → press n → StAttempting
  → press s → StSuccess

Reach StSuccess immediately (no attempts needed)

Start → StIdle
  → press s → StSuccess

Monitoring

# Current state hierarchy
ros2 topic echo /sm_retry_logic_1/smacc/status

# State transitions as they fire
ros2 topic echo /sm_retry_logic_1/smacc/transition_log

# All posted events (including EvCountdownEnd)
ros2 topic echo /sm_retry_logic_1/smacc/event_log

Watch the node console output for SB COUNTDOWN (N) log lines — these show the remaining failure count after each failure event is received by the reactor.