Timers

flowchart LR
  S[[Service Event]] --> T[[Timer]]
  T --> F[[Flow Triggers]]
  F --> E[[Signals / States / Services]]

Timers in Rind are one-shot runtime schedulers that start from lifecycle conditions and execute trigger actions when duration expires. They are often used for delayed stop/start behavior tied to Services.

Core Definition

The timer metadata defines a unique name and one-shot duration.

• name: The unique timer name.
• duration: One-shot timeout value.

Supported duration forms:

• suffix units: s, m, h, d (for example 5s, 10m, 1h)
• plain integer seconds (for example 30)

[[timer]]
name = "timeout_four"
duration = "5s"

Service-Dependent Start/Stop

flowchart TD
  A[Service started] --> B[start dependent timer]
  C[Service stopped/failed/exited] --> D[stop dependent timer]

Timers can bind to service lifecycle dependencies.

• after: List of service addresses (group@name).
• On dependent service start: timer starts.
• On dependent service stop/fail/exit: timer stops.

[[timer]]
name = "request_timeout"
duration = "30s"
after = ["else@four"]

Expiration Triggers

sequenceDiagram
  participant Runtime
  participant Timer
  participant Flow
  Runtime->>Timer: start one-shot fd
  Timer-->>Runtime: deadline reached
  Runtime->>Flow: execute finish triggers

When a timer expires, finish triggers are executed.

• finish: List of Trigger Objects.
• Common use: stop a service after timeout.

[[timer]]
name = "timeout_four"
duration = "5s"
finish = [{ service = "else@four", stop = true }]

Runtime Behavior

• Timers are one-shot, not periodic.
• Starting an already-active timer is a no-op.
• After expiration, timer instance is removed automatically.

Practical Pattern

Use timer + service together for watchdog-like control.

[[service]]
name = "four"
run.exec = "/usr/bin/ipc_so"
on-start = [{ timer = "else@timeout_four" }]
 
[[timer]]
name = "timeout_four"
duration = "5s"
finish = [{ service = "else@four", stop = true }]