reovim_kernel/sched/
state.rs

1//! Runtime lifecycle state machine.
2//!
3//! Linux equivalent: Task states in `kernel/sched/sched.h`
4//!
5//! The runtime transitions through these states during its lifecycle:
6//! - `Booting` -> `Running` -> `Stopping`
7//! - Any state can transition to `Emergency` on panic
8
9/// Runtime lifecycle state.
10///
11/// Represents the current operating mode of the scheduler runtime.
12///
13/// # State Transitions
14///
15/// ```text
16/// ┌─────────┐     ┌─────────┐     ┌──────────┐
17/// │ Booting │────>│ Running │────>│ Stopping │
18/// └─────────┘     └─────────┘     └──────────┘
19///      │               │               │
20///      └───────────────┴───────────────┘
21///                      │
22///                      v
23///               ┌───────────┐
24///               │ Emergency │
25///               └───────────┘
26/// ```
27#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
28pub enum RuntimeState {
29    /// Initializing subsystems, loading modules.
30    ///
31    /// Linux equivalent: `TASK_NEW`
32    #[default]
33    Booting,
34
35    /// Normal operation, processing events.
36    ///
37    /// Linux equivalent: `TASK_RUNNING`
38    Running,
39
40    /// Graceful shutdown in progress.
41    ///
42    /// Remaining work is drained before full stop.
43    ///
44    /// Linux equivalent: `TASK_STOPPED`
45    Stopping,
46
47    /// Emergency shutdown (panic recovery mode).
48    ///
49    /// No new work accepted, cleanup only.
50    ///
51    /// Linux equivalent: Kernel oops handling
52    Emergency,
53}
54
55impl RuntimeState {
56    /// Check if runtime is in the running state.
57    ///
58    /// Only in `Running` state can new work be accepted.
59    #[inline]
60    #[must_use]
61    pub const fn is_running(&self) -> bool {
62        matches!(self, Self::Running)
63    }
64
65    /// Check if shutdown is in progress.
66    ///
67    /// Returns `true` for both `Stopping` and `Emergency` states.
68    #[inline]
69    #[must_use]
70    pub const fn is_shutting_down(&self) -> bool {
71        matches!(self, Self::Stopping | Self::Emergency)
72    }
73
74    /// Check if runtime can accept new work.
75    ///
76    /// Equivalent to `is_running()` - only running runtime accepts work.
77    #[inline]
78    #[must_use]
79    pub const fn can_accept_work(&self) -> bool {
80        self.is_running()
81    }
82
83    /// Check if this is a terminal state.
84    ///
85    /// Terminal states indicate the runtime should stop its main loop.
86    #[inline]
87    #[must_use]
88    pub const fn is_terminal(&self) -> bool {
89        matches!(self, Self::Stopping | Self::Emergency)
90    }
91}
92
93impl std::fmt::Display for RuntimeState {
94    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
95        match self {
96            Self::Booting => write!(f, "Booting"),
97            Self::Running => write!(f, "Running"),
98            Self::Stopping => write!(f, "Stopping"),
99            Self::Emergency => write!(f, "Emergency"),
100        }
101    }
102}
reovim_kernel/sched/state.rs

reovim_kernel/sched/
state.rs
