Trait Host

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pub trait Host {
    type Gen: GenerationBackend;
    type Inv: InventoryBackend;

    // Required methods
    fn generations(&self) -> &Self::Gen;
    fn inventory(&self) -> &Self::Inv;
    fn execute_runtime(&self, t: &Transition, op: &OpId) -> Outcome;
    fn reobserve(&self, txn: &Transaction) -> Outcome;
    fn check(&self, txn: &Transaction, phase: CheckPhase) -> Verdict;
    fn release_gc_root(&self, path: &str) -> bool;
    fn now(&self) -> Timestamp;
    fn boot_now(&self) -> Timestamp;
    fn sleep(&self, d: Millis);
    fn kill_worker(&self, pid: u32) -> bool;
    fn pid_alive(&self, pid: u32) -> bool;

    // Provided method
    fn floor_fixes(
        &self,
        _txn: &Transaction,
        _floor: Option<GenerationId>,
    ) -> Result<Vec<String>, Outcome> { ... }
}

Expand description

Everything the kernel needs from below. One generic parameter (no dyn, §6).

Required Associated Types§

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Required Methods§

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fn generations(&self) -> &Self::Gen

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fn inventory(&self) -> &Self::Inv

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fn execute_runtime(&self, t: &Transition, op: &OpId) -> Outcome

Perform a ReobserveOnly transition’s backend effect (restart, stop, runtime option, GC). Override bookkeeping is the kernel’s job, not this.

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fn reobserve(&self, txn: &Transaction) -> Outcome

Settle, then observe and compare against the expectation; the outcome is recorded, never acted on (§12 step 7, UnitOp).

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fn check(&self, txn: &Transaction, phase: CheckPhase) -> Verdict

Run the applicable Readiness probes from the candidate’s UnitDefs and the installed core, plus the expectation and executor-owned requirements.

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fn release_gc_root(&self, path: &str) -> bool

Remove a GC root (I3). Returns false if it could not be removed.

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fn now(&self) -> Timestamp

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fn boot_now(&self) -> Timestamp

The boot clock (CLOCK_BOOTTIME): leases, deadlines and waits (§12h).

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fn sleep(&self, d: Millis)

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fn kill_worker(&self, pid: u32) -> bool

SIGTERM then SIGKILL the process group via pidfd; true once confirmed dead.

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fn pid_alive(&self, pid: u32) -> bool

Provided Methods§

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fn floor_fixes( &self, _txn: &Transaction, _floor: Option<GenerationId>, ) -> Result<Vec<String>, Outcome>

§12e, I25: the security fixes txn’s candidate brings, absent from the floor generation and every generation between it and the candidate (every earlier one, with no floor). Part of the commit: an error here means the transaction does not commit yet.