Struct StandbySlot 

pub struct StandbySlot {
    pub workload_id: String,
    pub primary_npub: String,
    pub standby_index: usize,
    pub standby_count: usize,
    pub container_config: ContainerConfig,
    pub spec_id: String,
    pub expires_at: u64,
    pub owner_npub: String,
    pub created_at: u64,
    pub peer_standby_npubs: Vec<String>,
}

A standby slot reserved for a warm-standby workload. The consumer’s spawn request was paid for and acknowledged, but no container has been created yet — the standby is “armed” and waiting for a LeaseRevocation event from the primary.

Stored in ProviderService::standby_slots keyed by workload_id (consumer-assigned UUID, shared by primary and all standbys). On revocation, the standby’s promotion handler:

1. Sleeps index * promotion_delay_secs (ordered backoff for single-writer; standby 0 promotes immediately, standby 1 waits one delay window, etc.)
2. Spawns the container using container_config
3. Removes the slot, adds to active_workloads, registers with the state machine as primary

Fields

workload_id: String

primary_npub: String

standby_index: usize

standby_count: usize

container_config: ContainerConfig

spec_id: String

expires_at: u64

owner_npub: String

created_at: u64

Unix-second timestamp at which the slot was reserved. Used as the silence-baseline by the watchdog when no primary heartbeat has been observed yet — without this, a fresh slot would treat last_seen == 0 as immediate silence and promote a healthy primary on the first watchdog tick (race window: 0–60s while waiting for the primary’s next heartbeat to land on the relay).

peer_standby_npubs: Vec<String>

Npubs of the OTHER standbys for this workload (excludes self and the primary). Used at promotion-time to detect that a lower-indexed peer has already promoted: a freshly-promoted peer publishes a heartbeat from its own npub immediately, and this standby queries those npubs before claiming the slot itself. Without this list, every standby would promote independently after the silence window, producing split-brain.

Trait Implementations

impl Clone for StandbySlot

fn clone(&self) -> StandbySlot

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StandbySlot

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.