Crate handoff 

Zero-downtime atomic binary handoff for long-running daemons.

See the crate-root ARCHITECTURE.md for the wire protocol, state machine, and correctness invariants. This module re-exports the public surface.

Re-exports

pub use drainable::DrainReport;

pub use drainable::Drainable;

pub use drainable::ReadinessSnapshot;

pub use drainable::SealReport;

pub use drainable::StateSnapshot;

pub use error::Error;

pub use error::Result;

pub use fd::arrange_inherited_fds_on_spawn;

pub use fd::pass_listener_fds_on_spawn;

pub use incumbent::Incumbent;

pub use lock::DataDirLock;

pub use protocol::HandoffId;

pub use role::BegunSuccessor;

pub use role::HandshookSuccessor;

pub use role::HeartbeatGuard;

pub use role::InheritedListeners;

pub use role::Role;

pub use role::Successor;

pub use role::detect_role;

pub use supervisor::HandoffOutcome;

pub use supervisor::SpawnSpec;

pub use supervisor::Supervisor;

Modules

crash

Crash-injection points for fault-tolerance testing.

drainable

The Drainable trait — the consumer contract for opaque handoff-side lifecycle hooks. The library calls these in a defined order over a handoff; the consumer (the primitive being handed off) implements them in terms of its own writer state, accept loop, and shard layout.

error

Public error type for the handoff crate.

fd

Parent-side FD inheritance helper.

frame

Length-prefixed framing over a sync byte stream (typically UnixStream).

incumbent

Incumbent-side control socket server.

lock

DataDirLock — RAII flock on <data_dir>/.handoff.lock.

metrics

Observability name constants.

protocol

Wire protocol message types and constants.

role

Successor detection via env vars + inherited listener handling.

state

Handoff state journal — persisted across supervisor restarts.

supervisor

Supervisor-side orchestration: spawn the successor, drive the protocol, handle abort/resume.

Macros

crash_here

Inject a crash point at the call site. No-op without the crash-points feature.