Struct DaemonChild 

pub struct DaemonChild { /* private fields */ }

A daemon started by DaemonCommand::spawn.

Dropping it leaves the daemon running, as dropping a std::process::Child does. On Unix the daemon is also reaped once it exits, so a launcher that gives up on it leaves no zombie: at once if it has exited, otherwise by a thread that waits for it while it runs. That thread is best effort: if it cannot be created, a running daemon becomes a zombie when it exits, as before. Candidate::from takes it as a candidate that is stopped unless selected.

Its ProcessHandle is opened at spawn, before anything can reap the daemon, so it follows the daemon even in a process that ignores SIGCHLD.

Implementations

impl DaemonChild

pub fn id(&self) -> ProcessId

The daemon’s process ID.

pub fn take_readiness(&mut self) -> Option<Channel>

The launcher’s end of the readiness channel, the first time it is asked for. None without DaemonCommand::readiness_channel.

pub fn in_callers_job(&self) -> bool

True when the daemon was left in the caller’s job object because that job forbids breakaway, so it will die with the caller’s job (see the job objects section of DaemonCommand). Always false on Unix, which has no job objects.

False does not prove the daemon is in no job. With nested jobs, a job that allows breakaway lets the daemon leave it even when an enclosing job does not; the daemon then stays in that outer job without the breakaway being refused.

pub fn try_wait(&mut self) -> Result<Option<ExitStatus>>

The exit status if the daemon has exited, without blocking.

pub fn wait(&mut self) -> Result<ExitStatus>

Block until the daemon exits.

pub fn wait_until(&mut self, deadline: Instant) -> Result<Option<ExitStatus>>

Block until the daemon exits or deadline passes: its exit status, or None while it still runs.

The status comes from waiting for the child, so in a process that ignores SIGCHLD, where the kernel discards it, this fails after the exit. Self::exit_handle still reports the exit there.

pub fn exit_handle(&mut self) -> &mut ProcessHandle

The daemon’s exit as an event, for a caller that waits on it together with other work, for example with exited under the async feature.

pub fn wait_until_live( &mut self, deadline: Instant, is_live: impl FnMut() -> bool, ) -> Result<Startup>

Probe with is_live until it succeeds, the daemon exits, or deadline passes.

Between probes this waits on the daemon’s exit rather than sleeping, for POLL at most, so a daemon that dies during startup ends the wait at once. is_live must attempt a connect or a protocol probe and bound its own blocking. An error means the exit could not be observed; the daemon may still be running.

pub fn kill(&mut self) -> Result<()>

Stop the daemon forcibly: SIGKILL on Unix, TerminateProcess on Windows. A daemon that already exited is not an error.

Trait Implementations

impl Debug for DaemonChild

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

Formats the value using the given formatter.

impl From<DaemonChild> for Candidate

Available on crate feature launch only.

A daemon started by DaemonCommand as a candidate: dropped before Candidate::selected, it is stopped. Take its readiness channel first; the candidate keeps it but does not give it out.

fn from(daemon: DaemonChild) -> Self

Converts to this type from the input type.