TerminateOnDrop

Struct TerminateOnDrop 

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pub struct TerminateOnDrop<O: OutputStream> { /* private fields */ }
Expand description

A wrapper that automatically terminates a process when dropped.

§Safety Requirements

WARNING: This type requires a multithreaded tokio runtime to function correctly!

§Usage Guidelines

This type should only be used when:

  • Your code is running in a multithreaded tokio runtime.
  • Automatic process cleanup on drop is absolutely necessary.

Instead of relying on automatic termination, prefer these safer approaches:

  1. Manual process termination using ProcessHandle::terminate
  2. Awaiting process completion using ProcessHandle::wait_for_completion
  3. Awaiting process completion or performing an explicit termination using ProcessHandle::wait_for_completion_or_terminate

§Implementation Details

The drop implementation tries to terminate the process if it was neither awaited nor terminated before being dropped. If termination fails, a panic is raised.

Methods from Deref<Target = ProcessHandle<O>>§

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pub fn id(&self) -> Option<u32>

Returns the OS process ID if the process hasn’t exited yet.

Once this process has been polled to completion this will return None.

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pub fn is_running(&mut self) -> RunningState

Checks if the process is currently running.

Returns RunningState::Running if the process is still running, RunningState::Terminated if it has exited, or RunningState::Uncertain if the state could not be determined.

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pub fn stdin(&mut self) -> &mut Stdin

Returns a mutable reference to the (potentially already closed) stdin stream.

Use this to write data to the child process’s stdin. The stdin stream implements tokio::io::AsyncWrite, allowing you to use methods like write_all() and flush().

§Example
// Whether we `spawn_broadcast` or `spawn_single_subscriber` does not make a difference here.
let mut process = Process::new(Command::new("cat"))
    .spawn_broadcast()
    .unwrap();

// Write to stdin.
if let Some(stdin) = process.stdin().as_mut() {
    stdin.write_all(b"Hello, process!\n").await.unwrap();
    stdin.flush().await.unwrap();
}

// Close stdin to signal EOF.
process.stdin().close();
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pub fn stdout(&self) -> &O

Returns a reference to the stdout stream.

For BroadcastOutputStream, this allows creating multiple concurrent consumers. For SingleSubscriberOutputStream, only one consumer can be created (subsequent attempts will panic with a helpful error message).

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pub fn stderr(&self) -> &O

Returns a reference to the stderr stream.

For BroadcastOutputStream, this allows creating multiple concurrent consumers. For SingleSubscriberOutputStream, only one consumer can be created (subsequent attempts will panic with a helpful error message).

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pub fn must_be_terminated(&mut self)

Sets a panic-on-drop mechanism for this ProcessHandle.

This method enables a safeguard that ensures that the process represented by this ProcessHandle is properly terminated or awaited before being dropped. If must_be_terminated is set and the ProcessHandle is dropped without invoking terminate() or wait(), an intentional panic will occur to prevent silent failure-states, ensuring that system resources are handled correctly.

You typically do not need to call this, as every ProcessHandle is marked by default. Call must_not_be_terminated to clear this safeguard to explicitly allow dropping the process without terminating it.

§Panic

If the ProcessHandle is dropped without being awaited or terminated after calling this method, a panic will occur with a descriptive message to inform about the incorrect usage.

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pub fn must_not_be_terminated(&mut self)

Disables the panic-on-drop safeguard, allowing the spawned process to be kept running uncontrolled in the background, while this handle can safely be dropped.

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pub fn send_interrupt_signal(&mut self) -> Result<(), Error>

Manually send a SIGINT on unix or equivalent on Windows to this process.

Prefer to call terminate instead, if you want to make sure this process is terminated.

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pub fn send_terminate_signal(&mut self) -> Result<(), Error>

Manually send a SIGTERM on unix or equivalent on Windows to this process.

Prefer to call terminate instead, if you want to make sure this process is terminated.

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pub async fn terminate( &mut self, interrupt_timeout: Duration, terminate_timeout: Duration, ) -> Result<ExitStatus, TerminationError>

Terminates this process by sending a SIGINT, SIGTERM or even a SIGKILL if the process doesn’t run to completion after receiving any of the first two signals.

This handle can be dropped safely after this call returned, no matter the outcome. We accept that in extremely rare cases, failed SIGKILL, a rogue process may be left over.

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

Forces the process to exit. Most users should call ProcessHandle::terminate instead.

This is equivalent to sending a SIGKILL on unix platforms followed by wait.

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pub async fn wait_for_completion( &mut self, timeout: Option<Duration>, ) -> Result<ExitStatus, WaitError>

Wait for this process to run to completion. Within timeout, if set, or unbound otherwise.

If the timeout is reached before the process terminated, an error is returned but the process remains untouched / keeps running. Use ProcessHandle::wait_for_completion_or_terminate if you want immediate termination.

This does not provide the processes output. You can take a look at the convenience function ProcessHandle::::wait_for_completion_with_output to see how the ProcessHandle::stdout and ProcessHandle::stderr streams (also available in *_mut variants) can be used to inspect / watch over / capture the processes output.

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pub async fn wait_for_completion_or_terminate( &mut self, wait_timeout: Duration, interrupt_timeout: Duration, terminate_timeout: Duration, ) -> Result<ExitStatus, TerminationError>

Wait for this process to run to completion within timeout.

If the timeout is reached before the process terminated normally, external termination of the process is forced through ProcessHandle::terminate.

Note that this function may return Ok even though the timeout was reached, carrying the exit status received after sending a termination signal!

Trait Implementations§

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impl<O: Debug + OutputStream> Debug for TerminateOnDrop<O>

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

Formats the value using the given formatter. Read more
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impl<O: OutputStream> Deref for TerminateOnDrop<O>

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type Target = ProcessHandle<O>

The resulting type after dereferencing.
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fn deref(&self) -> &Self::Target

Dereferences the value.
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impl<O: OutputStream> DerefMut for TerminateOnDrop<O>

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fn deref_mut(&mut self) -> &mut Self::Target

Mutably dereferences the value.
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impl<O: OutputStream> Drop for TerminateOnDrop<O>

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fn drop(&mut self)

Executes the destructor for this type. Read more

Auto Trait Implementations§

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impl<O> Freeze for TerminateOnDrop<O>
where O: Freeze,

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impl<O> !RefUnwindSafe for TerminateOnDrop<O>

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impl<O> Send for TerminateOnDrop<O>
where O: Send,

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impl<O> Sync for TerminateOnDrop<O>
where O: Sync,

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impl<O> Unpin for TerminateOnDrop<O>
where O: Unpin,

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impl<O> !UnwindSafe for TerminateOnDrop<O>

Blanket Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<P, T> Receiver for P
where P: Deref<Target = T> + ?Sized, T: ?Sized,

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type Target = T

🔬This is a nightly-only experimental API. (arbitrary_self_types)
The target type on which the method may be called.
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more
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impl<T> Sink for T
where T: Debug + Send + Sync + 'static,