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# Description This PR adds a new method to `EngineInterface`: `register_ctrlc_handler` which takes a closure to run when the plugin's driving engine receives a ctrlc-signal. It also adds a mirror of the `signals` attribute from the main shell `EngineState`. This is an example of how a plugin which makes a long poll http request can end the request on ctrlc: https://github.com/cablehead/nu_plugin_http/blob/main/src/commands/request.rs#L68-L77 To facilitate the feature, a new attribute has been added to `EngineState`: `ctrlc_handlers`. This is a Vec of closures that will be run when the engine's process receives a ctrlc signal. When plugins are added to an `engine_state` during a `merge_delta`, the engine passes the ctrlc_handlers to the plugin's `.configure_ctrlc_handler` method, which gives the plugin a chance to register a handler that sends a ctrlc packet through the `PluginInterface`, if an instance of the plugin is currently running. On the plugin side: `EngineInterface` also has a ctrlc_handlers Vec of closures. Plugin calls can use `register_ctrlc_handler` to register a closure that will be called in the plugin process when the PluginInput::Ctrlc command is received. For future reference these are some alternate places that were investigated for tying the ctrlc trigger to transmitting a Ctrlc packet through the `PluginInterface`: - Directly from `src/signals.rs`: the handler there would need a reference to the Vec<Arc<RegisteredPlugins>>, which would require us to wrap the plugins in a Mutex, which we don't want to do. - have `PersistentPlugin.get_plugin` pass down the engine's CtrlcHandlers to .get and then to .spawn (if the plugin isn't already running). Once we have CtrlcHandlers in spawn, we can register a handler to write directly to PluginInterface. We don't want to double down on passing engine_state to spawn this way though, as it's unpredictable because it would depend on whether the plugin has already been spawned or not. - pass `ctrlc_handlers` to PersistentPlugin::new so it can store it on itself so it's available to spawn. - in `PersistentPlugin.spawn`, create a handler that sends to a clone of the GC event loop's tx. this has the same issues with regards to how to get CtrlcHandlers to the spawn method, and is more complicated than a handler that writes directly to PluginInterface # User-Facing Changes No breaking changes --------- Co-authored-by: Ian Manske <ian.manske@pm.me>
65 lines
2.2 KiB
Rust
65 lines
2.2 KiB
Rust
use crate::ShellError;
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use std::sync::atomic::{AtomicUsize, Ordering::Relaxed};
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/// Implements an atomically incrementing sequential series of numbers
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#[derive(Debug, Default)]
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pub struct Sequence(AtomicUsize);
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impl Sequence {
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/// Return the next available id from a sequence, returning an error on overflow
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#[track_caller]
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pub fn next(&self) -> Result<usize, ShellError> {
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// It's totally safe to use Relaxed ordering here, as there aren't other memory operations
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// that depend on this value having been set for safety
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//
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// We're only not using `fetch_add` so that we can check for overflow, as wrapping with the
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// identifier would lead to a serious bug - however unlikely that is.
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self.0
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.fetch_update(Relaxed, Relaxed, |current| current.checked_add(1))
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.map_err(|_| ShellError::NushellFailedHelp {
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msg: "an accumulator for identifiers overflowed".into(),
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help: format!("see {}", std::panic::Location::caller()),
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})
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}
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}
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#[test]
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fn output_is_sequential() {
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let sequence = Sequence::default();
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for (expected, generated) in (0..1000).zip(std::iter::repeat_with(|| sequence.next())) {
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assert_eq!(expected, generated.expect("error in sequence"));
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}
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}
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#[test]
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fn output_is_unique_even_under_contention() {
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let sequence = Sequence::default();
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std::thread::scope(|scope| {
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// Spawn four threads, all advancing the sequence simultaneously
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let threads = (0..4)
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.map(|_| {
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scope.spawn(|| {
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(0..100000)
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.map(|_| sequence.next())
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.collect::<Result<Vec<_>, _>>()
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})
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})
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.collect::<Vec<_>>();
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// Collect all of the results into a single flat vec
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let mut results = threads
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.into_iter()
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.flat_map(|thread| thread.join().expect("panicked").expect("error"))
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.collect::<Vec<usize>>();
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// Check uniqueness
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results.sort();
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let initial_length = results.len();
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results.dedup();
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let deduplicated_length = results.len();
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assert_eq!(initial_length, deduplicated_length);
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})
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}
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