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feat: make ctrlc available to plugins (#13181)
# 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>
This commit is contained in:
50
crates/nu_plugin_example/src/commands/ctrlc.rs
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50
crates/nu_plugin_example/src/commands/ctrlc.rs
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@ -0,0 +1,50 @@
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use std::sync::mpsc;
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use nu_plugin::{EngineInterface, EvaluatedCall, PluginCommand};
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use nu_protocol::{Category, LabeledError, PipelineData, Signature};
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use crate::ExamplePlugin;
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/// `example ctrlc`
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pub struct Ctrlc;
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impl PluginCommand for Ctrlc {
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type Plugin = ExamplePlugin;
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fn name(&self) -> &str {
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"example ctrlc"
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}
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fn usage(&self) -> &str {
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"Example command that demonstrates registering a ctrl-c handler"
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}
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fn signature(&self) -> Signature {
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Signature::build(self.name()).category(Category::Experimental)
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}
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fn search_terms(&self) -> Vec<&str> {
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vec!["example"]
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}
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fn run(
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&self,
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_plugin: &ExamplePlugin,
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engine: &EngineInterface,
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_call: &EvaluatedCall,
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_input: PipelineData,
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) -> Result<PipelineData, LabeledError> {
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let (sender, receiver) = mpsc::channel::<()>();
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let _guard = engine.register_ctrlc_handler(Box::new(move || {
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let _ = sender.send(());
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}));
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eprintln!("interrupt status: {:?}", engine.signals().interrupted());
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eprintln!("waiting for ctrl-c signal...");
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receiver.recv().expect("handler went away");
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eprintln!("interrupt status: {:?}", engine.signals().interrupted());
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eprintln!("peace.");
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Ok(PipelineData::Empty)
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}
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}
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@ -15,12 +15,14 @@ pub use two::Two;
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// Engine interface demos
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mod call_decl;
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mod config;
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mod ctrlc;
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mod disable_gc;
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mod env;
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mod view_span;
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pub use call_decl::CallDecl;
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pub use config::Config;
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pub use ctrlc::Ctrlc;
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pub use disable_gc::DisableGc;
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pub use env::Env;
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pub use view_span::ViewSpan;
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@ -27,6 +27,7 @@ impl Plugin for ExamplePlugin {
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Box::new(Env),
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Box::new(ViewSpan),
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Box::new(DisableGc),
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Box::new(Ctrlc),
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Box::new(CallDecl),
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// Stream demos
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Box::new(CollectBytes),
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