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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> |
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Plugin Example
Crate with a simple example of the Plugin trait that needs to be implemented in order to create a binary that can be registered into nushell declaration list
example config
This subcommand demonstrates sending configuration from the nushell $env.config to a plugin.
To make use of the plugin after building nushell run:
plugin add target/debug/nu_plugin_example
# or then either restart your current nushell session or run:
plugin use target/debug/nu_plugin_example
The configuration for the plugin lives in $env.config.plugins.example:
$env.config = {
plugins: {
example: [
some
values
]
}
}
To list plugin values run:
example config