256 lines
8.2 KiB
Rust
256 lines
8.2 KiB
Rust
//! Zebrad Abscissa Application
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use crate::{commands::ZebradCmd, components::tracing::FlameGrapher, config::ZebradConfig};
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use abscissa_core::{
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application::{self, AppCell},
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config,
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config::Configurable,
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terminal::component::Terminal,
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trace::Tracing,
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Application, Component, EntryPoint, FrameworkError, Shutdown, StandardPaths,
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};
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use application::fatal_error;
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use std::{fmt, process};
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/// Application state
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pub static APPLICATION: AppCell<ZebradApp> = AppCell::new();
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/// Obtain a read-only (multi-reader) lock on the application state.
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///
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/// Panics if the application state has not been initialized.
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pub fn app_reader() -> application::lock::Reader<ZebradApp> {
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APPLICATION.read()
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}
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/// Obtain an exclusive mutable lock on the application state.
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pub fn app_writer() -> application::lock::Writer<ZebradApp> {
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APPLICATION.write()
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}
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/// Obtain a read-only (multi-reader) lock on the application configuration.
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///
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/// Panics if the application configuration has not been loaded.
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pub fn app_config() -> config::Reader<ZebradApp> {
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config::Reader::new(&APPLICATION)
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}
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/// Zebrad Application
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pub struct ZebradApp {
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/// Application configuration.
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config: Option<ZebradConfig>,
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/// drop handle for tracing-flame layer to ensure it flushes its buffer when
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/// the application exits
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flame_guard: Option<FlameGrapher>,
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/// Application state.
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state: application::State<Self>,
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}
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/// Initialize a new application instance.
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///
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/// By default no configuration is loaded, and the framework state is
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/// initialized to a default, empty state (no components, threads, etc).
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impl Default for ZebradApp {
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fn default() -> Self {
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Self {
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config: None,
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flame_guard: None,
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state: application::State::default(),
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}
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}
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}
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impl fmt::Debug for ZebradApp {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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f.debug_struct("ZebraApp")
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.field("config", &self.config)
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.field("state", &self.state)
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.finish()
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}
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}
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impl Application for ZebradApp {
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/// Entrypoint command for this application.
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type Cmd = EntryPoint<ZebradCmd>;
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/// Application configuration.
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type Cfg = ZebradConfig;
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/// Paths to resources within the application.
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type Paths = StandardPaths;
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/// Accessor for application configuration.
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fn config(&self) -> &ZebradConfig {
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self.config.as_ref().expect("config not loaded")
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}
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/// Borrow the application state immutably.
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fn state(&self) -> &application::State<Self> {
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&self.state
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}
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/// Borrow the application state mutably.
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fn state_mut(&mut self) -> &mut application::State<Self> {
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&mut self.state
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}
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/// Returns the framework components used by this application.
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fn framework_components(
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&mut self,
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command: &Self::Cmd,
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) -> Result<Vec<Box<dyn Component<Self>>>, FrameworkError> {
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let terminal = Terminal::new(self.term_colors(command));
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// This MUST happen after `Terminal::new` to ensure our preferred panic
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// handler is the last one installed
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color_eyre::install().unwrap();
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if ZebradApp::command_is_server(&command) {
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let tracing = self.tracing_component();
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Ok(vec![Box::new(terminal), Box::new(tracing)])
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} else {
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crate::components::tracing::init_backup(&self.config().tracing);
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Ok(vec![Box::new(terminal)])
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}
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}
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/// Register all components used by this application.
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///
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/// If you would like to add additional components to your application
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/// beyond the default ones provided by the framework, this is the place
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/// to do so.
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fn register_components(&mut self, command: &Self::Cmd) -> Result<(), FrameworkError> {
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use crate::components::{
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metrics::MetricsEndpoint, tokio::TokioComponent, tracing::TracingEndpoint,
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};
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let mut components = self.framework_components(command)?;
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// Launch network endpoints for long-running commands
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if ZebradApp::command_is_server(&command) {
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components.push(Box::new(TokioComponent::new()?));
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components.push(Box::new(TracingEndpoint::new()?));
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components.push(Box::new(MetricsEndpoint::new()?));
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}
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self.state.components.register(components)
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}
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/// Load this application's configuration and initialize its components.
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fn init(&mut self, command: &Self::Cmd) -> Result<(), FrameworkError> {
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// Load configuration
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let config = command
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.config_path()
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.map(|path| self.load_config(&path))
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.transpose()?
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.unwrap_or_default();
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let config = command.process_config(config)?;
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self.config = Some(config);
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// Create and register components with the application.
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// We do this first to calculate a proper dependency ordering before
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// application configuration is processed
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self.register_components(command)?;
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let config = self.config.take().unwrap();
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// Fire callback regardless of whether any config was loaded to
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// in order to signal state in the application lifecycle
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self.after_config(config, command)?;
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Ok(())
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}
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/// Post-configuration lifecycle callback.
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///
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/// Called regardless of whether config is loaded to indicate this is the
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/// time in app lifecycle when configuration would be loaded if
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/// possible.
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fn after_config(
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&mut self,
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config: Self::Cfg,
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command: &Self::Cmd,
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) -> Result<(), FrameworkError> {
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use crate::components::{
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metrics::MetricsEndpoint, tokio::TokioComponent, tracing::TracingEndpoint,
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};
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// Configure components
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self.state.components.after_config(&config)?;
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self.config = Some(config);
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if ZebradApp::command_is_server(&command) {
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if let Some(filter) = self.config.as_ref().unwrap().tracing.filter.as_ref() {
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self.state
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.components
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.get_downcast_mut::<Tracing>()
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.expect("Tracing component should be available")
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.reload_filter(filter);
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}
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// Work around some issues with dependency injection and configs
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let config = self
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.config
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.clone()
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.expect("config was set to Some earlier in this function");
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let tokio_component = self
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.state
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.components
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.get_downcast_ref::<TokioComponent>()
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.expect("Tokio component should be available");
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self.state
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.components
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.get_downcast_ref::<TracingEndpoint>()
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.expect("Tracing endpoint should be available")
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.open_endpoint(&config.tracing, tokio_component);
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self.state
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.components
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.get_downcast_ref::<MetricsEndpoint>()
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.expect("Metrics endpoint should be available")
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.open_endpoint(&config.metrics, tokio_component);
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}
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Ok(())
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}
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fn shutdown(&mut self, shutdown: Shutdown) -> ! {
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if let Err(e) = self.state().components.shutdown(self, shutdown) {
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fatal_error(self, &e)
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}
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// Swap out a fake app so we can trigger the destructor on the original
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let _ = std::mem::take(self);
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match shutdown {
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Shutdown::Graceful => process::exit(0),
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Shutdown::Forced => process::exit(1),
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Shutdown::Crash => process::exit(2),
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}
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}
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}
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impl ZebradApp {
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fn tracing_component(&mut self) -> Tracing {
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let config = &self.config().tracing;
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let (component, guard) = crate::components::tracing::init(config);
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self.flame_guard = guard;
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component
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}
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/// Returns true if command is a server command.
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///
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/// Server commands use long-running components such as tracing, metrics,
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/// and the tokio runtime.
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fn command_is_server(command: &EntryPoint<ZebradCmd>) -> bool {
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// `None` outputs zebrad usage information and exits
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match &command.command {
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None => false,
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Some(c) => c.is_server(),
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}
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}
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}
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