feat: Add timings subcommand (starship#1629)

* feat: Add computational duration to all computed modules

This also means that in case we do some computations and these end up empty, we submit an empty module

* feat: Add timings subcommand

This outputs the timings of all computed modules, sorted by the duration it took to compute the module.

Useful for debugging why the prompt takes so long.

* feat: Add timings to explain output

* fix: Ensure that even empty custom modules get timings

* format main.rs

* feat: Only show interesting timings

* fix(tests): Change tests to look for empty string instead of None

* Use proper wording in timings help

* Revert "fix(tests): Change tests to look for empty string instead of None"

This reverts commit aca5bd1.

* fix(tests): Returning None in case the module produced an empty string

* fix: Ensure that linebreaks (and space) make a module not-empty

* Make cargo clippy happy

* Make Module.duration a proper Duration

* Only return a module if we would report it

* Change to cleaner way to return None for empty modules

* Avoid unnecessary module creation

* Simplify a string comparison

* Add timings to trace

Co-authored-by: Thomas O'Donnell <[email protected]>

Co-authored-by: Thomas O'Donnell <[email protected]>

Author: jankatins

src/main.rs

@@ -71,87 +71,89 @@ fn main() {
         .long("print-full-init")
         .help("Print the main initialization script (as opposed to the init stub)");
 
-    let mut app =
-        App::new("starship")
-            .about("The cross-shell prompt for astronauts. ☄🌌️")
-            // pull the version number from Cargo.toml
-            .version(crate_version!())
-            // pull the authors from Cargo.toml
-            .author(crate_authors!())
-            .after_help("https://github.com/starship/starship")
-            .setting(AppSettings::SubcommandRequiredElseHelp)
-            .subcommand(
-                SubCommand::with_name("init")
-                    .about("Prints the shell function used to execute starship")
-                    .arg(&shell_arg)
-                    .arg(&init_scripts_arg),
-            )
-            .subcommand(
-                SubCommand::with_name("prompt")
-                    .about("Prints the full starship prompt")
-                    .arg(&status_code_arg)
-                    .arg(&path_arg)
-                    .arg(&cmd_duration_arg)
-                    .arg(&keymap_arg)
-                    .arg(&jobs_arg),
-            )
-            .subcommand(
-                SubCommand::with_name("module")
-                    .about("Prints a specific prompt module")
-                    .arg(
-                        Arg::with_name("name")
-                            .help("The name of the module to be printed")
-                            .required(true)
-                            .required_unless("list"),
-                    )
-                    .arg(
-                        Arg::with_name("list")
-                            .short("l")
-                            .long("list")
-                            .help("List out all supported modules"),
-                    )
-                    .arg(&status_code_arg)
-                    .arg(&path_arg)
-                    .arg(&cmd_duration_arg)
-                    .arg(&keymap_arg)
-                    .arg(&jobs_arg),
-            )
-            .subcommand(
-                SubCommand::with_name("config")
-                    .alias("configure")
-                    .about("Edit the starship configuration")
-                    .arg(
-                        Arg::with_name("name")
-                            .help("Configuration key to edit")
-                            .required(false)
-                            .requires("value"),
-                    )
-                    .arg(Arg::with_name("value").help("Value to place into that key")),
-            )
-            .subcommand(SubCommand::with_name("bug-report").about(
+    let mut app = App::new("starship")
+        .about("The cross-shell prompt for astronauts. ☄🌌️")
+        // pull the version number from Cargo.toml
+        .version(crate_version!())
+        // pull the authors from Cargo.toml
+        .author(crate_authors!())
+        .after_help("https://github.com/starship/starship")
+        .setting(AppSettings::SubcommandRequiredElseHelp)
+        .subcommand(
+            SubCommand::with_name("init")
+                .about("Prints the shell function used to execute starship")
+                .arg(&shell_arg)
+                .arg(&init_scripts_arg),
+        )
+        .subcommand(
+            SubCommand::with_name("prompt")
+                .about("Prints the full starship prompt")
+                .arg(&status_code_arg)
+                .arg(&path_arg)
+                .arg(&cmd_duration_arg)
+                .arg(&keymap_arg)
+                .arg(&jobs_arg),
+        )
+        .subcommand(
+            SubCommand::with_name("module")
+                .about("Prints a specific prompt module")
+                .arg(
+                    Arg::with_name("name")
+                        .help("The name of the module to be printed")
+                        .required(true)
+                        .required_unless("list"),
+                )
+                .arg(
+                    Arg::with_name("list")
+                        .short("l")
+                        .long("list")
+                        .help("List out all supported modules"),
+                )
+                .arg(&status_code_arg)
+                .arg(&path_arg)
+                .arg(&cmd_duration_arg)
+                .arg(&keymap_arg)
+                .arg(&jobs_arg),
+        )
+        .subcommand(
+            SubCommand::with_name("config")
+                .alias("configure")
+                .about("Edit the starship configuration")
+                .arg(
+                    Arg::with_name("name")
+                        .help("Configuration key to edit")
+                        .required(false)
+                        .requires("value"),
+                )
+                .arg(Arg::with_name("value").help("Value to place into that key")),
+        )
+        .subcommand(
+            SubCommand::with_name("bug-report").about(
                 "Create a pre-populated GitHub issue with information about your configuration",
-            ))
-            .subcommand(
-                SubCommand::with_name("time")
-                    .about("Prints time in milliseconds")
-                    .settings(&[AppSettings::Hidden]),
-            )
-            .subcommand(
-                SubCommand::with_name("explain").about("Explains the currently showing modules"),
-            )
-            .subcommand(
-                SubCommand::with_name("completions")
-                    .about("Generate starship shell completions for your shell to stdout")
-                    .arg(
-                        Arg::with_name("shell")
-                            .takes_value(true)
-                            .possible_values(&Shell::variants())
-                            .help("the shell to generate completions for")
-                            .value_name("SHELL")
-                            .required(true)
-                            .env("STARSHIP_SHELL"),
-                    ),
-            );
+            ),
+        )
+        .subcommand(
+            SubCommand::with_name("time")
+                .about("Prints time in milliseconds")
+                .settings(&[AppSettings::Hidden]),
+        )
+        .subcommand(
+            SubCommand::with_name("explain").about("Explains the currently showing modules"),
+        )
+        .subcommand(SubCommand::with_name("timings").about("Prints timings of all active modules"))
+        .subcommand(
+            SubCommand::with_name("completions")
+                .about("Generate starship shell completions for your shell to stdout")
+                .arg(
+                    Arg::with_name("shell")
+                        .takes_value(true)
+                        .possible_values(&Shell::variants())
+                        .help("the shell to generate completions for")
+                        .value_name("SHELL")
+                        .required(true)
+                        .env("STARSHIP_SHELL"),
+                ),
+        );
 
     let matches = app.clone().get_matches();
 
@@ -197,6 +199,7 @@ fn main() {
             }
         }
         ("explain", Some(sub_m)) => print::explain(sub_m.clone()),
+        ("timings", Some(sub_m)) => print::timings(sub_m.clone()),
         ("completions", Some(sub_m)) => {
             let shell: Shell = sub_m
                 .value_of("shell")

src/module.rs

@@ -3,6 +3,7 @@ use crate::segment::Segment;
 use crate::utils::wrap_colorseq_for_shell;
 use ansi_term::{ANSIString, ANSIStrings};
 use std::fmt;
+use std::time::Duration;
 
 // List of all modules
 // Keep these ordered alphabetically.
@@ -73,6 +74,9 @@ pub struct Module<'a> {
 
     /// The collection of segments that compose this module.
     pub segments: Vec<Segment>,
+
+    /// the time it took to compute this module
+    pub duration: Duration,
 }
 
 impl<'a> Module<'a> {
@@ -83,6 +87,7 @@ impl<'a> Module<'a> {
             name: name.to_string(),
             description: desc.to_string(),
             segments: Vec::new(),
+            duration: Duration::default(),
         }
     }
 
@@ -105,7 +110,8 @@ impl<'a> Module<'a> {
     pub fn is_empty(&self) -> bool {
         self.segments
             .iter()
-            .all(|segment| segment.value.trim().is_empty())
+            // no trim: if we add spaces/linebreaks it's not "empty" as we change the final output
+            .all(|segment| segment.value.is_empty())
     }
 
     /// Get values of the module's segments
@@ -167,6 +173,7 @@ mod tests {
             name: name.to_string(),
             description: desc.to_string(),
             segments: Vec::new(),
+            duration: Duration::default(),
         };
 
         assert!(module.is_empty());
@@ -181,8 +188,39 @@ mod tests {
             name: name.to_string(),
             description: desc.to_string(),
             segments: vec![Segment::new(None, "")],
+            duration: Duration::default(),
         };
 
         assert!(module.is_empty());
     }
+
+    #[test]
+    fn test_module_is_not_empty_with_linebreak_only() {
+        let name = "unit_test";
+        let desc = "This is a unit test";
+        let module = Module {
+            config: None,
+            name: name.to_string(),
+            description: desc.to_string(),
+            segments: vec![Segment::new(None, "\n")],
+            duration: Duration::default(),
+        };
+
+        assert!(!module.is_empty());
+    }
+
+    #[test]
+    fn test_module_is_not_empty_with_space_only() {
+        let name = "unit_test";
+        let desc = "This is a unit test";
+        let module = Module {
+            config: None,
+            name: name.to_string(),
+            description: desc.to_string(),
+            segments: vec![Segment::new(None, " ")],
+            duration: Duration::default(),
+        };
+
+        assert!(!module.is_empty());
+    }
 }

src/modules/custom.rs

@@ -1,5 +1,6 @@
 use std::io::Write;
 use std::process::{Command, Output, Stdio};
+use std::time::Instant;
 
 use super::{Context, Module, RootModuleConfig};
 
@@ -13,6 +14,7 @@ use crate::{configs::custom::CustomConfig, formatter::StringFormatter};
 ///
 /// Finally, the content of the module itself is also set by a command.
 pub fn module<'a>(name: &str, context: &'a Context) -> Option<Module<'a>> {
+    let start: Instant = Instant::now();
     let toml_config = context.config.get_custom_module_config(name).expect(
         "modules::custom::module should only be called after ensuring that the module exists",
     );
@@ -47,37 +49,36 @@ pub fn module<'a>(name: &str, context: &'a Context) -> Option<Module<'a>> {
     let output = exec_command(config.command, &config.shell.0)?;
 
     let trimmed = output.trim();
-    if trimmed.is_empty() {
-        return None;
+    if !trimmed.is_empty() {
+        let parsed = StringFormatter::new(config.format).and_then(|formatter| {
+            formatter
+                .map_meta(|var, _| match var {
+                    "symbol" => Some(config.symbol),
+                    _ => None,
+                })
+                .map_style(|variable| match variable {
+                    "style" => Some(Ok(config.style)),
+                    _ => None,
+                })
+                .map(|variable| match variable {
+                    // This may result in multiple calls to `get_module_version` when a user have
+                    // multiple `$version` variables defined in `format`.
+                    "output" => Some(Ok(trimmed)),
+                    _ => None,
+                })
+                .parse(None)
+        });
+
+        match parsed {
+            Ok(segments) => module.set_segments(segments),
+            Err(error) => {
+                log::warn!("Error in module `custom.{}`:\n{}", name, error);
+            }
+        };
     }
-
-    let parsed = StringFormatter::new(config.format).and_then(|formatter| {
-        formatter
-            .map_meta(|var, _| match var {
-                "symbol" => Some(config.symbol),
-                _ => None,
-            })
-            .map_style(|variable| match variable {
-                "style" => Some(Ok(config.style)),
-                _ => None,
-            })
-            .map(|variable| match variable {
-                // This may result in multiple calls to `get_module_version` when a user have
-                // multiple `$version` variables defined in `format`.
-                "output" => Some(Ok(trimmed)),
-                _ => None,
-            })
-            .parse(None)
-    });
-
-    module.set_segments(match parsed {
-        Ok(segments) => segments,
-        Err(error) => {
-            log::warn!("Error in module `custom.{}`:\n{}", name, error);
-            return None;
-        }
-    });
-
+    let elapsed = start.elapsed();
+    log::trace!("Took {:?} to compute custom module {:?}", elapsed, name);
+    module.duration = elapsed;
     Some(module)
 }
 

src/modules/line_break.rs

@@ -11,3 +11,19 @@ pub fn module<'a>(context: &'a Context) -> Option<Module<'a>> {
 
     Some(module)
 }
+
+#[cfg(test)]
+mod test {
+    use std::io;
+
+    use crate::test::ModuleRenderer;
+
+    #[test]
+    fn produces_result() -> io::Result<()> {
+        let expected = Some(String::from("\n"));
+        let actual = ModuleRenderer::new("line_break").collect();
+        assert_eq!(expected, actual);
+
+        Ok(())
+    }
+}