implement parallel job execution

Cargo.toml

@@ -23,6 +23,7 @@ atty = "0.2.0"
 camino = "1.0.4"
 clap = { version = "2.33.0", features = ["wrap_help"] }
 ctrlc = { version = "3.1.1", features = ["termination"] }
+crossbeam = "0.8.2"
 derivative = "2.0.0"
 dotenvy = "0.15"
 edit-distance = "2.0.0"

README.md

@@ -1255,6 +1255,7 @@ Recipes may be annotated with attributes that change their behavior.
 | `[macos]`<sup>1.8.0</sup>           | Enable recipe on MacOS.                         |
 | `[no-cd]`<sup>1.9.0</sup>           | Don't change directory before executing recipe. |
 | `[no-exit-message]`<sup>1.7.0</sup> | Don't print an error message if recipe fails.   |
+| `[parallel]`<sup>master</sup>       | See [Parallel execution](#parallel-execution).  |
 | `[private]`<sup>1.10.0</sup>        | See [Private Recipes](#private-recipes).        |
 | `[unix]`<sup>1.8.0</sup>            | Enable recipe on Unixes. (Includes MacOS).      |
 | `[windows]`<sup>1.8.0</sup>         | Enable recipe on Windows.                       |
@@ -2143,6 +2144,32 @@ Available recipes:
 
 This is useful for helper recipes which are only meant to be used as dependencies of other recipes.
 
+### Parallel execution
+
+`just` has two separate ways to enable parallel execution of tasks.
+
+Run the given recipes on the command line in parallel:
+
+```sh
+$ just --parallel recipe_1 recipe_2 recipe_3
+[...]
+```
+
+And using the `[parallel]` attribute, task dependencies are allowed to run in
+parallel:
+
+```just
+recipe_1:
+  sleep 1
+
+recipe_2:
+  sleep 2
+
+[parallel]
+foo: recipe_1 recipe_2
+  echo hello
+```
+
 ### Quiet Recipes
 
 A recipe name may be prefixed with `@` to invert the meaning of `@` before each line:

completions/just.bash

@@ -20,7 +20,7 @@ _just() {
 
     case "${cmd}" in
         just)
-            opts=" -n -q -u -v -e -l -h -V -f -d -c -s  --check --yes --dry-run --highlight --no-dotenv --no-highlight --quiet --shell-command --clear-shell-args --unsorted --unstable --verbose --changelog --choose --dump --edit --evaluate --fmt --init --list --summary --variables --help --version --chooser --color --command-color --dump-format --list-heading --list-prefix --justfile --set --shell --shell-arg --working-directory --command --completions --show --dotenv-filename --dotenv-path  <ARGUMENTS>... "
+            opts=" -n -p -q -u -v -e -l -h -V -f -d -c -s  --check --yes --dry-run --highlight --no-dotenv --no-highlight --parallel --quiet --shell-command --clear-shell-args --unsorted --unstable --verbose --changelog --choose --dump --edit --evaluate --fmt --init --list --summary --variables --help --version --chooser --color --command-color --dump-format --list-heading --list-prefix --justfile --set --shell --shell-arg --working-directory --command --completions --show --dotenv-filename --dotenv-path  <ARGUMENTS>... "
                 if [[ ${cur} == -* ]] ; then
                     COMPREPLY=( $(compgen -W "${opts}" -- "${cur}") )
                     return 0

completions/just.elvish

@@ -41,6 +41,8 @@ edit:completion:arg-completer[just] = [@words]{
             cand --highlight 'Highlight echoed recipe lines in bold'
             cand --no-dotenv 'Don''t load `.env` file'
             cand --no-highlight 'Don''t highlight echoed recipe lines in bold'
+            cand -p 'run given tasks in parallel'
+            cand --parallel 'run given tasks in parallel'
             cand -q 'Suppress all output'
             cand --quiet 'Suppress all output'
             cand --shell-command 'Invoke <COMMAND> with the shell used to run recipe lines and backticks'

completions/just.fish

@@ -57,6 +57,7 @@ complete -c just -n "__fish_use_subcommand" -s n -l dry-run -d 'Print what just
 complete -c just -n "__fish_use_subcommand" -l highlight -d 'Highlight echoed recipe lines in bold'
 complete -c just -n "__fish_use_subcommand" -l no-dotenv -d 'Don\'t load `.env` file'
 complete -c just -n "__fish_use_subcommand" -l no-highlight -d 'Don\'t highlight echoed recipe lines in bold'
+complete -c just -n "__fish_use_subcommand" -s p -l parallel -d 'run given tasks in parallel'
 complete -c just -n "__fish_use_subcommand" -s q -l quiet -d 'Suppress all output'
 complete -c just -n "__fish_use_subcommand" -l shell-command -d 'Invoke <COMMAND> with the shell used to run recipe lines and backticks'
 complete -c just -n "__fish_use_subcommand" -l clear-shell-args -d 'Clear shell arguments'

completions/just.powershell

@@ -46,6 +46,8 @@ Register-ArgumentCompleter -Native -CommandName 'just' -ScriptBlock {
             [CompletionResult]::new('--highlight', 'highlight', [CompletionResultType]::ParameterName, 'Highlight echoed recipe lines in bold')
             [CompletionResult]::new('--no-dotenv', 'no-dotenv', [CompletionResultType]::ParameterName, 'Don''t load `.env` file')
             [CompletionResult]::new('--no-highlight', 'no-highlight', [CompletionResultType]::ParameterName, 'Don''t highlight echoed recipe lines in bold')
+            [CompletionResult]::new('-p', 'p', [CompletionResultType]::ParameterName, 'run given tasks in parallel')
+            [CompletionResult]::new('--parallel', 'parallel', [CompletionResultType]::ParameterName, 'run given tasks in parallel')
             [CompletionResult]::new('-q', 'q', [CompletionResultType]::ParameterName, 'Suppress all output')
             [CompletionResult]::new('--quiet', 'quiet', [CompletionResultType]::ParameterName, 'Suppress all output')
             [CompletionResult]::new('--shell-command', 'shell-command', [CompletionResultType]::ParameterName, 'Invoke <COMMAND> with the shell used to run recipe lines and backticks')

completions/just.zsh

@@ -42,6 +42,8 @@ _just() {
 '--highlight[Highlight echoed recipe lines in bold]' \
 '--no-dotenv[Don'\''t load `.env` file]' \
 '--no-highlight[Don'\''t highlight echoed recipe lines in bold]' \
+'-p[run given tasks in parallel]' \
+'--parallel[run given tasks in parallel]' \
 '(-n --dry-run)-q[Suppress all output]' \
 '(-n --dry-run)--quiet[Suppress all output]' \
 '--shell-command[Invoke <COMMAND> with the shell used to run recipe lines and backticks]' \

justfile

@@ -225,4 +225,3 @@ pwd:
 # Local Variables:
 # mode: makefile
 # End:
-# vim: set ft=make :

src/alias.rs

@@ -1,8 +1,9 @@
 use super::*;
+use std::sync::Arc;
 
 /// An alias, e.g. `name := target`
 #[derive(Debug, PartialEq, Clone, Serialize)]
-pub(crate) struct Alias<'src, T = Rc<Recipe<'src>>> {
+pub(crate) struct Alias<'src, T = Arc<Recipe<'src>>> {
   pub(crate) attributes: BTreeSet<Attribute>,
   pub(crate) name: Name<'src>,
   #[serde(
@@ -17,7 +18,7 @@ impl<'src> Alias<'src, Name<'src>> {
     self.name.line
   }
 
-  pub(crate) fn resolve(self, target: Rc<Recipe<'src>>) -> Alias<'src> {
+  pub(crate) fn resolve(self, target: Arc<Recipe<'src>>) -> Alias<'src> {
     assert_eq!(self.target.lexeme(), target.name.lexeme());
 
     Alias {

src/analyzer.rs

@@ -1,3 +1,4 @@
+use std::sync::Arc;
 use {super::*, CompileErrorKind::*};
 
 #[derive(Default)]
@@ -87,11 +88,11 @@ impl<'src> Analyzer<'src> {
       first: recipes
         .values()
         .fold(None, |accumulator, next| match accumulator {
-          None => Some(Rc::clone(next)),
+          None => Some(Arc::clone(next)),
           Some(previous) => Some(if previous.line_number() < next.line_number() {
             previous
           } else {
-            Rc::clone(next)
+            Arc::clone(next)
           }),
         }),
       aliases,
@@ -190,7 +191,7 @@ impl<'src> Analyzer<'src> {
   }
 
   fn resolve_alias(
-    recipes: &Table<'src, Rc<Recipe<'src>>>,
+    recipes: &Table<'src, Arc<Recipe<'src>>>,
     alias: Alias<'src, Name<'src>>,
   ) -> CompileResult<'src, Alias<'src>> {
     let token = alias.name.token();
@@ -204,7 +205,7 @@ impl<'src> Analyzer<'src> {
 
     // Make sure the target recipe exists
     match recipes.get(alias.target.lexeme()) {
-      Some(target) => Ok(alias.resolve(Rc::clone(target))),
+      Some(target) => Ok(alias.resolve(Arc::clone(target))),
       None => Err(token.error(UnknownAliasTarget {
         alias: alias.name.lexeme(),
         target: alias.target.lexeme(),

src/attribute.rs

@@ -12,6 +12,7 @@ pub(crate) enum Attribute {
   NoCd,
   NoExitMessage,
   Private,
+  Parallel,
   Unix,
   Windows,
 }

src/config.rs

@@ -25,6 +25,7 @@ pub(crate) struct Config {
   pub(crate) list_heading: String,
   pub(crate) list_prefix: String,
   pub(crate) load_dotenv: bool,
+  pub(crate) parallel: bool,
   pub(crate) search_config: SearchConfig,
   pub(crate) shell: Option<String>,
   pub(crate) shell_args: Option<Vec<String>>,
@@ -98,6 +99,7 @@ mod arg {
   pub(crate) const LIST_PREFIX: &str = "LIST-PREFIX";
   pub(crate) const NO_DOTENV: &str = "NO-DOTENV";
   pub(crate) const NO_HIGHLIGHT: &str = "NO-HIGHLIGHT";
+  pub(crate) const PARALLEL: &str = "PARALLEL";
   pub(crate) const QUIET: &str = "QUIET";
   pub(crate) const SET: &str = "SET";
   pub(crate) const SHELL: &str = "SHELL";
@@ -225,6 +227,12 @@ impl Config {
           .takes_value(true)
           .help("Use <JUSTFILE> as justfile"),
       )
+      .arg(
+        Arg::with_name(arg::PARALLEL)
+          .short("p")
+          .long("parallel")
+          .help("run given tasks in parallel")
+      )
       .arg(
         Arg::with_name(arg::QUIET)
           .short("q")
@@ -630,6 +638,7 @@ impl Config {
       dotenv_filename: matches.value_of(arg::DOTENV_FILENAME).map(str::to_owned),
       dotenv_path: matches.value_of(arg::DOTENV_PATH).map(PathBuf::from),
       dry_run: matches.is_present(arg::DRY_RUN),
+      parallel: matches.is_present(arg::PARALLEL),
       dump_format: Self::dump_format_from_matches(matches)?,
       highlight: !matches.is_present(arg::NO_HIGHLIGHT),
       invocation_directory,
@@ -685,6 +694,7 @@ mod tests {
       args: [$($arg:expr),*],
       $(color: $color:expr,)?
       $(dry_run: $dry_run:expr,)?
+      $(parallel: $parallel:expr,)?
       $(dump_format: $dump_format:expr,)?
       $(highlight: $highlight:expr,)?
       $(search_config: $search_config:expr,)?
@@ -704,6 +714,7 @@ mod tests {
         let want = Config {
           $(color: $color,)?
           $(dry_run: $dry_run,)?
+          $(parallel: $parallel,)?
           $(dump_format: $dump_format,)?
           $(highlight: $highlight,)?
           $(search_config: $search_config,)?
@@ -840,6 +851,18 @@ mod tests {
     dry_run: true,
   }
 
+  test! {
+    name: parallel_long,
+    args: ["--parallel"],
+    parallel: true,
+  }
+
+  test! {
+    name: parallel_short,
+    args: ["-p"],
+    parallel: true,
+  }
+
   error! {
     name: dry_run_quiet,
     args: ["--dry-run", "--quiet"],

src/dependency.rs

@@ -1,10 +1,11 @@
 use super::*;
+use std::sync::Arc;
 
 #[derive(PartialEq, Debug, Serialize)]
 pub(crate) struct Dependency<'src> {
   pub(crate) arguments: Vec<Expression<'src>>,
   #[serde(serialize_with = "keyed::serialize")]
-  pub(crate) recipe: Rc<Recipe<'src>>,
+  pub(crate) recipe: Arc<Recipe<'src>>,
 }
 
 impl<'src> Display for Dependency<'src> {