Use raw executor by default, skip intermediate shell

This adds a new "raw executor" (next to the "shell executor") that
allows hyperfine to execute commands directly without any intermediate
shell.

The command line is split into tokens (using the `shell-words` crate),
and according to POSIX rules. The first token is taken as the executable,
and the rest as arguments.

The new executor is enabled by default. In order to select the shell
executor, users will have to pass `--shell=default`.

This allows us to reduce measurement noise and to benchmark very quick
commands. It also decreases the time to run benchmarks, as we don't need
the calibration phase.

Also, it allows one to make sure that the executed command is not
implemented as a shell builtin. For example `hyperfine true`
and `hyperfine --shell=default true` return different times due
to the fact that `bash` executes `true` as a NOP.

Co-authored: Ciprian Dorin Craciun <ciprian@volution.ro>

src/benchmark/executor.rs

@@ -64,6 +64,48 @@ fn run_command_and_measure_common(
     Ok(result)
 }
 
+pub struct RawExecutor<'a> {
+    options: &'a Options,
+}
+
+impl<'a> RawExecutor<'a> {
+    pub fn new(options: &'a Options) -> Self {
+        RawExecutor { options }
+    }
+}
+
+impl<'a> Executor for RawExecutor<'a> {
+    fn run_command_and_measure(
+        &self,
+        command: &Command<'_>,
+        command_failure_action: Option<CmdFailureAction>,
+    ) -> Result<(TimingResult, ExitStatus)> {
+        let result = run_command_and_measure_common(
+            command.get_command()?,
+            command_failure_action.unwrap_or(self.options.command_failure_action),
+            self.options.command_output_policy,
+            &command.get_command_line(),
+        )?;
+
+        Ok((
+            TimingResult {
+                time_real: result.time_real,
+                time_user: result.time_user,
+                time_system: result.time_system,
+            },
+            result.status,
+        ))
+    }
+
+    fn calibrate(&mut self) -> Result<()> {
+        Ok(())
+    }
+
+    fn time_overhead(&self) -> Second {
+        0.0
+    }
+}
+
 pub struct ShellExecutor<'a> {
     options: &'a Options,
     shell: &'a Shell,

src/benchmark/mod.rs

@@ -7,7 +7,7 @@ pub mod timing_result;
 use std::cmp;
 
 use crate::command::Command;
-use crate::options::{CmdFailureAction, Options, OutputStyleOption};
+use crate::options::{CmdFailureAction, ExecutorKind, Options, OutputStyleOption};
 use crate::outlier_detection::{modified_zscores, OUTLIER_THRESHOLD};
 use crate::output::format::{format_duration, format_duration_unit};
 use crate::output::progress_bar::get_progress_bar;
@@ -320,7 +320,9 @@ impl<'a> Benchmark<'a> {
         let mut warnings = vec![];
 
         // Check execution time
-        if times_real.iter().any(|&t| t < MIN_EXECUTION_TIME) {
+        if matches!(self.options.executor_kind, ExecutorKind::Shell(_))
+            && times_real.iter().any(|&t| t < MIN_EXECUTION_TIME)
+        {
             warnings.push(Warnings::FastExecutionTime);
         }
 

src/benchmark/scheduler.rs

@@ -1,7 +1,7 @@
 use colored::*;
 
 use super::benchmark_result::BenchmarkResult;
-use super::executor::{Executor, MockExecutor, ShellExecutor};
+use super::executor::{Executor, MockExecutor, RawExecutor, ShellExecutor};
 use super::{relative_speed, Benchmark};
 
 use crate::command::Commands;
@@ -33,6 +33,7 @@ impl<'a> Scheduler<'a> {
 
     pub fn run_benchmarks(&mut self) -> Result<()> {
         let mut executor: Box<dyn Executor> = match self.options.executor_kind {
+            ExecutorKind::Raw => Box::new(RawExecutor::new(self.options)),
             ExecutorKind::Mock(ref shell) => Box::new(MockExecutor::new(shell.clone())),
             ExecutorKind::Shell(ref shell) => Box::new(ShellExecutor::new(shell, self.options)),
         };

src/command.rs

@@ -15,7 +15,7 @@ use clap::ArgMatches;
 use crate::parameter::tokenize::tokenize;
 use crate::parameter::ParameterValue;
 
-use anyhow::{bail, Result};
+use anyhow::{bail, Context, Result};
 use clap::Values;
 use rust_decimal::Decimal;
 
@@ -64,6 +64,21 @@ impl<'a> Command<'a> {
         self.replace_parameters_in(self.expression)
     }
 
+    pub fn get_command(&self) -> Result<std::process::Command> {
+        let command_line = self.get_command_line();
+        let mut tokens = shell_words::split(&command_line)
+            .with_context(|| format!("Failed to parse command '{}'", command_line))?
+            .into_iter();
+
+        if let Some(program_name) = tokens.next() {
+            let mut command_builder = std::process::Command::new(program_name);
+            command_builder.args(tokens);
+            Ok(command_builder)
+        } else {
+            bail!("Can not execute empty command")
+        }
+    }
+
     pub fn get_parameters(&self) -> &[(&'a str, ParameterValue)] {
         &self.parameters
     }

src/options.rs

@@ -134,6 +134,7 @@ impl CommandOutputPolicy {
 }
 
 pub enum ExecutorKind {
+    Raw,
     Shell(Shell),
     Mock(Option<String>),
 }
@@ -283,8 +284,9 @@ impl Options {
 
         options.executor_kind = match (matches.is_present("debug-mode"), matches.value_of("shell"))
         {
+            (false, Some(shell)) if shell == "default" => ExecutorKind::Shell(Shell::default()),
             (false, Some(shell)) => ExecutorKind::Shell(Shell::parse_from_str(shell)?),
-            (false, None) => ExecutorKind::Shell(Shell::default()),
+            (false, None) => ExecutorKind::Raw,
             (true, Some(shell)) => ExecutorKind::Mock(Some(shell.into())),
             (true, None) => ExecutorKind::Mock(None),
         };

tests/common.rs

@@ -11,3 +11,9 @@ pub fn hyperfine_raw_command() -> Command {
 pub fn hyperfine() -> assert_cmd::Command {
     assert_cmd::Command::from_std(hyperfine_raw_command())
 }
+
+pub fn hyperfine_shell() -> assert_cmd::Command {
+    let mut cmd = hyperfine();
+    cmd.arg("--shell=default");
+    cmd
+}

tests/execution_order_tests.rs

@@ -3,7 +3,7 @@ use std::{fs::File, io::Read, path::PathBuf};
 use tempfile::{tempdir, TempDir};
 
 mod common;
-use common::hyperfine;
+use common::hyperfine_shell;
 
 struct ExecutionOrderTest {
     cmd: assert_cmd::Command,
@@ -19,7 +19,7 @@ impl ExecutionOrderTest {
         let logfile_path = tempdir.path().join("output.log");
 
         ExecutionOrderTest {
-            cmd: hyperfine(),
+            cmd: hyperfine_shell(),
             expected_content: String::new(),
             logfile_path,
             tempdir,

tests/integration_tests.rs

@@ -1,5 +1,5 @@
 mod common;
-use common::hyperfine;
+use common::{hyperfine, hyperfine_shell};
 
 use predicates::prelude::*;
 
@@ -81,6 +81,18 @@ fn fails_with_duplicate_parameter_names() {
 #[test]
 fn fails_for_unknown_command() {
     hyperfine()
+        .arg("--runs=1")
+        .arg("some-nonexisting-program-b5d9574198b7e4b12a71fa4747c0a577")
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains(
+            "Failed to run command 'some-nonexisting-program-b5d9574198b7e4b12a71fa4747c0a577'",
+        ));
+}
+
+#[test]
+fn fails_for_unknown_shell_command() {
+    hyperfine_shell()
         .arg("--runs=1")
         .arg("some-nonexisting-program-b5d9574198b7e4b12a71fa4747c0a577")
         .assert()