Add iteration information to failure error message

src/benchmark/executor.rs

@@ -16,11 +16,28 @@ use super::timing_result::TimingResult;
 use anyhow::{bail, Context, Result};
 use statistical::mean;
 
+pub enum BenchmarkIteration {
+    NonBenchmarkRun,
+    Warmup(u64),
+    Benchmark(u64),
+}
+
+impl BenchmarkIteration {
+    pub fn to_env_var_value(&self) -> Option<String> {
+        match self {
+            BenchmarkIteration::NonBenchmarkRun => None,
+            BenchmarkIteration::Warmup(i) => Some(format!("warmup-{}", i)),
+            BenchmarkIteration::Benchmark(i) => Some(format!("{}", i)),
+        }
+    }
+}
+
 pub trait Executor {
     /// Run the given command and measure the execution time
     fn run_command_and_measure(
         &self,
         command: &Command<'_>,
+        iteration: BenchmarkIteration,
         command_failure_action: Option<CmdFailureAction>,
     ) -> Result<(TimingResult, ExitStatus)>;
 
@@ -39,6 +56,7 @@ pub trait Executor {
 
 fn run_command_and_measure_common(
     mut command: std::process::Command,
+    iteration: BenchmarkIteration,
     command_failure_action: CmdFailureAction,
     command_input_policy: &CommandInputPolicy,
     command_output_policy: &CommandOutputPolicy,
@@ -53,17 +71,29 @@ fn run_command_and_measure_common(
         randomized_environment_offset::value(),
     );
 
+    if let Some(value) = iteration.to_env_var_value() {
+        command.env("HYPERFINE_ITERATION", value);
+    }
+
     let result = execute_and_measure(command)
         .with_context(|| format!("Failed to run command '{command_name}'"))?;
 
     if command_failure_action == CmdFailureAction::RaiseError && !result.status.success() {
+        let when = match iteration {
+            BenchmarkIteration::NonBenchmarkRun => "a non-benchmark run".to_string(),
+            BenchmarkIteration::Warmup(0) => "the first warmup run".to_string(),
+            BenchmarkIteration::Warmup(i) => format!("warmup iteration {i}"),
+            BenchmarkIteration::Benchmark(0) => "the first benchmark run".to_string(),
+            BenchmarkIteration::Benchmark(i) => format!("benchmark iteration {i}"),
+        };
         bail!(
-            "{}. Use the '-i'/'--ignore-failure' option if you want to ignore this. \
+            "{cause} in {when}. Use the '-i'/'--ignore-failure' option if you want to ignore this. \
             Alternatively, use the '--show-output' option to debug what went wrong.",
-            result.status.code().map_or(
+            cause=result.status.code().map_or(
                 "The process has been terminated by a signal".into(),
-                |c| format!("Command terminated with non-zero exit code: {c}")
+                |c| format!("Command terminated with non-zero exit code {c}")
-            )
+
+            ),
         );
     }
 
@@ -84,10 +114,12 @@ impl<'a> Executor for RawExecutor<'a> {
     fn run_command_and_measure(
         &self,
         command: &Command<'_>,
+        iteration: BenchmarkIteration,
         command_failure_action: Option<CmdFailureAction>,
     ) -> Result<(TimingResult, ExitStatus)> {
         let result = run_command_and_measure_common(
             command.get_command()?,
+            iteration,
             command_failure_action.unwrap_or(self.options.command_failure_action),
             &self.options.command_input_policy,
             &self.options.command_output_policy,
@@ -133,6 +165,7 @@ impl<'a> Executor for ShellExecutor<'a> {
     fn run_command_and_measure(
         &self,
         command: &Command<'_>,
+        iteration: BenchmarkIteration,
         command_failure_action: Option<CmdFailureAction>,
     ) -> Result<(TimingResult, ExitStatus)> {
         let on_windows_cmd = cfg!(windows) && *self.shell == Shell::Default("cmd.exe");
@@ -149,6 +182,7 @@ impl<'a> Executor for ShellExecutor<'a> {
 
         let mut result = run_command_and_measure_common(
             command_builder,
+            iteration,
             command_failure_action.unwrap_or(self.options.command_failure_action),
             &self.options.command_input_policy,
             &self.options.command_output_policy,
@@ -191,7 +225,11 @@ impl<'a> Executor for ShellExecutor<'a> {
 
         for _ in 0..COUNT {
             // Just run the shell without any command
-            let res = self.run_command_and_measure(&Command::new(None, ""), None);
+            let res = self.run_command_and_measure(
+                &Command::new(None, ""),
+                BenchmarkIteration::NonBenchmarkRun,
+                None,
+            );
 
             match res {
                 Err(_) => {
@@ -260,6 +298,7 @@ impl Executor for MockExecutor {
     fn run_command_and_measure(
         &self,
         command: &Command<'_>,
+        _iteration: BenchmarkIteration,
         _command_failure_action: Option<CmdFailureAction>,
     ) -> Result<(TimingResult, ExitStatus)> {
         #[cfg(unix)]

src/benchmark/mod.rs

@@ -6,6 +6,7 @@ pub mod timing_result;
 
 use std::cmp;
 
+use crate::benchmark::executor::BenchmarkIteration;
 use crate::command::Command;
 use crate::options::{CmdFailureAction, ExecutorKind, Options, OutputStyleOption};
 use crate::outlier_detection::{modified_zscores, OUTLIER_THRESHOLD};
@@ -57,7 +58,11 @@ impl<'a> Benchmark<'a> {
         error_output: &'static str,
     ) -> Result<TimingResult> {
         self.executor
-            .run_command_and_measure(command, Some(CmdFailureAction::RaiseError))
+            .run_command_and_measure(
+                command,
+                executor::BenchmarkIteration::NonBenchmarkRun,
+                Some(CmdFailureAction::RaiseError),
+            )
             .map(|r| r.0)
             .map_err(|_| anyhow!(error_output))
     }
@@ -187,9 +192,13 @@ impl<'a> Benchmark<'a> {
                 None
             };
 
-            for _ in 0..self.options.warmup_count {
+            for i in 0..self.options.warmup_count {
                 let _ = run_preparation_command()?;
-                let _ = self.executor.run_command_and_measure(self.command, None)?;
+                let _ = self.executor.run_command_and_measure(
+                    self.command,
+                    BenchmarkIteration::Warmup(i),
+                    None,
+                )?;
                 let _ = run_conclusion_command()?;
                 if let Some(bar) = progress_bar.as_ref() {
                     bar.inc(1)
@@ -216,7 +225,11 @@ impl<'a> Benchmark<'a> {
             preparation_result.map_or(0.0, |res| res.time_real + self.executor.time_overhead());
 
         // Initial timing run
-        let (res, status) = self.executor.run_command_and_measure(self.command, None)?;
+        let (res, status) = self.executor.run_command_and_measure(
+            self.command,
+            BenchmarkIteration::Benchmark(0),
+            None,
+        )?;
         let success = status.success();
 
         let conclusion_result = run_conclusion_command()?;
@@ -260,7 +273,7 @@ impl<'a> Benchmark<'a> {
         }
 
         // Gather statistics (perform the actual benchmark)
-        for _ in 0..count_remaining {
+        for i in 0..count_remaining {
             run_preparation_command()?;
 
             let msg = {
@@ -272,7 +285,11 @@ impl<'a> Benchmark<'a> {
                 bar.set_message(msg.to_owned())
             }
 
-            let (res, status) = self.executor.run_command_and_measure(self.command, None)?;
+            let (res, status) = self.executor.run_command_and_measure(
+                self.command,
+                BenchmarkIteration::Benchmark(i + 1),
+                None,
+            )?;
             let success = status.success();
 
             times_real.push(res.time_real);