cli: add a command for benchmarking many revsets

This command is similar to Mercurial's revset benchmarking command. It
lets you pass in a file containing revsets. I also included a file
with some revsets to test on the git.git repo. I put it in `testing/`,
which doesn't seem perfect. I'm happy to hear suggestions for better
places, or we can move it later if we find a better place.

Note that these tests don't clear caches between each run (or even
between tests), so revsets that rely on filtering commit data that's
not indexed appear faster than they typically are in reality.

src/commands/bench.rs

@@ -36,6 +36,8 @@ pub enum BenchCommands {
     ResolvePrefix(BenchResolvePrefixArgs),
     #[command(name = "revset")]
     Revset(BenchRevsetArgs),
+    #[command(name = "revsets")]
+    Revsets(BenchRevsetsArgs),
 }
 
 /// Find the common ancestor(s) of a set of commits
@@ -58,6 +60,12 @@ pub struct BenchRevsetArgs {
     revisions: String,
 }
 
+/// Benchmark multiple revsets specified in a file
+#[derive(clap::Args, Clone, Debug)]
+pub struct BenchRevsetsArgs {
+    file: String,
+}
+
 /// Resolve a commit ID prefix
 #[derive(clap::Args, Clone, Debug)]
 pub struct BenchResolvePrefixArgs {
@@ -151,6 +159,46 @@ pub(crate) fn cmd_bench(
                 routine,
             )?;
         }
+        BenchCommands::Revsets(command_matches) => {
+            let workspace_command = command.workspace_helper(ui)?;
+            let file_path = command.cwd().join(&command_matches.file);
+            let revsets = std::fs::read_to_string(&file_path)?;
+            let mut criterion = Criterion::default();
+            let mut group = criterion.benchmark_group("revsets");
+            for revset in revsets.lines() {
+                let revset = revset.trim();
+                if revset.starts_with('#') || revset.is_empty() {
+                    continue;
+                }
+                writeln!(ui, "----------Testing revset: {revset}----------\n")?;
+                let expression = workspace_command.parse_revset(revset)?;
+                // Time both evaluation and iteration. Note that we don't clear caches (such as
+                // commit objects in `Store`) between each run (`criterion`
+                // doesn't seem to support that).
+                let routine = || {
+                    workspace_command
+                        .evaluate_revset(expression.clone())
+                        .unwrap()
+                        .iter()
+                        .count()
+                };
+                let before = Instant::now();
+                let result = routine();
+                let after = Instant::now();
+                writeln!(
+                    ui,
+                    "First run took {:?} and produced {result} commits",
+                    after.duration_since(before),
+                )?;
+
+                group.bench_function(&format!("revset {}", &revset), |bencher| {
+                    bencher.iter(routine);
+                });
+            }
+            // Neither of these seem to report anything...
+            group.finish();
+            criterion.final_summary();
+        }
     }
     Ok(())
 }

testing/bench-revsets-git.txt

@@ -0,0 +1,41 @@
+# Revsets to pass to `jj bench revsets` on the Git 
+
+# Single tags
+v1.0.0
+v2.40.0
+# Old history
+:v1.0.0
+..v1.0.0
+# More history
+:v2.40.0
+..v2.40.0
+# Only recent history
+v2.39.0..v2.40.0
+:v2.40.0 ~ :v2.39.0
+v2.39.0:v2.40.0
+# Tags and branches
+tags()
+branches()
+# Intersection of range with a small subset
+tags() & :v2.40.0
+v2.39.0 & :v2.40.0
+# Author and committer
+author(peff)
+committer(gitster)
+# Intersection and union of large subsets
+author(peff) & committer(gitster)
+author(peff) | committer(gitster)
+# Roots and heads of small subsets
+roots(tags())
+heads(tags())
+# Roots and heads of large subsets
+roots(author(peff))
+heads(author(peff))
+# Roots and heads of range
+roots(:v2.40.0)
+heads(:v2.40.0)
+# Parents and children of small subset
+tags()-
+tags()+
+# Files are unbearably slow, so only filter within small set
+file(Makefile) & v1.0.0..v1.2.0