Add bench for backtracking

Cargo.toml

@@ -24,7 +24,8 @@ include = ["Cargo.toml", "LICENSE", "README.md", "src/**", "tests/**", "examples
 
 [dependencies]
 indexmap = "2.6.0"
-log = "0.4.22" # for debug logs in tests
+# for debug logs in tests
+log = "0.4.22"
 priority-queue = "2.1.1"
 rustc-hash = ">=1.0.0, <3.0.0"
 serde = { version = "1.0", features = ["derive"], optional = true }
@@ -42,6 +43,10 @@ version-ranges = { version = "0.1.0", path = "version-ranges", features = ["prop
 [features]
 serde = ["dep:serde", "version-ranges/serde"]
 
+[[bench]]
+name = "backtracking"
+harness = false
+
 [[bench]]
 name = "large_case"
 harness = false

benches/backtracking.rs

@@ -0,0 +1,56 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use std::collections::BTreeMap;
+use std::time::Duration;
+
+use criterion::*;
+use pubgrub::OfflineDependencyProvider;
+use version_ranges::Ranges;
+
+type Deps = BTreeMap<u32, BTreeMap<u8, BTreeMap<u32, Vec<(u8, u8)>>>>;
+
+fn bench(b: &mut Bencher, data: &str) {
+    let dependencies = ron::de::from_str::<Deps>(data).unwrap();
+
+    let mut dependency_provider = OfflineDependencyProvider::<u32, Ranges<u8>>::new();
+
+    for (&p, vmap) in &dependencies {
+        for (&v, dmap) in vmap {
+            let deps_iter = dmap.iter().map(|(&d, intervals)| {
+                let mut r = Ranges::empty();
+                for &(start, end) in intervals {
+                    r = r.r#union(&Ranges::from_range_bounds(start..=end));
+                }
+                (d, r)
+            });
+            dependency_provider.add_dependencies(p, v, deps_iter);
+        }
+    }
+
+    if let Some((p, v)) = dependencies
+        .first_key_value()
+        .and_then(|(&p, vmap)| vmap.first_key_value().map(|(&v, _)| (p, v)))
+    {
+        b.iter(|| {
+            let _ = pubgrub::resolve(&dependency_provider, p, v);
+        });
+    }
+}
+
+fn bench_group(c: &mut Criterion) {
+    let mut group = c.benchmark_group("bench");
+    group.measurement_time(Duration::from_secs(20));
+
+    for case in ["small", "medium", "large"] {
+        let name = format!("backtracking_{case}");
+        let data = std::fs::read_to_string(format!("test-examples/{name}.ron")).unwrap();
+        group.bench_function(name, |b| {
+            bench(b, &data);
+        });
+    }
+
+    group.finish();
+}
+
+criterion_group!(benches, bench_group);
+criterion_main!(benches);

benches/large_case.rs

@@ -1,4 +1,5 @@
 // SPDX-License-Identifier: MPL-2.0
+
 use std::time::Duration;
 
 use criterion::*;