better bench test

Cargo.toml

@@ -57,6 +57,7 @@ pmtiles = { version = "0.5", features = ["http-async", "mmap-async-tokio", "tile
 postgis = "0.9"
 postgres = { version = "0.19", features = ["with-time-0_3", "with-uuid-1", "with-serde_json-1"] }
 postgres-protocol = "0.6"
+pprof = { version = "0.13", features = ["flamegraph", "criterion"] }
 pretty_assertions = "1"
 regex = "1"
 reqwest = { version = "0.11", default-features = false, features = ["rustls-tls-native-roots"] }

justfile

@@ -93,8 +93,14 @@ start-pmtiles-server:
     docker-compose up -d fileserver
 
 # Run benchmark tests
-bench: start
-    cargo bench
+bench:
+    cargo bench --bench bench
+    open target/criterion/report/index.html
+
+# Run benchmark tests showing a flamegraph
+flamegraph:
+    cargo bench --bench bench -- --profile-time=10
+    /opt/google/chrome/chrome "file://$PWD/target/criterion/get_table_source_tile/profile/flamegraph.svg"
 
 # Start release-compiled Martin server and a test database
 bench-server: start

martin/Cargo.toml

@@ -116,3 +116,4 @@ criterion.workspace = true
 ctor.workspace = true
 indoc.workspace = true
 insta = { workspace = true, features = ["yaml"] }
+pprof.workspace = true

martin/benches/bench.rs

@@ -6,6 +6,7 @@ use martin::{
     CatalogSourceEntry, MartinResult, Source, TileCoord, TileData, TileSources, UrlQuery,
 };
 use martin_tile_utils::{Encoding, Format, TileInfo};
+use pprof::criterion::{Output, PProfProfiler};
 use tilejson::{tilejson, TileJSON};
 
 #[derive(Clone, Debug)]
@@ -48,7 +49,7 @@ impl Source for NullSource {
         _xyz: TileCoord,
         _url_query: Option<&UrlQuery>,
     ) -> MartinResult<TileData> {
-        Ok(Vec::new())
+        Ok(b"empty".to_vec())
     }
 
     fn get_catalog_entry(&self) -> CatalogSourceEntry {
@@ -69,5 +70,10 @@ fn bench_null_source(c: &mut Criterion) {
     });
 }
 
-criterion_group!(benches, bench_null_source);
+criterion_group! {
+    name = benches;
+    config = Criterion::default().with_profiler(PProfProfiler::new(1000, Output::Flamegraph(None)));
+    targets = bench_null_source
+}
+
 criterion_main!(benches);