[subsystem-benchmarks] Save results to json (paritytech#3829)

Here we add the ability to save subsystem benchmark results in JSON
format to display them as graphs

To draw graphs, CI team will use
[github-action-benchmark](https://github.com/benchmark-action/github-action-benchmark).
Since we are using custom benchmarks, we need to prepare [a specific
data
type](https://github.com/benchmark-action/github-action-benchmark?tab=readme-ov-file#examples):
```
[
    {
        "name": "CPU Load",
        "unit": "Percent",
        "value": 50
    }
]
```

Then we'll get graphs like this: 

![example](https://raw.githubusercontent.com/rhysd/ss/master/github-action-benchmark/main.png)

[A live page with
graphs](https://benchmark-action.github.io/github-action-benchmark/dev/bench/)

---------

Co-authored-by: ordian <[email protected]>

polkadot/node/network/availability-distribution/benches/availability-distribution-regression-bench.rs

@@ -27,6 +27,7 @@ use polkadot_subsystem_bench::{
 	availability::{benchmark_availability_write, prepare_test, TestState},
 	configuration::TestConfiguration,
 	usage::BenchmarkUsage,
+	utils::save_to_file,
 };
 use std::io::Write;
 
@@ -60,7 +61,13 @@ fn main() -> Result<(), String> {
 		})
 		.collect();
 	println!("\rDone!{}", " ".repeat(BENCH_COUNT));
+
 	let average_usage = BenchmarkUsage::average(&usages);
+	save_to_file(
+		"charts/availability-distribution-regression-bench.json",
+		average_usage.to_chart_json().map_err(|e| e.to_string())?,
+	)
+	.map_err(|e| e.to_string())?;
 	println!("{}", average_usage);
 
 	// We expect no variance for received and sent

polkadot/node/network/availability-recovery/benches/availability-recovery-regression-bench.rs

@@ -28,6 +28,7 @@ use polkadot_subsystem_bench::{
 	},
 	configuration::TestConfiguration,
 	usage::BenchmarkUsage,
+	utils::save_to_file,
 };
 use std::io::Write;
 
@@ -58,7 +59,13 @@ fn main() -> Result<(), String> {
 		})
 		.collect();
 	println!("\rDone!{}", " ".repeat(BENCH_COUNT));
+
 	let average_usage = BenchmarkUsage::average(&usages);
+	save_to_file(
+		"charts/availability-recovery-regression-bench.json",
+		average_usage.to_chart_json().map_err(|e| e.to_string())?,
+	)
+	.map_err(|e| e.to_string())?;
 	println!("{}", average_usage);
 
 	// We expect no variance for received and sent

polkadot/node/subsystem-bench/Cargo.toml

@@ -71,6 +71,7 @@ prometheus_endpoint = { package = "substrate-prometheus-endpoint", path = "../..
 prometheus = { version = "0.13.0", default-features = false }
 serde = { workspace = true, default-features = true }
 serde_yaml = { workspace = true }
+serde_json = { workspace = true }
 
 polkadot-node-core-approval-voting = { path = "../core/approval-voting" }
 polkadot-approval-distribution = { path = "../network/approval-distribution" }

polkadot/node/subsystem-bench/src/lib/environment.rs

@@ -404,7 +404,7 @@ impl TestEnvironment {
 		let total_cpu = test_env_cpu_metrics.sum_by("substrate_tasks_polling_duration_sum");
 
 		usage.push(ResourceUsage {
-			resource_name: "Test environment".to_string(),
+			resource_name: "test-environment".to_string(),
 			total: total_cpu,
 			per_block: total_cpu / num_blocks,
 		});

polkadot/node/subsystem-bench/src/lib/lib.rs

@@ -26,3 +26,4 @@ pub(crate) mod keyring;
 pub(crate) mod mock;
 pub(crate) mod network;
 pub mod usage;
+pub mod utils;

polkadot/node/subsystem-bench/src/lib/usage.rs

@@ -82,6 +82,27 @@ impl BenchmarkUsage {
 			_ => None,
 		}
 	}
+
+	// Prepares a json string for a graph representation
+	// See: https://github.com/benchmark-action/github-action-benchmark?tab=readme-ov-file#examples
+	pub fn to_chart_json(&self) -> color_eyre::eyre::Result<String> {
+		let chart = self
+			.network_usage
+			.iter()
+			.map(|v| ChartItem {
+				name: v.resource_name.clone(),
+				unit: "KiB".to_string(),
+				value: v.per_block,
+			})
+			.chain(self.cpu_usage.iter().map(|v| ChartItem {
+				name: v.resource_name.clone(),
+				unit: "seconds".to_string(),
+				value: v.per_block,
+			}))
+			.collect::<Vec<_>>();
+
+		Ok(serde_json::to_string(&chart)?)
+	}
 }
 
 fn check_usage(
@@ -151,3 +172,10 @@ impl ResourceUsage {
 }
 
 type ResourceUsageCheck<'a> = (&'a str, f64, f64);
+
+#[derive(Debug, Serialize)]
+pub struct ChartItem {
+	pub name: String,
+	pub unit: String,
+	pub value: f64,
+}

polkadot/node/subsystem-bench/src/lib/utils.rs

@@ -16,61 +16,26 @@
 
 //! Test utils
 
-use crate::usage::BenchmarkUsage;
-use std::io::{stdout, Write};
-
-pub struct WarmUpOptions<'a> {
-	/// The maximum number of runs considered for warming up.
-	pub warm_up: usize,
-	/// The number of runs considered for benchmarking.
-	pub bench: usize,
-	/// The difference in CPU usage between runs considered as normal
-	pub precision: f64,
-	/// The subsystems whose CPU usage is checked during warm-up cycles
-	pub subsystems: &'a [&'a str],
-}
-
-impl<'a> WarmUpOptions<'a> {
-	pub fn new(subsystems: &'a [&'a str]) -> Self {
-		Self { warm_up: 100, bench: 3, precision: 0.02, subsystems }
-	}
-}
-
-pub fn warm_up_and_benchmark(
-	options: WarmUpOptions,
-	run: impl Fn() -> BenchmarkUsage,
-) -> Result<BenchmarkUsage, String> {
-	println!("Warming up...");
-	let mut usages = Vec::with_capacity(options.bench);
-
-	for n in 1..=options.warm_up {
-		let curr = run();
-		if let Some(prev) = usages.last() {
-			let diffs = options
-				.subsystems
-				.iter()
-				.map(|&v| {
-					curr.cpu_usage_diff(prev, v)
-						.ok_or(format!("{} not found in benchmark {:?}", v, prev))
-				})
-				.collect::<Result<Vec<f64>, String>>()?;
-			if !diffs.iter().all(|&v| v < options.precision) {
-				usages.clear();
-			}
-		}
-		usages.push(curr);
-		print!("\r{}%", n * 100 / options.warm_up);
-		if usages.len() == options.bench {
-			println!("\rTook {} runs to warm up", n.saturating_sub(options.bench));
-			break;
-		}
-		stdout().flush().unwrap();
-	}
-
-	if usages.len() != options.bench {
-		println!("Didn't warm up after {} runs", options.warm_up);
-		return Err("Can't warm up".to_string())
+use std::{fs::File, io::Write};
+
+// Saves a given string to a file
+pub fn save_to_file(path: &str, value: String) -> color_eyre::eyre::Result<()> {
+	let output = std::process::Command::new(env!("CARGO"))
+		.arg("locate-project")
+		.arg("--workspace")
+		.arg("--message-format=plain")
+		.output()
+		.unwrap()
+		.stdout;
+	let workspace_dir = std::path::Path::new(std::str::from_utf8(&output).unwrap().trim())
+		.parent()
+		.unwrap();
+	let path = workspace_dir.join(path);
+	if let Some(dir) = path.parent() {
+		std::fs::create_dir_all(dir)?;
 	}
+	let mut file = File::create(path)?;
+	file.write_all(value.as_bytes())?;
 
-	Ok(BenchmarkUsage::average(&usages))
+	Ok(())
 }