Benchmark the HTTP hosts against axum

A C load generator, an axum service with the same document contract (in
memory, fdatasync, and crash-safe replacement), and a runner that pins the
servers and the load to separate CPUs. On the Pi 5, Pure uses about 40%
less memory, wins with a new connection per request and with eight durable
writers (3.2x the crash-safe axum), but loses 5x on keep-alive reads and
1.5x on 64 durable writers: no persistent connections, one thread, eight
connection slots and two fsyncs per commit. Note 075 records the numbers
and the targets.

3 files changed, 694 insertions, 0 deletions

diff --git a/benchmarks/http/axum-baseline/Cargo.lock b/benchmarks/http/axum-baseline/Cargo.lock
new file mode 100644
index 0000000..a3a7869
--- /dev/null
+++ b/benchmarks/http/axum-baseline/Cargo.lock
@@ -0,0 +1,518 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 4
+
+[[package]]
+name = "atomic-waker"
+version = "1.1.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1505bd5d3d116872e7271a6d4e16d81d0c8570876c8de68093a09ac269d8aac0"
+
+[[package]]
+name = "axum"
+version = "0.8.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "31b698c5f9a010f6573133b09e0de5408834d0c82f8d7475a89fc1867a71cd90"
+dependencies = [
+ "axum-core",
+ "bytes",
+ "form_urlencoded",
+ "futures-util",
+ "http",
+ "http-body",
+ "http-body-util",
+ "hyper",
+ "hyper-util",
+ "itoa",
+ "matchit",
+ "memchr",
+ "mime",
+ "percent-encoding",
+ "pin-project-lite",
+ "serde_core",
+ "serde_json",
+ "serde_path_to_error",
+ "serde_urlencoded",
+ "sync_wrapper",
+ "tokio",
+ "tower",
+ "tower-layer",
+ "tower-service",
+ "tracing",
+]
+
+[[package]]
+name = "axum-baseline"
+version = "0.1.0"
+dependencies = [
+ "axum",
+ "bytes",
+ "tokio",
+]
+
+[[package]]
+name = "axum-core"
+version = "0.5.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "08c78f31d7b1291f7ee735c1c6780ccde7785daae9a9206026862dab7d8792d1"
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+ "bytes",
+ "futures-core",
+ "http",
+ "http-body",
+ "http-body-util",
+ "mime",
+ "pin-project-lite",
+ "sync_wrapper",
+ "tower-layer",
+ "tower-service",
+ "tracing",
+]
+
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+
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+dependencies = [
+ "libc",
+ "windows-sys",
+]
+
+[[package]]
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+[[package]]
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+
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+dependencies = [
+ "bytes",
+ "itoa",
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+[[package]]
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+ "futures-core",
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diff --git a/benchmarks/http/axum-baseline/Cargo.toml b/benchmarks/http/axum-baseline/Cargo.toml
new file mode 100644
index 0000000..1a26451
--- /dev/null
+++ b/benchmarks/http/axum-baseline/Cargo.toml
@@ -0,0 +1,17 @@
+[package]
+name = "axum-baseline"
+version = "0.1.0"
+edition = "2021"
+publish = false
+
+# A reference service for Pure's HTTP benchmarks: the same document contract
+# as Pure's document server, written the way an axum service usually is.
+[dependencies]
+axum = "0.8"
+tokio = { version = "1", features = ["rt-multi-thread", "macros", "net", "fs", "sync", "signal"] }
+bytes = "1"
+
+[profile.release]
+lto = "fat"
+codegen-units = 1
+panic = "abort"
diff --git a/benchmarks/http/axum-baseline/src/main.rs b/benchmarks/http/axum-baseline/src/main.rs
new file mode 100644
index 0000000..6684bfc
--- /dev/null
+++ b/benchmarks/http/axum-baseline/src/main.rs
@@ -0,0 +1,159 @@
+//! Reference service for Pure's HTTP benchmarks: the same contract as Pure's
+//! document server (GET/PUT /objects/{key}, If-Match / If-None-Match: *,
+//! a PUT body of u32le start, u32le remove, then the bytes to insert; the
+//! reply is the inserted bytes; ETag is the revision).
+//!
+//! axum-baseline --port P [--durable DIR | --atomic DIR]
+//! Without either, documents live in memory. --durable writes the document to
+//! DIR/key and fdatasyncs before answering, as a straightforward durable
+//! handler would (not crash-safe: a crash after truncation loses it).
+//! --atomic writes DIR/key.tmp, fsyncs it, renames it over DIR/key and fsyncs
+//! the directory: the usual crash-safe replacement.
+use axum::{
+    body::Bytes,
+    extract::{Path, State},
+    http::{HeaderMap, HeaderValue, StatusCode},
+    response::{IntoResponse, Response},
+    routing::get,
+    Router,
+};
+use std::{collections::HashMap, path::PathBuf, sync::Arc};
+use tokio::sync::Mutex;
+
+#[derive(Default)]
+struct Document {
+    bytes: Vec<u8>,
+    revision: u64,
+}
+
+struct Service {
+    documents: Mutex<HashMap<String, Arc<Mutex<Document>>>>,
+    durable: Option<PathBuf>,
+    atomic: bool,
+}
+
+fn valid_key(key: &str) -> bool {
+    !key.is_empty()
+        && key.len() <= 64
+        && key.bytes().all(|b| b.is_ascii_alphanumeric() || b == b'-' || b == b'_')
+}
+
+fn tagged(status: StatusCode, revision: u64, error: &'static str, body: Bytes) -> Response {
+    let mut response = (status, body).into_response();
+    let headers = response.headers_mut();
+    headers.insert("X-Pure-Error", HeaderValue::from_static(error));
+    if revision > 0 {
+        headers.insert("ETag", HeaderValue::from_str(&format!("\"{revision}\"")).unwrap());
+    }
+    response
+}
+
+async fn document(service: &Service, key: &str) -> Arc<Mutex<Document>> {
+    let mut documents = service.documents.lock().await;
+    documents.entry(key.to_string()).or_default().clone()
+}
+
+async fn show(State(service): State<Arc<Service>>, Path(key): Path<String>) -> Response {
+    if !valid_key(&key) {
+        return tagged(StatusCode::BAD_REQUEST, 0, "request", Bytes::new());
+    }
+    let document = document(&service, &key).await;
+    let document = document.lock().await;
+    if document.revision == 0 {
+        return tagged(StatusCode::NOT_FOUND, 0, "not_found", Bytes::new());
+    }
+    tagged(StatusCode::OK, document.revision, "none", Bytes::copy_from_slice(&document.bytes))
+}
+
+async fn edit(
+    State(service): State<Arc<Service>>,
+    Path(key): Path<String>,
+    headers: HeaderMap,
+    body: Bytes,
+) -> Response {
+    let expected = match (headers.get("if-match"), headers.get("if-none-match")) {
+        (Some(tag), None) => tag
+            .to_str()
+            .ok()
+            .and_then(|t| t.strip_prefix('"')?.strip_suffix('"')?.parse::<u64>().ok()),
+        (None, Some(star)) if star == "*" => Some(0),
+        _ => None,
+    };
+    let Some(expected) = expected.filter(|_| valid_key(&key) && body.len() >= 8) else {
+        return tagged(StatusCode::BAD_REQUEST, 0, "request", Bytes::new());
+    };
+    let start = u32::from_le_bytes(body[0..4].try_into().unwrap()) as usize;
+    let remove = u32::from_le_bytes(body[4..8].try_into().unwrap()) as usize;
+    let document = document(&service, &key).await;
+    let mut document = document.lock().await;
+    if document.revision != expected {
+        return tagged(StatusCode::PRECONDITION_FAILED, document.revision, "conflict", Bytes::new());
+    }
+    if start > document.bytes.len() || remove > document.bytes.len() - start {
+        return tagged(StatusCode::PAYLOAD_TOO_LARGE, 0, "limit", Bytes::new());
+    }
+    let insert = body.slice(8..);
+    document.bytes.splice(start..start + remove, insert.iter().copied());
+    if let Some(directory) = &service.durable {
+        let (directory, path, atomic) = (directory.clone(), directory.join(&key), service.atomic);
+        let bytes = document.bytes.clone();
+        let written = tokio::task::spawn_blocking(move || -> std::io::Result<()> {
+            use std::io::Write;
+            if !atomic {
+                let mut file = std::fs::File::create(path)?;
+                file.write_all(&bytes)?;
+                return file.sync_data();
+            }
+            let temporary = path.with_extension("tmp");
+            let mut file = std::fs::File::create(&temporary)?;
+            file.write_all(&bytes)?;
+            file.sync_all()?;
+            std::fs::rename(&temporary, &path)?;
+            std::fs::File::open(&directory)?.sync_all()
+        })
+        .await;
+        if !matches!(written, Ok(Ok(()))) {
+            return tagged(StatusCode::INTERNAL_SERVER_ERROR, 0, "storage", Bytes::new());
+        }
+    }
+    document.revision += 1;
+    tagged(StatusCode::OK, document.revision, "none", insert)
+}
+
+#[tokio::main]
+async fn main() {
+    let arguments: Vec<String> = std::env::args().collect();
+    let mut port = 8768u16;
+    let mut durable = None;
+    let mut atomic = false;
+    let mut at = 1;
+    while at + 1 < arguments.len() {
+        match arguments[at].as_str() {
+            "--port" => port = arguments[at + 1].parse().expect("port"),
+            "--durable" => durable = Some(PathBuf::from(&arguments[at + 1])),
+            "--atomic" => {
+                durable = Some(PathBuf::from(&arguments[at + 1]));
+                atomic = true;
+            }
+            other => panic!("unknown argument {other}"),
+        }
+        at += 2;
+    }
+    if let Some(directory) = &durable {
+        std::fs::create_dir_all(directory).expect("durable directory");
+    }
+    let service = Arc::new(Service { documents: Mutex::new(HashMap::new()), durable, atomic });
+    let app = Router::new()
+        .route("/objects/{key}", get(show).put(edit))
+        .with_state(service);
+    let listener = tokio::net::TcpListener::bind(("127.0.0.1", port)).await.expect("bind");
+    println!("{{\"port\":{}}}", listener.local_addr().unwrap().port());
+    use std::io::Write;
+    std::io::stdout().flush().unwrap();
+    axum::serve(listener, app)
+        .with_graceful_shutdown(async {
+            tokio::signal::ctrl_c().await.ok();
+        })
+        .await
+        .unwrap();
+}