From 686793ae4950768591ba8f58783c92d9415dccbd Mon Sep 17 00:00:00 2001
From: Ben Kimock <kimockb@gmail.com>
Date: Thu, 6 Oct 2022 21:29:44 -0400
Subject: [PATCH] Add a BufReader benchmark for reads smaller than the buffer

---
 collector/runtime-benchmarks/Cargo.lock       | 14 ++++++++
 collector/runtime-benchmarks/Cargo.toml       |  2 +-
 .../runtime-benchmarks/bufreader/Cargo.toml   | 10 ++++++
 .../runtime-benchmarks/bufreader/src/main.rs  | 34 +++++++++++++++++++
 4 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 collector/runtime-benchmarks/bufreader/Cargo.toml
 create mode 100644 collector/runtime-benchmarks/bufreader/src/main.rs

diff --git a/collector/runtime-benchmarks/Cargo.lock b/collector/runtime-benchmarks/Cargo.lock
index cf977603a..3e972a4b5 100644
--- a/collector/runtime-benchmarks/Cargo.lock
+++ b/collector/runtime-benchmarks/Cargo.lock
@@ -64,6 +64,14 @@ version = "1.3.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "bef38d45163c2f1dde094a7dfd33ccf595c92905c8f8f4fdc18d06fb1037718a"
 
+[[package]]
+name = "bufreader"
+version = "0.1.0"
+dependencies = [
+ "benchlib",
+ "snap",
+]
+
 [[package]]
 name = "byteorder"
 version = "1.4.3"
@@ -351,6 +359,12 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "snap"
+version = "1.0.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "45456094d1983e2ee2a18fdfebce3189fa451699d0502cb8e3b49dba5ba41451"
+
 [[package]]
 name = "strsim"
 version = "0.10.0"
diff --git a/collector/runtime-benchmarks/Cargo.toml b/collector/runtime-benchmarks/Cargo.toml
index 5ce6021d7..25ad0d3af 100644
--- a/collector/runtime-benchmarks/Cargo.toml
+++ b/collector/runtime-benchmarks/Cargo.toml
@@ -1,2 +1,2 @@
 [workspace]
-members = ["hashmap"]
+members = ["hashmap", "bufreader"]
diff --git a/collector/runtime-benchmarks/bufreader/Cargo.toml b/collector/runtime-benchmarks/bufreader/Cargo.toml
new file mode 100644
index 000000000..2466a19a4
--- /dev/null
+++ b/collector/runtime-benchmarks/bufreader/Cargo.toml
@@ -0,0 +1,10 @@
+[package]
+name = "bufreader"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+benchlib = { path = "../../benchlib" }
+snap = "1.0.5"
diff --git a/collector/runtime-benchmarks/bufreader/src/main.rs b/collector/runtime-benchmarks/bufreader/src/main.rs
new file mode 100644
index 000000000..7a49591ce
--- /dev/null
+++ b/collector/runtime-benchmarks/bufreader/src/main.rs
@@ -0,0 +1,34 @@
+use benchlib::benchmark::{black_box, BenchmarkSuite};
+use snap::{read::FrameDecoder, write::FrameEncoder};
+use std::io::{BufRead, BufReader, Write};
+
+const BYTES: usize = 64 * 1024 * 1024;
+
+fn main() {
+    let mut suite = BenchmarkSuite::new();
+
+    // Inspired by https://github.com/rust-lang/rust/issues/102727
+    // The pattern we want is a BufReader which wraps a Read impl where one Read::read call will
+    // never fill the whole BufReader buffer.
+    suite.register("bufreader-snappy", || {
+        let data = vec![0u8; BYTES];
+        move || {
+            let mut compressed = Vec::new();
+            FrameEncoder::new(&mut compressed)
+                .write_all(&data[..])
+                .unwrap();
+            let mut reader = BufReader::with_capacity(BYTES, FrameDecoder::new(&compressed[..]));
+
+            while let Ok(buf) = reader.fill_buf() {
+                if buf.is_empty() {
+                    break;
+                }
+                black_box(buf);
+                let len = buf.len();
+                reader.consume(len);
+            }
+        }
+    });
+
+    suite.run().unwrap();
+}