Benchmark for read_tls with polled nbio

Cargo.toml

@@ -29,6 +29,7 @@ env_logger = "0.6.1"
 log = "0.4.0"
 tempfile = "3.0"
 webpki-roots = "0.16"
+criterion = "0.2"
 
 [[example]]
 name = "bogo_shim"
@@ -42,3 +43,8 @@ path = "examples/internal/trytls_shim.rs"
 [[example]]
 name = "bench"
 path = "examples/internal/bench.rs"
+
+[[bench]]
+name = "benchmarks"
+path = "tests/benchmarks.rs"
+harness = false

tests/benchmarks.rs

@@ -0,0 +1,26 @@
+/// Microbenchmarks go here.  Larger benchmarks of (eg.) protocol
+/// performance go in examples/internal/bench.rs.
+
+use criterion::Criterion;
+use criterion::criterion_group;
+use criterion::criterion_main;
+
+#[allow(dead_code)]
+mod common;
+use crate::common::*;
+
+use rustls::{Session, ServerSession};
+
+use std::sync::Arc;
+use std::io;
+
+fn bench_ewouldblock(c: &mut Criterion) {
+    let server_config = make_server_config(KeyType::RSA);
+    let mut server = ServerSession::new(&Arc::new(server_config));
+    let mut read_ewouldblock = FailsReads::new(io::ErrorKind::WouldBlock);
+    c.bench_function("read_tls with EWOULDBLOCK",
+                     move |b| b.iter(|| server.read_tls(&mut read_ewouldblock)));
+}
+
+criterion_group!(benches, bench_ewouldblock);
+criterion_main!(benches);

tests/common/mod.rs

@@ -274,3 +274,19 @@ pub fn do_handshake_until_error(client: &mut ClientSession,
 pub fn dns_name(name: &'static str) -> webpki::DNSNameRef<'_> {
     webpki::DNSNameRef::try_from_ascii_str(name).unwrap()
 }
+
+pub struct FailsReads {
+    errkind: io::ErrorKind
+}
+
+impl FailsReads {
+    pub fn new(errkind: io::ErrorKind) -> FailsReads {
+        FailsReads { errkind }
+    }
+}
+
+impl io::Read for FailsReads {
+    fn read(&mut self, _b: &mut [u8]) -> io::Result<usize> {
+        Err(io::Error::from(self.errkind))
+    }
+}