Add native support for regex benchmark (#266)

* Add native support for regex benchmark

* Remove comments in Dockerfile.native for regex

benchmarks/regex/.gitignore

@@ -0,0 +1 @@
+/rust-benchmark-native/

benchmarks/regex/Dockerfile.native

@@ -0,0 +1,17 @@
+FROM rust:1.70
+
+# Copy in the `src` directory.
+ENV SRC=/usr/src/regex/
+WORKDIR $SRC
+ADD rust-benchmark rust-benchmark
+COPY sightglass.native.patch ./
+COPY build-native.sh .
+COPY libengine.so /usr/lib/
+
+# Compile each of the benchmarks into the `/benchmark` directory.
+RUN ./build-native.sh
+
+# We copy the shared libraries to the `/benchmark` directory, where the client
+# expects it.
+WORKDIR /benchmark
+RUN cp $SRC/*so .

benchmarks/regex/build-native.sh

@@ -0,0 +1,13 @@
+#!/usr/bin/env bash
+
+# Build regex benchmark as native shared libraries (Linux-only).
+#
+# Usage: ./build-native.sh
+
+(set -x;)
+(rm -rf rust-benchmark-native);
+(cp -r rust-benchmark rust-benchmark-native/);
+(cp sightglass.native.patch rust-benchmark-native/);
+(cd rust-benchmark-native; patch -Np1 -i ./sightglass.native.patch; cd -);
+(cd rust-benchmark-native; cargo build --release; cp target/release/libbenchmark.so ../benchmark.so; cd -);
+(set +x;)

benchmarks/regex/sightglass.native.patch

@@ -0,0 +1,59 @@
+diff --git a/Cargo.toml b/Cargo.toml
+index ee59a1c..dbeccb7 100644
+--- a/Cargo.toml
++++ b/Cargo.toml
+@@ -8,3 +8,6 @@ regex = "1.7.1"
+ sightglass-api = "0.1"
+
+ [workspace]
++
++[lib]
++crate-type = ["cdylib"]
+\ No newline at end of file
+diff --git a/build.rs b/build.rs
+new file mode 100644
+index 0000000..6d7d743
+--- /dev/null
++++ b/build.rs
+@@ -0,0 +1,3 @@
++fn main() {
++    println!("cargo:rustc-cdylib-link-arg=-L../../../engines/native/");
++}
+diff --git a/src/main.rs b/src/lib.rs
+similarity index 84%
+rename from src/main.rs
+rename to src/lib.rs
+index a1ef2f8..0bf007d 100644
+--- a/src/main.rs
++++ b/src/lib.rs
+@@ -13,16 +13,27 @@ const URI_PATTERN: &str = r"[\w]+://[^/\s?#]+[^\s?#]+(?:\?[^\s#]*)?(?:#[^\s]*)?"
+ const IP_PATTERN: &str =
+     r"(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9])\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9])";
+
+-fn main() {
++#[link(name = "engine")]
++extern "C" {
++    fn bench_start() -> ();
++    fn bench_end() -> ();
++}
++
++#[no_mangle]
++pub extern "C" fn native_entry() {
+     let path = "default.input";
+     eprintln!("[regex] matching {}", path);
+     let data = std::fs::read_to_string(path).expect("unable to find `*.input` text file");
+
+-    bench::start();
++    unsafe {
++        bench_start();
++    }
+     let emails = count_matches(&data, EMAIL_PATTERN);
+     let uris = count_matches(&data, URI_PATTERN);
+     let ips = count_matches(&data, IP_PATTERN);
+-    bench::end();
++    unsafe {
++        bench_end();
++    }
+
+     eprintln!("[regex] found {} emails", emails);
+     eprintln!("[regex] found {} URIs", uris);