[r2r_rcl] More advanced binding generation

- Add "save-bindgen" to save generated bindings file to source
  directory.
- Cache generated bindings file to speed up bindgen process.
- Add "docs-only" feature to disable linking and bindgen on docs.rs.

r2r_rcl/Cargo.toml

@@ -17,3 +17,10 @@ widestring = "1.0.2"
 [build-dependencies]
 bindgen = "0.63.0"
 r2r_common = { path = "../r2r_common", version = "0.3.2" }
+
+[features]
+save-bindgen = []
+doc-only = []
+
+[package.metadata.docs.rs]
+features = ["doc-only"]

r2r_rcl/build.rs

@@ -1,22 +1,83 @@
 use std::env;
+use std::fs;
+use std::fs::OpenOptions;
+use std::path::Path;
 use std::path::PathBuf;
 
 fn main() {
     r2r_common::print_cargo_watches();
-    r2r_common::print_cargo_link_search();
+    run_bindgen();
+    run_dynlink();
+}
 
-    let mut builder = r2r_common::setup_bindgen_builder();
-    builder = builder.header("src/rcl_wrapper.h");
+fn run_bindgen() {
+    let env_hash = r2r_common::get_env_hash();
+    let out_dir: PathBuf = env::var_os("OUT_DIR").unwrap().into();
+    let manifest_dir = Path::new(env!("CARGO_MANIFEST_DIR"));
+    let bindgen_dir = out_dir.join(env_hash);
+    let cached_file = bindgen_dir.join("rcl_bindings.rs");
+    let mark_file = bindgen_dir.join("done");
+    let target_file = out_dir.join("rcl_bindings.rs");
+    let saved_file = manifest_dir.join("bindings").join("rcl_bindings.rs");
 
-    println!("cargo:rustc-link-lib=dylib=rcl");
-    println!("cargo:rustc-link-lib=dylib=rcl_logging_spdlog");
-    println!("cargo:rustc-link-lib=dylib=rcl_yaml_param_parser");
-    println!("cargo:rustc-link-lib=dylib=rcutils");
-    println!("cargo:rustc-link-lib=dylib=rmw");
-    println!("cargo:rustc-link-lib=dylib=rosidl_typesupport_c");
-    println!("cargo:rustc-link-lib=dylib=rosidl_runtime_c");
+    // Use saved bindings file if "docs-only" feature is enabled.
+    let src_file = if cfg!(feature = "doc-only") {
+        &saved_file
+    } else {
+        // Generate bindings if bindings file does not
+        // exist. Otherwise, use cached bindings file.
+        if !mark_file.exists() {
+            eprintln!("Generate bindings file '{}'", cached_file.display());
+            gen_bindings(&cached_file);
+            touch(&mark_file);
+        } else {
+            eprintln!("Use cached bindings file '{}'", cached_file.display());
+        }
 
-    let bindings = builder
+        #[cfg(feature = "save-bindgen")]
+        {
+            if let Some(dir) = saved_file.parent() {
+                fs::create_dir_all(dir)
+                    .unwrap_or_else(|_| panic!("Unable to create directory '{}'", dir.display()));
+            }
+            fs::copy(&cached_file, &saved_file).expect("File copy failed");
+        }
+
+        &cached_file
+    };
+
+    fs::copy(src_file, &target_file).unwrap_or_else(|_| {
+        panic!(
+            "Unable to copy from '{}' to '{}'",
+            src_file.display(),
+            target_file.display()
+        )
+    });
+}
+
+fn run_dynlink() {
+    // Run dynamic linking if (1) "docs-only" feature is disabled.
+    #[cfg(not(feature = "doc-only"))]
+    {
+        r2r_common::print_cargo_link_search();
+        println!("cargo:rustc-link-lib=dylib=rcl");
+        println!("cargo:rustc-link-lib=dylib=rcl_logging_spdlog");
+        println!("cargo:rustc-link-lib=dylib=rcl_yaml_param_parser");
+        println!("cargo:rustc-link-lib=dylib=rcutils");
+        println!("cargo:rustc-link-lib=dylib=rmw");
+        println!("cargo:rustc-link-lib=dylib=rosidl_typesupport_c");
+        println!("cargo:rustc-link-lib=dylib=rosidl_runtime_c");
+    }
+}
+
+fn gen_bindings(out_file: &Path) {
+    if let Some(dir) = out_file.parent() {
+        fs::create_dir_all(dir)
+            .unwrap_or_else(|_| panic!("Unable to create directory '{}'", dir.display()));
+    }
+
+    let bindings = r2r_common::setup_bindgen_builder()
+        .header("src/rcl_wrapper.h")
         .allowlist_type("rcl_.*")
         .allowlist_type("rcutils_.*")
         .allowlist_type("rmw_.*")
@@ -25,6 +86,7 @@ fn main() {
         .allowlist_var("RCUTILS_.*")
         .allowlist_var("RMW_.*")
         .allowlist_var("rosidl_.*")
+        .allowlist_var("g_rcutils_.*")
         .allowlist_function("rcl_.*")
         .allowlist_function("rcutils_.*")
         .allowlist_function("rmw_.*")
@@ -38,8 +100,15 @@ fn main() {
         .generate()
         .expect("Unable to generate bindings");
 
-    let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
     bindings
-        .write_to_file(out_path.join("rcl_bindings.rs"))
+        .write_to_file(out_file)
         .expect("Couldn't write bindings!");
 }
+
+fn touch(path: &Path) {
+    OpenOptions::new()
+        .create(true)
+        .write(true)
+        .open(path)
+        .unwrap_or_else(|_| panic!("Unable to create file '{}'", path.display()));
+}