Loader: support .wasm imports (#3328)

* loader: support .wasm imports

* http_server: true

* Support named exports

* Clippy

1 files changed, 174 insertions, 0 deletions

diff --git a/cli/compilers/wasm.rs b/cli/compilers/wasm.rs
new file mode 100644
index 000000000..e0a715f84
--- /dev/null
+++ b/cli/compilers/wasm.rs
@@ -0,0 +1,174 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+use crate::compilers::CompiledModule;
+use crate::compilers::CompiledModuleFuture;
+use crate::file_fetcher::SourceFile;
+use crate::global_state::ThreadSafeGlobalState;
+use crate::startup_data;
+use crate::state::*;
+use crate::worker::Worker;
+use deno::Buf;
+use futures::Future;
+use futures::IntoFuture;
+use serde_derive::Deserialize;
+use serde_json;
+use std::collections::HashMap;
+use std::sync::atomic::Ordering;
+use std::sync::{Arc, Mutex};
+use url::Url;
+
+// TODO(kevinkassimo): This is a hack to encode/decode data as base64 string.
+// (Since Deno namespace might not be available, Deno.read can fail).
+// Binary data is already available through source_file.source_code.
+// If this is proven too wasteful in practice, refactor this.
+
+// Ref: https://webassembly.github.io/esm-integration/js-api/index.html#esm-integration
+// https://github.com/nodejs/node/blob/35ec01097b2a397ad0a22aac536fe07514876e21/lib/internal/modules/esm/translators.js#L190-L210
+
+// Dynamically construct JS wrapper with custom static imports and named exports.
+// Boots up an internal worker to resolve imports/exports through query from V8.
+
+static WASM_WRAP: &str = include_str!("./wasm_wrap.js");
+
+#[derive(Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+struct WasmModuleInfo {
+  import_list: Vec<String>,
+  export_list: Vec<String>,
+}
+
+#[derive(Default)]
+pub struct WasmCompiler {
+  cache: Arc<Mutex<HashMap<Url, CompiledModule>>>,
+}
+
+impl WasmCompiler {
+  /// Create a new V8 worker with snapshot of WASM compiler and setup compiler's runtime.
+  fn setup_worker(global_state: ThreadSafeGlobalState) -> Worker {
+    let (int, ext) = ThreadSafeState::create_channels();
+    let worker_state =
+      ThreadSafeState::new(global_state.clone(), None, true, int)
+        .expect("Unable to create worker state");
+
+    // Count how many times we start the compiler worker.
+    global_state
+      .metrics
+      .compiler_starts
+      .fetch_add(1, Ordering::SeqCst);
+
+    let mut worker = Worker::new(
+      "WASM".to_string(),
+      startup_data::compiler_isolate_init(),
+      worker_state,
+      ext,
+    );
+    worker.execute("denoMain('WASM')").unwrap();
+    worker.execute("workerMain()").unwrap();
+    worker.execute("wasmCompilerMain()").unwrap();
+    worker
+  }
+
+  pub fn compile_async(
+    self: &Self,
+    global_state: ThreadSafeGlobalState,
+    source_file: &SourceFile,
+  ) -> Box<CompiledModuleFuture> {
+    let cache = self.cache.clone();
+    let maybe_cached = { cache.lock().unwrap().get(&source_file.url).cloned() };
+    if let Some(m) = maybe_cached {
+      return Box::new(futures::future::ok(m.clone()));
+    }
+    let cache_ = self.cache.clone();
+
+    debug!(">>>>> wasm_compile_async START");
+    let base64_data = base64::encode(&source_file.source_code);
+    let worker = WasmCompiler::setup_worker(global_state.clone());
+    let worker_ = worker.clone();
+    let url = source_file.url.clone();
+
+    let fut = worker
+      .post_message(
+        serde_json::to_string(&base64_data)
+          .unwrap()
+          .into_boxed_str()
+          .into_boxed_bytes(),
+      )
+      .into_future()
+      .then(move |_| worker)
+      .then(move |result| {
+        if let Err(err) = result {
+          // TODO(ry) Need to forward the error instead of exiting.
+          eprintln!("{}", err.to_string());
+          std::process::exit(1);
+        }
+        debug!("Sent message to worker");
+        worker_.get_message()
+      })
+      .map_err(|_| panic!("not handled"))
+      .and_then(move |maybe_msg: Option<Buf>| {
+        debug!("Received message from worker");
+        let json_msg = maybe_msg.unwrap();
+        let module_info: WasmModuleInfo =
+          serde_json::from_slice(&json_msg).unwrap();
+        debug!("WASM module info: {:#?}", &module_info);
+        let code = wrap_wasm_code(
+          &base64_data,
+          &module_info.import_list,
+          &module_info.export_list,
+        );
+        debug!("Generated code: {}", &code);
+        let module = CompiledModule {
+          code,
+          name: url.to_string(),
+        };
+        {
+          cache_.lock().unwrap().insert(url.clone(), module.clone());
+        }
+        debug!("<<<<< wasm_compile_async END");
+        Ok(module)
+      });
+    Box::new(fut)
+  }
+}
+
+fn build_single_import(index: usize, origin: &str) -> String {
+  let origin_json = serde_json::to_string(origin).unwrap();
+  format!(
+    r#"import * as m{} from {};
+importObject[{}] = m{};
+"#,
+    index, &origin_json, &origin_json, index
+  )
+}
+
+fn build_imports(imports: &[String]) -> String {
+  let mut code = String::from("");
+  for (index, origin) in imports.iter().enumerate() {
+    code.push_str(&build_single_import(index, origin));
+  }
+  code
+}
+
+fn build_single_export(name: &str) -> String {
+  format!("export const {} = instance.exports.{};\n", name, name)
+}
+
+fn build_exports(exports: &[String]) -> String {
+  let mut code = String::from("");
+  for e in exports {
+    code.push_str(&build_single_export(e));
+  }
+  code
+}
+
+fn wrap_wasm_code(
+  base64_data: &str,
+  imports: &[String],
+  exports: &[String],
+) -> String {
+  let imports_code = build_imports(imports);
+  let exports_code = build_exports(exports);
+  String::from(WASM_WRAP)
+    .replace("//IMPORTS\n", &imports_code)
+    .replace("//EXPORTS\n", &exports_code)
+    .replace("BASE64_DATA", base64_data)
+}