Wasm threading (#2517)

* Add threading on the Web

Use the `wasm_thread` library to enable real `spawn_blocking` on the
Web in `linera_base::task`.

Author: Twey

Cargo.lock

@@ -159,6 +159,7 @@ wasm-bindgen-futures = "0.4.42"
 wasm-bindgen-test = "0.3.42"
 wasm-encoder = "0.24.1"
 wasm-instrument = "0.4.0"
+wasm_thread = "0.3.0"
 wasmer = { package = "linera-wasmer", version = "4.3.6-linera.3", default-features = false }
 wasmer-compiler-singlepass = { package = "linera-wasmer-compiler-singlepass", version = "4.3.6-linera.3" }
 wasmparser = "0.101.1"

Cargo.toml

@@ -23,6 +23,7 @@ web = [
     "tracing-web",
     "wasmtimer",
     "wasm-bindgen-futures",
+    "wasm_thread",
     "web-time",
 ]
 
@@ -57,6 +58,7 @@ tokio = { workspace = true, features = ["time"] }
 tracing.workspace = true
 tracing-subscriber = { workspace = true, features = ["json", "fmt", "ansi"] }
 wasm-bindgen-futures = { workspace = true, optional = true }
+wasm_thread = { workspace = true, optional = true }
 wasmtimer = { workspace = true, optional = true }
 web-time = { workspace = true, optional = true }
 

examples/Cargo.lock

@@ -46,7 +46,7 @@ mod implementation {
     /// The type of a future awaiting another thread.
     pub type BlockingFuture<R> = oneshot::Receiver<R>;
 
-    /// Spawns a new task, potentially on the current thread.
+    /// Spawns a new task on the current thread.
     pub fn spawn<F: Future + 'static>(future: F) -> NonblockingFuture<F::Output> {
         let (send, recv) = oneshot::channel();
         wasm_bindgen_futures::spawn_local(async {
@@ -55,12 +55,15 @@ mod implementation {
         recv
     }
 
-    /// Spawns a blocking task on the same thread (!).
-    /// TODO(#2399): replace this by a Web worker.
+    /// Spawns a blocking task on a new Web Worker.
     pub fn spawn_blocking<R: Send + 'static, F: FnOnce() -> R + Send + 'static>(
         task: F,
     ) -> BlockingFuture<R> {
-        spawn(async { task() })
+        let (send, recv) = oneshot::channel();
+        wasm_thread::spawn(move || {
+            let _ = send.send(task());
+        });
+        recv
     }
 }
 

linera-base/Cargo.toml

@@ -68,7 +68,7 @@ wasmer = { workspace = true, optional = true, features = ["sys-default", "single
 
 [target.'cfg(target_arch = "wasm32")'.dependencies]
 tokio = { workspace = true, features = ["rt"] }
-wasmer = { workspace = true, optional = true, features = ["js-default"] }
+wasmer = { workspace = true, optional = true, features = ["js-default", "js-serializable-module"] }
 
 [dev-dependencies]
 anyhow.workspace = true

linera-base/src/task.rs

@@ -12,13 +12,7 @@ repository.workspace = true
 version.workspace = true
 
 [features]
-test = [
-    "tokio/rt",
-    "tokio/test-util",
-    "tokio/time",
-    "linera-execution/test",
-    "linera-views/test",
-]
+test = ["linera-execution/test", "linera-views/test"]
 wasmer = ["linera-execution/wasmer"]
 wasmtime = ["linera-execution/wasmtime"]
 metrics = [
@@ -45,7 +39,6 @@ linera-execution.workspace = true
 linera-views.workspace = true
 prometheus.workspace = true
 serde.workspace = true
-tokio = { workspace = true, features = ["macros"] }
 
 [dev-dependencies]
 anyhow.workspace = true

linera-execution/Cargo.toml

@@ -5,7 +5,7 @@ fn main() {
     cfg_aliases::cfg_aliases! {
         with_testing: { any(test, feature = "test") },
         with_metrics: { all(not(target_arch = "wasm32"), feature = "metrics") },
-        with_wasmer: { all(not(target_arch = "wasm32"), feature = "wasmer") },
+        with_wasmer: { all(any(feature = "web", not(target_arch = "wasm32")), feature = "wasmer") },
         with_wasmtime: { all(not(target_arch = "wasm32"), feature = "wasmtime") },
         with_wasm_runtime: { any(with_wasmer, with_wasmtime) },
     };

linera-storage/Cargo.toml

@@ -193,7 +193,7 @@ pub trait Storage: Sized {
         let mut tasks = Vec::new();
         for key in keys {
             let client = self.clone();
-            tasks.push(tokio::task::spawn(async move {
+            tasks.push(linera_base::task::spawn(async move {
                 client.read_certificate(key).await
             }));
         }
@@ -295,7 +295,7 @@ pub trait Storage: Sized {
             .into_inner_contract_bytecode()
             .expect("Contract Bytecode Blob is of the wrong Blob type!");
         let contract_bytecode =
-            tokio::task::spawn_blocking(move || compressed_contract_bytecode.decompress())
+            linera_base::task::spawn_blocking(move || compressed_contract_bytecode.decompress())
                 .await??;
         Ok(Arc::new(
             WasmContractModule::new(contract_bytecode, wasm_runtime).await?,
@@ -333,7 +333,8 @@ pub trait Storage: Sized {
             .into_inner_service_bytecode()
             .expect("Service Bytecode Blob is of the wrong Blob type!");
         let service_bytecode =
-            tokio::task::spawn_blocking(move || compressed_service_bytecode.decompress()).await??;
+            linera_base::task::spawn_blocking(move || compressed_service_bytecode.decompress())
+                .await??;
         Ok(Arc::new(
             WasmServiceModule::new(service_bytecode, wasm_runtime).await?,
         ))