add eager initialization to tokio example

examples/tokio/main.rs

@@ -7,35 +7,42 @@ use wasmtime::{Config, Engine, Linker, Module, Store};
 // when sleeping in `poll_oneoff`.
 use wasmtime_wasi::{tokio::WasiCtxBuilder, WasiCtx};
 
-#[tokio::main]
-async fn main() -> Result<(), Error> {
- // Create an environment shared by all wasm execution. This contains
- // the `Engine` and the `Module` we are executing.
- let env = Environment::new()?;
+fn main() -> Result<(), Error> {
+ tokio::runtime::Builder::new_multi_thread()
+ .enable_all()
+ // Eagerly initialize the thread-local resources used by the engine
+ .on_thread_start(|| Engine::tls_eager_initialize().expect("initialize tls"))
+ .build()
+ .expect("create runtime")
+ .block_on(async {
+ // Create an environment shared by all wasm execution. This contains
+ // the `Engine` and the `Module` we are executing.
+ let env = Environment::new()?;
 
- // The inputs to run_wasm are `Send`: we can create them here and send
- // them to a new task that we spawn.
- let inputs1 = Inputs::new(env.clone(), "Gussie");
- let inputs2 = Inputs::new(env.clone(), "Willa");
- let inputs3 = Inputs::new(env, "Sparky");
+  // The inputs to run_wasm are `Send`: we can create them here and send
+  // them to a new task that we spawn.
+  let inputs1 = Inputs::new(env.clone(), "Gussie");
+  let inputs2 = Inputs::new(env.clone(), "Willa");
+  let inputs3 = Inputs::new(env, "Sparky");
 
- // Spawn some tasks. Insert sleeps before run_wasm so that the
- // interleaving is easy to observe.
- let join1 = tokio::task::spawn(async move { run_wasm(inputs1).await });
- let join2 = tokio::task::spawn(async move {
- tokio::time::sleep(Duration::from_millis(750)).await;
- run_wasm(inputs2).await
- });
- let join3 = tokio::task::spawn(async move {
- tokio::time::sleep(Duration::from_millis(1250)).await;
- run_wasm(inputs3).await
- });
+  // Spawn some tasks. Insert sleeps before run_wasm so that the
+  // interleaving is easy to observe.
+  let join1 = tokio::task::spawn(async move { run_wasm(inputs1).await });
+  let join2 = tokio::task::spawn(async move {
+  tokio::time::sleep(Duration::from_millis(750)).await;
+  run_wasm(inputs2).await
+  });
+  let join3 = tokio::task::spawn(async move {
+  tokio::time::sleep(Duration::from_millis(1250)).await;
+  run_wasm(inputs3).await
+  });
 
- // All tasks should join successfully.
- join1.await??;
- join2.await??;
- join3.await??;
- Ok(())
+ // All tasks should join successfully.
+ join1.await??;
+ join2.await??;
+ join3.await??;
+ Ok(())
+ })
 }
 
 #[derive(Clone)]