async_trait

Cargo.toml

@@ -1,5 +1,5 @@
 [workspace]
-members = ["unit_struct", "build_script", "stateful"]
+members = ["unit_struct", "build_script", "stateful", "async_trait"]
 resolver = "2"
 
 [workspace.dependencies]

async_trait/Cargo.toml

@@ -0,0 +1,13 @@
+[package]
+name = "async_trait"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+ic-cdk.workspace = true
+async-trait = "0.1"
+
+[lib]
+crate-type = ["cdylib"]

async_trait/src/lib.rs

@@ -0,0 +1,46 @@
+// ic_cdk::generate!({path: "../../counter.did", service : Canister, trait: Counter});
+
+// Expand Start
+#[async_trait::async_trait]
+trait Counter {
+    async fn inc();
+    async fn read() -> u64;
+}
+
+#[export_name = "canister_update inc"]
+fn __canister_method_inc() {
+    ic_cdk::setup();
+    ic_cdk::spawn(async {
+        let _result = Canister::inc().await;
+        ic_cdk::api::call::reply(())
+    });
+}
+
+#[export_name = "canister_query read"]
+fn __canister_method_read() {
+    ic_cdk::setup();
+    ic_cdk::spawn(async {
+        let result = Canister::read().await;
+        ic_cdk::api::call::reply((result,))
+    });
+}
+// Expand End
+
+use std::cell::Cell;
+
+thread_local! {
+    static COUNTER: Cell<u64> = Cell::new(0);
+}
+
+struct Canister;
+
+#[async_trait::async_trait]
+impl Counter for Canister {
+    async fn inc() {
+        COUNTER.set(COUNTER.get() + 1);
+    }
+
+    async fn read() -> u64 {
+        COUNTER.get()
+    }
+}

build.sh

@@ -4,11 +4,3 @@ set -e
 cargo build --target wasm32-unknown-unknown \
     --release \
     --package "$1"
-
-# ic-wasm "$example_root/target/wasm32-unknown-unknown/release/$package.wasm" \
-#     -o "$example_root/target/wasm32-unknown-unknown/release/$package.wasm" \
-#     metadata candid:service -v public -f $did_file
-
-# ic-wasm "$example_root/target/wasm32-unknown-unknown/release/$package.wasm" \
-#     -o "$example_root/target/wasm32-unknown-unknown/release/$package-opt.wasm" \
-#     shrink

dfx.json

@@ -20,6 +20,13 @@
             "candid": "counter.did",
             "wasm": "target/wasm32-unknown-unknown/release/stateful.wasm",
             "shrink": true
+        },
+        "async_trait": {
+            "type": "custom",
+            "build": "sh build.sh async_trait",
+            "candid": "counter.did",
+            "wasm": "target/wasm32-unknown-unknown/release/async_trait.wasm",
+            "shrink": true
         }
     }
 }