From 8fce2563c4ab884da66bcb3b031d512a6c1cfad5 Mon Sep 17 00:00:00 2001
From: Linwei Shang <linwei.shang@dfinity.org>
Date: Fri, 27 Oct 2023 16:38:13 -0400
Subject: [PATCH] async_trait

---
 Cargo.lock             | 19 +++++++++++++++++
 Cargo.toml             |  2 +-
 async_trait/Cargo.toml | 13 ++++++++++++
 async_trait/src/lib.rs | 46 ++++++++++++++++++++++++++++++++++++++++++
 build.sh               |  8 --------
 dfx.json               |  7 +++++++
 6 files changed, 86 insertions(+), 9 deletions(-)
 create mode 100644 async_trait/Cargo.toml
 create mode 100644 async_trait/src/lib.rs

diff --git a/Cargo.lock b/Cargo.lock
index 4602e17..479070e 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -14,6 +14,25 @@ version = "0.5.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "23b62fc65de8e4e7f52534fb52b0f3ed04746ae267519eef2a83941e8085068b"
 
+[[package]]
+name = "async-trait"
+version = "0.1.74"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a66537f1bb974b254c98ed142ff995236e81b9d0fe4db0575f46612cb15eb0f9"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.38",
+]
+
+[[package]]
+name = "async_trait"
+version = "0.1.0"
+dependencies = [
+ "async-trait",
+ "ic-cdk",
+]
+
 [[package]]
 name = "autocfg"
 version = "1.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index 1911c72..e397ba5 100644
--- a/Cargo.toml
+++ b/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]
diff --git a/async_trait/Cargo.toml b/async_trait/Cargo.toml
new file mode 100644
index 0000000..41a6398
--- /dev/null
+++ b/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"]
diff --git a/async_trait/src/lib.rs b/async_trait/src/lib.rs
new file mode 100644
index 0000000..1206361
--- /dev/null
+++ b/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()
+    }
+}
diff --git a/build.sh b/build.sh
index b3b4d1d..81d32ed 100644
--- a/build.sh
+++ b/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
diff --git a/dfx.json b/dfx.json
index b4f814d..6027d4c 100644
--- a/dfx.json
+++ b/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
         }
     }
 }
\ No newline at end of file