intorduce macros for wasm function search and call

examples/ipfs_node/src/node/imports.rs

@@ -14,7 +14,8 @@
  * limitations under the License.
  */
 
-use super::utils::get_export_func_by_name;
+use crate::init_wasm_func_once;
+use crate::call_wasm_func;
 
 use wasmer_core::vm::Ctx;
 use wasmer_core::typed_func::DynamicFunc;
@@ -54,6 +55,7 @@ where
     use wasmer_core::Func;
     use std::cell::RefCell;
 
+    //#[rustfmt:skip]
     let allocate_func: Box<RefCell<Option<Func<'static, i32, i32>>>> = Box::new(RefCell::new(None));
     let set_result_ptr_func: Box<RefCell<Option<Func<'static, i32, ()>>>> =
         Box::new(RefCell::new(None));
@@ -75,65 +77,14 @@ where
         };
 
         unsafe {
-            if allocate_func.borrow().is_none() {
+            init_wasm_func_once!(allocate_func, ctx, i32, i32, ALLOCATE_FUNC_NAME, 4);
-                let raw_allocate_func =
+            init_wasm_func_once!(set_result_ptr_func, ctx, i32, (), SET_PTR_FUNC_NAME, 5);
-                    match get_export_func_by_name::<i32, i32>(ctx, ALLOCATE_FUNC_NAME) {
+            init_wasm_func_once!(set_result_size_func, ctx, i32, (), SET_SIZE_FUNC_NAME, 6);
-                        Ok(func) => func,
-                        Err(_) => return vec![Value::I32(4)],
-                    };
 
-                let raw_allocate_func =
+            let mem_address = call_wasm_func!(allocate_func, result.len() as i32);
-                    std::mem::transmute::<Func<'_, _, _>, Func<'static, _, _>>(raw_allocate_func);
-                *allocate_func.borrow_mut() = Some(raw_allocate_func);
-            }
-
-            if set_result_ptr_func.borrow().is_none() {
-                let raw_set_result_ptr_func =
-                    match get_export_func_by_name::<i32, ()>(ctx, SET_PTR_FUNC_NAME) {
-                        Ok(func) => func,
-                        Err(_) => return vec![Value::I32(5)],
-                    };
-
-                let raw_set_result_ptr_func = std::mem::transmute::<
-                    Func<'_, _, _>,
-                    Func<'static, _, _>,
-                >(raw_set_result_ptr_func);
-                *set_result_ptr_func.borrow_mut() = Some(raw_set_result_ptr_func);
-            }
-
-            if set_result_size_func.borrow().is_none() {
-                let raw_set_result_size_func =
-                    match get_export_func_by_name::<i32, ()>(ctx, SET_SIZE_FUNC_NAME) {
-                        Ok(func) => func,
-                        Err(_) => return vec![Value::I32(6)],
-                    };
-
-                let raw_set_result_size_func = std::mem::transmute::<
-                    Func<'_, _, _>,
-                    Func<'static, _, _>,
-                >(raw_set_result_size_func);
-                *set_result_size_func.borrow_mut() = Some(raw_set_result_size_func);
-            }
-
-            let mem_address = allocate_func
-                .borrow()
-                .as_ref()
-                .unwrap()
-                .call(result.len() as i32)
-                .unwrap();
             write_to_mem(ctx, mem_address as usize, result.as_bytes());
-            set_result_ptr_func
+            call_wasm_func!(set_result_ptr_func, mem_address);
-                .borrow()
+            call_wasm_func!(set_result_size_func, result.len() as i32);
-                .as_ref()
-                .unwrap()
-                .call(mem_address as i32)
-                .unwrap();
-            set_result_size_func
-                .borrow()
-                .as_ref()
-                .unwrap()
-                .call(result.len() as i32)
-                .unwrap();
 
             vec![Value::I32(0)]
         }

examples/ipfs_node/src/node/utils.rs

@@ -32,6 +32,7 @@ use wasmer_core::module::ExportIndex;
 use std::path::PathBuf;
 
 // based on Wasmer: https://github.com/wasmerio/wasmer/blob/081f6250e69b98b9f95a8f62ad6d8386534f3279/lib/runtime-core/src/instance.rs#L863
+/// Extract export function from Wasmer instance by name.
 pub(super) unsafe fn get_export_func_by_name<'a, Args, Rets>(
     ctx: &'a mut Ctx,
     name: &str,
@@ -101,6 +102,7 @@ where
     Ok(typed_func)
 }
 
+/// Make FCE config based on parsed raw config.
 pub(super) fn make_wasm_process_config(
     config: Option<ModuleConfig>,
 ) -> Result<FCEModuleConfig, NodeError> {
@@ -170,3 +172,31 @@ pub(super) fn make_wasm_process_config(
 
     Ok(wasm_module_config)
 }
+
+#[macro_export] // https://github.com/rust-lang/rust/issues/57966#issuecomment-461077932
+/// Initialize Wasm function in form of Box<RefCell<Option<Func<'static, args, rets>>>> only once.
+macro_rules! init_wasm_func_once {
+    ($func:ident, $ctx:ident, $args:ty, $rets:ty, $func_name:ident, $ret_error_code: expr) => {
+        if $func.borrow().is_none() {
+            let raw_func =
+                match super::utils::get_export_func_by_name::<$args, $rets>($ctx, $func_name) {
+                    Ok(func) => func,
+                    Err(_) => return vec![Value::I32($ret_error_code)],
+                };
+
+            // assumed that this function will be used only in the context of closure
+            // linked to a corresponding Wasm import - os it is safe to make is static
+            let raw_func = std::mem::transmute::<Func<'_, _, _>, Func<'static, _, _>>(raw_func);
+
+            *$func.borrow_mut() = Some(raw_func);
+        }
+    };
+}
+
+#[macro_export]
+/// Call Wasm function that have Box<RefCell<Option<Func<'static, args, rets>>>> type.
+macro_rules! call_wasm_func {
+    ($func:ident, $arg:expr) => {
+        $func.borrow().as_ref().unwrap().call($arg).unwrap()
+    };
+}