From 612535e32873bc19f3758cf86124a937643213fb Mon Sep 17 00:00:00 2001
From: Matthias Beyer <matthias.beyer@ifm.com>
Date: Sat, 2 Jul 2022 17:18:17 +0200
Subject: WIP: Optimize: Do not allocate in MessageBundle::get_ids()

---
 crates/core/tedge_api/src/plugin.rs | 25 ++++++++++++++-----------
 1 file changed, 14 insertions(+), 11 deletions(-)

diff --git a/crates/core/tedge_api/src/plugin.rs b/crates/core/tedge_api/src/plugin.rs
index d57a41f7..24161a4a 100644
--- a/crates/core/tedge_api/src/plugin.rs
+++ b/crates/core/tedge_api/src/plugin.rs
@@ -373,14 +373,14 @@ pub trait Handle<Msg: Message> {
 
 #[derive(Debug)]
 #[doc(hidden)]
-pub struct HandleTypes(Vec<MessageType>);
+pub struct HandleTypes(&'static [MessageType]);
 
 impl HandleTypes {
     pub fn get_types(&self) -> &[MessageType] {
         &self.0
     }
 
-    pub fn into_types(self) -> Vec<MessageType> {
+    pub fn into_types(self) -> &'static [MessageType] {
         self.0
     }
 
@@ -445,7 +445,7 @@ impl HandleTypes {
     where
         P: DoesHandle<P::HandledMessages>,
     {
-        HandleTypes(P::HandledMessages::get_ids())
+        HandleTypes(P::HandledMessages::get_ids().as_slice())
     }
 }
 
@@ -454,7 +454,7 @@ impl HandleTypes {
 /// This trait is implemented on types that represent a bundle of different types of messages.
 pub trait MessageBundle {
     /// Get the names and ids of the types that are represented by this bundle
-    fn get_ids() -> Vec<MessageType>;
+    fn get_ids() -> std::slice::Iter<'static, MessageType>;
 }
 
 /// An extension for a Plugin implementing type
@@ -594,8 +594,8 @@ macro_rules! impl_does_handle_tuple {
 impl_does_handle_tuple!(M10 M9 M8 M7 M6 M5 M4 M3 M2 M1);
 
 impl MessageBundle for () {
-    fn get_ids() -> Vec<MessageType> {
-        vec![]
+    fn get_ids() -> std::slice::Iter<'static, MessageType> {
+        [].iter()
     }
 }
 
@@ -619,8 +619,9 @@ impl<P: Plugin> DoesHandle<()> for P {
 pub struct AnyMessages;
 
 impl MessageBundle for AnyMessages {
-    fn get_ids() -> Vec<MessageType> {
-        vec![MessageType::for_message::<crate::message::AnyMessage>()]
+    fn get_ids() -> std::slice::Iter<'static, MessageType> {
+        static ary : [MessageType; 1] = [MessageType::for_message::<crate::message::AnyMessage>()];
+        ary.iter()
     }
 }
 
@@ -665,11 +666,13 @@ macro_rules! impl_msg_bundle_tuple {
     };
     ($cur:ident $($rest:tt)*) => {
         impl<$cur: Message + TypeUuid, $($rest: Message + TypeUuid),*> MessageBundle for ($cur,$($rest),*) {
-            fn get_ids() -> Vec<MessageType> {
-                vec![
+            fn get_ids() -> std::slice::Iter<'static, MessageType> {
+                static ary: [MessageType; (1 + $crate::count!($($rest)*))] = [
                     MessageType::for_message::<$cur>(),
                     $(MessageType::for_message::<$rest>()),*
-                ]
+                ];
+
+                ary.iter()
             }
         }
 
-- 
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