auto-register messages via inventory

message_registry! is gone, the registry is a process-wide global now.

Cargo.lock

@@ -103,6 +103,15 @@ dependencies = [
  "wasi",
 ]
 
+[[package]]
+name = "inventory"
+version = "0.3.24"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4f0c30c76f2f4ccee3fe55a2435f691ca00c0e4bd87abe4f4a851b1d4dac39b"
+dependencies = [
+ "rustversion",
+]
+
 [[package]]
 name = "itoa"
 version = "1.0.18"
@@ -257,6 +266,12 @@ version = "0.8.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d6f6ff9a378485b298a5286656da665ba74413d36db0979633275d2e708145d4"
 
+[[package]]
+name = "rustversion"
+version = "1.0.23"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "cf54715a573b99ac80df0bc206da022bcd442c974952c7b9720069370852e21f"
+
 [[package]]
 name = "scroll-server"
 version = "0.1.0"
@@ -419,6 +434,7 @@ dependencies = [
 name = "titan"
 version = "0.1.0"
 dependencies = [
+ "inventory",
  "thiserror",
  "titan-derive",
  "tokio",

Cargo.toml

@@ -34,6 +34,7 @@ serde = { version = "1", features = ["derive"] }
 serde_json = "1"
 rand = "0.8"
 async-trait = "0.1"
+inventory = "0.3"
 proc-macro2 = "1"
 quote = "1"
 syn = { version = "2", features = ["full", "extra-traits"] }

logic/logic/src/factory.rs

@@ -1,36 +1,11 @@
-use titan::{message_registry, MessageRegistry};
-use crate::messages::{
-    AskForAvatarStreamMessage, AskForBattleReplayStreamMessage,
-    AskForPlayingFacebookFriendsMessage, AskForTVContentMessage, AvailableServerCommandMessage,
-    ClientCapabilitiesMessage, EndClientTurnMessage, GoHomeMessage, KeepAliveMessage,
-    KeepAliveServerMessage, LoginFailedMessage, LoginMessage, LoginOkMessage, OwnHomeDataMessage,
-    OutOfSyncMessage, ServerErrorMessage, SetDeviceTokenMessage, StartMissionMessage,
-};
+use std::sync::Arc;
+use titan::MessageRegistry;
 pub struct LogicScrollMessageFactory;
 impl LogicScrollMessageFactory {
-    pub fn registry() -> MessageRegistry {
+    pub fn registry() -> Arc<MessageRegistry> {
         scroll_message_registry()
     }
 }
-pub fn scroll_message_registry() -> MessageRegistry {
-    message_registry![
-        LoginMessage,
-        ClientCapabilitiesMessage,
-        KeepAliveMessage,
-        GoHomeMessage,
-        EndClientTurnMessage,
-        StartMissionMessage,
-        SetDeviceTokenMessage,
-        AskForPlayingFacebookFriendsMessage,
-        AskForTVContentMessage,
-        AskForAvatarStreamMessage,
-        AskForBattleReplayStreamMessage,
-        LoginOkMessage,
-        LoginFailedMessage,
-        KeepAliveServerMessage,
-        OwnHomeDataMessage,
-        AvailableServerCommandMessage,
-        OutOfSyncMessage,
-        ServerErrorMessage,
-    ]
+pub fn scroll_message_registry() -> Arc<MessageRegistry> {
+    MessageRegistry::global()
 }

services/gateway/src/bin/scroll-probe.rs

@@ -66,6 +66,10 @@ async fn main() -> Result<(), Box<dyn std::error::Error>> {
         }
         Err(error) => println!("no data tables ({error}), printing raw ids"),
     }
+    println!(
+        "message registry: {} type(s)",
+        logic::scroll_message_registry().len()
+    );
     println!("connecting to {endpoint}");
     let mut probe = Probe::connect(&endpoint).await?;
     let login = LoginMessage {

services/gateway/src/session.rs

@@ -23,7 +23,7 @@ impl Session {
         config: Arc<GatewayConfig>,
         backends: Arc<Backends>,
     ) -> Result<(), SessionError> {
-        let registry: Arc<MessageRegistry> = Arc::new(logic::scroll_message_registry());
+        let registry: Arc<MessageRegistry> = logic::scroll_message_registry();
         let messaging_config = MessagingConfig {
             read_timeout: config.read_timeout,
             max_payload_len: config.max_payload_len,

titan/titan-derive/src/lib.rs

@@ -20,9 +20,11 @@ pub fn derive_message(input: TokenStream) -> TokenStream {
         Ok(tokens) => tokens,
         Err(error) => return error.into_compile_error().into(),
     };
+    let registration = meta::expand_registration(&input);
     quote::quote! {
         #payload
         #meta
+        #registration
     }
     .into()
 }

titan/titan-derive/src/meta.rs

@@ -87,3 +87,14 @@ fn parse_message_attr(input: &DeriveInput) -> Result<MessageAttr> {
         name,
     })
 }
+pub fn expand_registration(input: &DeriveInput) -> TokenStream {
+    if !input.generics.params.is_empty() {
+        return TokenStream::new();
+    }
+    let ident = &input.ident;
+    quote! {
+        ::titan::inventory::submit! {
+            ::titan::factory::RegistryEntry::of::<#ident>()
+        }
+    }
+}

titan/titan/Cargo.toml

@@ -9,5 +9,6 @@ description = "Engine layer of the scroll server: byte streams, checksum encoder
 [dependencies]
 titan-derive = { workspace = true }
 thiserror = { workspace = true }
+inventory = { workspace = true }
 tokio = { workspace = true }
 tracing = { workspace = true }

titan/titan/src/factory.rs

@@ -1,7 +1,8 @@
 use std::collections::HashMap;
 use std::fmt::Debug;
+use std::sync::{Arc, OnceLock};
 use crate::error::{Error, Result};
-use crate::message::{Direction, Message, MessageMeta};
+use crate::message::{Direction, Message, MessageMeta, Payload};
 type DecodeFn = fn(&[u8]) -> Result<Box<dyn Message>>;
 #[derive(Clone, Copy)]
 pub struct RegistryEntry {
@@ -20,7 +21,7 @@ impl Debug for RegistryEntry {
     }
 }
 impl RegistryEntry {
-    pub fn of<T>() -> Self
+    pub const fn of<T>() -> Self
     where
         T: MessageMeta + Debug + Send + Sync + 'static,
     {
@@ -28,13 +29,21 @@ impl RegistryEntry {
             message_type: T::MESSAGE_TYPE,
             name: T::NAME,
             direction: T::DIRECTION,
-            decode: |bytes| Ok(Box::new(T::from_bytes(bytes)?)),
+            decode: decode_into_box::<T>,
         }
     }
     pub fn decode(&self, payload: &[u8]) -> Result<Box<dyn Message>> {
         (self.decode)(payload)
     }
 }
+fn decode_into_box<T>(payload: &[u8]) -> Result<Box<dyn Message>>
+where
+    T: MessageMeta + Debug + Send + Sync + 'static,
+{
+    Ok(Box::new(T::from_bytes(payload)?))
+}
+inventory::collect!(RegistryEntry);
+static GLOBAL: OnceLock<Arc<MessageRegistry>> = OnceLock::new();
 pub trait MessageFactory: Send + Sync {
     fn create(&self, message_type: u16, message_version: u16, payload: &[u8]) -> Result<Box<dyn Message>>;
     fn lookup(&self, message_type: u16) -> Option<&RegistryEntry>;
@@ -54,8 +63,25 @@ impl MessageRegistry {
         }
         registry
     }
+    pub fn collect() -> Self {
+        Self::from_entries(inventory::iter::<RegistryEntry>.into_iter().copied())
+    }
+    pub fn global() -> Arc<MessageRegistry> {
+        Arc::clone(GLOBAL.get_or_init(|| {
+            let registry = Self::collect();
+            tracing::debug!(messages = registry.len(), "message registry collected");
+            Arc::new(registry)
+        }))
+    }
     pub fn insert(&mut self, entry: RegistryEntry) {
-        self.entries.insert(entry.message_type, entry);
+        if let Some(previous) = self.entries.insert(entry.message_type, entry) {
+            tracing::warn!(
+                message_type = entry.message_type,
+                previous = previous.name,
+                replacement = entry.name,
+                "two messages declare the same type"
+            );
+        }
     }
     pub fn len(&self) -> usize {
         self.entries.len()
@@ -76,11 +102,3 @@ impl MessageFactory for MessageRegistry {
         self.entries.get(&message_type)
     }
 }
-#[macro_export]
-macro_rules! message_registry {
-    ($($ty:ty),* $(,)?) => {
-        $crate::factory::MessageRegistry::from_entries([
-            $($crate::factory::RegistryEntry::of::<$ty>()),*
-        ])
-    };
-}

titan/titan/src/lib.rs

@@ -26,6 +26,7 @@ pub use json::JsonValue;
 pub use logic_long::LogicLong;
 pub use message::{Direction, Message, MessageMeta, Payload};
 pub use net::{Incoming, Messaging, MessagingConfig, MessagingError, MessagingSender, OutboundMessage};
+pub use inventory;
 pub use titan_derive::{Message, Payload};
 pub mod prelude {
     pub use crate::codec::{
@@ -37,5 +38,6 @@ pub mod prelude {
     pub use crate::io::{ByteStreamReader, ByteStreamWriter};
     pub use crate::logic_long::LogicLong;
     pub use crate::message::{Direction, Message, MessageMeta, Payload};
-    pub use titan_derive::{Message, Payload};
+    pub use inventory;
+pub use titan_derive::{Message, Payload};
 }