wayland: optimize parsing of fixed-size messages

build/wire.rs

@@ -6,7 +6,7 @@ use {
         wire::parser::{Field, Lined, Message, Type, parse_messages, to_camel},
     },
     anyhow::{Context, Result},
-    std::{fs::DirEntry, io::Write, os::unix::ffi::OsStrExt},
+    std::{fmt, fs::DirEntry, io::Write, os::unix::ffi::OsStrExt},
 };
 
 fn write_type<W: Write>(f: &mut W, ty: &Type) -> Result<()> {
@@ -110,8 +110,60 @@ fn write_message<W: Write>(f: &mut W, obj: &str, message: &Message) -> Result<()
         "        fn parse({}: &mut MsgParser<'_, 'a>) -> Result<Self, MsgParserError> {{",
         parser
     )?;
+    if message.is_fixed_size {
+        writeln!(f, "            let [")?;
+        for (i, field) in message.fields.iter().enumerate() {
+            match &field.val.ty.val {
+                Type::U64 => {
+                    writeln!(f, "                arg{i}_hi,")?;
+                    writeln!(f, "                arg{i}_lo,")?;
+                }
+                Type::U64Rev => {
+                    writeln!(f, "                arg{i}_lo,")?;
+                    writeln!(f, "                arg{i}_hi,")?;
+                }
+                Type::Fd => {}
+                _ => {
+                    writeln!(f, "                arg{i},")?;
+                }
+            }
+        }
+        writeln!(f, "            ] = *{parser}.data() else {{")?;
+        writeln!(
+            f,
+            "                return Err(MsgParserError::UnexpectedMessageSize);"
+        )?;
+        writeln!(f, "            }};")?;
         writeln!(f, "            Ok(Self {{")?;
         writeln!(f, "                self_id: {}Id::NONE,", obj)?;
+        for (i, field) in message.fields.iter().enumerate() {
+            writeln!(
+                f,
+                "                {}: {},",
+                field.val.name,
+                fmt::from_fn(|f| {
+                    match &field.val.ty.val {
+                        Type::Id(_, name) => write!(f, "{name}Id(arg{i})"),
+                        Type::U32 => write!(f, "arg{i}"),
+                        Type::I32 => write!(f, "arg{i} as i32"),
+                        Type::U64 | Type::U64Rev => {
+                            write!(f, "((arg{i}_hi as u64) << 32) | (arg{i}_lo as u64)")
+                        }
+                        Type::OptStr => unreachable!(),
+                        Type::Str => unreachable!(),
+                        Type::Fixed => write!(f, "Fixed(arg{i} as i32)"),
+                        Type::Fd => write!(f, "parser.fd()?"),
+                        Type::BStr => unreachable!(),
+                        Type::Array(_) => unreachable!(),
+                        Type::Pod(_) => unreachable!(),
+                    }
+                })
+            )?;
+        }
+        writeln!(f, "            }})")?;
+    } else {
+        writeln!(f, "            let res = Ok(Self {{")?;
+        writeln!(f, "                self_id: {}Id::NONE,", obj)?;
         for field in &message.fields {
             let p = match &field.val.ty.val {
                 Type::Id(..) => "object",
@@ -129,7 +181,10 @@ fn write_message<W: Write>(f: &mut W, obj: &str, message: &Message) -> Result<()
             };
             writeln!(f, "                {}: parser.{}()?,", field.val.name, p)?;
         }
-    writeln!(f, "            }})")?;
+        writeln!(f, "            }});")?;
+        writeln!(f, "            parser.eof()?;")?;
+        writeln!(f, "            res")?;
+    }
     writeln!(f, "        }}")?;
     writeln!(f, "    }}")?;
     writeln!(

build/wire/parser.rs

@@ -235,6 +235,7 @@ pub struct Message {
     pub fields: Vec<Lined<Field>>,
     pub attribs: MessageAttribs,
     pub has_reference_type: bool,
+    pub is_fixed_size: bool,
 }
 
 #[derive(Debug, Default)]
@@ -344,6 +345,11 @@ impl<'a> Parser<'a> {
                 Type::OptStr | Type::Str | Type::BStr | Type::Array(..) => true,
                 _ => false,
             });
+            let is_variable_size = fields.iter().any(|f| match &f.val.ty.val {
+                Type::OptStr | Type::Str | Type::BStr | Type::Array(..) | Type::Pod(..) => true,
+                _ => false,
+            });
+            let is_fixed_size = !is_variable_size;
             let safe_name = match name {
                 "move" => "move_",
                 "type" => "type_",
@@ -361,6 +367,7 @@ impl<'a> Parser<'a> {
                     fields,
                     attribs,
                     has_reference_type,
+                    is_fixed_size,
                 },
             })
         })();

src/client.rs

@@ -427,7 +427,6 @@ impl Client {
         mut parser: MsgParser<'_, 'a>,
     ) -> Result<R, MsgParserError> {
         let res = R::parse(&mut parser)?;
-        parser.eof()?;
         log::trace!(
             "Client {} -> {}@{}.{:?}",
             self.id,

src/it/testrun.rs

@@ -146,9 +146,7 @@ pub trait ParseFull<'a>: Sized {
 
 impl<'a, T: RequestParser<'a>> ParseFull<'a> for T {
     fn parse_full(mut parser: MsgParser<'_, 'a>) -> Result<Self, TestError> {
-        let res = T::parse(&mut parser)?;
-        parser.eof()?;
-        Ok(res)
+        T::parse(&mut parser).map_err(Into::into)
     }
 }
 

src/utils/buffd/parser.rs

@@ -22,6 +22,8 @@ pub enum MsgParserError {
     TrailingData,
     #[error("String is not UTF-8")]
     NonUtf8,
+    #[error("The message has an unexpected size")]
+    UnexpectedMessageSize,
 }
 
 pub struct MsgParser<'a, 'b> {
@@ -35,6 +37,11 @@ impl<'a, 'b> MsgParser<'a, 'b> {
         Self { buf, pos: 0, data }
     }
 
+    #[inline(always)]
+    pub fn data(&self) -> &[u32] {
+        self.data
+    }
+
     pub fn int(&mut self) -> Result<i32, MsgParserError> {
         if self.pos >= self.data.len() {
             return Err(MsgParserError::UnexpectedEof);
@@ -48,12 +55,14 @@ impl<'a, 'b> MsgParser<'a, 'b> {
         self.int().map(|i| i as u32)
     }
 
+    #[expect(dead_code)]
     pub fn u64(&mut self) -> Result<u64, MsgParserError> {
         let hi = self.uint()?;
         let lo = self.uint()?;
         Ok(((hi as u64) << 32) | lo as u64)
     }
 
+    #[expect(dead_code)]
     pub fn u64_rev(&mut self) -> Result<u64, MsgParserError> {
         let lo = self.uint()?;
         let hi = self.uint()?;

src/wl_usr.rs

@@ -257,7 +257,6 @@ impl UsrCon {
         mut parser: MsgParser<'_, 'a>,
     ) -> Result<R, MsgParserError> {
         let res = R::parse(&mut parser)?;
-        parser.eof()?;
         log::trace!(
             "Server {} -> {}@{}.{:?}",
             self.server_id,