aya-log: s/Result<usize, ()>/Option<NonZeroUsize>/

`Option<NonZeroUsize>` is guaranteed to have the same size as `usize`,
which is not guarnateed for `Result`. This is a minor optimization, but
also results in simpler code.

aya-log-common/src/lib.rs

@@ -1,6 +1,6 @@
 #![no_std]
 
-use core::num;
+use core::num::{NonZeroUsize, TryFromIntError};
 
 use num_enum::IntoPrimitive;
 
@@ -151,16 +151,16 @@ pub enum DisplayHint {
 //
 // llvm: <unknown>:0:0: in function _ZN14aya_log_common5write17hc9ed05433e23a663E { i64, i64 } (i8, ptr, i64, ptr, i64): only integer returns supported
 #[inline(always)]
-pub(crate) fn write(tag: u8, value: &[u8], buf: &mut [u8]) -> Result<usize, ()> {
-    let wire_len: LogValueLength = value
-        .len()
-        .try_into()
-        .map_err(|num::TryFromIntError { .. }| ())?;
+pub(crate) fn write(tag: u8, value: &[u8], buf: &mut [u8]) -> Option<NonZeroUsize> {
+    let wire_len: LogValueLength = match value.len().try_into() {
+        Ok(wire_len) => Some(wire_len),
+        Err(TryFromIntError { .. }) => None,
+    }?;
     let mut size = 0;
     macro_rules! copy_from_slice {
         ($value:expr) => {{
-            let buf = buf.get_mut(size..).ok_or(())?;
-            let buf = buf.get_mut(..$value.len()).ok_or(())?;
+            let buf = buf.get_mut(size..)?;
+            let buf = buf.get_mut(..$value.len())?;
             buf.copy_from_slice($value);
             size += $value.len();
         }};
@@ -168,12 +168,11 @@ pub(crate) fn write(tag: u8, value: &[u8], buf: &mut [u8]) -> Result<usize, ()>
     copy_from_slice!(&[tag]);
     copy_from_slice!(&wire_len.to_ne_bytes());
     copy_from_slice!(value);
-    Ok(size)
+    NonZeroUsize::new(size)
 }
 
 pub trait WriteToBuf {
-    #[allow(clippy::result_unit_err)]
-    fn write(self, buf: &mut [u8]) -> Result<usize, ()>;
+    fn write(self, buf: &mut [u8]) -> Option<NonZeroUsize>;
 }
 
 macro_rules! impl_write_to_buf {
@@ -182,7 +181,7 @@ macro_rules! impl_write_to_buf {
             // This need not be inlined because the return value is Result<N, ()> where N is
             // mem::size_of<$type>, which is a compile-time constant.
             #[inline(never)]
-            fn write(self, buf: &mut [u8]) -> Result<usize, ()> {
+            fn write(self, buf: &mut [u8]) -> Option<NonZeroUsize> {
                 write($arg_type.into(), &self.to_ne_bytes(), buf)
             }
         }
@@ -208,7 +207,7 @@ impl WriteToBuf for [u8; 16] {
     // This need not be inlined because the return value is Result<N, ()> where N is 16, which is a
     // compile-time constant.
     #[inline(never)]
-    fn write(self, buf: &mut [u8]) -> Result<usize, ()> {
+    fn write(self, buf: &mut [u8]) -> Option<NonZeroUsize> {
         write(Argument::ArrU8Len16.into(), &self, buf)
     }
 }
@@ -217,7 +216,7 @@ impl WriteToBuf for [u16; 8] {
     // This need not be inlined because the return value is Result<N, ()> where N is 16, which is a
     // compile-time constant.
     #[inline(never)]
-    fn write(self, buf: &mut [u8]) -> Result<usize, ()> {
+    fn write(self, buf: &mut [u8]) -> Option<NonZeroUsize> {
         let bytes = unsafe { core::mem::transmute::<_, [u8; 16]>(self) };
         write(Argument::ArrU16Len8.into(), &bytes, buf)
     }
@@ -227,7 +226,7 @@ impl WriteToBuf for [u8; 6] {
     // This need not be inlined because the return value is Result<N, ()> where N is 6, which is a
     // compile-time constant.
     #[inline(never)]
-    fn write(self, buf: &mut [u8]) -> Result<usize, ()> {
+    fn write(self, buf: &mut [u8]) -> Option<NonZeroUsize> {
         write(Argument::ArrU8Len6.into(), &self, buf)
     }
 }
@@ -237,7 +236,7 @@ impl WriteToBuf for &[u8] {
     //
     // llvm: <unknown>:0:0: in function _ZN63_$LT$$RF$$u5b$u8$u5d$$u20$as$u20$aya_log_common..WriteToBuf$GT$5write17h08f30a45f7b9f09dE { i64, i64 } (ptr, i64, ptr, i64): only integer returns supported
     #[inline(always)]
-    fn write(self, buf: &mut [u8]) -> Result<usize, ()> {
+    fn write(self, buf: &mut [u8]) -> Option<NonZeroUsize> {
         write(Argument::Bytes.into(), self, buf)
     }
 }
@@ -247,7 +246,7 @@ impl WriteToBuf for &str {
     //
     // llvm: <unknown>:0:0: in function _ZN54_$LT$$RF$str$u20$as$u20$aya_log_common..WriteToBuf$GT$5write17h7e2d1ccaa758e2b5E { i64, i64 } (ptr, i64, ptr, i64): only integer returns supported
     #[inline(always)]
-    fn write(self, buf: &mut [u8]) -> Result<usize, ()> {
+    fn write(self, buf: &mut [u8]) -> Option<NonZeroUsize> {
         write(Argument::Str.into(), self.as_bytes(), buf)
     }
 }
@@ -256,13 +255,12 @@ impl WriteToBuf for DisplayHint {
     // This need not be inlined because the return value is Result<N, ()> where N is 1, which is a
     // compile-time constant.
     #[inline(never)]
-    fn write(self, buf: &mut [u8]) -> Result<usize, ()> {
+    fn write(self, buf: &mut [u8]) -> Option<NonZeroUsize> {
         let v: u8 = self.into();
         write(Argument::DisplayHint.into(), &v.to_ne_bytes(), buf)
     }
 }
 
-#[allow(clippy::result_unit_err)]
 #[doc(hidden)]
 #[inline(always)] // This function takes too many arguments to not be inlined.
 pub fn write_record_header(
@@ -273,13 +271,14 @@ pub fn write_record_header(
     file: &str,
     line: u32,
     num_args: usize,
-) -> Result<usize, ()> {
+) -> Option<NonZeroUsize> {
     let level: u8 = level.into();
     let mut size = 0;
     macro_rules! write {
         ($tag:expr, $value:expr) => {{
-            let buf = buf.get_mut(size..).ok_or(())?;
-            size += write($tag.into(), $value, buf)?;
+            let buf = buf.get_mut(size..)?;
+            let len = write($tag.into(), $value, buf)?;
+            size += len.get();
         }};
     }
     write!(RecordField::Target, target.as_bytes());
@@ -288,7 +287,7 @@ pub fn write_record_header(
     write!(RecordField::File, file.as_bytes());
     write!(RecordField::Line, &line.to_ne_bytes());
     write!(RecordField::NumArgs, &num_args.to_ne_bytes());
-    Ok(size)
+    NonZeroUsize::new(size)
 }
 
 #[cfg(test)]

aya-log-ebpf-macros/src/expand.rs

@@ -147,8 +147,8 @@ pub(crate) fn log(args: LogArgs, level: Option<TokenStream>) -> Result<TokenStre
         match unsafe { &mut ::aya_log_ebpf::AYA_LOG_BUF }.get_ptr_mut(0).and_then(|ptr| unsafe { ptr.as_mut() }) {
             None => {},
             Some(::aya_log_ebpf::LogBuf { buf }) => {
-                let _: Result<(), ()> = (|| {
-                    let mut len = ::aya_log_ebpf::write_record_header(
+                let _: Option<()> = (|| {
+                    let size = ::aya_log_ebpf::write_record_header(
                         buf,
                         #target,
                         #lvl,
@@ -157,13 +157,15 @@ pub(crate) fn log(args: LogArgs, level: Option<TokenStream>) -> Result<TokenStre
                         line!(),
                         #num_args,
                     )?;
+                    let mut size = size.get();
                     #(
-                        let slice = buf.get_mut(len..).ok_or(())?;
-                        len += ::aya_log_ebpf::WriteToBuf::write(#values_iter, slice)?;
+                        let slice = buf.get_mut(size..)?;
+                        let len = ::aya_log_ebpf::WriteToBuf::write(#values_iter, slice)?;
+                        size += len.get();
                     )*
-                    let record = buf.get(..len).ok_or(())?;
+                    let record = buf.get(..size)?;
                     unsafe { &mut ::aya_log_ebpf::AYA_LOGS }.output(#ctx, record, 0);
-                    Ok(())
+                    Some(())
                 })();
             }
         }

aya-log/src/lib.rs

@@ -584,7 +584,7 @@ mod test {
     use aya_log_common::{write_record_header, WriteToBuf};
     use log::{logger, Level};
 
-    fn new_log(args: usize) -> Result<(usize, Vec<u8>), ()> {
+    fn new_log(args: usize) -> Option<(usize, Vec<u8>)> {
         let mut buf = vec![0; 8192];
         let len = write_record_header(
             &mut buf,
@@ -595,7 +595,7 @@ mod test {
             123,
             args,
         )?;
-        Ok((len, buf))
+        Some((len.get(), buf))
     }
 
     #[test]
@@ -603,7 +603,7 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(1).unwrap();
 
-        len += "test".write(&mut input[len..]).unwrap();
+        len += "test".write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -621,8 +621,8 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(2).unwrap();
 
-        len += "hello ".write(&mut input[len..]).unwrap();
-        len += "test".write(&mut input[len..]).unwrap();
+        len += "hello ".write(&mut input[len..]).unwrap().get();
+        len += "test".write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -640,8 +640,11 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(2).unwrap();
 
-        len += DisplayHint::LowerHex.write(&mut input[len..]).unwrap();
-        len += [0xde, 0xad].write(&mut input[len..]).unwrap();
+        len += DisplayHint::LowerHex
+            .write(&mut input[len..])
+            .unwrap()
+            .get();
+        len += [0xde, 0xad].write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -659,13 +662,19 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(5).unwrap();
 
-        len += DisplayHint::LowerHex.write(&mut input[len..]).unwrap();
-        len += [0xde, 0xad].write(&mut input[len..]).unwrap();
+        len += DisplayHint::LowerHex
+            .write(&mut input[len..])
+            .unwrap()
+            .get();
+        len += [0xde, 0xad].write(&mut input[len..]).unwrap().get();
 
-        len += " ".write(&mut input[len..]).unwrap();
+        len += " ".write(&mut input[len..]).unwrap().get();
 
-        len += DisplayHint::UpperHex.write(&mut input[len..]).unwrap();
-        len += [0xbe, 0xef].write(&mut input[len..]).unwrap();
+        len += DisplayHint::UpperHex
+            .write(&mut input[len..])
+            .unwrap()
+            .get();
+        len += [0xbe, 0xef].write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -683,9 +692,9 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(3).unwrap();
 
-        len += "default hint: ".write(&mut input[len..]).unwrap();
-        len += DisplayHint::Default.write(&mut input[len..]).unwrap();
-        len += 14.write(&mut input[len..]).unwrap();
+        len += "default hint: ".write(&mut input[len..]).unwrap().get();
+        len += DisplayHint::Default.write(&mut input[len..]).unwrap().get();
+        len += 14.write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -703,9 +712,12 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(3).unwrap();
 
-        len += "lower hex: ".write(&mut input[len..]).unwrap();
-        len += DisplayHint::LowerHex.write(&mut input[len..]).unwrap();
-        len += 200.write(&mut input[len..]).unwrap();
+        len += "lower hex: ".write(&mut input[len..]).unwrap().get();
+        len += DisplayHint::LowerHex
+            .write(&mut input[len..])
+            .unwrap()
+            .get();
+        len += 200.write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -723,9 +735,12 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(3).unwrap();
 
-        len += "upper hex: ".write(&mut input[len..]).unwrap();
-        len += DisplayHint::UpperHex.write(&mut input[len..]).unwrap();
-        len += 200.write(&mut input[len..]).unwrap();
+        len += "upper hex: ".write(&mut input[len..]).unwrap().get();
+        len += DisplayHint::UpperHex
+            .write(&mut input[len..])
+            .unwrap()
+            .get();
+        len += 200.write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -743,10 +758,10 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(3).unwrap();
 
-        len += "ipv4: ".write(&mut input[len..]).unwrap();
-        len += DisplayHint::Ip.write(&mut input[len..]).unwrap();
+        len += "ipv4: ".write(&mut input[len..]).unwrap().get();
+        len += DisplayHint::Ip.write(&mut input[len..]).unwrap().get();
         // 10.0.0.1 as u32
-        len += 167772161u32.write(&mut input[len..]).unwrap();
+        len += 167772161u32.write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -764,14 +779,14 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(3).unwrap();
 
-        len += "ipv6: ".write(&mut input[len..]).unwrap();
-        len += DisplayHint::Ip.write(&mut input[len..]).unwrap();
+        len += "ipv6: ".write(&mut input[len..]).unwrap().get();
+        len += DisplayHint::Ip.write(&mut input[len..]).unwrap().get();
         // 2001:db8::1:1 as byte array
         let ipv6_arr: [u8; 16] = [
             0x20, 0x01, 0x0d, 0xb8, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01,
             0x00, 0x01,
         ];
-        len += ipv6_arr.write(&mut input[len..]).unwrap();
+        len += ipv6_arr.write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -789,13 +804,13 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(3).unwrap();
 
-        len += "ipv6: ".write(&mut input[len..]).unwrap();
-        len += DisplayHint::Ip.write(&mut input[len..]).unwrap();
+        len += "ipv6: ".write(&mut input[len..]).unwrap().get();
+        len += DisplayHint::Ip.write(&mut input[len..]).unwrap().get();
         // 2001:db8::1:1 as u16 array
         let ipv6_arr: [u16; 8] = [
             0x2001, 0x0db8, 0x0000, 0x0000, 0x0000, 0x0000, 0x0001, 0x0001,
         ];
-        len += ipv6_arr.write(&mut input[len..]).unwrap();
+        len += ipv6_arr.write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -813,11 +828,14 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(3).unwrap();
 
-        len += "mac: ".write(&mut input[len..]).unwrap();
-        len += DisplayHint::LowerMac.write(&mut input[len..]).unwrap();
+        len += "mac: ".write(&mut input[len..]).unwrap().get();
+        len += DisplayHint::LowerMac
+            .write(&mut input[len..])
+            .unwrap()
+            .get();
         // 00:00:5e:00:53:af as byte array
         let mac_arr: [u8; 6] = [0x00, 0x00, 0x5e, 0x00, 0x53, 0xaf];
-        len += mac_arr.write(&mut input[len..]).unwrap();
+        len += mac_arr.write(&mut input[len..]).unwrap().get();
 
         _ = len;
 
@@ -835,11 +853,14 @@ mod test {
         testing_logger::setup();
         let (mut len, mut input) = new_log(3).unwrap();
 
-        len += "mac: ".write(&mut input[len..]).unwrap();
-        len += DisplayHint::UpperMac.write(&mut input[len..]).unwrap();
+        len += "mac: ".write(&mut input[len..]).unwrap().get();
+        len += DisplayHint::UpperMac
+            .write(&mut input[len..])
+            .unwrap()
+            .get();
         // 00:00:5E:00:53:AF as byte array
         let mac_arr: [u8; 6] = [0x00, 0x00, 0x5e, 0x00, 0x53, 0xaf];
-        len += mac_arr.write(&mut input[len..]).unwrap();
+        len += mac_arr.write(&mut input[len..]).unwrap().get();
 
         _ = len;
 

xtask/public-api/aya-log-common.txt

@@ -54,7 +54,7 @@ pub aya_log_common::DisplayHint::LowerMac
 pub aya_log_common::DisplayHint::UpperHex
 pub aya_log_common::DisplayHint::UpperMac
 impl aya_log_common::WriteToBuf for aya_log_common::DisplayHint
-pub fn aya_log_common::DisplayHint::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn aya_log_common::DisplayHint::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl core::convert::From<aya_log_common::DisplayHint> for u8
 pub fn u8::from(enum_value: aya_log_common::DisplayHint) -> Self
 impl core::clone::Clone for aya_log_common::DisplayHint
@@ -216,41 +216,41 @@ impl aya_log_common::UpperHexFormatter for usize
 pub trait aya_log_common::UpperMacFormatter
 impl aya_log_common::UpperMacFormatter for [u8; 6]
 pub trait aya_log_common::WriteToBuf
-pub fn aya_log_common::WriteToBuf::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn aya_log_common::WriteToBuf::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for &[u8]
-pub fn &[u8]::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn &[u8]::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for &str
-pub fn &str::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn &str::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for [u16; 8]
-pub fn [u16; 8]::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn [u16; 8]::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for [u8; 16]
-pub fn [u8; 16]::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn [u8; 16]::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for [u8; 6]
-pub fn [u8; 6]::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn [u8; 6]::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for aya_log_common::DisplayHint
-pub fn aya_log_common::DisplayHint::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn aya_log_common::DisplayHint::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for f32
-pub fn f32::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn f32::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for f64
-pub fn f64::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn f64::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for i16
-pub fn i16::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn i16::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for i32
-pub fn i32::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn i32::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for i64
-pub fn i64::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn i64::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for i8
-pub fn i8::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn i8::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for isize
-pub fn isize::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn isize::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for u16
-pub fn u16::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn u16::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for u32
-pub fn u32::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn u32::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for u64
-pub fn u64::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn u64::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for u8
-pub fn u8::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn u8::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 impl aya_log_common::WriteToBuf for usize
-pub fn usize::write(self, buf: &mut [u8]) -> core::result::Result<usize, ()>
+pub fn usize::write(self, buf: &mut [u8]) -> core::option::Option<core::num::nonzero::NonZeroUsize>
 pub type aya_log_common::LogValueLength = u16