Implement MallocSizeOf for SmallVec (v2) (#369)

* Implement MallocSizeOf for SmallVec (v2)

Signed-off-by: Nico Burns <nico@nicoburns.com>

* Bump malloc_size_of crate to version with lower MSRV

Signed-off-by: Nico Burns <nico@nicoburns.com>

---------

Signed-off-by: Nico Burns <nico@nicoburns.com>

Author: nicoburns

.github/workflows/main.yml

@@ -39,6 +39,9 @@ jobs:
       - name: Cargo test w/ serde
         run: cargo test --verbose --features serde
 
+      - name: Cargo test w/ malloc_size_of
+        run: cargo test --verbose --features malloc_size_of
+
       - name: Cargo check w/o default features
         if: matrix.toolchain == 'nightly'
         run: cargo check --verbose --no-default-features

Cargo.toml

@@ -20,6 +20,7 @@ extract_if = []
 
 [dependencies]
 serde = { version = "1", optional = true, default-features = false }
+malloc_size_of = { version = "0.1.1", optional = true, default-features = false }
 
 [dev-dependencies]
 bincode = "1.0.1"

src/lib.rs

@@ -92,6 +92,8 @@ use core::ptr::copy;
 use core::ptr::copy_nonoverlapping;
 use core::ptr::NonNull;
 
+#[cfg(feature = "malloc_size_of")]
+use malloc_size_of::{MallocShallowSizeOf, MallocSizeOf, MallocSizeOfOps};
 #[cfg(feature = "serde")]
 use serde::{
     de::{Deserialize, Deserializer, SeqAccess, Visitor},
@@ -2176,6 +2178,28 @@ where
     }
 }
 
+#[cfg(feature = "malloc_size_of")]
+impl<T, const N: usize> MallocShallowSizeOf for SmallVec<T, N> {
+    fn shallow_size_of(&self, ops: &mut MallocSizeOfOps) -> usize {
+        if self.spilled() {
+            unsafe { ops.malloc_size_of(self.as_ptr()) }
+        } else {
+            0
+        }
+    }
+}
+
+#[cfg(feature = "malloc_size_of")]
+impl<T: MallocSizeOf, const N: usize> MallocSizeOf for SmallVec<T, N> {
+    fn size_of(&self, ops: &mut MallocSizeOfOps) -> usize {
+        let mut n = self.shallow_size_of(ops);
+        for elem in self.iter() {
+            n += elem.size_of(ops);
+        }
+        n
+    }
+}
+
 #[cfg(feature = "std")]
 #[cfg_attr(docsrs, doc(cfg(feature = "std")))]
 impl<const N: usize> io::Write for SmallVec<u8, N> {