Merge pull request #117 from nathaniel-daniel/fix-pr-106

Author: octavonce

libmimalloc-sys/src/extended.rs

@@ -202,6 +202,11 @@ extern "C" {
     /// know for certain.
     pub fn mi_zalloc_small(size: usize) -> *mut c_void;
 
+    /// Return the available bytes in a memory block.
+    ///
+    /// The returned size can be used to call `mi_expand` successfully.
+    pub fn mi_usable_size(p: *const c_void) -> usize;
+
     /// Return the used allocation size.
     ///
     /// Returns the size `n` that will be allocated, where `n >= size`.

libmimalloc-sys/src/lib.rs

@@ -65,11 +65,6 @@ extern "C" {
     ///
     /// The pointer `p` must have been allocated before (or be null).
     pub fn mi_free(p: *mut c_void);
-
-    /// Return the available bytes in a memory block.
-    ///
-    /// The returned size can be used to call `mi_expand` successfully.
-    pub fn mi_usable_size(p: *const c_void) -> usize;
 }
 
 #[cfg(test)]

src/extended.rs

@@ -1,4 +1,5 @@
 use crate::MiMalloc;
+use core::ffi::c_void;
 
 impl MiMalloc {
     /// Get the mimalloc version.
@@ -7,15 +8,39 @@ impl MiMalloc {
     pub fn version(&self) -> u32 {
         unsafe { ffi::mi_version() as u32 }
     }
+
+    /// Return the amount of available bytes in a memory block.
+    ///
+    /// # Safety
+    /// `ptr` must point to a memory block allocated by mimalloc, or be null.
+    #[inline]
+    pub unsafe fn usable_size(&self, ptr: *const u8) -> usize {
+        ffi::mi_usable_size(ptr as *const c_void)
+    }
 }
 
 #[cfg(test)]
 mod test {
     use super::*;
+    use core::alloc::GlobalAlloc;
+    use core::alloc::Layout;
 
     #[test]
     fn it_gets_version() {
         let version = MiMalloc.version();
         assert!(version != 0);
     }
+
+    #[test]
+    fn it_checks_usable_size() {
+        unsafe {
+            let layout = Layout::from_size_align(8, 8).unwrap();
+            let alloc = MiMalloc;
+
+            let ptr = alloc.alloc(layout);
+            let usable_size = alloc.usable_size(ptr);
+            alloc.dealloc(ptr, layout);
+            assert!(usable_size >= 8);
+        }
+    }
 }

src/lib.rs

@@ -67,14 +67,6 @@ unsafe impl GlobalAlloc for MiMalloc {
     }
 }
 
-impl MiMalloc {
-    #[allow(dead_code)]
-    #[inline]
-    unsafe fn usable_size(&self, ptr: *const u8) -> usize {
-        mi_usable_size(ptr as *const c_void)
-    }
-}
-
 #[cfg(test)]
 mod tests {
     use super::*;
@@ -146,17 +138,4 @@ mod tests {
             alloc.dealloc(ptr, layout);
         }
     }
-
-    #[test]
-    fn it_usable_size() {
-        unsafe {
-            let layout = Layout::from_size_align(8, 8).unwrap();
-            let alloc = MiMalloc;
-
-            let ptr = alloc.alloc(layout);
-            let usable_size = alloc.usable_size(ptr);
-            alloc.dealloc(ptr, layout);
-            assert!(usable_size >= 8);
-        }
-    }
 }