Allow negative bytes

Gotta be optimistic about those memory usage optimizations

1 files changed, 20 insertions, 12 deletions

diff --git a/crates/ra_prof/src/memory_usage.rs b/crates/ra_prof/src/memory_usage.rs
index 857b51321..22b61e4a2 100644
--- a/crates/ra_prof/src/memory_usage.rs
+++ b/crates/ra_prof/src/memory_usage.rs
@@ -3,16 +3,30 @@ use std::fmt;
 
 use cfg_if::cfg_if;
 
+#[derive(Copy, Clone)]
 pub struct MemoryUsage {
     pub allocated: Bytes,
 }
 
+impl fmt::Display for MemoryUsage {
+    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
+        write!(fmt, "{}", self.allocated)
+    }
+}
+
+impl std::ops::Sub for MemoryUsage {
+    type Output = MemoryUsage;
+    fn sub(self, rhs: MemoryUsage) -> MemoryUsage {
+        MemoryUsage { allocated: self.allocated - rhs.allocated }
+    }
+}
+
 impl MemoryUsage {
     pub fn current() -> MemoryUsage {
         cfg_if! {
             if #[cfg(target_os = "linux")] {
                 // Note: This is incredibly slow.
-                let alloc = unsafe { libc::mallinfo() }.uordblks as u32 as usize;
+                let alloc = unsafe { libc::mallinfo() }.uordblks as u32 as isize;
                 MemoryUsage { allocated: Bytes(alloc) }
             } else {
                 MemoryUsage { allocated: Bytes(0) }
@@ -21,17 +35,11 @@ impl MemoryUsage {
     }
 }
 
-impl fmt::Display for MemoryUsage {
-    fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
-        write!(fmt, "{}", self.allocated)
-    }
-}
-
 #[derive(Default, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy)]
-pub struct Bytes(usize);
+pub struct Bytes(isize);
 
 impl Bytes {
-    pub fn megabytes(self) -> usize {
+    pub fn megabytes(self) -> isize {
         self.0 / 1024 / 1024
     }
 }
@@ -41,10 +49,10 @@ impl fmt::Display for Bytes {
         let bytes = self.0;
         let mut value = bytes;
         let mut suffix = "b";
-        if value > 4096 {
+        if value.abs() > 4096 {
             value /= 1024;
             suffix = "kb";
-            if value > 4096 {
+            if value.abs() > 4096 {
                 value /= 1024;
                 suffix = "mb";
             }
@@ -55,7 +63,7 @@ impl fmt::Display for Bytes {
 
 impl std::ops::AddAssign<usize> for Bytes {
     fn add_assign(&mut self, x: usize) {
-        self.0 += x;
+        self.0 += x as isize;
     }
 }