[GitHub] [arrow] alamb commented on a change in pull request #8545: ARROW-9674: [Rust] Make the parquet read and writers Send

[GitBox <gi...@apache.org>]

alamb commented on a change in pull request #8545:
URL: https://github.com/apache/arrow/pull/8545#discussion_r527993120



##########
File path: rust/parquet/src/util/memory.rs
##########
@@ -39,37 +41,39 @@ pub type WeakMemTrackerPtr = Weak<MemTracker>;
 pub struct MemTracker {
     // In the tuple, the first element is the current memory allocated (in bytes),
     // and the second element is the maximum memory allocated so far (in bytes).
-    memory_usage: Cell<(i64, i64)>,
+    current_memory_usage: AtomicI64,
+    max_memory_usage: AtomicI64,
 }
 
 impl MemTracker {
     /// Creates new memory tracker.
     #[inline]
     pub fn new() -> MemTracker {
         MemTracker {
-            memory_usage: Cell::new((0, 0)),
+            current_memory_usage: Default::default(),
+            max_memory_usage: Default::default(),
         }
     }
 
     /// Returns the current memory consumption, in bytes.
     pub fn memory_usage(&self) -> i64 {
-        self.memory_usage.get().0
+        self.current_memory_usage.load(Ordering::Acquire)
     }
 
     /// Returns the maximum memory consumption so far, in bytes.
     pub fn max_memory_usage(&self) -> i64 {
-        self.memory_usage.get().1
+        self.max_memory_usage.load(Ordering::Acquire)
     }
 
     /// Adds `num_bytes` to the memory consumption tracked by this memory tracker.
     #[inline]
     pub fn alloc(&self, num_bytes: i64) {
-        let (current, mut maximum) = self.memory_usage.get();
-        let new_current = current + num_bytes;
-        if new_current > maximum {
-            maximum = new_current
-        }
-        self.memory_usage.set((new_current, maximum));
+        let new_current = self
+            .current_memory_usage

Review comment:
       👍  This is a nice change to remove the use of `Cell`




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