append-only-vec - cargo Package Compare versions

Comparing version 0.1.4 to 0.1.5

.cargo_vcs_info.json

 {
   "git": {
-    "sha1": "969572f1ef4c42fddaff572f07d509598042b341"
+    "sha1": "d991d30ecde2d25b3b7b2293eef3b28e592dfcc1"
   },
   "path_in_vcs": ""
 }

Cargo.toml

@@ -15,3 +15,3 @@ # THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
 name = "append-only-vec"
-version = "0.1.4"
+version = "0.1.5"
 authors = ["David Roundy <[e-mail]>"]
@@ -18,0 +18,0 @@ description = "Append-only, concurrent vector"

src/lib.rs

@@ -38,3 +38,3 @@ //! AppendOnlyVec
 use std::cell::UnsafeCell;
-use std::ops::Index;
+use std::ops::{Index, IndexMut};
 use std::sync::atomic::AtomicUsize;
@@ -217,3 +217,3 @@ use std::sync::atomic::Ordering;
 
-            // Copy the element value. The copy remaining in the array must not 
+            // Copy the element value. The copy remaining in the array must not
             // be used again (i.e. make sure we do not drop it)
@@ -240,2 +240,3 @@ let value = unsafe { ptr.add(offset).read() };
 }
+
 impl<T> Index<usize> for AppendOnlyVec<T> {
@@ -256,2 +257,18 @@ type Output = T;
 
+impl<T> IndexMut<usize> for AppendOnlyVec<T> {
+    fn index_mut(&mut self, idx: usize) -> &mut Self::Output {
+        assert!(idx < self.len()); // this includes the required ordering memory barrier
+        let (array, offset) = indices(idx);
+        // The ptr value below is safe, because the length check above will
+        // ensure that the data we want is already visible, since it used
+        // Ordering::Acquire on `self.count` which synchronizes with the
+        // Ordering::Release write in `self.push`.
+        let ptr = unsafe { *self.data[array as usize].get() };
+
+        // `&mut` is safe because there can be no access to data owned by
+        // `self` except via `self`, and we have `&mut` on `self`
+        unsafe { &mut *ptr.add(offset) }
+    }
+}
+
 impl<T> Drop for AppendOnlyVec<T> {
@@ -387,1 +404,15 @@ fn drop(&mut self) {
 }
+
+#[test]
+fn test_push_then_index_mut() {
+    let mut v = AppendOnlyVec::<usize>::new();
+    for i in 0..1024 {
+        v.push(i);
+    }
+    for i in 0..1024 {
+        v[i] += i;
+    }
+    for i in 0..1024 {
+        assert_eq!(v[i], 2 * i);
+    }
+}

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