Remove `Sync` marker for Reader/Writer.v0.3.0

These are not sync, as they can only be used from one thread at a
time.

Also add a `Send` trait for `RingBuffer`, as long as its element type
is also `Send`.

3 files changed, 8 insertions, 4 deletions

diff --git a/Cargo.toml b/Cargo.toml
index 28e5c6b..bebb670 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,7 +1,7 @@
 [package]
 name = "starb"
 description = "STAtic Ring Buffers."
-version = "0.2.0"
+version = "0.3.0"
 authors = ["Brian Cully <bjc@kublai.com>"]
 edition = "2018"
 license = "LGPL-3.0-or-later"
diff --git a/Changelog.org b/Changelog.org
index 93327cc..74c731f 100644
--- a/Changelog.org
+++ b/Changelog.org
@@ -1,5 +1,10 @@
-* Since 0.1
+* Since 0.2
+  - API CHANGE: The `Reader` and `Writer` types were inadvertently
+    marked `Sync` when they are not. While you may read and write from
+    separate threads safely, it is neither safe to read from two
+    threads or more threads nor write from two or more threads.
 
+* Since 0.1
   - API CHANGE: `RingBuffer::new()` no longer takes an argument.
   - `Copy` trait is no longer required on most `RingBuffer` methods.
   - Added two methods for bulk copying data in/out of the ring buffer:
diff --git a/src/lib.rs b/src/lib.rs
index 254d833..96a947b 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -73,6 +73,7 @@ impl<T> RingBuffer<T> {
         (rbr, rbw)
     }
 }
+unsafe impl<T> Send for RingBuffer<T> where T: Send {}
 
 /// Consumer of `RingBuffer`.
 pub struct Reader<'a, T> {
@@ -80,7 +81,6 @@ pub struct Reader<'a, T> {
     _marker: PhantomData<&'a ()>,
 }
 unsafe impl<T> Send for Reader<'_, T> where T: Send {}
-unsafe impl<T> Sync for Reader<'_, T> {}
 
 /// Producer for `Ringbuffer`.
 pub struct Writer<'a, T> {
@@ -88,7 +88,6 @@ pub struct Writer<'a, T> {
     _marker: PhantomData<&'a ()>,
 }
 unsafe impl<T> Send for Writer<'_, T> where T: Send {}
-unsafe impl<T> Sync for Writer<'_, T> {}
 
 impl<T> Reader<'_, T> {
     /// The number of elements currently available for reading.