Add in the tests

aeron-rs/src/client/concurrent/broadcast.rs

@@ -11,11 +11,14 @@ pub mod buffer_descriptor {
     use crate::util::{AeronError, IndexT, Result};
     use std::mem::size_of;
 
-    pub(super) const TAIL_INTENT_COUNTER_OFFSET: IndexT = 0;
-    pub(super) const TAIL_COUNTER_OFFSET: IndexT =
-        TAIL_INTENT_COUNTER_OFFSET + size_of::<i64>() as IndexT;
-    pub(super) const LATEST_COUNTER_OFFSET: IndexT =
-        TAIL_COUNTER_OFFSET + size_of::<i64>() as IndexT;
+    /// Offset within the trailer for the tail intended value
+    pub const TAIL_INTENT_COUNTER_OFFSET: IndexT = 0;
+
+    /// Offset within the trailer for the tail value
+    pub const TAIL_COUNTER_OFFSET: IndexT = TAIL_INTENT_COUNTER_OFFSET + size_of::<i64>() as IndexT;
+
+    /// Offset within the buffer trailer for the latest sequence value
+    pub const LATEST_COUNTER_OFFSET: IndexT = TAIL_COUNTER_OFFSET + size_of::<i64>() as IndexT;
 
     /// Size of the broadcast buffer metadata trailer
     pub const TRAILER_LENGTH: IndexT = CACHE_LINE_LENGTH as IndexT * 2;
@@ -95,10 +98,10 @@ where
     pub fn new(buffer: A) -> Result<Self> {
         let capacity = buffer.capacity() - buffer_descriptor::TRAILER_LENGTH;
         buffer_descriptor::check_capacity(capacity)?;
+        let mask = capacity - 1;
 
         let latest_counter_index = capacity + buffer_descriptor::LATEST_COUNTER_OFFSET;
         let cursor = buffer.get_i64(latest_counter_index)?;
-        let mask = capacity - 1;
 
         Ok(BroadcastReceiver {
             buffer,
@@ -136,8 +139,8 @@ where
         let mut cursor: i64 = self.next_record;
 
         if tail > cursor {
-            // The way we set `record_offset` is slightly different from C++;
-            // Clippy was yelling at me, and I think this makes more sense.
+            // NOTE: C++ and Java clients do these first lines slightly differently. As far
+            // as I can tell, this is structurally equivalent, and Clippy yells less at me.
             if !self._validate(cursor) {
                 self.lapped_count.fetch_add(1, Ordering::SeqCst);
                 cursor = self.buffer.get_i64(self.latest_counter_index)?;

aeron-rs/tests/broadcast_receiver.rs

@@ -1,12 +1,22 @@
-use aeron_rs::client::concurrent::broadcast::{buffer_descriptor, BroadcastReceiver};
+use aeron_rs::client::concurrent::broadcast::{
+    buffer_descriptor, record_descriptor, BroadcastReceiver,
+};
+use aeron_rs::client::concurrent::AtomicBuffer;
+use aeron_rs::util::bit::align;
 use aeron_rs::util::IndexT;
 
 const CAPACITY: usize = 1024;
 const TOTAL_BUFFER_LENGTH: usize = CAPACITY + buffer_descriptor::TRAILER_LENGTH as usize;
+const MSG_TYPE_ID: i32 = 7;
+const TAIL_INTENT_COUNTER_INDEX: i32 =
+    CAPACITY as i32 + buffer_descriptor::TAIL_INTENT_COUNTER_OFFSET;
+const TAIL_COUNTER_INDEX: i32 = CAPACITY as i32 + buffer_descriptor::TAIL_COUNTER_OFFSET;
+const LATEST_COUNTER_INDEX: i32 = CAPACITY as i32 + buffer_descriptor::LATEST_COUNTER_OFFSET;
 
 // NOTE: The C++ tests use a mock atomic buffer for testing to validate behavior.
-// This is rather hard to do with Rust, so we skip behavior validation for now,
-// and assume that other tests will end up verifying needed behavior.
+// I haven't implemented this in Rust mostly because it's a great deal of work,
+// but it means we're not verifying that BroadcastReceiver uses the properly
+// synchronized method calls on the underlying buffer.
 
 #[test]
 fn should_calculate_capacity_for_buffer() {
@@ -32,3 +42,152 @@ fn should_not_receive_from_empty_buffer() {
     let mut receiver = BroadcastReceiver::new(vec![0u8; TOTAL_BUFFER_LENGTH]).unwrap();
     assert_eq!(receiver.receive_next(), Ok(false));
 }
+
+#[test]
+fn should_receive_first_message_from_buffer() {
+    let length: i32 = 8;
+    let record_length: i32 = length + record_descriptor::HEADER_LENGTH;
+    let aligned_record_length: i32 = align(
+        record_length as usize,
+        record_descriptor::RECORD_ALIGNMENT as usize,
+    ) as i32;
+    let tail = aligned_record_length as i64;
+    let latest_record = tail - aligned_record_length as i64;
+    let record_offset = latest_record as i32;
+
+    let mut buffer = vec![0u8; TOTAL_BUFFER_LENGTH];
+    buffer.put_i64(TAIL_COUNTER_INDEX, tail).unwrap();
+    buffer.put_i64(TAIL_INTENT_COUNTER_INDEX, tail).unwrap();
+    buffer
+        .put_i32(
+            record_descriptor::length_offset(record_offset),
+            record_length,
+        )
+        .unwrap();
+    buffer
+        .put_i32(record_descriptor::type_offset(record_offset), MSG_TYPE_ID)
+        .unwrap();
+
+    let mut receiver = BroadcastReceiver::new(buffer).unwrap();
+    assert_eq!(receiver.receive_next(), Ok(true));
+    assert_eq!(receiver.msg_type_id(), Ok(MSG_TYPE_ID));
+    assert_eq!(
+        receiver.offset(),
+        record_descriptor::msg_offset(record_offset)
+    );
+    assert_eq!(receiver.length(), Ok(length));
+    assert!(receiver.validate());
+}
+
+#[test]
+fn should_receive_two_messages_from_buffer() {
+    let length: i32 = 8;
+    let record_length: i32 = length + record_descriptor::HEADER_LENGTH;
+    let aligned_record_length: i32 = align(
+        record_length as usize,
+        record_descriptor::RECORD_ALIGNMENT as usize,
+    ) as i32;
+    let tail = (aligned_record_length * 2) as i64;
+    let latest_record = tail - aligned_record_length as i64;
+    let record_offset_one = 0;
+    let record_offset_two = latest_record as i32;
+
+    let mut buffer = vec![0u8; TOTAL_BUFFER_LENGTH];
+    buffer.put_i64(TAIL_COUNTER_INDEX, tail).unwrap();
+    buffer.put_i64(TAIL_INTENT_COUNTER_INDEX, tail).unwrap();
+
+    buffer
+        .put_i32(
+            record_descriptor::length_offset(record_offset_one),
+            record_length,
+        )
+        .unwrap();
+    buffer
+        .put_i32(
+            record_descriptor::type_offset(record_offset_one),
+            MSG_TYPE_ID,
+        )
+        .unwrap();
+
+    buffer
+        .put_i32(
+            record_descriptor::length_offset(record_offset_two),
+            record_length,
+        )
+        .unwrap();
+    buffer
+        .put_i32(
+            record_descriptor::type_offset(record_offset_two),
+            MSG_TYPE_ID,
+        )
+        .unwrap();
+
+    let mut receiver = BroadcastReceiver::new(buffer).unwrap();
+    assert_eq!(receiver.receive_next(), Ok(true));
+    assert_eq!(receiver.msg_type_id(), Ok(MSG_TYPE_ID));
+    assert_eq!(
+        receiver.offset(),
+        record_descriptor::msg_offset(record_offset_one)
+    );
+    assert_eq!(receiver.length(), Ok(length));
+    assert!(receiver.validate());
+
+    assert_eq!(receiver.receive_next(), Ok(true));
+    assert_eq!(receiver.msg_type_id(), Ok(MSG_TYPE_ID));
+    assert_eq!(
+        receiver.offset(),
+        record_descriptor::msg_offset(record_offset_two)
+    );
+    assert_eq!(receiver.length(), Ok(length));
+    assert!(receiver.validate());
+}
+
+#[test]
+fn should_late_join_transmission() {
+    let length: i32 = 8;
+    let record_length: i32 = length + record_descriptor::HEADER_LENGTH;
+    let aligned_record_length: i32 = align(
+        record_length as usize,
+        record_descriptor::RECORD_ALIGNMENT as usize,
+    ) as i32;
+    let tail = (CAPACITY * 3) as i64
+        + record_descriptor::HEADER_LENGTH as i64
+        + aligned_record_length as i64;
+    let latest_record = tail - aligned_record_length as i64;
+    let record_offset = latest_record as i32 & (CAPACITY - 1) as i32;
+
+    let mut buffer = vec![0u8; TOTAL_BUFFER_LENGTH];
+    // In order to properly do this test, we have to initialize the broadcast receiver
+    // while the buffer is empty, and then write into the buffer afterward. Rust is understandably
+    // not happy about that, but that's the price we pay for not dealing with mocking.
+    let receiver_buffer =
+        unsafe { ::std::slice::from_raw_parts_mut(buffer.as_mut_ptr(), buffer.len()) };
+    let mut receiver = BroadcastReceiver::new(receiver_buffer).unwrap();
+
+    buffer.put_i64(TAIL_COUNTER_INDEX, tail).unwrap();
+    buffer.put_i64(TAIL_INTENT_COUNTER_INDEX, tail).unwrap();
+    buffer.put_i64(LATEST_COUNTER_INDEX, latest_record).unwrap();
+
+    buffer
+        .put_i32(
+            record_descriptor::length_offset(record_offset),
+            record_length,
+        )
+        .unwrap();
+    buffer
+        .put_i32(record_descriptor::type_offset(record_offset), MSG_TYPE_ID)
+        .unwrap();
+
+    assert_eq!(receiver.receive_next(), Ok(true));
+    assert_eq!(receiver.msg_type_id(), Ok(MSG_TYPE_ID));
+    assert_eq!(
+        receiver.offset(),
+        record_descriptor::msg_offset(record_offset)
+    );
+    assert_eq!(receiver.length(), Ok(length));
+    assert!(receiver.validate());
+    assert!(receiver.lapped_count() > 0);
+}
+
+// TODO: Implement the rest of the tests
+// Currently not done because of the need to mock the AtomicBuffer