Finally able to terminate a driver.

Need to write a test for it, but it's working locally.

examples/do_terminate.rs

@@ -6,6 +6,7 @@ use aeron_rs::util::IndexT;
 use memmap::MmapOptions;
 use std::fs::OpenOptions;
 use std::mem::size_of;
+use aeron_rs::client::cnc_descriptor;
 
 fn main() {
     let path = ClientContext::default_aeron_path();
@@ -22,8 +23,8 @@ fn main() {
     println!("MMap len: {}", mmap.len());
 
     // When creating the buffer, we need to offset by the CnC metadata
-    let cnc_metadata_len = size_of::<MetaDataDefinition>();
-    println!("Buffer len: {}", mmap[cnc_metadata_len..].len());
+    let cnc_metadata_len = cnc_descriptor::META_DATA_LENGTH;
+    println!("Buffer start: {}", cnc_metadata_len);
 
     // Read metadata to get buffer length
     let buffer_len = {
@@ -31,6 +32,7 @@ fn main() {
         let metadata = atomic_buffer.overlay::<MetaDataDefinition>(0).unwrap();
         metadata.to_driver_buffer_length
     };
+    println!("Buffer len: {}", buffer_len);
 
     let buffer_end = cnc_metadata_len + buffer_len as usize;
     let atomic_buffer = AtomicBuffer::wrap(&mut mmap[cnc_metadata_len..buffer_end]);
@@ -43,6 +45,7 @@ fn main() {
     let mut source_buffer = AtomicBuffer::wrap(&mut terminate_bytes);
     let client_id = ring_buffer.next_correlation_id();
     source_buffer.put_i64_ordered(0, client_id).unwrap();
+    source_buffer.put_i64_ordered(8, -1).unwrap();
 
     let term_id: i32 = 0x0E;
     ring_buffer

src/client/cnc_descriptor.rs

@@ -19,6 +19,9 @@
 //! +-----------------------------+
 //! ```
 
+use crate::util::bit;
+use std::mem::size_of;
+
 /// The CnC file metadata header. Layout:
 ///
 /// ```text
@@ -61,6 +64,10 @@ pub struct MetaDataDefinition {
     _pid: i64,
 }
 
+/// Length of the metadata block in a CnC file. Note that it's not equivalent
+/// to the actual struct length.
+pub const META_DATA_LENGTH: usize = bit::align_usize(size_of::<MetaDataDefinition>(), bit::CACHE_LINE_LENGTH * 2);
+
 /// Version code for the Aeron CnC file format
 pub const CNC_VERSION: i32 = crate::sematic_version_compose(0, 0, 16);
 

src/client/concurrent/ring_buffer.rs

@@ -5,9 +5,9 @@ use crate::util::{bit, AeronError, IndexT, Result};
 /// Description of the Ring Buffer schema.
 pub mod buffer_descriptor {
     use crate::client::concurrent::atomic_buffer::AtomicBuffer;
-    use crate::util::bit::is_power_of_two;
+    use crate::util::bit::{is_power_of_two, CACHE_LINE_LENGTH};
     use crate::util::AeronError::IllegalArgument;
-    use crate::util::{IndexT, Result, CACHE_LINE_LENGTH};
+    use crate::util::{IndexT, Result};
 
     // QUESTION: Why are these offsets so large when we only ever use i64 types?
 

src/util.rs

@@ -6,9 +6,6 @@
 // QUESTION: Can this just be updated to be `usize` in Rust?
 pub type IndexT = i32;
 
-/// Length of the data blocks used by the CPU cache sub-system in bytes
-pub const CACHE_LINE_LENGTH: usize = 64;
-
 /// Error types from operations in the Aeron client. Synonymous with the exceptions
 /// generated by the C++ client.
 #[derive(Debug, PartialEq)]
@@ -29,6 +26,9 @@ pub mod bit {
     use crate::util::IndexT;
     use num::PrimInt;
 
+    /// Length of the data blocks used by the CPU cache sub-system in bytes
+    pub const CACHE_LINE_LENGTH: usize = 64;
+
     /// Helper method for quick verification that `IndexT` is a positive power of two
     ///
     /// ```rust
@@ -56,4 +56,9 @@ pub mod bit {
     {
         (val + (alignment - T::one())) & !(alignment - T::one())
     }
+
+    /// Align a `usize` value. See `align` for similar functionality on general types.
+    pub const fn align_usize(val: usize, alignment: usize) -> usize {
+        (val + (alignment - 1)) & !(alignment - 1)
+    }
 }