From 204d65ad050ba14bb44fce93fba537c0cb87eed1 Mon Sep 17 00:00:00 2001
From: Pekka Enberg <penberg@iki.fi>
Date: Thu, 13 Apr 2023 10:09:23 +0300
Subject: [PATCH] Move clock code to `clock.rs`

---
 core/mvcc/database/src/database.rs           | 27 ++------------------
 core/mvcc/database/src/lib.rs                |  1 +
 core/mvcc/database/tests/concurrency_test.rs |  3 ++-
 3 files changed, 5 insertions(+), 26 deletions(-)

diff --git a/core/mvcc/database/src/database.rs b/core/mvcc/database/src/database.rs
index 837df7ef1..14f11e252 100644
--- a/core/mvcc/database/src/database.rs
+++ b/core/mvcc/database/src/database.rs
@@ -1,3 +1,4 @@
+use crate::clock::LogicalClock;
 use crate::errors::DatabaseError;
 use std::cell::RefCell;
 use std::collections::{HashMap, HashSet};
@@ -86,31 +87,6 @@ pub struct Database<Clock: LogicalClock> {
 
 type TxID = u64;
 
-/// Logical clock.
-pub trait LogicalClock {
-    fn get_timestamp(&self) -> u64;
-}
-
-/// A node-local clock backed by an atomic counter.
-#[derive(Debug, Default)]
-pub struct LocalClock {
-    ts_sequence: AtomicU64,
-}
-
-impl LocalClock {
-    pub fn new() -> Self {
-        Self {
-            ts_sequence: AtomicU64::new(0),
-        }
-    }
-}
-
-impl LogicalClock for LocalClock {
-    fn get_timestamp(&self) -> u64 {
-        self.ts_sequence.fetch_add(1, Ordering::SeqCst)
-    }
-}
-
 #[derive(Debug)]
 pub struct DatabaseInner<Clock: LogicalClock> {
     rows: RefCell<HashMap<u64, Vec<RowVersion>>>,
@@ -441,6 +417,7 @@ fn is_end_visible(txs: &HashMap<TxID, Transaction>, tx: &Transaction, rv: &RowVe
 #[cfg(test)]
 mod tests {
     use super::*;
+    use crate::clock::LocalClock;
 
     #[test]
     fn test_insert_read() {
diff --git a/core/mvcc/database/src/lib.rs b/core/mvcc/database/src/lib.rs
index e5ad14df6..a3b2e105f 100644
--- a/core/mvcc/database/src/lib.rs
+++ b/core/mvcc/database/src/lib.rs
@@ -31,5 +31,6 @@
 //! * Optimistic reads and writes
 //! * Garbage collection
 
+pub mod clock;
 pub mod database;
 pub mod errors;
diff --git a/core/mvcc/database/tests/concurrency_test.rs b/core/mvcc/database/tests/concurrency_test.rs
index b18e9a9bd..bc1e4f90a 100644
--- a/core/mvcc/database/tests/concurrency_test.rs
+++ b/core/mvcc/database/tests/concurrency_test.rs
@@ -1,4 +1,5 @@
-use mvcc_rs::database::{Database, LocalClock, Row};
+use mvcc_rs::clock::LocalClock;
+use mvcc_rs::database::{Database, Row};
 use shuttle::sync::atomic::AtomicU64;
 use shuttle::sync::Arc;
 use shuttle::thread;