Add getter/setter for checkpoint threshold in LogicalLog

Wire threshold access through Storage

Add checkpoint threshold accessors to MvStore

core/mvcc/database/mod.rs

@@ -2035,6 +2035,10 @@ impl<Clock: LogicalClock> MvStore<Clock> {
     pub fn set_checkpoint_threshold(&self, threshold: u64) {
         self.storage.set_checkpoint_threshold(threshold)
     }
+
+    pub fn checkpoint_threshold(&self) -> u64 {
+        self.storage.checkpoint_threshold()
+    }
 }
 
 /// A write-write conflict happens when transaction T_current attempts to update a

core/mvcc/persistent_storage/logical_log.rs

@@ -235,6 +235,10 @@ impl LogicalLog {
     pub fn set_checkpoint_threshold(&mut self, threshold: u64) {
         self.checkpoint_threshold = threshold;
     }
+
+    pub fn checkpoint_threshold(&self) -> u64 {
+        self.checkpoint_threshold
+    }
 }
 
 pub enum StreamingResult {

core/mvcc/persistent_storage/mod.rs

@@ -49,6 +49,10 @@ impl Storage {
             .unwrap()
             .set_checkpoint_threshold(threshold)
     }
+
+    pub fn checkpoint_threshold(&self) -> u64 {
+        self.logical_log.read().unwrap().checkpoint_threshold()
+    }
 }
 
 impl Debug for Storage {