refactor: address feedback

db/src/access.rs

@@ -242,7 +242,7 @@ impl QueryDatabase for QueryCatalogAccess {
         // When the query token is dropped the query entry's completion time
         // will be set.
         let entry = self.query_log.push(query_type, query_text);
-        QueryCompletedToken::new(move || self.query_log.set_completed(Arc::clone(&entry)))
+        QueryCompletedToken::new(move || self.query_log.set_completed(entry))
     }
 }
 

db/src/query_log.rs

@@ -9,6 +9,9 @@ use std::{
 use parking_lot::Mutex;
 use time::{Time, TimeProvider};
 
+// The query duration used for queries still running.
+const UNCOMPLETED_DURATION: i64 = -1;
+
 /// Information about a single query that was executed
 #[derive(Debug)]
 pub struct QueryLogEntry {
@@ -33,7 +36,7 @@ impl QueryLogEntry {
             query_type,
             query_text,
             issue_time,
-            query_completed_duration: (-1_i64).into(),
+            query_completed_duration: UNCOMPLETED_DURATION.into(),
         }
     }
 
@@ -42,7 +45,7 @@ impl QueryLogEntry {
             .query_completed_duration
             .load(atomic::Ordering::Relaxed)
         {
-            -1 => None,
+            UNCOMPLETED_DURATION => None,
             d => Some(Duration::from_nanos(d as u64)),
         }
     }
@@ -54,7 +57,7 @@ impl QueryLogEntry {
     }
 }
 
-/// Stores a fixed number `QueryExcutions` -- handles locking
+/// Stores a fixed number `QueryExecutions` -- handles locking
 /// internally so can be shared across multiple
 #[derive(Debug)]
 pub struct QueryLog {

query/src/lib.rs

@@ -81,7 +81,7 @@ pub trait QueryChunkMeta: Sized {
 /// a `QueryDatabase`. It is used to trigger side-effects (such as query timing)
 /// on query completion.
 pub struct QueryCompletedToken<'a> {
-    f: Box<dyn Fn() + Send + 'a>,
+    f: Option<Box<dyn FnOnce() + Send + 'a>>,
 }
 
 impl<'a> Debug for QueryCompletedToken<'a> {
@@ -91,14 +91,18 @@ impl<'a> Debug for QueryCompletedToken<'a> {
 }
 
 impl<'a> QueryCompletedToken<'a> {
-    pub fn new(f: impl Fn() + Send + 'a) -> Self {
+    pub fn new(f: impl FnOnce() + Send + 'a) -> Self {
-        Self { f: Box::new(f) }
+        Self {
+            f: Some(Box::new(f)),
+        }
     }
 }
 
 impl<'a> Drop for QueryCompletedToken<'a> {
     fn drop(&mut self) {
-        (self.f)()
+        if let Some(f) = self.f.take() {
+            (f)()
+        }
     }
 }