Add more iterator methods and unit tests

Author: gabotechs

datafusion/physical-expr-common/src/metrics/mod.rs

@@ -226,12 +226,11 @@ impl MetricsSet {
         self.metrics.push(metric)
     }
 
-    /// Extends the current list of metrics with the provided ones
-    pub fn extend(&mut self, metrics: impl IntoIterator<Item = Arc<Metric>>) {
-        self.metrics.extend(metrics)
-    }
-
     /// Returns an iterator across all metrics
+    #[deprecated(
+        since = "53.1.0",
+        note = "use `IntoIterator for &MetricsSet` instead, e.g. `for m in &metrics_set` or `(&metrics_set).into_iter()`"
+    )]
     pub fn iter(&self) -> impl Iterator<Item = &Arc<Metric>> {
         self.metrics.iter()
     }
@@ -447,6 +446,21 @@ impl IntoIterator for MetricsSet {
     }
 }
 
+impl<'a> IntoIterator for &'a MetricsSet {
+    type Item = &'a Arc<Metric>;
+    type IntoIter = std::slice::Iter<'a, Arc<Metric>>;
+
+    fn into_iter(self) -> Self::IntoIter {
+        self.metrics.iter()
+    }
+}
+
+impl Extend<Arc<Metric>> for MetricsSet {
+    fn extend<I: IntoIterator<Item = Arc<Metric>>>(&mut self, iter: I) {
+        self.metrics.extend(iter);
+    }
+}
+
 impl FromIterator<Arc<Metric>> for MetricsSet {
     fn from_iter<T: IntoIterator<Item = Arc<Metric>>>(iter: T) -> Self {
         Self {
@@ -783,6 +797,52 @@ mod tests {
         };
     }
 
+    #[test]
+    fn test_extend() {
+        let mut metrics = MetricsSet::new();
+        let m1 = Arc::new(Metric::new(MetricValue::OutputRows(Count::new()), None));
+        let m2 = Arc::new(Metric::new(MetricValue::SpillCount(Count::new()), None));
+
+        metrics.extend([Arc::clone(&m1), Arc::clone(&m2)]);
+        assert_eq!(metrics.iter().count(), 2);
+
+        let m3 = Arc::new(Metric::new(MetricValue::SpilledBytes(Count::new()), None));
+        metrics.extend(std::iter::once(Arc::clone(&m3)));
+        assert_eq!(metrics.iter().count(), 3);
+    }
+
+    #[test]
+    fn test_collect() {
+        let m1 = Arc::new(Metric::new(MetricValue::OutputRows(Count::new()), None));
+        let m2 = Arc::new(Metric::new(MetricValue::SpillCount(Count::new()), None));
+
+        let metrics: MetricsSet =
+            vec![Arc::clone(&m1), Arc::clone(&m2)].into_iter().collect();
+        assert_eq!(metrics.iter().count(), 2);
+
+        let empty: MetricsSet = std::iter::empty().collect();
+        assert_eq!(empty.iter().count(), 0);
+    }
+
+    #[test]
+    fn test_into_iterator_by_ref() {
+        let mut metrics = MetricsSet::new();
+        metrics.push(Arc::new(Metric::new(
+            MetricValue::OutputRows(Count::new()),
+            None,
+        )));
+        metrics.push(Arc::new(Metric::new(
+            MetricValue::SpillCount(Count::new()),
+            None,
+        )));
+
+        let mut count = 0;
+        for _m in &metrics {
+            count += 1;
+        }
+        assert_eq!(count, 2);
+    }
+
     #[test]
     fn test_sorted_for_display() {
         let metrics = ExecutionPlanMetricsSet::new();