1 files changed, 179 insertions, 0 deletions
diff --git a/toolkit/components/glean/api/src/private/labeled_counter.rs b/toolkit/components/glean/api/src/private/labeled_counter.rs
new file mode 100644
index 0000000000..73a6697601
--- /dev/null
+++ b/toolkit/components/glean/api/src/private/labeled_counter.rs
@@ -0,0 +1,179 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at https://mozilla.org/MPL/2.0/.
+
+use inherent::inherent;
+
+use glean::traits::Counter;
+
+use super::CommonMetricData;
+
+use crate::ipc::{need_ipc, with_ipc_payload};
+use crate::private::{CounterMetric, MetricId};
+use std::collections::HashMap;
+
+/// A counter metric that knows it's a labeled counter's submetric.
+///
+/// It has special work to do when in a non-parent process.
+/// When on the parent process, it dispatches calls to the normal CounterMetric.
+#[derive(Clone)]
+pub enum LabeledCounterMetric {
+    Parent(CounterMetric),
+    Child { id: MetricId, label: String },
+}
+
+impl LabeledCounterMetric {
+    /// Create a new labeled counter submetric.
+    pub fn new(id: MetricId, meta: CommonMetricData, label: String) -> Self {
+        if need_ipc() {
+            LabeledCounterMetric::Child { id, label }
+        } else {
+            LabeledCounterMetric::Parent(CounterMetric::new(id, meta))
+        }
+    }
+
+    #[cfg(test)]
+    pub(crate) fn metric_id(&self) -> MetricId {
+        match self {
+            LabeledCounterMetric::Parent(p) => p.metric_id(),
+            LabeledCounterMetric::Child { id, .. } => *id,
+        }
+    }
+}
+
+#[inherent]
+impl Counter for LabeledCounterMetric {
+    /// Increase the counter by `amount`.
+    ///
+    /// ## Arguments
+    ///
+    /// * `amount` - The amount to increase by. Should be positive.
+    ///
+    /// ## Notes
+    ///
+    /// Logs an error if the `amount` is 0 or negative.
+    pub fn add(&self, amount: i32) {
+        match self {
+            LabeledCounterMetric::Parent(p) => p.add(amount),
+            LabeledCounterMetric::Child { id, label } => {
+                with_ipc_payload(move |payload| {
+                    if let Some(map) = payload.labeled_counters.get_mut(id) {
+                        if let Some(v) = map.get_mut(label) {
+                            *v += amount;
+                        } else {
+                            map.insert(label.to_string(), amount);
+                        }
+                    } else {
+                        let mut map = HashMap::new();
+                        map.insert(label.to_string(), amount);
+                        payload.labeled_counters.insert(*id, map);
+                    }
+                });
+            }
+        }
+    }
+
+    /// **Test-only API.**
+    ///
+    /// Get the currently stored value as an integer.
+    /// This doesn't clear the stored value.
+    ///
+    /// ## Arguments
+    ///
+    /// * `ping_name` - the storage name to look into.
+    ///
+    /// ## Return value
+    ///
+    /// Returns the stored value or `None` if nothing stored.
+    pub fn test_get_value<'a, S: Into<Option<&'a str>>>(&self, ping_name: S) -> Option<i32> {
+        match self {
+            LabeledCounterMetric::Parent(p) => p.test_get_value(ping_name),
+            LabeledCounterMetric::Child { id, .. } => {
+                panic!("Cannot get test value for {:?} in non-parent process!", id)
+            }
+        }
+    }
+
+    /// **Test-only API.**
+    ///
+    /// Gets the number of recorded errors for the given metric and error type.
+    ///
+    /// # Arguments
+    ///
+    /// * `error` - The type of error
+    /// * `ping_name` - represents the optional name of the ping to retrieve the
+    ///   metric for. Defaults to the first value in `send_in_pings`.
+    ///
+    /// # Returns
+    ///
+    /// The number of errors reported.
+    pub fn test_get_num_recorded_errors(&self, error: glean::ErrorType) -> i32 {
+        match self {
+            LabeledCounterMetric::Parent(p) => p.test_get_num_recorded_errors(error),
+            LabeledCounterMetric::Child { id, .. } => panic!(
+                "Cannot get the number of recorded errors for {:?} in non-parent process!",
+                id
+            ),
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use crate::{common_test::*, ipc, metrics};
+
+    #[test]
+    fn sets_labeled_counter_value_parent() {
+        let _lock = lock_test();
+
+        let metric = &metrics::test_only_ipc::a_labeled_counter;
+        metric.get("a_label").add(1);
+
+        assert_eq!(1, metric.get("a_label").test_get_value("store1").unwrap());
+    }
+
+    #[test]
+    fn sets_labeled_counter_value_child() {
+        let _lock = lock_test();
+
+        let label = "some_label";
+
+        let parent_metric = &metrics::test_only_ipc::a_labeled_counter;
+        parent_metric.get(label).add(3);
+
+        {
+            // scope for need_ipc RAII
+            let _raii = ipc::test_set_need_ipc(true);
+            let child_metric = parent_metric.get(label);
+
+            let metric_id = child_metric.metric_id();
+
+            child_metric.add(42);
+
+            ipc::with_ipc_payload(move |payload| {
+                assert_eq!(
+                    42,
+                    *payload
+                        .labeled_counters
+                        .get(&metric_id)
+                        .unwrap()
+                        .get(label)
+                        .unwrap(),
+                    "Stored the correct value in the ipc payload"
+                );
+            });
+        }
+
+        assert!(
+            false == ipc::need_ipc(),
+            "RAII dropped, should not need ipc any more"
+        );
+        assert!(ipc::replay_from_buf(&ipc::take_buf().unwrap()).is_ok());
+
+        assert_eq!(
+            45,
+            parent_metric.get(label).test_get_value("store1").unwrap(),
+            "Values from the 'processes' should be summed"
+        );
+    }
+}