1 files changed, 171 insertions, 0 deletions
diff --git a/toolkit/components/glean/api/src/private/uuid.rs b/toolkit/components/glean/api/src/private/uuid.rs
new file mode 100644
index 0000000000..101a1a9875
--- /dev/null
+++ b/toolkit/components/glean/api/src/private/uuid.rs
@@ -0,0 +1,171 @@
+// 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 uuid::Uuid;
+
+use super::{CommonMetricData, MetricId};
+
+use crate::ipc::need_ipc;
+
+/// A UUID metric.
+///
+/// Stores UUID values.
+pub enum UuidMetric {
+    Parent(glean::private::UuidMetric),
+    Child(UuidMetricIpc),
+}
+
+#[derive(Debug)]
+pub struct UuidMetricIpc;
+
+impl UuidMetric {
+    /// Create a new UUID metric.
+    pub fn new(_id: MetricId, meta: CommonMetricData) -> Self {
+        if need_ipc() {
+            UuidMetric::Child(UuidMetricIpc)
+        } else {
+            UuidMetric::Parent(glean::private::UuidMetric::new(meta))
+        }
+    }
+
+    #[cfg(test)]
+    pub(crate) fn child_metric(&self) -> Self {
+        match self {
+            UuidMetric::Parent(_) => UuidMetric::Child(UuidMetricIpc),
+            UuidMetric::Child(_) => panic!("Can't get a child metric from a child metric"),
+        }
+    }
+}
+
+#[inherent]
+impl glean::traits::Uuid for UuidMetric {
+    /// Set to the specified value.
+    ///
+    /// ## Arguments
+    ///
+    /// * `value` - The UUID to set the metric to.
+    pub fn set(&self, value: Uuid) {
+        match self {
+            UuidMetric::Parent(p) => p.set(value.to_string()),
+            UuidMetric::Child(_c) => {
+                log::error!("Unable to set the uuid metric in non-main process. This operation will be ignored.");
+                // If we're in automation we can panic so the instrumentor knows they've gone wrong.
+                // This is a deliberate violation of Glean's "metric APIs must not throw" design.
+                assert!(!crate::ipc::is_in_automation(), "Attempted to set uuid metric in non-main process, which is forbidden. This panics in automation.");
+                // TODO: Record an error.
+            }
+        };
+    }
+
+    /// Generate a new random UUID and set the metric to it.
+    ///
+    /// ## Return value
+    ///
+    /// Returns the stored UUID value or `Uuid::nil` if called from
+    /// a non-main process.
+    pub fn generate_and_set(&self) -> Uuid {
+        match self {
+            UuidMetric::Parent(p) => Uuid::parse_str(&p.generate_and_set()).unwrap(),
+            UuidMetric::Child(_c) => {
+                log::error!("Unable to set the uuid metric in non-main process. This operation will be ignored.");
+                // If we're in automation we can panic so the instrumentor knows they've gone wrong.
+                // This is a deliberate violation of Glean's "metric APIs must not throw" design.
+                assert!(!crate::ipc::is_in_automation(), "Attempted to set uuid metric in non-main process, which is forbidden. This panics in automation.");
+                // TODO: Record an error.
+                Uuid::nil()
+            }
+        }
+    }
+
+    /// **Test-only API.**
+    ///
+    /// Get the stored UUID value.
+    /// This doesn't clear the stored value.
+    ///
+    /// ## Arguments
+    ///
+    /// * `storage_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, storage_name: S) -> Option<Uuid> {
+        let storage_name = storage_name.into().map(|s| s.to_string());
+        match self {
+            UuidMetric::Parent(p) => p
+                .test_get_value(storage_name)
+                .and_then(|s| Uuid::parse_str(&s).ok()),
+            UuidMetric::Child(_c) => panic!("Cannot get test value for in non-main process!"),
+        }
+    }
+
+    /// **Exported for test purposes.**
+    ///
+    /// 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 {
+            UuidMetric::Parent(p) => p.test_get_num_recorded_errors(error),
+            UuidMetric::Child(_c) => {
+                panic!("Cannot get test value for UuidMetric in non-main process!")
+            }
+        }
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use crate::{common_test::*, ipc, metrics};
+
+    #[test]
+    fn sets_uuid_value() {
+        let _lock = lock_test();
+
+        let metric = &metrics::test_only_ipc::a_uuid;
+        let expected = Uuid::new_v4();
+        metric.set(expected.clone());
+
+        assert_eq!(expected, metric.test_get_value("store1").unwrap());
+    }
+
+    #[test]
+    fn uuid_ipc() {
+        // UuidMetric doesn't support IPC.
+        let _lock = lock_test();
+
+        let parent_metric = &metrics::test_only_ipc::a_uuid;
+        let expected = Uuid::new_v4();
+        parent_metric.set(expected.clone());
+
+        {
+            let child_metric = parent_metric.child_metric();
+
+            // Instrumentation calls do not panic.
+            child_metric.set(Uuid::new_v4());
+
+            // (They also shouldn't do anything,
+            // but that's not something we can inspect in this test)
+        }
+
+        assert!(ipc::replay_from_buf(&ipc::take_buf().unwrap()).is_ok());
+
+        assert_eq!(
+            expected,
+            parent_metric.test_get_value("store1").unwrap(),
+            "UUID metrics should only work in the parent process"
+        );
+    }
+}