1 files changed, 129 insertions, 0 deletions
diff --git a/toolkit/components/glean/src/init/user_activity.rs b/toolkit/components/glean/src/init/user_activity.rs
new file mode 100644
index 0000000000..dbafeca4e8
--- /dev/null
+++ b/toolkit/components/glean/src/init/user_activity.rs
@@ -0,0 +1,129 @@
+// 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 std::ffi::CStr;
+use std::os::raw::c_char;
+use std::sync::{
+    atomic::{AtomicBool, Ordering},
+    RwLock,
+};
+use std::time::{Duration, Instant};
+
+use nserror::{nsresult, NS_ERROR_FAILURE, NS_OK};
+use xpcom::{
+    interfaces::{nsIObserverService, nsISupports},
+    RefPtr,
+};
+
+// Partially cargo-culted from UploadPrefObserver.
+#[xpcom(implement(nsIObserver), atomic)]
+pub(crate) struct UserActivityObserver {
+    last_edge: RwLock<Instant>,
+    was_active: AtomicBool,
+}
+
+/// Listens to Firefox Desktop's `user-interaction-(in)active` topics,
+/// debouncing them before calling into the Glean SDK Client Activity API.
+/// See
+/// [the docs](https://firefox-source-docs.mozilla.org/toolkit/components/glean/builtin_pings.html)
+/// for more info.
+#[allow(non_snake_case)]
+impl UserActivityObserver {
+    pub(crate) fn begin_observing() -> Result<(), nsresult> {
+        // First and foremost, even if we can't get the ObserverService,
+        // init always means client activity.
+        glean::handle_client_active();
+
+        // SAFETY: Everything here is self-contained.
+        //
+        // * We allocate the activity observer, created by the xpcom macro
+        // * We create cstr from a static string.
+        // * We control all input to `AddObserver`
+        unsafe {
+            let activity_obs = Self::allocate(InitUserActivityObserver {
+                last_edge: RwLock::new(Instant::now()),
+                was_active: AtomicBool::new(false),
+            });
+            let obs_service: RefPtr<nsIObserverService> =
+                xpcom::components::Observer::service().map_err(|_| NS_ERROR_FAILURE)?;
+            let rv = obs_service.AddObserver(
+                activity_obs.coerce(),
+                cstr!("user-interaction-active").as_ptr(),
+                false,
+            );
+            if !rv.succeeded() {
+                return Err(rv);
+            }
+            let rv = obs_service.AddObserver(
+                activity_obs.coerce(),
+                cstr!("user-interaction-inactive").as_ptr(),
+                false,
+            );
+            if !rv.succeeded() {
+                return Err(rv);
+            }
+        }
+        Ok(())
+    }
+
+    unsafe fn Observe(
+        &self,
+        _subject: *const nsISupports,
+        topic: *const c_char,
+        _data: *const u16,
+    ) -> nserror::nsresult {
+        match CStr::from_ptr(topic).to_str() {
+            Ok("user-interaction-active") => self.handle_active(),
+            Ok("user-interaction-inactive") => self.handle_inactive(),
+            _ => NS_OK,
+        }
+    }
+
+    fn handle_active(&self) -> nserror::nsresult {
+        let was_active = self.was_active.swap(true, Ordering::SeqCst);
+        if !was_active {
+            let inactivity = self
+                .last_edge
+                .read()
+                .expect("Edge lock poisoned.")
+                .elapsed();
+            // We only care after a certain period of inactivity (default 20min).
+            let limit = static_prefs::pref!("telemetry.fog.test.inactivity_limit");
+            if inactivity >= Duration::from_secs(limit.into()) {
+                log::info!(
+                    "User triggers core activity after {}s!",
+                    inactivity.as_secs()
+                );
+                glean::handle_client_active();
+            }
+            let mut edge = self.last_edge.write().expect("Edge lock poisoned.");
+            *edge = Instant::now();
+        }
+        NS_OK
+    }
+
+    fn handle_inactive(&self) -> nserror::nsresult {
+        let was_active = self.was_active.swap(false, Ordering::SeqCst);
+        // This is actually always so. Inactivity is only notified once.
+        if was_active {
+            let activity = self
+                .last_edge
+                .read()
+                .expect("Edge lock poisoned.")
+                .elapsed();
+            // We only care after a certain period of activity (default 2min).
+            let limit = static_prefs::pref!("telemetry.fog.test.activity_limit");
+            if activity >= Duration::from_secs(limit.into()) {
+                log::info!(
+                    "User triggers core inactivity after {}s!",
+                    activity.as_secs()
+                );
+                glean::handle_client_inactive();
+            }
+            let mut edge = self.last_edge.write().expect("Edge lock poisoned.");
+            *edge = Instant::now();
+        }
+        NS_OK
+    }
+}