Bug 1591564 - Initialize the Glean SDK off the main thread r=janerik

Glean init does some I/O which is forbidden on the main thread (especially
during startup). Though not recommended for mobile platforms, let's init it
off the main thread.

Later versions of the Glean SDK might take care of off-thread I/O during init.
But for now, let's do it ourselves.

Depends on D59532

Differential Revision: https://phabricator.services.mozilla.com/D59760

--HG--
extra : moz-landing-system : lando

toolkit/components/telemetry/fog/src/lib.rs

@@ -23,26 +23,37 @@ use xpcom::RefPtr;
 pub unsafe extern "C" fn fog_init(data_dir: &nsAString, pingsender_path: &nsAString) -> nsresult {
     let upload_enabled = static_prefs::pref!("datareporting.healthreport.uploadEnabled");
 
-    let cfg = Configuration {
-        data_path: data_dir.to_string(),
-        application_id: "org.mozilla.fogotype".into(),
-        upload_enabled,
-        max_events: None,
-        delay_ping_lifetime_io: false, // We will want this eventually.
-        channel: Some("nightly".into()),
-    };
+    let pingsender_path = pingsender_path.to_string();
+    let data_dir = data_dir.to_string();
+    if thread::Builder::new()
+        .name("fogotype_init".to_owned())
+        .spawn(move || {
+            let cfg = Configuration {
+                data_path: data_dir.clone(),
+                application_id: "org.mozilla.fogotype".into(),
+                upload_enabled,
+                max_events: None,
+                delay_ping_lifetime_io: false, // We will want this eventually.
+                channel: Some("nightly".into()),
+            };
 
-    // TODO: Build our own ClientInfoMetrics instead of using unknown().
-    if glean_preview::initialize(cfg, ClientInfoMetrics::unknown()).is_err() {
-        return NS_ERROR_FAILURE;
-    }
+            // TODO: Build our own ClientInfoMetrics instead of using unknown().
+            if let Err(e) = glean_preview::initialize(cfg, ClientInfoMetrics::unknown()) {
+                error!("Failed to init glean_preview due to {:?}", e);
+                return;
+            }
 
-    let mut data_path = PathBuf::from(data_dir.to_string());
-    data_path.push("pending_pings");
+            let mut data_path = PathBuf::from(data_dir);
+            data_path.push("pending_pings");
 
-    // We ignore the returned JoinHandle for the nonce.
-    // The detached thread will live until this process (the main process) dies.
-    if prototype_ping_init(data_path, pingsender_path).is_err() {
+            // We ignore the returned JoinHandle for the nonce.
+            // The detached thread will live until this process (the main process) dies.
+            if let Err(e) = prototype_ping_init(data_path, pingsender_path) {
+                error!("Failed to init fogtotype prototype ping due to {:?}", e);
+            }
+        })
+        .is_err()
+    {
         return NS_ERROR_FAILURE;
     }
 
@@ -51,9 +62,8 @@ pub unsafe extern "C" fn fog_init(data_dir: &nsAString, pingsender_path: &nsAStr
 
 fn prototype_ping_init(
     ping_dir: PathBuf,
-    pingsender_path: &nsAString,
+    pingsender_path: String,
 ) -> Result<JoinHandle<()>, Error> {
-    let pingsender_path = pingsender_path.to_string();
     thread::Builder::new()
         .name("fogotype_ping".to_owned())
         .spawn(move || {