eds: still not able to resolve sometimes, some AI generated attempts at solving

kordophoned/src/daemon/contact_resolver/eds.rs

@@ -5,7 +5,6 @@ use once_cell::sync::OnceCell;
 use std::collections::HashMap;
 use std::time::Duration;
 use std::sync::Mutex;
-use std::thread;
 
 #[derive(Clone)]
 pub struct EDSContactResolverBackend;
@@ -39,16 +38,40 @@ impl AddressBookHandle {
 /// Obtain the global address-book handle, initialising it on the first call.
 static ADDRESS_BOOK_HANDLE: OnceCell<Mutex<AddressBookHandle>> = OnceCell::new();
 
-fn get_address_book_handle() -> Option<&'static Mutex<AddressBookHandle>> {
-    ADDRESS_BOOK_HANDLE
+/// Check whether a given well-known name currently has an owner on the bus.
+fn name_has_owner(conn: &Connection, name: &str) -> bool {
+    let proxy = conn.with_proxy("org.freedesktop.DBus", "/org/freedesktop/DBus", Duration::from_secs(2));
+    let result: Result<(bool,), _> = proxy.method_call("org.freedesktop.DBus", "NameHasOwner", (name.to_string(),));
+    result.map(|(b,)| b).unwrap_or(false)
+}
+
+/// Returns a fresh handle, ensuring the cached one is still valid. If the backend owning the
+/// address-book disappeared, the cache is cleared and we try to create a new handle.
+fn obtain_handle() -> Option<std::sync::MutexGuard<'static, AddressBookHandle>> {
+    // Initialize cell if necessary.
+    let cell = ADDRESS_BOOK_HANDLE
         .get_or_try_init(|| AddressBookHandle::new().map(Mutex::new))
-        .map_err(|e| {
-            log::debug!(
-                "EDS resolver: failed to initialise address book handle: {}",
-                e
-            );
-        })
-        .ok()
+        .ok()?;
+
+    // Validate existing handle.
+    {
+        let mut guard = cell.lock().ok()?;
+        if !name_has_owner(&guard.connection, &guard.bus_name) {
+            // Try to refresh the handle in-place.
+            match AddressBookHandle::new() {
+                Ok(new_h) => {
+                    *guard = new_h;
+                }
+                Err(e) => {
+                    log::debug!("EDS resolver: failed to refresh address book handle: {}", e);
+                    // keep the stale handle but report failure
+                    return None;
+                }
+            }
+        }
+        // Return guard after ensuring validity.
+        return Some(guard);
+    }
 }
 
 /// Helper that returns a blocking D-Bus session connection. Creating the
@@ -144,22 +167,35 @@ fn open_address_book(
     Ok((object_path, bus_name))
 }
 
+/// Ensure that the backend for the given address-book proxy is opened.
+/// Evolution-Data-Server returns "Backend is not opened yet" until someone
+/// calls the `Open` method once per process.  We ignore any error here
+/// because the backend might already be open.
+fn ensure_address_book_open(proxy: &dbus::blocking::Proxy<&Connection>) {
+    let _: Result<(), _> = proxy.method_call(
+        "org.gnome.evolution.dataserver.AddressBook",
+        "Open",
+        (),
+    );
+}
+
 impl ContactResolverBackend for EDSContactResolverBackend {
     type ContactID = String;
 
     fn resolve_contact_id(&self, address: &str) -> Option<Self::ContactID> {
-        let handle_mutex = match get_address_book_handle() {
+        let handle = match obtain_handle() {
             Some(h) => h,
             None => return None,
         };
 
-        let handle = handle_mutex.lock().unwrap();
         let address_book_proxy = handle.connection.with_proxy(
             &handle.bus_name,
             &handle.object_path,
             Duration::from_secs(60),
         );
 
+        ensure_address_book_open(&address_book_proxy);
+
         let filter = if address.contains('@') {
             format!("(is \"email\" \"{}\")", address)
         } else {
@@ -207,18 +243,19 @@ impl ContactResolverBackend for EDSContactResolverBackend {
     }
 
     fn get_contact_display_name(&self, contact_id: &Self::ContactID) -> Option<String> {
-        let handle_mutex = match get_address_book_handle() {
+        let handle = match obtain_handle() {
             Some(h) => h,
             None => return None,
         };
 
-        let handle = handle_mutex.lock().unwrap();
         let address_book_proxy = handle.connection.with_proxy(
             &handle.bus_name,
             &handle.object_path,
             Duration::from_secs(60),
         );
 
+        ensure_address_book_open(&address_book_proxy);
+
         let vcard_result: Result<(String,), _> = address_book_proxy.method_call(
             "org.gnome.evolution.dataserver.AddressBook",
             "GetContact",