feat(sdk): Expose the list of tracked users publicly

matrix_sdk/src/client.rs

@@ -14,7 +14,10 @@
 // limitations under the License.
 
 #[cfg(feature = "encryption")]
-use std::io::{Cursor, Write};
+use std::{
+    collections::HashSet,
+    io::{Cursor, Write},
+};
 #[cfg(all(feature = "encryption", not(target_arch = "wasm32")))]
 use std::path::PathBuf;
 use std::{
@@ -716,6 +719,16 @@ impl Client {
         self.base_client.olm_machine().await.map(|o| o.identity_keys().ed25519().to_owned())
     }
 
+    /// Get all the tracked users we know about
+    ///
+    /// Tracked users are users for which we keep the device list of E2EE
+    /// capable devices up to date.
+    #[cfg(feature = "encryption")]
+    #[cfg_attr(feature = "docs", doc(cfg(encryption)))]
+    pub async fn tracked_users(&self) -> HashSet<UserId> {
+        self.base_client.olm_machine().await.map(|o| o.tracked_users()).unwrap_or_default()
+    }
+
     /// Fetches the display name of the owner of the client.
     ///
     /// # Example

matrix_sdk_crypto/src/machine.rs

@@ -14,7 +14,11 @@
 
 #[cfg(feature = "sled_cryptostore")]
 use std::path::Path;
-use std::{collections::BTreeMap, mem, sync::Arc};
+use std::{
+    collections::{BTreeMap, HashSet},
+    mem,
+    sync::Arc,
+};
 
 use dashmap::DashMap;
 use matrix_sdk_common::{
@@ -293,6 +297,11 @@ impl OlmMachine {
         self.store.device_display_name().await
     }
 
+    /// Get all the tracked users we know about
+    pub fn tracked_users(&self) -> HashSet<UserId> {
+        self.store.tracked_users()
+    }
+
     /// Get the outgoing requests that need to be sent out.
     ///
     /// This returns a list of `OutGoingRequest`, those requests need to be sent

matrix_sdk_crypto/src/store/memorystore.rs

@@ -183,6 +183,10 @@ impl CryptoStore for MemoryStore {
         self.users_for_key_query.iter().map(|u| u.clone()).collect()
     }
 
+    fn tracked_users(&self) -> HashSet<UserId> {
+        self.tracked_users.iter().map(|u| u.to_owned()).collect()
+    }
+
     async fn update_tracked_user(&self, user: &UserId, dirty: bool) -> Result<bool> {
         // TODO to prevent a race between the sync and a key query in flight we
         // need to have an additional state to mention that the user changed.

matrix_sdk_crypto/src/store/mod.rs

@@ -584,6 +584,9 @@ pub trait CryptoStore: AsyncTraitDeps {
     /// the tracked users.
     fn users_for_key_query(&self) -> HashSet<UserId>;
 
+    /// Get all tracked users we know about.
+    fn tracked_users(&self) -> HashSet<UserId>;
+
     /// Add an user for tracking.
     ///
     /// Returns true if the user wasn't already tracked, false otherwise.

matrix_sdk_crypto/src/store/sled.rs

@@ -673,6 +673,10 @@ impl CryptoStore for SledStore {
         !self.users_for_key_query_cache.is_empty()
     }
 
+    fn tracked_users(&self) -> HashSet<UserId> {
+        self.tracked_users_cache.to_owned().iter().map(|u| u.clone()).collect()
+    }
+
     fn users_for_key_query(&self) -> HashSet<UserId> {
         #[allow(clippy::map_clone)]
         self.users_for_key_query_cache.iter().map(|u| u.clone()).collect()