bench: Add the room_list bench.

Example of the output:

```
room_list/sync/10       time:   [3.5673 ms 3.5899 ms 3.6181 ms]
                        thrpt:  [2.7639 Kelem/s 2.7856 Kelem/s 2.8032 Kelem/s]
Found 12 outliers among 100 measurements (12.00%)
  1 (1.00%) low severe
  3 (3.00%) high mild
  8 (8.00%) high severe
room_list/sync/100      time:   [3.6342 ms 3.6667 ms 3.7037 ms]
                        thrpt:  [27.000 Kelem/s 27.273 Kelem/s 27.516 Kelem/s]
Found 12 outliers among 100 measurements (12.00%)
  5 (5.00%) high mild
  7 (7.00%) high severe
room_list/sync/1000     time:   [30.426 ms 30.611 ms 30.810 ms]
                        thrpt:  [32.457 Kelem/s 32.668 Kelem/s 32.867 Kelem/s]
Found 20 outliers among 100 measurements (20.00%)
  13 (13.00%) high mild
  7 (7.00%) high severe
Benchmarking room_list/sync/10000: Warming up for 3.0000 s
Warning: Unable to complete 100 samples in 5.0s. You may wish to increase target time to 35.7s, or reduce sample count to 10.
room_list/sync/10000    time:   [353.56 ms 355.14 ms 356.97 ms]
                        thrpt:  [28.014 Kelem/s 28.158 Kelem/s 28.284 Kelem/s]
Found 5 outliers among 100 measurements (5.00%)
  3 (3.00%) high mild
  2 (2.00%) high severe
```

benchmarks/Cargo.toml

@@ -9,12 +9,14 @@ publish = false
 
 [dependencies]
 criterion = { version = "0.5.1", features = ["async", "async_tokio", "html_reports"] }
+futures-util = { workspace = true }
 matrix-sdk-base = { workspace = true }
 matrix-sdk-crypto = { workspace = true }
 matrix-sdk-sqlite = { workspace = true, features = ["crypto-store"] }
 matrix-sdk-test = { workspace = true }
 matrix-sdk-ui = { workspace = true }
 matrix-sdk = { workspace = true, features = ["native-tls", "e2e-encryption", "sqlite"] }
+matrix-sdk-ui = { workspace = true }
 ruma = { workspace = true }
 serde = { workspace = true }
 serde_json = { workspace = true }
@@ -37,5 +39,9 @@ harness = false
 name = "room_bench"
 harness = false
 
+[[bench]]
+name = "room_list_bench"
+harness = false
+
 [package.metadata.release]
 release = false

benchmarks/benches/room_list_bench.rs

@@ -0,0 +1,176 @@
+use criterion::{criterion_group, criterion_main, BenchmarkId, Criterion, Throughput};
+use futures_util::{pin_mut, StreamExt};
+use matrix_sdk::test_utils::logged_in_client_with_server;
+use matrix_sdk_ui::{room_list_service::filters::new_filter_non_left, RoomListService};
+use serde::Deserialize;
+use serde_json::{json, Map, Value};
+use tokio::runtime::Builder;
+use wiremock::{http::Method, Match, Mock, Request, ResponseTemplate};
+
+struct SlidingSyncMatcher;
+
+impl Match for SlidingSyncMatcher {
+    fn matches(&self, request: &Request) -> bool {
+        request.url.path() == "/_matrix/client/unstable/org.matrix.msc3575/sync"
+            && request.method == Method::POST
+    }
+}
+
+#[derive(Deserialize)]
+pub(crate) struct PartialSlidingSyncRequest {
+    pub txn_id: Option<String>,
+}
+
+fn criterion() -> Criterion {
+    #[cfg(target_os = "linux")]
+    let criterion = Criterion::default().with_profiler(pprof::criterion::PProfProfiler::new(
+        100,
+        pprof::criterion::Output::Flamegraph(None),
+    ));
+
+    #[cfg(not(target_os = "linux"))]
+    let criterion = Criterion::default();
+
+    criterion
+}
+
+pub fn room_list(c: &mut Criterion) {
+    let runtime = Builder::new_multi_thread()
+        .enable_time()
+        .enable_io()
+        .build()
+        .expect("Can't create runtime");
+
+    let mut benchmark = c.benchmark_group("room_list");
+
+    for number_of_rooms in [10, 100, 1000, 10_000] {
+        benchmark.throughput(Throughput::Elements(number_of_rooms));
+        benchmark.bench_with_input(
+            BenchmarkId::new("sync", number_of_rooms),
+            &number_of_rooms,
+            |benchmark, maximum_number_of_rooms| {
+                benchmark.to_async(&runtime).iter(|| async {
+                    // Create a fresh new `Client` and a mocked server.
+                    let (client, server) = logged_in_client_with_server().await;
+
+                    // Create a new `RoomListService`.
+                    let room_list_service = RoomListService::new(client.clone())
+                        .await
+                        .expect("Failed to create the `RoomListService`");
+
+                    // Get the `RoomListService` sync stream.
+                    let room_list_stream = room_list_service.sync();
+                    pin_mut!(room_list_stream);
+
+                    // Get the `RoomList` itself with a default filter.
+                    let room_list = room_list_service
+                        .all_rooms()
+                        .await
+                        .expect("Failed to fetch the `all_rooms` room list");
+                    let (room_list_entries, room_list_entries_controller) = room_list
+                        .entries_with_dynamic_adapters(100, client.roominfo_update_receiver());
+                    pin_mut!(room_list_entries);
+                    room_list_entries_controller.set_filter(Box::new(new_filter_non_left()));
+                    room_list_entries.next().await;
+
+                    // “Send” (mocked) and receive rooms.
+                    {
+                        const ROOMS_BATCH_SIZE: u64 = 100;
+                        let maximum_number_of_rooms = *maximum_number_of_rooms;
+                        let mut number_of_sent_rooms = 0;
+                        let mut room_nth = 0;
+
+                        while number_of_sent_rooms < maximum_number_of_rooms {
+                            let number_of_rooms_to_send = u64::max(
+                                number_of_sent_rooms + ROOMS_BATCH_SIZE,
+                                maximum_number_of_rooms,
+                            ) - number_of_sent_rooms;
+
+                            number_of_sent_rooms += number_of_rooms_to_send;
+
+                            let rooms_as_json = Value::Object(
+                                (0..number_of_rooms_to_send)
+                                    .map(|_| {
+                                        let room_id = format!("!r{room_nth}:matrix.org");
+
+                                        let room = json!({
+                                            // The recency timestamp is different, so that it triggers a re-ordering of the
+                                            // room list every time, just to stress the APIs.
+                                            "timestamp": room_nth % 10,
+                                            // One state event to activate the associated code path.
+                                            "required_state": [
+                                                {
+                                                    "content": {
+                                                        "name": format!("Room #{room_nth}"),
+                                                    },
+                                                    "event_id": format!("$s{room_nth}"),
+                                                    "origin_server_ts": 1,
+                                                    "sender": "@example:matrix.org",
+                                                    "state_key": "",
+                                                    "type": "m.room.name"
+                                                },
+                                            ],
+                                            // One room event to active the associated code path.
+                                            "timeline": [
+                                                {
+                                                    "event_id": format!("$t{room_nth}"),
+                                                    "sender": "@example:matrix.org",
+                                                    "type": "m.room.message",
+                                                    "content": {
+                                                        "body": "foo",
+                                                        "msgtype": "m.text",
+                                                    },
+                                                    "origin_server_ts": 1,
+                                                }
+                                            ],
+                                        });
+
+                                        room_nth += 1;
+
+                                        (room_id, room)
+                                    })
+                                    .collect::<Map<_, _>>(),
+                            );
+
+                            // Mock the response from the server.
+                            let _mock_guard = Mock::given(SlidingSyncMatcher)
+                                .respond_with(move |request: &Request| {
+                                    let partial_request: PartialSlidingSyncRequest =
+                                        request.body_json().unwrap();
+
+                                    ResponseTemplate::new(200).set_body_json(json!({
+                                        "txn_id": partial_request.txn_id,
+                                        "pos": room_nth.to_string(),
+                                        "rooms": rooms_as_json,
+                                    }))
+                                })
+                                .mount_as_scoped(&server)
+                                .await;
+
+                            // Sync the room list service.
+                            assert!(
+                                room_list_stream.next().await.is_some(),
+                                "`room_list_stream` has stopped"
+                            );
+
+                            // Sync the room list entries.
+                            assert!(
+                                room_list_entries.next().await.is_some(),
+                                "`room_list_entries` has stopped"
+                            );
+                        }
+                    }
+                })
+            },
+        );
+    }
+
+    benchmark.finish();
+}
+
+criterion_group! {
+    name = benches;
+    config = criterion();
+    targets = room_list
+}
+criterion_main!(benches);