Speedup sending encrypted messages after metasync was reenabled

Calling fsync everytime we save to the db is slow, which is actually
fairly noticeable in some larger E2EE rooms. Speed that up slightly by
batching the olm session persisting.

1 files changed, 23 insertions, 0 deletions

diff --git a/src/Cache.cpp b/src/Cache.cpp

index e090e40d..2784cf50 100644
--- a/src/Cache.cpp
+++ b/src/Cache.cpp
@@ -913,6 +913,29 @@ Cache::getMegolmSessionData(const MegolmSessionIndex &index)
 //
 
 void
+Cache::saveOlmSessions(std::vector<std::pair<std::string, mtx::crypto::OlmSessionPtr>> sessions,
+                       uint64_t timestamp)
+{
+    using namespace mtx::crypto;
+
+    auto txn = lmdb::txn::begin(env_);
+    for (const auto &[curve25519, session] : sessions) {
+        auto db = getOlmSessionsDb(txn, curve25519);
+
+        const auto pickled    = pickle<SessionObject>(session.get(), pickle_secret_);
+        const auto session_id = mtx::crypto::session_id(session.get());
+
+        StoredOlmSession stored_session;
+        stored_session.pickled_session = pickled;
+        stored_session.last_message_ts = timestamp;
+
+        db.put(txn, session_id, nlohmann::json(stored_session).dump());
+    }
+
+    txn.commit();
+}
+
+void
 Cache::saveOlmSession(const std::string &curve25519,
                       mtx::crypto::OlmSessionPtr session,
                       uint64_t timestamp)