28 files changed, 817 insertions, 510 deletions

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5a1950b3..8a3193a4 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -76,6 +76,7 @@ set(libqmatrixclient_SRCS
     lib/room.cpp
     lib/user.cpp
     lib/avatar.cpp
+    lib/syncdata.cpp
     lib/settings.cpp
     lib/networksettings.cpp
     lib/converters.cpp
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index d50dc157..6ee39eec 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -237,6 +237,14 @@ We want the software to have decent performance for typical users. At the same t
 
 Having said that, there's always a trade-off between various attributes; in particular, readability and maintainability of the code is more important than squeezing every bit out of that clumsy algorithm. Beware of premature optimization and have profiling data around before going into some hardcore optimization.
 
+Speaking of profiling logs (see README.md on how to turn them on) - in order
+to reduce small timespan logging spam, there's a default limit of at least
+200 microseconds to log most operations with the PROFILER
+(aka libqmatrixclient.profile.debug) logging category. You can override this
+limit by passing the new value (in microseconds) in PROFILER_LOG_USECS to
+the compiler. In the future, this parameter will be made changeable at runtime
+_if_ needed.
+
 ## How to check proposed changes before submitting them
 
 Checking the code on at least one configuration is essential; if you only have
diff --git a/QMatrixClient.pc.in b/QMatrixClient.pc.in
index d2938ab7..efb41498 100644
--- a/QMatrixClient.pc.in
+++ b/QMatrixClient.pc.in
@@ -1,7 +1,7 @@
 prefix=@CMAKE_INSTALL_PREFIX@
 exec_prefix=${prefix}
-includedir=${prefix}/include
-libdir=${prefix}/lib
+includedir=${prefix}/@CMAKE_INSTALL_INCLUDEDIR@
+libdir=${prefix}/@CMAKE_INSTALL_LIBDIR@
 
 Name: QMatrixClient
 Description: A Qt5 library to write cross-platfrom clients for Matrix
diff --git a/lib/avatar.cpp b/lib/avatar.cpp
index b8e1096d..c0ef3cba 100644
--- a/lib/avatar.cpp
+++ b/lib/avatar.cpp
@@ -190,18 +190,8 @@ bool Avatar::Private::checkUrl(const QUrl& url) const
     return _imageSource != Banned;
 }
 
-QString cacheLocation() {
-    const auto cachePath =
-        QStandardPaths::writableLocation(QStandardPaths::CacheLocation)
-            + "/avatar/";
-    QDir dir;
-    if (!dir.exists(cachePath))
-        dir.mkpath(cachePath);
-    return cachePath;
-}
-
 QString Avatar::Private::localFile() const {
-    static const auto cachePath = cacheLocation();
+    static const auto cachePath = cacheLocation("avatars");
     return cachePath % _url.authority() % '_' % _url.fileName() % ".png";
 }
 
diff --git a/lib/connection.cpp b/lib/connection.cpp
index 3d635a7e..9372acd5 100644
--- a/lib/connection.cpp
+++ b/lib/connection.cpp
@@ -39,7 +39,6 @@
 #include <QtNetwork/QDnsLookup>
 #include <QtCore/QFile>
 #include <QtCore/QDir>
-#include <QtCore/QFileInfo>
 #include <QtCore/QStandardPaths>
 #include <QtCore/QStringBuilder>
 #include <QtCore/QElapsedTimer>
@@ -65,10 +64,6 @@ HashT erase_if(HashT& hashMap, Pred pred)
     return removals;
 }
 
-#ifndef TRIM_RAW_DATA
-#define TRIM_RAW_DATA 65535
-#endif
-
 class Connection::Private
 {
     public:
@@ -228,8 +223,7 @@ void Connection::doConnectToServer(const QString& user, const QString& password,
         });
     connect(loginJob, &BaseJob::failure, this,
         [this, loginJob] {
-            emit loginError(loginJob->errorString(),
-                            loginJob->rawData(TRIM_RAW_DATA));
+            emit loginError(loginJob->errorString(), loginJob->rawDataSample());
         });
 }
 
@@ -306,7 +300,7 @@ void Connection::sync(int timeout)
     connect( job, &SyncJob::retryScheduled, this,
         [this,job] (int retriesTaken, int nextInMilliseconds)
         {
-            emit networkError(job->errorString(), job->rawData(TRIM_RAW_DATA),
+            emit networkError(job->errorString(), job->rawDataSample(),
                               retriesTaken, nextInMilliseconds);
         });
     connect( job, &SyncJob::failure, this, [this, job] {
@@ -315,14 +309,14 @@ void Connection::sync(int timeout)
         {
             qCWarning(SYNCJOB)
                 << "Sync job failed with ContentAccessError - login expired?";
-            emit loginError(job->errorString(), job->rawData(TRIM_RAW_DATA));
+            emit loginError(job->errorString(), job->rawDataSample());
         }
         else
-            emit syncError(job->errorString(), job->rawData(TRIM_RAW_DATA));
+            emit syncError(job->errorString(), job->rawDataSample());
     });
 }
 
-void Connection::onSyncSuccess(SyncData &&data) {
+void Connection::onSyncSuccess(SyncData &&data, bool fromCache) {
     d->data->setLastEvent(data.nextBatch());
     for (auto&& roomData: data.takeRoomData())
     {
@@ -343,7 +337,7 @@ void Connection::onSyncSuccess(SyncData &&data) {
         }
         if ( auto* r = provideRoom(roomData.roomId, roomData.joinState) )
         {
-            r->updateData(std::move(roomData));
+            r->updateData(std::move(roomData), fromCache);
             if (d->firstTimeRooms.removeOne(r))
                 emit loadedRoomState(r);
         }
@@ -422,9 +416,10 @@ PostReceiptJob* Connection::postReceipt(Room* room, RoomEvent* event) const
     return callApi<PostReceiptJob>(room->id(), "m.read", event->id());
 }
 
-JoinRoomJob* Connection::joinRoom(const QString& roomAlias)
+JoinRoomJob* Connection::joinRoom(const QString& roomAlias,
+                                  const QStringList& serverNames)
 {
-    auto job = callApi<JoinRoomJob>(roomAlias);
+    auto job = callApi<JoinRoomJob>(roomAlias, serverNames);
     connect(job, &JoinRoomJob::success,
             this, [this, job] { provideRoom(job->roomId(), JoinState::Join); });
     return job;
@@ -1063,47 +1058,54 @@ void Connection::setHomeserver(const QUrl& url)
     emit homeserverChanged(homeserver());
 }
 
-static constexpr int CACHE_VERSION_MAJOR = 8;
-static constexpr int CACHE_VERSION_MINOR = 0;
+void Connection::saveRoomState(Room* r) const
+{
+    Q_ASSERT(r);
+    if (!d->cacheState)
+        return;
+
+    QFile outRoomFile { stateCachePath() % SyncData::fileNameForRoom(r->id()) };
+    if (outRoomFile.open(QFile::WriteOnly))
+    {
+        QJsonDocument json { r->toJson() };
+        auto data = d->cacheToBinary ? json.toBinaryData()
+                                     : json.toJson(QJsonDocument::Compact);
+        outRoomFile.write(data.data(), data.size());
+        qCDebug(MAIN) << "Room state cache saved to" << outRoomFile.fileName();
+    } else {
+        qCWarning(MAIN) << "Error opening" << outRoomFile.fileName()
+                        << ":" << outRoomFile.errorString();
+    }
+}
 
-void Connection::saveState(const QUrl &toFile) const
+void Connection::saveState() const
 {
     if (!d->cacheState)
         return;
 
     QElapsedTimer et; et.start();
 
-    QFileInfo stateFile {
-        toFile.isEmpty() ? stateCachePath() : toFile.toLocalFile()
-    };
-    if (!stateFile.dir().exists())
-        stateFile.dir().mkpath(".");
-
-    QFile outfile { stateFile.absoluteFilePath() };
-    if (!outfile.open(QFile::WriteOnly))
+    QFile outFile { stateCachePath() % "state.json" };
+    if (!outFile.open(QFile::WriteOnly))
     {
-        qCWarning(MAIN) << "Error opening" << stateFile.absoluteFilePath()
-                        << ":" << outfile.errorString();
+        qCWarning(MAIN) << "Error opening" << outFile.fileName()
+                        << ":" << outFile.errorString();
         qCWarning(MAIN) << "Caching the rooms state disabled";
         d->cacheState = false;
         return;
     }
 
-    QJsonObject rootObj;
+    QJsonObject rootObj {
+        { QStringLiteral("cache_version"), QJsonObject {
+            { QStringLiteral("major"), SyncData::cacheVersion().first },
+            { QStringLiteral("minor"), SyncData::cacheVersion().second }
+    }}};
     {
         QJsonObject rooms;
         QJsonObject inviteRooms;
         for (const auto* i : roomMap()) // Pass on rooms in Leave state
-        {
-            if (i->joinState() == JoinState::Invite)
-                inviteRooms.insert(i->id(), i->toJson());
-            else
-                rooms.insert(i->id(), i->toJson());
-            QElapsedTimer et1; et1.start();
-            QCoreApplication::processEvents();
-            if (et1.elapsed() > 1)
-                qCDebug(PROFILER) << "processEvents() borrowed" << et1;
-        }
+            (i->joinState() == JoinState::Invite ? inviteRooms : rooms)
+            .insert(i->id(), QJsonValue::Null);
 
         QJsonObject roomObj;
         if (!rooms.isEmpty())
@@ -1126,63 +1128,35 @@ void Connection::saveState(const QUrl &toFile) const
             QJsonObject {{ QStringLiteral("events"), accountDataEvents }});
     }
 
-    QJsonObject versionObj;
-    versionObj.insert("major", CACHE_VERSION_MAJOR);
-    versionObj.insert("minor", CACHE_VERSION_MINOR);
-    rootObj.insert("cache_version", versionObj);
-
     QJsonDocument json { rootObj };
     auto data = d->cacheToBinary ? json.toBinaryData() :
                                    json.toJson(QJsonDocument::Compact);
     qCDebug(PROFILER) << "Cache for" << userId() << "generated in" << et;
 
-    outfile.write(data.data(), data.size());
-    qCDebug(MAIN) << "State cache saved to" << outfile.fileName();
+    outFile.write(data.data(), data.size());
+    qCDebug(MAIN) << "State cache saved to" << outFile.fileName();
 }
 
-void Connection::loadState(const QUrl &fromFile)
+void Connection::loadState()
 {
     if (!d->cacheState)
         return;
 
     QElapsedTimer et; et.start();
-    QFile file {
-        fromFile.isEmpty() ? stateCachePath() : fromFile.toLocalFile()
-    };
-    if (!file.exists())
-    {
-        qCDebug(MAIN) << "No state cache file found";
-        return;
-    }
-    if(!file.open(QFile::ReadOnly))
-    {
-        qCWarning(MAIN) << "file " << file.fileName() << "failed to open for read";
-        return;
-    }
-    QByteArray data = file.readAll();
 
-    auto jsonDoc = d->cacheToBinary ? QJsonDocument::fromBinaryData(data) :
-                                      QJsonDocument::fromJson(data);
-    if (jsonDoc.isNull())
-    {
-        qCWarning(MAIN) << "Cache file broken, discarding";
+    SyncData sync { stateCachePath() % "state.json" };
+    if (sync.nextBatch().isEmpty()) // No token means no cache by definition
         return;
-    }
-    auto actualCacheVersionMajor =
-            jsonDoc.object()
-            .value("cache_version").toObject()
-            .value("major").toInt();
-    if (actualCacheVersionMajor < CACHE_VERSION_MAJOR)
+
+    if (!sync.unresolvedRooms().isEmpty())
     {
-        qCWarning(MAIN)
-            << "Major version of the cache file is" << actualCacheVersionMajor
-            << "but" << CACHE_VERSION_MAJOR << "required; discarding the cache";
+        qCWarning(MAIN) << "State cache incomplete, discarding";
         return;
     }
-
-    SyncData sync;
-    sync.parseJson(jsonDoc);
-    onSyncSuccess(std::move(sync));
+    // TODO: to handle load failures, instead of the above block:
+    // 1. Do initial sync on failed rooms without saving the nextBatch token
+    // 2. Do the sync across all rooms as normal
+    onSyncSuccess(std::move(sync), true);
     qCDebug(PROFILER) << "*** Cached state for" << userId() << "loaded in" << et;
 }
 
@@ -1190,8 +1164,7 @@ QString Connection::stateCachePath() const
 {
     auto safeUserId = userId();
     safeUserId.replace(':', '_');
-    return QStandardPaths::writableLocation(QStandardPaths::CacheLocation)
-            % '/' % safeUserId % "_state.json";
+    return cacheLocation(safeUserId);
 }
 
 bool Connection::cacheState() const
diff --git a/lib/connection.h b/lib/connection.h
index cfad8774..32533b6e 100644
--- a/lib/connection.h
+++ b/lib/connection.h
@@ -280,7 +280,7 @@ namespace QMatrixClient
              * to be QML-friendly. Empty parameter means using a path
              * defined by stateCachePath().
              */
-            Q_INVOKABLE void loadState(const QUrl &fromFile = {});
+            Q_INVOKABLE void loadState();
             /**
              * This method saves the current state of rooms (but not messages
              * in them) to a local cache file, so that it could be loaded by
@@ -290,7 +290,10 @@ namespace QMatrixClient
              * QML-friendly. Empty parameter means using a path defined by
              * stateCachePath().
              */
-            Q_INVOKABLE void saveState(const QUrl &toFile = {}) const;
+            Q_INVOKABLE void saveState() const;
+
+            /// This method saves the current state of a single room.
+            void saveRoomState(Room* r) const;
 
             /**
              * The default path to store the cached room state, defined as
@@ -461,7 +464,8 @@ namespace QMatrixClient
             CreateRoomJob* createDirectChat(const QString& userId,
                 const QString& topic = {}, const QString& name = {});
 
-            virtual JoinRoomJob* joinRoom(const QString& roomAlias);
+            virtual JoinRoomJob* joinRoom(const QString& roomAlias,
+                                          const QStringList& serverNames = {});
 
             /** Sends /forget to the server and also deletes room locally.
              * This method is in Connection, not in Room, since it's a
@@ -518,7 +522,7 @@ namespace QMatrixClient
              * a successful login and logout and are constant at other times.
              */
             void stateChanged();
-            void loginError(QString message, QByteArray details);
+            void loginError(QString message, QString details);
 
             /** A network request (job) failed
              *
@@ -536,11 +540,11 @@ namespace QMatrixClient
              * @param retriesTaken - how many retries have already been taken
              * @param nextRetryInMilliseconds - when the job will retry again
              */
-            void networkError(QString message, QByteArray details,
+            void networkError(QString message, QString details,
                               int retriesTaken, int nextRetryInMilliseconds);
 
             void syncDone();
-            void syncError(QString message, QByteArray details);
+            void syncError(QString message, QString details);
 
             void newUser(User* user);
 
@@ -673,7 +677,7 @@ namespace QMatrixClient
             /**
              * Completes loading sync data.
              */
-            void onSyncSuccess(SyncData &&data);
+            void onSyncSuccess(SyncData &&data, bool fromCache = false);
 
         private:
             class Private;
diff --git a/lib/converters.h b/lib/converters.h
index 70938ab9..53855a1f 100644
--- a/lib/converters.h
+++ b/lib/converters.h
@@ -61,7 +61,7 @@ namespace QMatrixClient
     inline auto toJson(const QJsonValue& val) { return val; }
     inline auto toJson(const QJsonObject& o) { return o; }
     inline auto toJson(const QJsonArray& arr) { return arr; }
-    // Special-case QStrings and bools to avoid ambiguity between QJsonValue
+    // Special-case QString to avoid ambiguity between QJsonValue
     // and QVariant (also, QString.isEmpty() is used in _impl::AddNode<> below)
     inline auto toJson(const QString& s) { return s; }
 
diff --git a/lib/events/event.cpp b/lib/events/event.cpp
index fd6e3939..c98dfbb6 100644
--- a/lib/events/event.cpp
+++ b/lib/events/event.cpp
@@ -77,3 +77,8 @@ const QJsonObject Event::unsignedJson() const
 {
     return fullJson()[UnsignedKeyL].toObject();
 }
+
+void Event::dumpTo(QDebug dbg) const
+{
+    dbg << QJsonDocument(contentJson()).toJson(QJsonDocument::Compact);
+}
diff --git a/lib/events/event.h b/lib/events/event.h
index 5b33628f..c51afcc4 100644
--- a/lib/events/event.h
+++ b/lib/events/event.h
@@ -209,7 +209,7 @@ namespace QMatrixClient
     inline auto registerEventType()
     {
         static const auto _ = setupFactory<EventT>();
-        return _;
+        return _; // Only to facilitate usage in static initialisation
     }
 
     // === Event ===
@@ -257,8 +257,18 @@ namespace QMatrixClient
                 return fromJson<T>(contentJson()[key]);
             }
 
+            friend QDebug operator<<(QDebug dbg, const Event& e)
+            {
+                QDebugStateSaver _dss { dbg };
+                dbg.noquote().nospace()
+                        << e.matrixType() << '(' << e.type() << "): ";
+                e.dumpTo(dbg);
+                return dbg;
+            }
+
             virtual bool isStateEvent() const { return false; }
             virtual bool isCallEvent() const { return false; }
+            virtual void dumpTo(QDebug dbg) const;
 
         protected:
             QJsonObject& editJson() { return _json; }
diff --git a/lib/events/eventloader.h b/lib/events/eventloader.h
index 3ee9a181..cd2f9149 100644
--- a/lib/events/eventloader.h
+++ b/lib/events/eventloader.h
@@ -19,7 +19,6 @@
 #pragma once
 
 #include "stateevent.h"
-#include "converters.h"
 
 namespace QMatrixClient {
     namespace _impl {
diff --git a/lib/events/simplestateevents.h b/lib/events/simplestateevents.h
index 56be947c..5aa24c15 100644
--- a/lib/events/simplestateevents.h
+++ b/lib/events/simplestateevents.h
@@ -59,21 +59,23 @@ namespace QMatrixClient
         };
     } // namespace EventContent
 
-#define DEFINE_SIMPLE_STATE_EVENT(_Name, _TypeId, _ContentType, _ContentKey) \
-    class _Name : public StateEvent<EventContent::SimpleContent<_ContentType>> \
+#define DEFINE_SIMPLE_STATE_EVENT(_Name, _TypeId, _ValueType, _ContentKey) \
+    class _Name : public StateEvent<EventContent::SimpleContent<_ValueType>> \
     { \
         public: \
-            using content_type = _ContentType; \
+            using value_type = content_type::value_type; \
             DEFINE_EVENT_TYPEID(_TypeId, _Name) \
-            explicit _Name(const QJsonObject& obj) \
-                : StateEvent(typeId(), obj, QStringLiteral(#_ContentKey)) \
-            { } \
+            explicit _Name() : _Name(value_type()) { } \
             template <typename T> \
             explicit _Name(T&& value) \
                 : StateEvent(typeId(), matrixTypeId(), \
                              QStringLiteral(#_ContentKey), \
                              std::forward<T>(value)) \
             { } \
+            explicit _Name(QJsonObject obj) \
+                : StateEvent(typeId(), std::move(obj), \
+                             QStringLiteral(#_ContentKey)) \
+            { } \
             auto _ContentKey() const { return content().value; } \
     }; \
     REGISTER_EVENT_TYPE(_Name) \
diff --git a/lib/events/stateevent.cpp b/lib/events/stateevent.cpp
index fd5d2642..fd8079be 100644
--- a/lib/events/stateevent.cpp
+++ b/lib/events/stateevent.cpp
@@ -28,3 +28,18 @@ bool StateEventBase::repeatsState() const
     const auto prevContentJson = unsignedJson().value(PrevContentKeyL);
     return fullJson().value(ContentKeyL) == prevContentJson;
 }
+
+QString StateEventBase::replacedState() const
+{
+    return unsignedJson().value("replaces_state"_ls).toString();
+}
+
+void StateEventBase::dumpTo(QDebug dbg) const
+{
+    if (!stateKey().isEmpty())
+        dbg << '<' << stateKey() << "> ";
+    if (unsignedJson().contains(PrevContentKeyL))
+        dbg << QJsonDocument(unsignedJson()[PrevContentKeyL].toObject())
+               .toJson(QJsonDocument::Compact) << " -> ";
+    RoomEvent::dumpTo(dbg);
+}
diff --git a/lib/events/stateevent.h b/lib/events/stateevent.h
index 6032132e..d4a7e8b3 100644
--- a/lib/events/stateevent.h
+++ b/lib/events/stateevent.h
@@ -30,11 +30,21 @@ namespace QMatrixClient {
             ~StateEventBase() override = default;
 
             bool isStateEvent() const override { return true; }
+            QString replacedState() const;
+            void dumpTo(QDebug dbg) const override;
+
             virtual bool repeatsState() const;
     };
     using StateEventPtr = event_ptr_tt<StateEventBase>;
     using StateEvents = EventsArray<StateEventBase>;
 
+    /**
+     * A combination of event type and state key uniquely identifies a piece
+     * of state in Matrix.
+     * \sa https://matrix.org/docs/spec/client_server/unstable.html#types-of-room-events
+     */
+    using StateEventKey = std::pair<QString, QString>;
+
     template <typename ContentT>
     struct Prev
     {
@@ -90,3 +100,13 @@ namespace QMatrixClient {
             std::unique_ptr<Prev<ContentT>> _prev;
     };
 } // namespace QMatrixClient
+
+namespace std {
+    template <> struct hash<QMatrixClient::StateEventKey>
+    {
+        size_t operator()(const QMatrixClient::StateEventKey& k) const Q_DECL_NOEXCEPT
+        {
+            return qHash(k);
+        }
+    };
+}
diff --git a/lib/jobs/basejob.cpp b/lib/jobs/basejob.cpp
index b21173ae..4a7780b1 100644
--- a/lib/jobs/basejob.cpp
+++ b/lib/jobs/basejob.cpp
@@ -426,8 +426,8 @@ BaseJob::Status BaseJob::parseReply(QNetworkReply* reply)
     const auto& json = QJsonDocument::fromJson(d->rawResponse, &error);
     if( error.error == QJsonParseError::NoError )
         return parseJson(json);
-    else
-        return { IncorrectResponseError, error.errorString() };
+
+    return { IncorrectResponseError, error.errorString() };
 }
 
 BaseJob::Status BaseJob::parseJson(const QJsonDocument&)
@@ -519,8 +519,19 @@ BaseJob::Status BaseJob::status() const
 
 QByteArray BaseJob::rawData(int bytesAtMost) const
 {
-    return bytesAtMost > 0 && d->rawResponse.size() > bytesAtMost ?
-        d->rawResponse.left(bytesAtMost) + "...(truncated)" : d->rawResponse;
+    return bytesAtMost > 0 && d->rawResponse.size() > bytesAtMost
+            ? d->rawResponse.left(bytesAtMost) : d->rawResponse;
+}
+
+QString BaseJob::rawDataSample(int bytesAtMost) const
+{
+    auto data = rawData(bytesAtMost);
+    Q_ASSERT(data.size() <= d->rawResponse.size());
+    return data.size() == d->rawResponse.size()
+            ? data : data + tr("...(truncated, %Ln bytes in total)",
+                               "Comes after trimmed raw network response",
+                               d->rawResponse.size());
+
 }
 
 QString BaseJob::statusCaption() const
diff --git a/lib/jobs/basejob.h b/lib/jobs/basejob.h
index 4ef25ab8..3d50344d 100644
--- a/lib/jobs/basejob.h
+++ b/lib/jobs/basejob.h
@@ -138,8 +138,20 @@ namespace QMatrixClient
             Status status() const;
             /** Short human-friendly message on the job status */
             QString statusCaption() const;
-            /** Raw response body as received from the server */
+            /** Get raw response body as received from the server
+             * \param bytesAtMost return this number of leftmost bytes, or -1
+             *                    to return the entire response
+             */
             QByteArray rawData(int bytesAtMost = -1) const;
+            /** Get UI-friendly sample of raw data
+             *
+             * This is almost the same as rawData but appends the "truncated"
+             * suffix if not all data fit in bytesAtMost. This call is
+             * recommended to present a sample of raw data as "details" next to
+             * error messages. Note that the default \p bytesAtMost value is
+             * also tailored to UI cases.
+             */
+            QString rawDataSample(int bytesAtMost = 65535) const;
 
             /** Error (more generally, status) code
              * Equivalent to status().code
diff --git a/lib/jobs/mediathumbnailjob.cpp b/lib/jobs/mediathumbnailjob.cpp
index 8dfb6094..aeb49839 100644
--- a/lib/jobs/mediathumbnailjob.cpp
+++ b/lib/jobs/mediathumbnailjob.cpp
@@ -23,7 +23,8 @@ using namespace QMatrixClient;
 QUrl MediaThumbnailJob::makeRequestUrl(QUrl baseUrl,
                                        const QUrl& mxcUri, QSize requestedSize)
 {
-    return makeRequestUrl(baseUrl, mxcUri.authority(), mxcUri.path().mid(1),
+    return makeRequestUrl(std::move(baseUrl),
+                          mxcUri.authority(), mxcUri.path().mid(1),
                           requestedSize.width(), requestedSize.height());
 }
 
@@ -34,9 +35,8 @@ MediaThumbnailJob::MediaThumbnailJob(const QString& serverName,
 { }
 
 MediaThumbnailJob::MediaThumbnailJob(const QUrl& mxcUri, QSize requestedSize)
-    : GetContentThumbnailJob(mxcUri.authority(),
-                             mxcUri.path().mid(1), // sans leading '/'
-                             requestedSize.width(), requestedSize.height())
+    : MediaThumbnailJob(mxcUri.authority(), mxcUri.path().mid(1), // sans leading '/'
+                        requestedSize)
 { }
 
 QImage MediaThumbnailJob::thumbnail() const
diff --git a/lib/jobs/syncjob.cpp b/lib/jobs/syncjob.cpp
index 9cbac71b..ac0f6685 100644
--- a/lib/jobs/syncjob.cpp
+++ b/lib/jobs/syncjob.cpp
@@ -18,10 +18,6 @@
 
 #include "syncjob.h"
 
-#include "events/eventloader.h"
-
-#include <QtCore/QElapsedTimer>
-
 using namespace QMatrixClient;
 
 static size_t jobId = 0;
@@ -46,110 +42,14 @@ SyncJob::SyncJob(const QString& since, const QString& filter, int timeout,
     setMaxRetries(std::numeric_limits<int>::max());
 }
 
-QString SyncData::nextBatch() const
-{
-    return nextBatch_;
-}
-
-SyncDataList&& SyncData::takeRoomData()
-{
-    return std::move(roomData);
-}
-
-Events&& SyncData::takePresenceData()
-{
-    return std::move(presenceData);
-}
-
-Events&& SyncData::takeAccountData()
-{
-    return std::move(accountData);
-}
-
-Events&&SyncData::takeToDeviceEvents()
-{
-    return std::move(toDeviceEvents);
-}
-
-template <typename EventsArrayT, typename StrT>
-inline EventsArrayT load(const QJsonObject& batches, StrT keyName)
-{
-    return fromJson<EventsArrayT>(batches[keyName].toObject().value("events"_ls));
-}
-
 BaseJob::Status SyncJob::parseJson(const QJsonDocument& data)
 {
-    return d.parseJson(data);
-}
-
-BaseJob::Status SyncData::parseJson(const QJsonDocument &data)
-{
-    QElapsedTimer et; et.start();
-
-    auto json = data.object();
-    nextBatch_ = json.value("next_batch"_ls).toString();
-    presenceData = load<Events>(json, "presence"_ls);
-    accountData = load<Events>(json, "account_data"_ls);
-    toDeviceEvents = load<Events>(json, "to_device"_ls);
+    d.parseJson(data.object());
+    if (d.unresolvedRooms().isEmpty())
+        return BaseJob::Success;
 
-    auto rooms = json.value("rooms"_ls).toObject();
-    JoinStates::Int ii = 1; // ii is used to make a JoinState value
-    auto totalRooms = 0;
-    auto totalEvents = 0;
-    for (size_t i = 0; i < JoinStateStrings.size(); ++i, ii <<= 1)
-    {
-        const auto rs = rooms.value(JoinStateStrings[i]).toObject();
-        // We have a Qt container on the right and an STL one on the left
-        roomData.reserve(static_cast<size_t>(rs.size()));
-        for(auto roomIt = rs.begin(); roomIt != rs.end(); ++roomIt)
-        {
-            roomData.emplace_back(roomIt.key(), JoinState(ii),
-                                  roomIt.value().toObject());
-            const auto& r = roomData.back();
-            totalEvents += r.state.size() + r.ephemeral.size() +
-                           r.accountData.size() + r.timeline.size();
-        }
-        totalRooms += roomData.size();
-    }
-    qCDebug(PROFILER) << "*** SyncData::parseJson(): batch with"
-                      << totalRooms << "room(s),"
-                      << totalEvents << "event(s) in" << et;
-    return BaseJob::Success;
+    qCCritical(MAIN).noquote() << "Incomplete sync response, missing rooms:"
+                               << d.unresolvedRooms().join(',');
+    return BaseJob::IncorrectResponseError;
 }
 
-const QString SyncRoomData::UnreadCountKey =
-        QStringLiteral("x-qmatrixclient.unread_count");
-
-SyncRoomData::SyncRoomData(const QString& roomId_, JoinState joinState_,
-                           const QJsonObject& room_)
-    : roomId(roomId_)
-    , joinState(joinState_)
-    , state(load<StateEvents>(room_,
-                joinState == JoinState::Invite ? "invite_state"_ls : "state"_ls))
-{
-    switch (joinState) {
-        case JoinState::Join:
-            ephemeral = load<Events>(room_, "ephemeral"_ls);
-            FALLTHROUGH;
-        case JoinState::Leave:
-        {
-            accountData = load<Events>(room_, "account_data"_ls);
-            timeline = load<RoomEvents>(room_, "timeline"_ls);
-            const auto timelineJson = room_.value("timeline"_ls).toObject();
-            timelineLimited = timelineJson.value("limited"_ls).toBool();
-            timelinePrevBatch = timelineJson.value("prev_batch"_ls).toString();
-
-            break;
-        }
-        default: /* nothing on top of state */;
-    }
-
-    const auto unreadJson = room_.value("unread_notifications"_ls).toObject();
-    unreadCount = unreadJson.value(UnreadCountKey).toInt(-2);
-    highlightCount = unreadJson.value("highlight_count"_ls).toInt();
-    notificationCount = unreadJson.value("notification_count"_ls).toInt();
-    if (highlightCount > 0 || notificationCount > 0)
-        qCDebug(SYNCJOB) << "Room" << roomId_
-                         << "has highlights:" << highlightCount
-                         << "and notifications:" << notificationCount;
-}
diff --git a/lib/jobs/syncjob.h b/lib/jobs/syncjob.h
index 6b9bedfa..a0a3c026 100644
--- a/lib/jobs/syncjob.h
+++ b/lib/jobs/syncjob.h
@@ -20,56 +20,10 @@
 
 #include "basejob.h"
 
-#include "joinstate.h"
-#include "events/stateevent.h"
-#include "util.h"
+#include "../syncdata.h"
 
 namespace QMatrixClient
 {
-    class SyncRoomData
-    {
-        public:
-            QString roomId;
-            JoinState joinState;
-            StateEvents state;
-            RoomEvents timeline;
-            Events ephemeral;
-            Events accountData;
-
-            bool timelineLimited;
-            QString timelinePrevBatch;
-            int unreadCount;
-            int highlightCount;
-            int notificationCount;
-
-            SyncRoomData(const QString& roomId, JoinState joinState_,
-                         const QJsonObject& room_);
-            SyncRoomData(SyncRoomData&&) = default;
-            SyncRoomData& operator=(SyncRoomData&&) = default;
-
-            static const QString UnreadCountKey;
-    };
-    // QVector cannot work with non-copiable objects, std::vector can.
-    using SyncDataList = std::vector<SyncRoomData>;
-
-    class SyncData
-    {
-        public:
-            BaseJob::Status parseJson(const QJsonDocument &data);
-            Events&& takePresenceData();
-            Events&& takeAccountData();
-            Events&& takeToDeviceEvents();
-            SyncDataList&& takeRoomData();
-            QString nextBatch() const;
-
-        private:
-            QString nextBatch_;
-            Events presenceData;
-            Events accountData;
-            Events toDeviceEvents;
-            SyncDataList roomData;
-    };
-
     class SyncJob: public BaseJob
     {
         public:
diff --git a/lib/logging.h b/lib/logging.h
index 8dbfdf30..a3a65887 100644
--- a/lib/logging.h
+++ b/lib/logging.h
@@ -65,6 +65,17 @@ namespace QMatrixClient
     {
         return qdm(debug_object);
     }
+
+    inline qint64 profilerMinNsecs()
+    {
+        return
+#ifdef PROFILER_LOG_USECS
+            PROFILER_LOG_USECS
+#else
+            200
+#endif
+        * 1000;
+    }
 }
 
 inline QDebug operator<< (QDebug debug_object, const QElapsedTimer& et)
diff --git a/lib/room.cpp b/lib/room.cpp
index 7c45bf89..8b81bfb2 100644
--- a/lib/room.cpp
+++ b/lib/room.cpp
@@ -25,7 +25,6 @@
 #include "csapi/receipts.h"
 #include "csapi/redaction.h"
 #include "csapi/account-data.h"
-#include "csapi/message_pagination.h"
 #include "csapi/room_state.h"
 #include "csapi/room_send.h"
 #include "csapi/tags.h"
@@ -46,10 +45,10 @@
 #include "connection.h"
 #include "user.h"
 #include "converters.h"
+#include "syncdata.h"
 
 #include <QtCore/QHash>
 #include <QtCore/QStringBuilder> // for efficient string concats (operator%)
-#include <QtCore/QElapsedTimer>
 #include <QtCore/QPointer>
 #include <QtCore/QDir>
 #include <QtCore/QTemporaryFile>
@@ -92,18 +91,19 @@ class Room::Private
         void updateDisplayname();
 
         Connection* connection;
+        QString id;
+        JoinState joinState;
+        /// The state of the room at timeline position before-0
+        /// \sa timelineBase
+        std::unordered_map<StateEventKey, StateEventPtr> baseState;
+        /// The state of the room at timeline position after-maxTimelineIndex()
+        /// \sa Room::syncEdge
+        QHash<StateEventKey, const StateEventBase*> currentState;
         Timeline timeline;
         PendingEvents unsyncedEvents;
         QHash<QString, TimelineItem::index_t> eventsIndex;
-        QString id;
-        QStringList aliases;
-        QString canonicalAlias;
-        QString name;
         QString displayname;
-        QString topic;
-        QString encryptionAlgorithm;
         Avatar avatar;
-        JoinState joinState;
         int highlightCount = 0;
         int notificationCount = 0;
         members_map_t membersMap;
@@ -157,8 +157,8 @@ class Room::Private
             fileTransfers[tid].status = FileTransferInfo::Failed;
             emit q->fileTransferFailed(tid, errorMessage);
         }
-        // A map from event/txn ids to information about the long operation;
-        // used for both download and upload operations
+        /// A map from event/txn ids to information about the long operation;
+        /// used for both download and upload operations
         QHash<QString, FileTransferPrivateInfo> fileTransfers;
 
         const RoomMessageEvent* getEventWithFile(const QString& eventId) const;
@@ -169,8 +169,22 @@ class Room::Private
         void renameMember(User* u, QString oldName);
         void removeMemberFromMap(const QString& username, User* u);
 
+        /// A point in the timeline corresponding to baseState
+        rev_iter_t timelineBase() const { return q->findInTimeline(-1); }
+
         void getPreviousContent(int limit = 10);
 
+        template <typename EventT>
+        const EventT* getCurrentState(QString stateKey = {}) const
+        {
+            static const EventT empty;
+            const auto* evt =
+                currentState.value({EventT::matrixTypeId(), stateKey}, &empty);
+            Q_ASSERT(evt->type() == EventT::typeId() &&
+                     evt->matrixType() == EventT::matrixTypeId());
+            return static_cast<const EventT*>(evt);
+        }
+
         bool isEventNotable(const TimelineItem& ti) const
         {
             return !ti->isRedacted() &&
@@ -178,7 +192,7 @@ class Room::Private
                 is<RoomMessageEvent>(*ti);
         }
 
-        void addNewMessageEvents(RoomEvents&& events);
+        Changes addNewMessageEvents(RoomEvents&& events);
         void addHistoricalMessageEvents(RoomEvents&& events);
 
         /** Move events into the timeline
@@ -215,6 +229,8 @@ class Room::Private
 
         QString doSendEvent(const RoomEvent* pEvent);
         PendingEvents::iterator findAsPending(const RoomEvent* rawEvtPtr);
+        void onEventSendingFailure(const RoomEvent* pEvent,
+                const QString& txnId, BaseJob* call = nullptr);
 
         template <typename EvT>
         auto requestSetState(const QString& stateKey, const EvT& event)
@@ -288,17 +304,17 @@ const Room::PendingEvents& Room::pendingEvents() const
 
 QString Room::name() const
 {
-    return d->name;
+    return d->getCurrentState<RoomNameEvent>()->name();
 }
 
 QStringList Room::aliases() const
 {
-    return d->aliases;
+    return d->getCurrentState<RoomAliasesEvent>()->aliases();
 }
 
 QString Room::canonicalAlias() const
 {
-    return d->canonicalAlias;
+    return d->getCurrentState<RoomCanonicalAliasEvent>()->alias();
 }
 
 QString Room::displayName() const
@@ -308,7 +324,7 @@ QString Room::displayName() const
 
 QString Room::topic() const
 {
-    return d->topic;
+    return d->getCurrentState<RoomTopicEvent>()->topic();
 }
 
 QString Room::avatarMediaId() const
@@ -366,6 +382,7 @@ void Room::setJoinState(JoinState state)
     d->joinState = state;
     qCDebug(MAIN) << "Room" << id() << "changed state: "
                   << int(oldState) << "->" << int(state);
+    emit changed(Change::JoinStateChange);
     emit joinStateChanged(oldState, state);
 }
 
@@ -384,6 +401,7 @@ void Room::Private::setLastReadEvent(User* u, QString eventId)
         if (storedId != serverReadMarker)
             connection->callApi<PostReadMarkersJob>(id, storedId);
         emit q->readMarkerMoved(eventId, storedId);
+        connection->saveRoomState(q);
     }
 }
 
@@ -408,7 +426,7 @@ void Room::Private::updateUnreadCount(rev_iter_t from, rev_iter_t to)
     QElapsedTimer et; et.start();
     const auto newUnreadMessages = count_if(from, to,
             std::bind(&Room::Private::isEventNotable, this, _1));
-    if (et.nsecsElapsed() > 10000)
+    if (et.nsecsElapsed() > profilerMinNsecs() / 10)
         qCDebug(PROFILER) << "Counting gained unread messages took" << et;
 
     if(newUnreadMessages > 0)
@@ -418,7 +436,7 @@ void Room::Private::updateUnreadCount(rev_iter_t from, rev_iter_t to)
             unreadMessages = 0;
 
         unreadMessages += newUnreadMessages;
-        qCDebug(MAIN) << "Room" << displayname << "has gained"
+        qCDebug(MAIN) << "Room" << q->objectName() << "has gained"
             << newUnreadMessages << "unread message(s),"
             << (q->readMarker() == timeline.crend() ?
                     "in total at least" : "in total")
@@ -450,7 +468,7 @@ void Room::Private::promoteReadMarker(User* u, rev_iter_t newMarker, bool force)
         QElapsedTimer et; et.start();
         unreadMessages = count_if(eagerMarker, timeline.cend(),
                     std::bind(&Room::Private::isEventNotable, this, _1));
-        if (et.nsecsElapsed() > 10000)
+        if (et.nsecsElapsed() > profilerMinNsecs() / 10)
             qCDebug(PROFILER) << "Recounting unread messages took" << et;
 
         // See https://github.com/QMatrixClient/libqmatrixclient/wiki/unread_count
@@ -513,11 +531,21 @@ int Room::unreadCount() const
     return d->unreadMessages;
 }
 
-Room::rev_iter_t Room::timelineEdge() const
+Room::rev_iter_t Room::historyEdge() const
 {
     return d->timeline.crend();
 }
 
+Room::Timeline::const_iterator Room::syncEdge() const
+{
+    return d->timeline.cend();
+}
+
+Room::rev_iter_t Room::timelineEdge() const
+{
+    return historyEdge();
+}
+
 TimelineItem::index_t Room::minTimelineIndex() const
 {
     return d->timeline.empty() ? 0 : d->timeline.front().index();
@@ -945,7 +973,12 @@ int Room::timelineSize() const
 
 bool Room::usesEncryption() const
 {
-    return !d->encryptionAlgorithm.isEmpty();
+    return !d->getCurrentState<EncryptionEvent>()->algorithm().isEmpty();
+}
+
+GetRoomEventsJob* Room::eventsHistoryJob() const
+{
+    return d->eventsHistoryJob;
 }
 
 void Room::Private::insertMemberIntoMap(User *u)
@@ -1006,8 +1039,9 @@ Room::Timeline::difference_type Room::Private::moveEventsToTimeline(
 {
     Q_ASSERT(!events.empty());
     // Historical messages arrive in newest-to-oldest order, so the process for
-    // them is symmetric to the one for new messages.
-    auto index = timeline.empty() ? -int(placement) :
+    // them is almost symmetric to the one for new messages. New messages get
+    // appended from index 0; old messages go backwards from index -1.
+    auto index = timeline.empty() ? -((placement+1)/2) /* 1 -> -1; -1 -> 0 */ :
                  placement == Older ? timeline.front().index() :
                  timeline.back().index();
     auto baseIndex = index;
@@ -1028,7 +1062,7 @@ Room::Timeline::difference_type Room::Private::moveEventsToTimeline(
         eventsIndex.insert(eId, index);
         Q_ASSERT(q->findInTimeline(eId)->event()->id() == eId);
     }
-    const auto insertedSize = (index - baseIndex) * int(placement);
+    const auto insertedSize = (index - baseIndex) * placement;
     Q_ASSERT(insertedSize == int(events.size()));
     return insertedSize;
 }
@@ -1074,45 +1108,48 @@ QString Room::roomMembername(const QString& userId) const
     return roomMembername(user(userId));
 }
 
-void Room::updateData(SyncRoomData&& data)
+void Room::updateData(SyncRoomData&& data, bool fromCache)
 {
     if( d->prevBatch.isEmpty() )
         d->prevBatch = data.timelinePrevBatch;
     setJoinState(data.joinState);
 
+    Changes roomChanges = Change::NoChange;
     QElapsedTimer et; et.start();
     for (auto&& event: data.accountData)
-        processAccountDataEvent(move(event));
+        roomChanges |= processAccountDataEvent(move(event));
 
-    bool emitNamesChanged = false;
     if (!data.state.empty())
     {
         et.restart();
-        for (const auto& e: data.state)
-            emitNamesChanged |= processStateEvent(*e);
+        for (auto&& eptr: data.state)
+        {
+            const auto& evt = *eptr;
+            Q_ASSERT(evt.isStateEvent());
+            d->baseState[{evt.matrixType(),evt.stateKey()}] = move(eptr);
+            roomChanges |= processStateEvent(evt);
+        }
 
-        qCDebug(PROFILER) << "*** Room::processStateEvents():"
-                          << data.state.size() << "event(s)," << et;
+        if (data.state.size() > 9 || et.nsecsElapsed() >= profilerMinNsecs())
+            qCDebug(PROFILER) << "*** Room::processStateEvents():"
+                              << data.state.size() << "event(s)," << et;
     }
     if (!data.timeline.empty())
     {
         et.restart();
-        // State changes can arrive in a timeline event; so check those.
-        for (const auto& e: data.timeline)
-            emitNamesChanged |= processStateEvent(*e);
-        qCDebug(PROFILER) << "*** Room::processStateEvents(timeline):"
-                          << data.timeline.size() << "event(s)," << et;
+        roomChanges |= d->addNewMessageEvents(move(data.timeline));
+        if (data.timeline.size() > 9 || et.nsecsElapsed() >= profilerMinNsecs())
+            qCDebug(PROFILER) << "*** Room::addNewMessageEvents():"
+                              << data.timeline.size() << "event(s)," << et;
     }
-    if (emitNamesChanged)
+    if (roomChanges&TopicChange)
+        emit topicChanged();
+
+    if (roomChanges&NameChange)
         emit namesChanged(this);
+
     d->updateDisplayname();
 
-    if (!data.timeline.empty())
-    {
-        et.restart();
-        d->addNewMessageEvents(move(data.timeline));
-        qCDebug(PROFILER) << "*** Room::addNewMessageEvents():" << et;
-    }
     for( auto&& ephemeralEvent: data.ephemeral )
         processEphemeralEvent(move(ephemeralEvent));
 
@@ -1134,6 +1171,12 @@ void Room::updateData(SyncRoomData&& data)
         d->notificationCount = data.notificationCount;
         emit notificationCountChanged(this);
     }
+    if (roomChanges != Change::NoChange)
+    {
+        emit changed(roomChanges);
+        if (!fromCache)
+            connection()->saveRoomState(this);
+    }
 }
 
 QString Room::Private::sendEvent(RoomEventPtr&& event)
@@ -1150,50 +1193,42 @@ QString Room::Private::sendEvent(RoomEventPtr&& event)
 QString Room::Private::doSendEvent(const RoomEvent* pEvent)
 {
     auto txnId = pEvent->transactionId();
-    // TODO: Enqueue the job rather than immediately trigger it
-    auto call = connection->callApi<SendMessageJob>(BackgroundRequest,
-                    id, pEvent->matrixType(), txnId, pEvent->contentJson());
-    Room::connect(call, &BaseJob::started, q,
-        [this,pEvent,txnId] {
-            auto it = findAsPending(pEvent);
-            if (it == unsyncedEvents.end())
-            {
-                qWarning(EVENTS) << "Pending event for transaction" << txnId
-                                 << "not found - got synced so soon?";
-                return;
-            }
-            it->setDeparted();
-            emit q->pendingEventChanged(it - unsyncedEvents.begin());
-        });
-    Room::connect(call, &BaseJob::failure, q,
-        [this,pEvent,txnId,call] {
-            auto it = findAsPending(pEvent);
-            if (it == unsyncedEvents.end())
-            {
-                qCritical(EVENTS) << "Pending event for transaction" << txnId
-                                  << "got lost without successful sending";
-                return;
-            }
-            it->setSendingFailed(
-                        call->statusCaption() % ": " % call->errorString());
-            emit q->pendingEventChanged(it - unsyncedEvents.begin());
-
-        });
-    Room::connect(call, &BaseJob::success, q,
-        [this,call,pEvent,txnId] {
-            // Find an event by the pointer saved in the lambda (the pointer
-            // may be dangling by now but we can still search by it).
-            auto it = findAsPending(pEvent);
-            if (it == unsyncedEvents.end())
-            {
-                qDebug(EVENTS) << "Pending event for transaction" << txnId
-                               << "already merged";
-                return;
-            }
+    // TODO, #133: Enqueue the job rather than immediately trigger it.
+    if (auto call = connection->callApi<SendMessageJob>(BackgroundRequest,
+                        id, pEvent->matrixType(), txnId, pEvent->contentJson()))
+    {
+        Room::connect(call, &BaseJob::started, q,
+            [this,pEvent,txnId] {
+                auto it = findAsPending(pEvent);
+                if (it == unsyncedEvents.end())
+                {
+                    qWarning(EVENTS) << "Pending event for transaction" << txnId
+                                     << "not found - got synced so soon?";
+                    return;
+                }
+                it->setDeparted();
+                emit q->pendingEventChanged(it - unsyncedEvents.begin());
+            });
+        Room::connect(call, &BaseJob::failure, q,
+            std::bind(&Room::Private::onEventSendingFailure,
+                      this, pEvent, txnId, call));
+        Room::connect(call, &BaseJob::success, q,
+            [this,call,pEvent,txnId] {
+                // Find an event by the pointer saved in the lambda (the pointer
+                // may be dangling by now but we can still search by it).
+                auto it = findAsPending(pEvent);
+                if (it == unsyncedEvents.end())
+                {
+                    qDebug(EVENTS) << "Pending event for transaction" << txnId
+                                   << "already merged";
+                    return;
+                }
 
-            it->setReachedServer(call->eventId());
-            emit q->pendingEventChanged(it - unsyncedEvents.begin());
-        });
+                it->setReachedServer(call->eventId());
+                emit q->pendingEventChanged(it - unsyncedEvents.begin());
+            });
+    } else
+        onEventSendingFailure(pEvent, txnId);
     return txnId;
 }
 
@@ -1206,6 +1241,22 @@ Room::PendingEvents::iterator Room::Private::findAsPending(
     return std::find_if(unsyncedEvents.begin(), unsyncedEvents.end(), comp);
 }
 
+void Room::Private::onEventSendingFailure(const RoomEvent* pEvent,
+        const QString& txnId, BaseJob* call)
+{
+    auto it = findAsPending(pEvent);
+    if (it == unsyncedEvents.end())
+    {
+        qCritical(EVENTS) << "Pending event for transaction" << txnId
+                          << "could not be sent";
+        return;
+    }
+    it->setSendingFailed(call
+        ? call->statusCaption() % ": " % call->errorString()
+        : tr("The call could not be started"));
+    emit q->pendingEventChanged(it - unsyncedEvents.begin());
+}
+
 QString Room::retryMessage(const QString& txnId)
 {
     auto it = std::find_if(d->unsyncedEvents.begin(), d->unsyncedEvents.end(),
@@ -1285,15 +1336,15 @@ bool isEchoEvent(const RoomEventPtr& le, const PendingEventItem& re)
     if (le->type() != re->type())
         return false;
 
-    if (!le->id().isEmpty())
+    if (!re->id().isEmpty())
         return le->id() == re->id();
-    if (!le->transactionId().isEmpty())
+    if (!re->transactionId().isEmpty())
         return le->transactionId() == re->transactionId();
 
     // This one is not reliable (there can be two unsynced
     // events with the same type, sender and state key) but
     // it's the best we have for state events.
-    if (le->isStateEvent())
+    if (re->isStateEvent())
         return le->stateKey() == re->stateKey();
 
     // Empty id and no state key, hmm... (shrug)
@@ -1349,10 +1400,13 @@ void Room::Private::getPreviousContent(int limit)
     {
         eventsHistoryJob =
             connection->callApi<GetRoomEventsJob>(id, prevBatch, "b", "", limit);
+        emit q->eventsHistoryJobChanged();
         connect( eventsHistoryJob, &BaseJob::success, q, [=] {
             prevBatch = eventsHistoryJob->end();
             addHistoricalMessageEvents(eventsHistoryJob->chunk());
         });
+        connect( eventsHistoryJob, &QObject::destroyed,
+                 q, &Room::eventsHistoryJobChanged);
     }
 }
 
@@ -1587,11 +1641,26 @@ bool Room::Private::processRedaction(const RedactionEvent& redaction)
         return true;
     }
 
-    // Make a new event from the redacted JSON, exchange events,
-    // notify everyone and delete the old event
+    // Make a new event from the redacted JSON and put it in the timeline
+    // instead of the redacted one. oldEvent will be deleted on return.
     auto oldEvent = ti.replaceEvent(makeRedacted(*ti, redaction));
-    q->onRedaction(*oldEvent, *ti.event());
     qCDebug(MAIN) << "Redacted" << oldEvent->id() << "with" << redaction.id();
+    if (oldEvent->isStateEvent())
+    {
+        const StateEventKey evtKey { oldEvent->matrixType(), oldEvent->stateKey() };
+        Q_ASSERT(currentState.contains(evtKey));
+        if (currentState[evtKey] == oldEvent.get())
+        {
+            Q_ASSERT(ti.index() >= 0); // Historical states can't be in currentState
+            qCDebug(MAIN).nospace() << "Reverting state "
+                << oldEvent->matrixType() << "/" << oldEvent->stateKey();
+            // Retarget the current state to the newly made event.
+            if (q->processStateEvent(*ti))
+                emit q->namesChanged(q);
+            updateDisplayname();
+        }
+    }
+    q->onRedaction(*oldEvent, *ti);
     emit q->replacedEvent(ti.event(), rawPtr(oldEvent));
     return true;
 }
@@ -1613,48 +1682,49 @@ inline bool isRedaction(const RoomEventPtr& ep)
     return is<RedactionEvent>(*ep);
 }
 
-void Room::Private::addNewMessageEvents(RoomEvents&& events)
+Room::Changes Room::Private::addNewMessageEvents(RoomEvents&& events)
 {
     dropDuplicateEvents(events);
+    if (events.empty())
+        return Change::NoChange;
 
     // Pre-process redactions so that events that get redacted in the same
     // batch landed in the timeline already redacted.
-    // XXX: The code below is written (and commented) so that it could be
-    // quickly converted to not-saving redaction events in the timeline.
-    // See #220 for details.
-    auto newEnd = std::find_if(events.begin(), events.end(), isRedaction);
-    // Either process the redaction, or shift the non-redaction event
-    // overwriting redactions in a remove_if fashion.
-    for(const auto& eptr: RoomEventsRange(newEnd, events.end()))
+    // NB: We have to store redaction events to the timeline too - see #220.
+    auto redactionIt = std::find_if(events.begin(), events.end(), isRedaction);
+    for(const auto& eptr: RoomEventsRange(redactionIt, events.end()))
         if (auto* r = eventCast<RedactionEvent>(eptr))
         {
             // Try to find the target in the timeline, then in the batch.
             if (processRedaction(*r))
                 continue;
-            auto targetIt = std::find_if(events.begin(), newEnd,
+            auto targetIt = std::find_if(events.begin(), redactionIt,
                 [id=r->redactedEvent()] (const RoomEventPtr& ep) {
                     return ep->id() == id;
                 });
-            if (targetIt != newEnd)
+            if (targetIt != redactionIt)
                 *targetIt = makeRedacted(**targetIt, *r);
             else
                 qCDebug(MAIN) << "Redaction" << r->id()
                               << "ignored: target event" << r->redactedEvent()
                               << "is not found";
-            // If the target events comes later, it comes already redacted.
+            // If the target event comes later, it comes already redacted.
         }
-//        else // This should be uncommented once we stop adding redactions to the timeline
-//            *newEnd++ = std::move(eptr);
-    newEnd = events.end(); // This line should go if/when we stop adding redactions to the timeline
 
-    if (events.begin() == newEnd)
-        return;
+    // State changes arrive as a part of timeline; the current room state gets
+    // updated before merging events to the timeline because that's what
+    // clients historically expect. This may eventually change though if we
+    // postulate that the current state is only current between syncs but not
+    // within a sync.
+    Changes stateChanges = Change::NoChange;
+    for (const auto& eptr: events)
+        stateChanges |= q->processStateEvent(*eptr);
 
     auto timelineSize = timeline.size();
     auto totalInserted = 0;
-    for (auto it = events.begin(); it != newEnd;)
+    for (auto it = events.begin(); it != events.end();)
     {
-        auto nextPendingPair = findFirstOf(it, newEnd,
+        auto nextPendingPair = findFirstOf(it, events.end(),
                     unsyncedEvents.begin(), unsyncedEvents.end(), isEchoEvent);
         auto nextPending = nextPendingPair.first;
 
@@ -1668,7 +1738,7 @@ void Room::Private::addNewMessageEvents(RoomEvents&& events)
             q->onAddNewTimelineEvents(firstInserted);
             emit q->addedMessages(firstInserted->index(), timeline.back().index());
         }
-        if (nextPending == newEnd)
+        if (nextPending == events.end())
             break;
 
         it = nextPending + 1;
@@ -1696,7 +1766,7 @@ void Room::Private::addNewMessageEvents(RoomEvents&& events)
     if (totalInserted > 0)
     {
         qCDebug(MAIN)
-                << "Room" << displayname << "received" << totalInserted
+                << "Room" << q->objectName() << "received" << totalInserted
                 << "new events; the last event is now" << timeline.back();
 
         // The first event in the just-added batch (referred to by `from`)
@@ -1717,21 +1787,34 @@ void Room::Private::addNewMessageEvents(RoomEvents&& events)
     }
 
     Q_ASSERT(timeline.size() == timelineSize + totalInserted);
+    return stateChanges;
 }
 
 void Room::Private::addHistoricalMessageEvents(RoomEvents&& events)
 {
+    QElapsedTimer et; et.start();
     const auto timelineSize = timeline.size();
 
     dropDuplicateEvents(events);
-    RoomEventsRange normalEvents {
-        events.begin(), events.end() //remove_if(events.begin(), events.end(), isRedaction)
-    };
-    if (normalEvents.empty())
+    if (events.empty())
         return;
 
-    emit q->aboutToAddHistoricalMessages(normalEvents);
-    const auto insertedSize = moveEventsToTimeline(normalEvents, Older);
+    // In case of lazy-loading new members may be loaded with historical
+    // messages. Also, the cache doesn't store events with empty content;
+    // so when such events show up in the timeline they should be properly
+    // incorporated.
+    for (const auto& eptr: events)
+    {
+        const auto& e = *eptr;
+        if (e.isStateEvent() &&
+                !currentState.contains({e.matrixType(), e.stateKey()}))
+        {
+            q->processStateEvent(e);
+        }
+    }
+
+    emit q->aboutToAddHistoricalMessages(events);
+    const auto insertedSize = moveEventsToTimeline(events, Older);
     const auto from = timeline.crend() - insertedSize;
 
     qCDebug(MAIN) << "Room" << displayname << "received" << insertedSize
@@ -1743,51 +1826,46 @@ void Room::Private::addHistoricalMessageEvents(RoomEvents&& events)
         updateUnreadCount(from, timeline.crend());
 
     Q_ASSERT(timeline.size() == timelineSize + insertedSize);
+    if (insertedSize > 9 || et.nsecsElapsed() >= profilerMinNsecs())
+        qCDebug(PROFILER) << "*** Room::addHistoricalMessageEvents():"
+                          << insertedSize << "event(s)," << et;
 }
 
-bool Room::processStateEvent(const RoomEvent& e)
+Room::Changes Room::processStateEvent(const RoomEvent& e)
 {
+    if (!e.isStateEvent())
+        return Change::NoChange;
+
+    d->currentState[{e.matrixType(),e.stateKey()}] =
+            static_cast<const StateEventBase*>(&e);
+    if (!is<RoomMemberEvent>(e))
+        qCDebug(EVENTS) << "Room state event:" << e;
+
     return visit(e
-        , [this] (const RoomNameEvent& evt) {
-            d->name = evt.name();
-            qCDebug(MAIN) << "Room name updated:" << d->name;
-            return true;
+        , [] (const RoomNameEvent&) {
+            return NameChange;
         }
-        , [this] (const RoomAliasesEvent& evt) {
-            d->aliases = evt.aliases();
-            qCDebug(MAIN) << "Room aliases updated:" << d->aliases;
-            return true;
+        , [] (const RoomAliasesEvent&) {
+            return OtherChange;
         }
         , [this] (const RoomCanonicalAliasEvent& evt) {
-            d->canonicalAlias = evt.alias();
-            if (!d->canonicalAlias.isEmpty())
-                setObjectName(d->canonicalAlias);
-            qCDebug(MAIN) << "Room canonical alias updated:"
-                          << d->canonicalAlias;
-            return true;
+            setObjectName(evt.alias().isEmpty() ? d->id : evt.alias());
+            return CanonicalAliasChange;
         }
-        , [this] (const RoomTopicEvent& evt) {
-            d->topic = evt.topic();
-            qCDebug(MAIN) << "Room topic updated:" << d->topic;
-            emit topicChanged();
-            return false;
+        , [] (const RoomTopicEvent&) {
+            return TopicChange;
         }
         , [this] (const RoomAvatarEvent& evt) {
             if (d->avatar.updateUrl(evt.url()))
-            {
-                qCDebug(MAIN) << "Room avatar URL updated:"
-                              << evt.url().toString();
                 emit avatarChanged();
-            }
-            return false;
+            return AvatarChange;
         }
         , [this] (const RoomMemberEvent& evt) {
             auto* u = user(evt.userId());
             u->processEvent(evt, this);
             if (u == localUser() && memberJoinState(u) == JoinState::Invite
                     && evt.isDirect())
-                connection()->addToDirectChats(this,
-                                user(evt.senderId()));
+                connection()->addToDirectChats(this, user(evt.senderId()));
 
             if( evt.membership() == MembershipType::Join )
             {
@@ -1807,24 +1885,23 @@ bool Room::processStateEvent(const RoomEvent& e)
                     emit userAdded(u);
                 }
             }
-            else if( evt.membership() == MembershipType::Leave )
+            else if( evt.membership() != MembershipType::Join )
             {
                 if (memberJoinState(u) == JoinState::Join)
                 {
+                    if (evt.membership() == MembershipType::Invite)
+                        qCWarning(MAIN) << "Invalid membership change:" << evt;
                     if (!d->membersLeft.contains(u))
                         d->membersLeft.append(u);
                     d->removeMemberFromMap(u->name(this), u);
                     emit userRemoved(u);
                 }
             }
-            return false;
+            return MembersChange;
         }
-        , [this] (const EncryptionEvent& evt) {
-            d->encryptionAlgorithm = evt.algorithm();
-            qCDebug(MAIN) << "Encryption switched on in room" << id()
-                          << "with algorithm" << d->encryptionAlgorithm;
-            emit encryption();
-            return false;
+        , [this] (const EncryptionEvent&) {
+            emit encryption(); // It can only be done once, so emit it here.
+            return EncryptionOn;
         }
     );
 }
@@ -1841,15 +1918,17 @@ void Room::processEphemeralEvent(EventPtr&& event)
             if (memberJoinState(u) == JoinState::Join)
                 d->usersTyping.append(u);
         }
-        if (!evt->users().isEmpty())
+        if (evt->users().size() > 3 || et.nsecsElapsed() >= profilerMinNsecs())
             qCDebug(PROFILER) << "*** Room::processEphemeralEvent(typing):"
                 << evt->users().size() << "users," << et;
         emit typingChanged();
     }
     if (auto* evt = eventCast<ReceiptEvent>(event))
     {
+        int totalReceipts = 0;
         for( const auto &p: qAsConst(evt->eventsWithReceipts()) )
         {
+            totalReceipts += p.receipts.size();
             {
                 if (p.receipts.size() == 1)
                     qCDebug(EPHEMERAL) << "Marking" << p.evtId
@@ -1888,14 +1967,15 @@ void Room::processEphemeralEvent(EventPtr&& event)
                 }
             }
         }
-        if (!evt->eventsWithReceipts().isEmpty())
+        if (evt->eventsWithReceipts().size() > 3 || totalReceipts > 10 ||
+                et.nsecsElapsed() >= profilerMinNsecs())
             qCDebug(PROFILER) << "*** Room::processEphemeralEvent(receipts):"
                 << evt->eventsWithReceipts().size()
-                << "events with receipts," << et;
+                << "event(s) with" << totalReceipts << "receipt(s)," << et;
     }
 }
 
-void Room::processAccountDataEvent(EventPtr&& event)
+Room::Changes Room::processAccountDataEvent(EventPtr&& event)
 {
     if (auto* evt = eventCast<TagEvent>(event))
         d->setTags(evt->tags());
@@ -1922,7 +2002,9 @@ void Room::processAccountDataEvent(EventPtr&& event)
         qCDebug(MAIN) << "Updated account data of type"
                       << currentData->matrixType();
         emit accountDataChanged(currentData->matrixType());
+        return Change::AccountDataChange;
     }
+    return Change::NoChange;
 }
 
 QString Room::Private::roomNameFromMemberNames(const QList<User *> &userlist) const
@@ -1963,9 +2045,8 @@ QString Room::Private::roomNameFromMemberNames(const QList<User *> &userlist) co
 
     // iii. More users.
     if (userlist.size() > 3)
-        return tr("%1 and %L2 others")
-                .arg(q->roomMembername(first_two[0]))
-                .arg(userlist.size() - 3);
+        return tr("%1 and %Ln other(s)", "", userlist.size() - 3)
+                .arg(q->roomMembername(first_two[0]));
 
     // userlist.size() < 2 - apparently, there's only current user in the room
     return QString();
@@ -1977,27 +2058,29 @@ QString Room::Private::calculateDisplayname() const
     // Numbers below refer to respective parts in the spec.
 
     // 1. Name (from m.room.name)
-    if (!name.isEmpty()) {
-        return name;
+    auto dispName = q->name();
+    if (!dispName.isEmpty()) {
+        return dispName;
     }
 
     // 2. Canonical alias
-    if (!canonicalAlias.isEmpty())
-        return canonicalAlias;
+    dispName = q->canonicalAlias();
+    if (!dispName.isEmpty())
+        return dispName;
 
     // Using m.room.aliases in naming is explicitly discouraged by the spec
-    //if (!aliases.empty() && !aliases.at(0).isEmpty())
-    //    return aliases.at(0);
+    //if (!q->aliases().empty() && !q->aliases().at(0).isEmpty())
+    //    return q->aliases().at(0);
 
     // 3. Room members
-    QString topMemberNames = roomNameFromMemberNames(membersMap.values());
-    if (!topMemberNames.isEmpty())
-        return topMemberNames;
+    dispName = roomNameFromMemberNames(membersMap.values());
+    if (!dispName.isEmpty())
+        return dispName;
 
     // 4. Users that previously left the room
-    topMemberNames = roomNameFromMemberNames(membersLeft);
-    if (!topMemberNames.isEmpty())
-        return tr("Empty room (was: %1)").arg(topMemberNames);
+    dispName = roomNameFromMemberNames(membersLeft);
+    if (!dispName.isEmpty())
+        return tr("Empty room (was: %1)").arg(dispName);
 
     // 5. Fail miserably
     return tr("Empty room (%1)").arg(id);
@@ -2016,34 +2099,6 @@ void Room::Private::updateDisplayname()
     }
 }
 
-void appendStateEvent(QJsonArray& events, const QString& type,
-                      const QJsonObject& content, const QString& stateKey = {})
-{
-    if (!content.isEmpty() || !stateKey.isEmpty())
-    {
-        auto json = basicEventJson(type, content);
-        json.insert(QStringLiteral("state_key"), stateKey);
-        events.append(json);
-    }
-}
-
-#define ADD_STATE_EVENT(events, type, name, content) \
-    appendStateEvent((events), QStringLiteral(type), \
-                     {{ QStringLiteral(name), content }});
-
-void appendEvent(QJsonArray& events, const QString& type,
-                 const QJsonObject& content)
-{
-    if (!content.isEmpty())
-        events.append(basicEventJson(type, content));
-}
-
-template <typename EvtT>
-void appendEvent(QJsonArray& events, const EvtT& event)
-{
-    appendEvent(events, EvtT::matrixTypeId(), event.toJson());
-}
-
 QJsonObject Room::Private::toJson() const
 {
     QElapsedTimer et; et.start();
@@ -2051,23 +2106,19 @@ QJsonObject Room::Private::toJson() const
     {
         QJsonArray stateEvents;
 
-        ADD_STATE_EVENT(stateEvents, "m.room.name", "name", name);
-        ADD_STATE_EVENT(stateEvents, "m.room.topic", "topic", topic);
-        ADD_STATE_EVENT(stateEvents, "m.room.avatar", "url",
-                        avatar.url().toString());
-        ADD_STATE_EVENT(stateEvents, "m.room.aliases", "aliases",
-                        QJsonArray::fromStringList(aliases));
-        ADD_STATE_EVENT(stateEvents, "m.room.canonical_alias", "alias",
-                        canonicalAlias);
-        ADD_STATE_EVENT(stateEvents, "m.room.encryption", "algorithm",
-                        encryptionAlgorithm);
-
-        for (const auto *m : membersMap)
-            appendStateEvent(stateEvents, QStringLiteral("m.room.member"),
-                { { QStringLiteral("membership"), QStringLiteral("join") }
-                , { QStringLiteral("displayname"), m->rawName(q) }
-                , { QStringLiteral("avatar_url"), m->avatarUrl(q).toString() }
-            }, m->id());
+        for (const auto* evt: currentState)
+        {
+            Q_ASSERT(evt->isStateEvent());
+            if ((evt->isRedacted() && !is<RoomMemberEvent>(*evt)) ||
+                    evt->contentJson().isEmpty())
+                continue;
+
+            auto json = evt->fullJson();
+            auto unsignedJson = evt->unsignedJson();
+            unsignedJson.remove(QStringLiteral("prev_content"));
+            json[UnsignedKeyL] = unsignedJson;
+            stateEvents.append(json);
+        }
 
         const auto stateObjName = joinState == JoinState::Invite ?
                     QStringLiteral("invite_state") : QStringLiteral("state");
@@ -2075,14 +2126,17 @@ QJsonObject Room::Private::toJson() const
             QJsonObject {{ QStringLiteral("events"), stateEvents }});
     }
 
-    QJsonArray accountDataEvents;
     if (!accountData.empty())
     {
+        QJsonArray accountDataEvents;
         for (const auto& e: accountData)
-            appendEvent(accountDataEvents, e.first, e.second->contentJson());
+        {
+            if (!e.second->contentJson().isEmpty())
+                accountDataEvents.append(e.second->fullJson());
+        }
+        result.insert(QStringLiteral("account_data"),
+                      QJsonObject {{ QStringLiteral("events"), accountDataEvents }});
     }
-    result.insert(QStringLiteral("account_data"),
-                  QJsonObject {{ QStringLiteral("events"), accountDataEvents }});
 
     QJsonObject unreadNotifObj
         { { SyncRoomData::UnreadCountKey, unreadMessages } };
@@ -2094,7 +2148,7 @@ QJsonObject Room::Private::toJson() const
 
     result.insert(QStringLiteral("unread_notifications"), unreadNotifObj);
 
-    if (et.elapsed() > 50)
+    if (et.elapsed() > 30)
         qCDebug(PROFILER) << "Room::toJson() for" << displayname << "took" << et;
 
     return result;
diff --git a/lib/room.h b/lib/room.h
index f1566ac5..9d4561e5 100644
--- a/lib/room.h
+++ b/lib/room.h
@@ -18,7 +18,7 @@
 
 #pragma once
 
-#include "jobs/syncjob.h"
+#include "csapi/message_pagination.h"
 #include "events/roommessageevent.h"
 #include "events/accountdataevents.h"
 #include "eventitem.h"
@@ -33,6 +33,7 @@
 namespace QMatrixClient
 {
     class Event;
+    class SyncRoomData;
     class RoomMemberEvent;
     class Connection;
     class User;
@@ -95,12 +96,32 @@ namespace QMatrixClient
             Q_PROPERTY(bool isFavourite READ isFavourite NOTIFY tagsChanged)
             Q_PROPERTY(bool isLowPriority READ isLowPriority NOTIFY tagsChanged)
 
+            Q_PROPERTY(GetRoomEventsJob* eventsHistoryJob READ eventsHistoryJob NOTIFY eventsHistoryJobChanged)
+
         public:
             using Timeline = std::deque<TimelineItem>;
             using PendingEvents = std::vector<PendingEventItem>;
             using rev_iter_t = Timeline::const_reverse_iterator;
             using timeline_iter_t = Timeline::const_iterator;
 
+            enum Change : uint {
+                NoChange = 0x0,
+                NameChange = 0x1,
+                CanonicalAliasChange = 0x2,
+                TopicChange = 0x4,
+                UnreadNotifsChange = 0x8,
+                AvatarChange = 0x10,
+                JoinStateChange = 0x20,
+                TagsChange = 0x40,
+                MembersChange = 0x80,
+                EncryptionOn = 0x100,
+                AccountDataChange = 0x200,
+                OtherChange = 0x1000,
+                AnyChange = 0x1FFF
+            };
+            Q_DECLARE_FLAGS(Changes, Change)
+            Q_FLAG(Changes)
+
             Room(Connection* connection, QString id, JoinState initialJoinState);
             ~Room() override;
 
@@ -126,6 +147,8 @@ namespace QMatrixClient
             int timelineSize() const;
             bool usesEncryption() const;
 
+            GetRoomEventsJob* eventsHistoryJob() const;
+
             /**
              * Returns a square room avatar with the given size and requests it
              * from the network if needed
@@ -177,9 +200,16 @@ namespace QMatrixClient
             const Timeline& messageEvents() const;
             const PendingEvents& pendingEvents() const;
             /**
-             * A convenience method returning the read marker to
-             * the before-oldest message
+             * A convenience method returning the read marker to the position
+             * before the "oldest" event; same as messageEvents().crend()
+             */
+            rev_iter_t historyEdge() const;
+            /**
+             * A convenience method returning the iterator beyond the latest
+             * arrived event; same as messageEvents().cend()
              */
+            Timeline::const_iterator syncEdge() const;
+            /// \deprecated Use historyEdge instead
             rev_iter_t timelineEdge() const;
             Q_INVOKABLE TimelineItem::index_t minTimelineIndex() const;
             Q_INVOKABLE TimelineItem::index_t maxTimelineIndex() const;
@@ -323,6 +353,7 @@ namespace QMatrixClient
              *
              * Takes ownership of the event, deleting it once the matching one
              * arrives with the sync
+             * \return transaction id associated with the event.
              */
             QString postEvent(RoomEvent* event);
             QString postJson(const QString& matrixType,
@@ -356,6 +387,7 @@ namespace QMatrixClient
             void markAllMessagesAsRead();
 
         signals:
+            void eventsHistoryJobChanged();
             void aboutToAddHistoricalMessages(RoomEventsRange events);
             void aboutToAddNewMessages(RoomEventsRange events);
             void addedMessages(int fromIndex, int toIndex);
@@ -368,6 +400,13 @@ namespace QMatrixClient
             void pendingEventDiscarded();
             void pendingEventChanged(int pendingEventIndex);
 
+            /** A common signal for various kinds of changes in the room
+             * Aside from all changes in the room state
+             * @param changes a set of flags describing what changes occured
+             *                upon the last sync
+             * \sa StateChange
+             */
+            void changed(Changes changes);
             /**
              * \brief The room name, the canonical alias or other aliases changed
              *
@@ -417,27 +456,28 @@ namespace QMatrixClient
             /// The room is about to be deleted
             void beforeDestruction(Room*);
 
-        public: // Used by Connection - not a part of the client API
-            QJsonObject toJson() const;
-            void updateData(SyncRoomData&& data );
-
-            // Clients should use Connection::joinRoom() and Room::leaveRoom()
-            // to change the room state
-            void setJoinState( JoinState state );
-
         protected:
             /// Returns true if any of room names/aliases has changed
-            virtual bool processStateEvent(const RoomEvent& e);
+            virtual Changes processStateEvent(const RoomEvent& e);
             virtual void processEphemeralEvent(EventPtr&& event);
-            virtual void processAccountDataEvent(EventPtr&& event);
+            virtual Changes processAccountDataEvent(EventPtr&& event);
             virtual void onAddNewTimelineEvents(timeline_iter_t /*from*/) { }
             virtual void onAddHistoricalTimelineEvents(rev_iter_t /*from*/) { }
             virtual void onRedaction(const RoomEvent& /*prevEvent*/,
                                      const RoomEvent& /*after*/) { }
+            virtual QJsonObject toJson() const;
+            virtual void updateData(SyncRoomData&& data, bool fromCache = false);
 
         private:
+            friend class Connection;
+
             class Private;
             Private* d;
+
+            // This is called from Connection, reflecting a state change that
+            // arrived from the server. Clients should use
+            // Connection::joinRoom() and Room::leaveRoom() to change the state.
+            void setJoinState(JoinState state);
     };
 
     class MemberSorter
@@ -460,3 +500,4 @@ namespace QMatrixClient
     };
 }  // namespace QMatrixClient
 Q_DECLARE_METATYPE(QMatrixClient::FileTransferInfo)
+Q_DECLARE_OPERATORS_FOR_FLAGS(QMatrixClient::Room::Changes)
diff --git a/lib/syncdata.cpp b/lib/syncdata.cpp
new file mode 100644
index 00000000..1023ed6a
--- /dev/null
+++ b/lib/syncdata.cpp
@@ -0,0 +1,180 @@
+/******************************************************************************
+ * Copyright (C) 2018 Kitsune Ral <kitsune-ral@users.sf.net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include "syncdata.h"
+
+#include "events/eventloader.h"
+
+#include <QtCore/QFile>
+#include <QtCore/QFileInfo>
+
+using namespace QMatrixClient;
+
+const QString SyncRoomData::UnreadCountKey =
+        QStringLiteral("x-qmatrixclient.unread_count");
+
+template <typename EventsArrayT, typename StrT>
+inline EventsArrayT load(const QJsonObject& batches, StrT keyName)
+{
+    return fromJson<EventsArrayT>(batches[keyName].toObject().value("events"_ls));
+}
+
+SyncRoomData::SyncRoomData(const QString& roomId_, JoinState joinState_,
+                           const QJsonObject& room_)
+    : roomId(roomId_)
+    , joinState(joinState_)
+    , state(load<StateEvents>(room_, joinState == JoinState::Invite
+                                     ? "invite_state"_ls : "state"_ls))
+{
+    switch (joinState) {
+        case JoinState::Join:
+            ephemeral = load<Events>(room_, "ephemeral"_ls);
+            FALLTHROUGH;
+        case JoinState::Leave:
+        {
+            accountData = load<Events>(room_, "account_data"_ls);
+            timeline = load<RoomEvents>(room_, "timeline"_ls);
+            const auto timelineJson = room_.value("timeline"_ls).toObject();
+            timelineLimited = timelineJson.value("limited"_ls).toBool();
+            timelinePrevBatch = timelineJson.value("prev_batch"_ls).toString();
+
+            break;
+        }
+        default: /* nothing on top of state */;
+    }
+
+    const auto unreadJson = room_.value("unread_notifications"_ls).toObject();
+    unreadCount = unreadJson.value(UnreadCountKey).toInt(-2);
+    highlightCount = unreadJson.value("highlight_count"_ls).toInt();
+    notificationCount = unreadJson.value("notification_count"_ls).toInt();
+    if (highlightCount > 0 || notificationCount > 0)
+        qCDebug(SYNCJOB) << "Room" << roomId_
+                         << "has highlights:" << highlightCount
+                         << "and notifications:" << notificationCount;
+}
+
+SyncData::SyncData(const QString& cacheFileName)
+{
+    QFileInfo cacheFileInfo { cacheFileName };
+    auto json = loadJson(cacheFileName);
+    auto requiredVersion = std::get<0>(cacheVersion());
+    auto actualVersion = json.value("cache_version").toObject()
+                             .value("major").toInt();
+    if (actualVersion == requiredVersion)
+        parseJson(json, cacheFileInfo.absolutePath() + '/');
+    else
+        qCWarning(MAIN)
+            << "Major version of the cache file is" << actualVersion << "but"
+            << requiredVersion << "is required; discarding the cache";
+}
+
+SyncDataList&& SyncData::takeRoomData()
+{
+    return move(roomData);
+}
+
+QString SyncData::fileNameForRoom(QString roomId)
+{
+    roomId.replace(':', '_');
+    return roomId + ".json";
+}
+
+Events&& SyncData::takePresenceData()
+{
+    return std::move(presenceData);
+}
+
+Events&& SyncData::takeAccountData()
+{
+    return std::move(accountData);
+}
+
+Events&& SyncData::takeToDeviceEvents()
+{
+    return std::move(toDeviceEvents);
+}
+
+QJsonObject SyncData::loadJson(const QString& fileName)
+{
+    QFile roomFile { fileName };
+    if (!roomFile.exists())
+    {
+        qCWarning(MAIN) << "No state cache file" << fileName;
+        return {};
+    }
+    if(!roomFile.open(QIODevice::ReadOnly))
+    {
+        qCWarning(MAIN) << "Failed to open state cache file"
+                        << roomFile.fileName();
+        return {};
+    }
+    auto data = roomFile.readAll();
+
+    const auto json =
+        (data.startsWith('{') ? QJsonDocument::fromJson(data)
+                              : QJsonDocument::fromBinaryData(data)).object();
+    if (json.isEmpty())
+    {
+        qCWarning(MAIN) << "State cache in" << fileName
+                        << "is broken or empty, discarding";
+    }
+    return json;
+}
+
+void SyncData::parseJson(const QJsonObject& json, const QString& baseDir)
+{
+    QElapsedTimer et; et.start();
+
+    nextBatch_ = json.value("next_batch"_ls).toString();
+    presenceData = load<Events>(json, "presence"_ls);
+    accountData = load<Events>(json, "account_data"_ls);
+    toDeviceEvents = load<Events>(json, "to_device"_ls);
+
+    auto rooms = json.value("rooms"_ls).toObject();
+    JoinStates::Int ii = 1; // ii is used to make a JoinState value
+    auto totalRooms = 0;
+    auto totalEvents = 0;
+    for (size_t i = 0; i < JoinStateStrings.size(); ++i, ii <<= 1)
+    {
+        const auto rs = rooms.value(JoinStateStrings[i]).toObject();
+        // We have a Qt container on the right and an STL one on the left
+        roomData.reserve(static_cast<size_t>(rs.size()));
+        for(auto roomIt = rs.begin(); roomIt != rs.end(); ++roomIt)
+        {
+            auto roomJson = roomIt->isObject()
+                            ? roomIt->toObject()
+                            : loadJson(baseDir + fileNameForRoom(roomIt.key()));
+            if (roomJson.isEmpty())
+            {
+                unresolvedRoomIds.push_back(roomIt.key());
+                continue;
+            }
+            roomData.emplace_back(roomIt.key(), JoinState(ii), roomJson);
+            const auto& r = roomData.back();
+            totalEvents += r.state.size() + r.ephemeral.size() +
+                           r.accountData.size() + r.timeline.size();
+        }
+        totalRooms += rs.size();
+    }
+    if (!unresolvedRoomIds.empty())
+        qCWarning(MAIN) << "Unresolved rooms:" << unresolvedRoomIds.join(',');
+    if (totalRooms > 9 || et.nsecsElapsed() >= profilerMinNsecs())
+        qCDebug(PROFILER) << "*** SyncData::parseJson(): batch with"
+                          << totalRooms << "room(s),"
+                          << totalEvents << "event(s) in" << et;
+}
diff --git a/lib/syncdata.h b/lib/syncdata.h
new file mode 100644
index 00000000..aa8948bc
--- /dev/null
+++ b/lib/syncdata.h
@@ -0,0 +1,86 @@
+/******************************************************************************
+ * Copyright (C) 2018 Kitsune Ral <kitsune-ral@users.sf.net>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#pragma once
+
+#include "joinstate.h"
+#include "events/stateevent.h"
+
+namespace QMatrixClient {
+    class SyncRoomData
+    {
+        public:
+            QString roomId;
+            JoinState joinState;
+            StateEvents state;
+            RoomEvents timeline;
+            Events ephemeral;
+            Events accountData;
+
+            bool timelineLimited;
+            QString timelinePrevBatch;
+            int unreadCount;
+            int highlightCount;
+            int notificationCount;
+
+            SyncRoomData(const QString& roomId, JoinState joinState_,
+                         const QJsonObject& room_);
+            SyncRoomData(SyncRoomData&&) = default;
+            SyncRoomData& operator=(SyncRoomData&&) = default;
+
+            static const QString UnreadCountKey;
+    };
+
+    // QVector cannot work with non-copiable objects, std::vector can.
+    using SyncDataList = std::vector<SyncRoomData>;
+
+    class SyncData
+    {
+        public:
+            SyncData() = default;
+            explicit SyncData(const QString& cacheFileName);
+            /** Parse sync response into room events
+             * \param json response from /sync or a room state cache
+             * \return the list of rooms with missing cache files; always
+             *         empty when parsing response from /sync
+             */
+            void parseJson(const QJsonObject& json, const QString& baseDir = {});
+
+            Events&& takePresenceData();
+            Events&& takeAccountData();
+            Events&& takeToDeviceEvents();
+            SyncDataList&& takeRoomData();
+
+            QString nextBatch() const { return nextBatch_; }
+
+            QStringList unresolvedRooms() const { return unresolvedRoomIds; }
+
+            static std::pair<int, int> cacheVersion() { return { 9, 0 }; }
+            static QString fileNameForRoom(QString roomId);
+
+        private:
+            QString nextBatch_;
+            Events presenceData;
+            Events accountData;
+            Events toDeviceEvents;
+            SyncDataList roomData;
+            QStringList unresolvedRoomIds;
+
+            static QJsonObject loadJson(const QString& fileName);
+    };
+}  // namespace QMatrixClient
diff --git a/lib/user.cpp b/lib/user.cpp
index eec08ad9..eec41957 100644
--- a/lib/user.cpp
+++ b/lib/user.cpp
@@ -312,6 +312,11 @@ void User::unmarkIgnore()
     connection()->removeFromIgnoredUsers(this);
 }
 
+bool User::isIgnored() const
+{
+    return connection()->isIgnored(this);
+}
+
 void User::Private::setAvatarOnServer(QString contentUri, User* q)
 {
     auto* j = connection->callApi<SetAvatarUrlJob>(userId, contentUri);
@@ -321,14 +326,16 @@ void User::Private::setAvatarOnServer(QString contentUri, User* q)
 
 QString User::displayname(const Room* room) const
 {
-    auto name = d->nameForRoom(room);
-    return name.isEmpty() ? d->userId :
-           room ? room->roomMembername(this) : name;
+    if (room)
+        return room->roomMembername(this);
+
+    const auto name = d->nameForRoom(nullptr);
+    return name.isEmpty() ? d->userId : name;
 }
 
 QString User::fullName(const Room* room) const
 {
-    auto name = d->nameForRoom(room);
+    const auto name = d->nameForRoom(room);
     return name.isEmpty() ? d->userId : name % " (" % d->userId % ')';
 }
 
diff --git a/lib/user.h b/lib/user.h
index 17f5625f..0023b44a 100644
--- a/lib/user.h
+++ b/lib/user.h
@@ -125,6 +125,8 @@ namespace QMatrixClient
             void ignore();
             /** Remove the user from the ignore list */
             void unmarkIgnore();
+            /** Check whether the user is in ignore list */
+            bool isIgnored() const;
 
         signals:
             void nameAboutToChange(QString newName, QString oldName,
diff --git a/lib/util.cpp b/lib/util.cpp
index 1773fcfe..af06013c 100644
--- a/lib/util.cpp
+++ b/lib/util.cpp
@@ -19,6 +19,9 @@
 #include "util.h"
 
 #include <QtCore/QRegularExpression>
+#include <QtCore/QStandardPaths>
+#include <QtCore/QDir>
+#include <QtCore/QStringBuilder>
 
 static const auto RegExpOptions =
     QRegularExpression::CaseInsensitiveOption
@@ -61,3 +64,14 @@ QString QMatrixClient::prettyPrint(const QString& plainText)
     linkifyUrls(pt);
     return pt;
 }
+
+QString QMatrixClient::cacheLocation(const QString& dirName)
+{
+    const QString cachePath =
+        QStandardPaths::writableLocation(QStandardPaths::CacheLocation)
+            % '/' % dirName % '/';
+    QDir dir;
+    if (!dir.exists(cachePath))
+        dir.mkpath(cachePath);
+    return cachePath;
+}
diff --git a/lib/util.h b/lib/util.h
index 13eec143..88c756a1 100644
--- a/lib/util.h
+++ b/lib/util.h
@@ -240,5 +240,11 @@ namespace QMatrixClient
      * This includes HTML escaping of <,>,",& and URLs linkification.
      */
     QString prettyPrint(const QString& plainText);
+
+    /** Return a path to cache directory after making sure that it exists
+     * The returned path has a trailing slash, clients don't need to append it.
+     * \param dir path to cache directory relative to the standard cache path
+     */
+    QString cacheLocation(const QString& dirName);
 }  // namespace QMatrixClient
 
diff --git a/libqmatrixclient.pri b/libqmatrixclient.pri
index cb90a9fd..8ca43e56 100644
--- a/libqmatrixclient.pri
+++ b/libqmatrixclient.pri
@@ -17,6 +17,7 @@ HEADERS += \
     $$SRCPATH/room.h \
     $$SRCPATH/user.h \
     $$SRCPATH/avatar.h \
+    $$SRCPATH/syncdata.h \
     $$SRCPATH/util.h \
     $$SRCPATH/events/event.h \
     $$SRCPATH/events/roomevent.h \
@@ -60,6 +61,7 @@ SOURCES += \
     $$SRCPATH/room.cpp \
     $$SRCPATH/user.cpp \
     $$SRCPATH/avatar.cpp \
+    $$SRCPATH/syncdata.cpp \
     $$SRCPATH/util.cpp \
     $$SRCPATH/events/event.cpp \
     $$SRCPATH/events/roomevent.cpp \