Introduced a QueryRunner object

The QueryRunner object lives for the duration of the query (so just
for the initial query for non-live queries, and for the lifetime of the
result model for live queries).
It's supposed to handle all the threading internally and decouple the
lifetime of the facade.

1 files changed, 292 insertions, 0 deletions

diff --git a/common/queryrunner.cpp b/common/queryrunner.cpp
new file mode 100644
index 0000000..4159112
--- /dev/null
+++ b/common/queryrunner.cpp
@@ -0,0 +1,292 @@
+/*
+    Copyright (c) 2015 Christian Mollekopf <mollekopf@kolabsys.com>
+
+    This library is free software; you can redistribute it and/or modify it
+    under the terms of the GNU Library General Public License as published by
+    the Free Software Foundation; either version 2 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 Library General Public
+    License for more details.
+
+    You should have received a copy of the GNU Library General Public License
+    along with this library; see the file COPYING.LIB.  If not, write to the
+    Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301, USA.
+*/
+#include "queryrunner.h"
+
+#include <QtConcurrent/QtConcurrentRun>
+#include <QFuture>
+#include <QFutureWatcher>
+#include "commands.h"
+#include "log.h"
+#include "storage.h"
+#include "definitions.h"
+#include "domainadaptor.h"
+
+using namespace Akonadi2;
+
+static inline ResultSet fullScan(const Akonadi2::Storage::Transaction &transaction, const QByteArray &bufferType)
+{
+    //TODO use a result set with an iterator, to read values on demand
+    QVector<QByteArray> keys;
+    transaction.openDatabase(bufferType + ".main").scan(QByteArray(), [&](const QByteArray &key, const QByteArray &value) -> bool {
+        //Skip internals
+        if (Akonadi2::Storage::isInternalKey(key)) {
+            return true;
+        }
+        keys << Akonadi2::Storage::uidFromKey(key);
+        return true;
+    },
+    [](const Akonadi2::Storage::Error &error) {
+        qWarning() << "Error during query: " << error.message;
+    });
+
+    Trace() << "Full scan found " << keys.size() << " results";
+    return ResultSet(keys);
+}
+
+template<class DomainType>
+QueryRunner<DomainType>::QueryRunner(const Akonadi2::Query &query, const Akonadi2::ResourceAccessInterface::Ptr &resourceAccess, const QByteArray &instanceIdentifier, const DomainTypeAdaptorFactoryInterface::Ptr &factory, const QByteArray &bufferType)
+    : QueryRunnerBase(),
+    mResourceAccess(resourceAccess),
+    mResultProvider(new ResultProvider<typename DomainType::Ptr>),
+    mDomainTypeAdaptorFactory(factory),
+    mQuery(query),
+    mResourceInstanceIdentifier(instanceIdentifier),
+    mBufferType(bufferType)
+{
+    Trace() << "Starting query";
+    //We delegate loading of initial data to the result provider, os it can decide for itself what it needs to load.
+    mResultProvider->setFetcher([this, query](const typename DomainType::Ptr &parent) {
+        Trace() << "Running fetcher";
+
+        // auto watcher = new QFutureWatcher<qint64>;
+        // QObject::connect(watcher, &QFutureWatcher::finished, [](qint64 newRevision) {
+        //     mResourceAccess->sendRevisionReplayedCommand(newRevision);
+        // });
+        // auto future = QtConcurrent::run([&resultProvider]() -> qint64 {
+        //     const qint64 newRevision = executeInitialQuery(query, parent, resultProvider);
+        //     return newRevision;
+        // });
+        // watcher->setFuture(future);
+        const qint64 newRevision = executeInitialQuery(query, parent, *mResultProvider);
+        mResourceAccess->sendRevisionReplayedCommand(newRevision);
+    });
+
+
+    //In case of a live query we keep the runner for as long alive as the result provider exists
+    if (query.liveQuery) {
+        //Incremental updates are always loaded directly, leaving it up to the result to discard the changes if they are not interesting
+        setQuery([this, query] () -> KAsync::Job<void> {
+            return KAsync::start<void>([this, query](KAsync::Future<void> &future) {
+                //TODO execute in thread
+                const qint64 newRevision = executeIncrementalQuery(query, *mResultProvider);
+                mResourceAccess->sendRevisionReplayedCommand(newRevision);
+                future.setFinished();
+            });
+        });
+        //Ensure the connection is open, if it wasn't already opened
+        //TODO If we are not connected already, we have to check for the latest revision once connected, otherwise we could miss some updates
+        mResourceAccess->open();
+        QObject::connect(mResourceAccess.data(), &Akonadi2::ResourceAccess::revisionChanged, this, &QueryRunner::revisionChanged);
+    }
+}
+
+template<class DomainType>
+typename Akonadi2::ResultEmitter<typename DomainType::Ptr>::Ptr QueryRunner<DomainType>::emitter()
+{
+    return mResultProvider->emitter();
+}
+
+//TODO move into result provider?
+template<class DomainType>
+void QueryRunner<DomainType>::replaySet(ResultSet &resultSet, Akonadi2::ResultProviderInterface<typename DomainType::Ptr> &resultProvider)
+{
+    // Trace() << "Replay set";
+    while (resultSet.next([&resultProvider](const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &value, Akonadi2::Operation operation) -> bool {
+        switch (operation) {
+        case Akonadi2::Operation_Creation:
+            // Trace() << "Got creation";
+            resultProvider.add(Akonadi2::ApplicationDomain::ApplicationDomainType::getInMemoryRepresentation<DomainType>(*value).template staticCast<DomainType>());
+            break;
+        case Akonadi2::Operation_Modification:
+            // Trace() << "Got modification";
+            resultProvider.modify(Akonadi2::ApplicationDomain::ApplicationDomainType::getInMemoryRepresentation<DomainType>(*value).template staticCast<DomainType>());
+            break;
+        case Akonadi2::Operation_Removal:
+            // Trace() << "Got removal";
+            resultProvider.remove(Akonadi2::ApplicationDomain::ApplicationDomainType::getInMemoryRepresentation<DomainType>(*value).template staticCast<DomainType>());
+            break;
+        }
+        return true;
+    })){};
+}
+
+template<class DomainType>
+void QueryRunner<DomainType>::readEntity(const Akonadi2::Storage::NamedDatabase &db, const QByteArray &key, const std::function<void(const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &, Akonadi2::Operation)> &resultCallback)
+{
+    //This only works for a 1:1 mapping of resource to domain types.
+    //Not i.e. for tags that are stored as flags in each entity of an imap store.
+    //additional properties that don't have a 1:1 mapping (such as separately stored tags),
+    //could be added to the adaptor.
+    db.findLatest(key, [=](const QByteArray &key, const QByteArray &value) -> bool {
+        Akonadi2::EntityBuffer buffer(value.data(), value.size());
+        const Akonadi2::Entity &entity = buffer.entity();
+        const auto metadataBuffer = Akonadi2::EntityBuffer::readBuffer<Akonadi2::Metadata>(entity.metadata());
+        Q_ASSERT(metadataBuffer);
+        const qint64 revision = metadataBuffer ? metadataBuffer->revision() : -1;
+        resultCallback(DomainType::Ptr::create(mResourceInstanceIdentifier, Akonadi2::Storage::uidFromKey(key), revision, mDomainTypeAdaptorFactory->createAdaptor(entity)), metadataBuffer->operation());
+        return false;
+    },
+    [](const Akonadi2::Storage::Error &error) {
+        qWarning() << "Error during query: " << error.message;
+    });
+}
+
+template<class DomainType>
+ResultSet QueryRunner<DomainType>::loadInitialResultSet(const Akonadi2::Query &query, Akonadi2::Storage::Transaction &transaction, QSet<QByteArray> &remainingFilters)
+{
+    QSet<QByteArray> appliedFilters;
+    auto resultSet = Akonadi2::ApplicationDomain::TypeImplementation<DomainType>::queryIndexes(query, mResourceInstanceIdentifier, appliedFilters, transaction);
+    remainingFilters = query.propertyFilter.keys().toSet() - appliedFilters;
+
+    //We do a full scan if there were no indexes available to create the initial set.
+    if (appliedFilters.isEmpty()) {
+        //TODO this should be replaced by an index lookup as well
+        resultSet = fullScan(transaction, mBufferType);
+    }
+    return resultSet;
+}
+
+template<class DomainType>
+ResultSet QueryRunner<DomainType>::loadIncrementalResultSet(qint64 baseRevision, const Akonadi2::Query &query, Akonadi2::Storage::Transaction &transaction, QSet<QByteArray> &remainingFilters)
+{
+    const auto bufferType = mBufferType;
+    auto revisionCounter = QSharedPointer<qint64>::create(baseRevision);
+    remainingFilters = query.propertyFilter.keys().toSet();
+    return ResultSet([bufferType, revisionCounter, &transaction]() -> QByteArray {
+        const qint64 topRevision = Akonadi2::Storage::maxRevision(transaction);
+        //Spit out the revision keys one by one.
+        while (*revisionCounter <= topRevision) {
+            const auto uid = Akonadi2::Storage::getUidFromRevision(transaction, *revisionCounter);
+            const auto type = Akonadi2::Storage::getTypeFromRevision(transaction, *revisionCounter);
+            // Trace() << "Revision" << *revisionCounter << type << uid;
+            if (type != bufferType) {
+                //Skip revision
+                *revisionCounter += 1;
+                continue;
+            }
+            const auto key = Akonadi2::Storage::assembleKey(uid, *revisionCounter);
+            *revisionCounter += 1;
+            return key;
+        }
+        Trace() << "Finished reading incremental result set:" << *revisionCounter;
+        //We're done
+        return QByteArray();
+    });
+}
+
+template<class DomainType>
+ResultSet QueryRunner<DomainType>::filterSet(const ResultSet &resultSet, const std::function<bool(const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &domainObject)> &filter, const Akonadi2::Storage::NamedDatabase &db, bool initialQuery)
+{
+    auto resultSetPtr = QSharedPointer<ResultSet>::create(resultSet);
+
+    //Read through the source values and return whatever matches the filter
+    std::function<bool(std::function<void(const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &, Akonadi2::Operation)>)> generator = [this, resultSetPtr, &db, filter, initialQuery](std::function<void(const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &, Akonadi2::Operation)> callback) -> bool {
+        while (resultSetPtr->next()) {
+            //readEntity is only necessary if we actually want to filter or know the operation type (but not a big deal if we do it always I guess)
+            readEntity(db, resultSetPtr->id(), [this, filter, callback, initialQuery](const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &domainObject, Akonadi2::Operation operation) {
+                //Always remove removals, they probably don't match due to non-available properties
+                if (filter(domainObject) || operation == Akonadi2::Operation_Removal) {
+                    Trace() << "entity is not filtered" << initialQuery;
+                    if (initialQuery) {
+                        //We're not interested in removals during the initial query
+                        if (operation != Akonadi2::Operation_Removal) {
+                            callback(domainObject, Akonadi2::Operation_Creation);
+                        }
+                    } else {
+                        callback(domainObject, operation);
+                    }
+                }
+            });
+        }
+        return false;
+    };
+    return ResultSet(generator);
+}
+
+
+template<class DomainType>
+std::function<bool(const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &domainObject)> QueryRunner<DomainType>::getFilter(const QSet<QByteArray> remainingFilters, const Akonadi2::Query &query)
+{
+    return [remainingFilters, query](const Akonadi2::ApplicationDomain::ApplicationDomainType::Ptr &domainObject) -> bool {
+        for (const auto &filterProperty : remainingFilters) {
+            const auto property = domainObject->getProperty(filterProperty);
+            if (property.isValid()) {
+                //TODO implement other comparison operators than equality
+                if (property != query.propertyFilter.value(filterProperty)) {
+                    Trace() << "Filtering entity due to property mismatch: " << domainObject->getProperty(filterProperty);
+                    return false;
+                }
+            } else {
+                Warning() << "Ignored property filter because value is invalid: " << filterProperty;
+            }
+        }
+        return true;
+    };
+}
+
+template<class DomainType>
+qint64 QueryRunner<DomainType>::load(const Akonadi2::Query &query, const std::function<ResultSet(Akonadi2::Storage::Transaction &, QSet<QByteArray> &)> &baseSetRetriever, Akonadi2::ResultProviderInterface<typename DomainType::Ptr> &resultProvider, bool initialQuery)
+{
+    Akonadi2::Storage storage(Akonadi2::storageLocation(), mResourceInstanceIdentifier);
+    storage.setDefaultErrorHandler([](const Akonadi2::Storage::Error &error) {
+        Warning() << "Error during query: " << error.store << error.message;
+    });
+    auto transaction = storage.createTransaction(Akonadi2::Storage::ReadOnly);
+    auto db = transaction.openDatabase(mBufferType + ".main");
+
+    QSet<QByteArray> remainingFilters;
+    auto resultSet = baseSetRetriever(transaction, remainingFilters);
+    auto filteredSet = filterSet(resultSet, getFilter(remainingFilters, query), db, initialQuery);
+    replaySet(filteredSet, resultProvider);
+    resultProvider.setRevision(Akonadi2::Storage::maxRevision(transaction));
+    return Akonadi2::Storage::maxRevision(transaction);
+}
+
+
+template<class DomainType>
+qint64 QueryRunner<DomainType>::executeIncrementalQuery(const Akonadi2::Query &query, Akonadi2::ResultProviderInterface<typename DomainType::Ptr> &resultProvider)
+{
+    const qint64 baseRevision = resultProvider.revision() + 1;
+    Trace() << "Running incremental query " << baseRevision;
+    return load(query, [&](Akonadi2::Storage::Transaction &transaction, QSet<QByteArray> &remainingFilters) -> ResultSet {
+        return loadIncrementalResultSet(baseRevision, query, transaction, remainingFilters);
+    }, resultProvider, false);
+}
+
+template<class DomainType>
+qint64 QueryRunner<DomainType>::executeInitialQuery(const Akonadi2::Query &query, const typename DomainType::Ptr &parent, Akonadi2::ResultProviderInterface<typename DomainType::Ptr> &resultProvider)
+{
+    auto modifiedQuery = query;
+    if (!query.parentProperty.isEmpty()) {
+        if (parent) {
+            Trace() << "Running initial query for parent:" << parent->identifier();
+            modifiedQuery.propertyFilter.insert(query.parentProperty, parent->identifier());
+        } else {
+            Trace() << "Running initial query for toplevel";
+            modifiedQuery.propertyFilter.insert(query.parentProperty, QVariant());
+        }
+    }
+    return load(modifiedQuery, [&](Akonadi2::Storage::Transaction &transaction, QSet<QByteArray> &remainingFilters) -> ResultSet {
+        return loadInitialResultSet(modifiedQuery, transaction, remainingFilters);
+    }, resultProvider, true);
+}
+
+template class QueryRunner<Akonadi2::ApplicationDomain::Folder>;
+template class QueryRunner<Akonadi2::ApplicationDomain::Mail>;
+template class QueryRunner<Akonadi2::ApplicationDomain::Event>;