pollymc/api/logic/FolderInstanceProvider.cpp

#include "FolderInstanceProvider.h"
#include "settings/INISettingsObject.h"
#include "FileSystem.h"
#include "minecraft/MinecraftInstance.h"
#include "minecraft/legacy/LegacyInstance.h"
#include "NullInstance.h"

#include <QDir>
#include <QDirIterator>
#include <QFileSystemWatcher>
#include <QJsonDocument>
#include <QJsonObject>
#include <QJsonArray>
#include <QUuid>
#include <QTimer>

const static int GROUP_FILE_FORMAT_VERSION = 1;

struct WatchLock
{
    WatchLock(QFileSystemWatcher * watcher, const QString& instDir)
        : m_watcher(watcher), m_instDir(instDir)
    {
        m_watcher->removePath(m_instDir);
    }
    ~WatchLock()
    {
        m_watcher->addPath(m_instDir);
    }
    QFileSystemWatcher * m_watcher;
    QString m_instDir;
};

FolderInstanceProvider::FolderInstanceProvider(SettingsObjectPtr settings, const QString& instDir)
    : BaseInstanceProvider(settings)
{
    // Create aand normalize path
    if (!QDir::current().exists(instDir))
    {
        QDir::current().mkpath(instDir);
    }
    // NOTE: canonicalPath requires the path to exist. Do not move this above the creation block!
    m_instDir = QDir(instDir).canonicalPath();
    m_watcher = new QFileSystemWatcher(this);
    connect(m_watcher, &QFileSystemWatcher::directoryChanged, this, &FolderInstanceProvider::instanceDirContentsChanged);
    m_watcher->addPath(m_instDir);
}

QList< InstanceId > FolderInstanceProvider::discoverInstances()
{
    QList<InstanceId> out;
    QDirIterator iter(m_instDir, QDir::Dirs | QDir::NoDot | QDir::NoDotDot | QDir::Readable | QDir::Hidden, QDirIterator::FollowSymlinks);
    while (iter.hasNext())
    {
        QString subDir = iter.next();
        QFileInfo dirInfo(subDir);
        if (!QFileInfo(FS::PathCombine(subDir, "instance.cfg")).exists())
            continue;
        // if it is a symlink, ignore it if it goes to the instance folder
        if(dirInfo.isSymLink())
        {
            QFileInfo targetInfo(dirInfo.symLinkTarget());
            QFileInfo instDirInfo(m_instDir);
            if(targetInfo.canonicalPath() == instDirInfo.canonicalFilePath())
            {
                qDebug() << "Ignoring symlink" << subDir << "that leads into the instances folder";
                continue;
            }
        }
        auto id = dirInfo.fileName();
        out.append(id);
        qDebug() << "Found instance ID" << id;
    }
    return out;
}

InstancePtr FolderInstanceProvider::loadInstance(const InstanceId& id)
{
    if(!m_groupsLoaded)
    {
        loadGroupList();
    }

    auto instanceRoot = FS::PathCombine(m_instDir, id);
    auto instanceSettings = std::make_shared<INISettingsObject>(FS::PathCombine(instanceRoot, "instance.cfg"));
    InstancePtr inst;

    instanceSettings->registerSetting("InstanceType", "Legacy");

    QString inst_type = instanceSettings->get("InstanceType").toString();

    if (inst_type == "OneSix" || inst_type == "Nostalgia")
    {
        inst.reset(new MinecraftInstance(m_globalSettings, instanceSettings, instanceRoot));
    }
    else if (inst_type == "Legacy")
    {
        inst.reset(new LegacyInstance(m_globalSettings, instanceSettings, instanceRoot));
    }
    else
    {
        inst.reset(new NullInstance(m_globalSettings, instanceSettings, instanceRoot));
    }
    inst->init();
    inst->setProvider(this);
    auto iter = groupMap.find(id);
    if (iter != groupMap.end())
    {
        inst->setGroupInitial((*iter));
    }
    connect(inst.get(), &BaseInstance::groupChanged, this, &FolderInstanceProvider::groupChanged);
    qDebug() << "Loaded instance " << inst->name() << " from " << inst->instanceRoot();
    return inst;
}

void FolderInstanceProvider::saveGroupList()
{
    WatchLock foo(m_watcher, m_instDir);
    QString groupFileName = m_instDir + "/instgroups.json";
    QMap<QString, QSet<QString>> reverseGroupMap;
    for (auto iter = groupMap.begin(); iter != groupMap.end(); iter++)
    {
        QString id = iter.key();
        QString group = iter.value();
        if (group.isEmpty())
            continue;

        if (!reverseGroupMap.count(group))
        {
            QSet<QString> set;
            set.insert(id);
            reverseGroupMap[group] = set;
        }
        else
        {
            QSet<QString> &set = reverseGroupMap[group];
            set.insert(id);
        }
    }
    QJsonObject toplevel;
    toplevel.insert("formatVersion", QJsonValue(QString("1")));
    QJsonObject groupsArr;
    for (auto iter = reverseGroupMap.begin(); iter != reverseGroupMap.end(); iter++)
    {
        auto list = iter.value();
        auto name = iter.key();
        QJsonObject groupObj;
        QJsonArray instanceArr;
        groupObj.insert("hidden", QJsonValue(QString("false")));
        for (auto item : list)
        {
            instanceArr.append(QJsonValue(item));
        }
        groupObj.insert("instances", instanceArr);
        groupsArr.insert(name, groupObj);
    }
    toplevel.insert("groups", groupsArr);
    QJsonDocument doc(toplevel);
    try
    {
        FS::write(groupFileName, doc.toJson());
    }
    catch (const FS::FileSystemException &e)
    {
        qCritical() << "Failed to write instance group file :" << e.cause();
    }
}

void FolderInstanceProvider::loadGroupList()
{
    QSet<QString> groupSet;

    QString groupFileName = m_instDir + "/instgroups.json";

    // if there's no group file, fail
    if (!QFileInfo(groupFileName).exists())
        return;

    QByteArray jsonData;
    try
    {
        jsonData = FS::read(groupFileName);
    }
    catch (const FS::FileSystemException &e)
    {
        qCritical() << "Failed to read instance group file :" << e.cause();
        return;
    }

    QJsonParseError error;
    QJsonDocument jsonDoc = QJsonDocument::fromJson(jsonData, &error);

    // if the json was bad, fail
    if (error.error != QJsonParseError::NoError)
    {
        qCritical() << QString("Failed to parse instance group file: %1 at offset %2")
                            .arg(error.errorString(), QString::number(error.offset))
                            .toUtf8();
        return;
    }

    // if the root of the json wasn't an object, fail
    if (!jsonDoc.isObject())
    {
        qWarning() << "Invalid group file. Root entry should be an object.";
        return;
    }

    QJsonObject rootObj = jsonDoc.object();

    // Make sure the format version matches, otherwise fail.
    if (rootObj.value("formatVersion").toVariant().toInt() != GROUP_FILE_FORMAT_VERSION)
        return;

    // Get the groups. if it's not an object, fail
    if (!rootObj.value("groups").isObject())
    {
        qWarning() << "Invalid group list JSON: 'groups' should be an object.";
        return;
    }

    groupMap.clear();

    // Iterate through all the groups.
    QJsonObject groupMapping = rootObj.value("groups").toObject();
    for (QJsonObject::iterator iter = groupMapping.begin(); iter != groupMapping.end(); iter++)
    {
        QString groupName = iter.key();

        // If not an object, complain and skip to the next one.
        if (!iter.value().isObject())
        {
            qWarning() << QString("Group '%1' in the group list should "
                                   "be an object.")
                               .arg(groupName)
                               .toUtf8();
            continue;
        }

        QJsonObject groupObj = iter.value().toObject();
        if (!groupObj.value("instances").isArray())
        {
            qWarning() << QString("Group '%1' in the group list is invalid. "
                                   "It should contain an array "
                                   "called 'instances'.")
                               .arg(groupName)
                               .toUtf8();
            continue;
        }

        // keep a list/set of groups for choosing
        groupSet.insert(groupName);

        // Iterate through the list of instances in the group.
        QJsonArray instancesArray = groupObj.value("instances").toArray();

        for (QJsonArray::iterator iter2 = instancesArray.begin(); iter2 != instancesArray.end();
             iter2++)
        {
            groupMap[(*iter2).toString()] = groupName;
        }
    }
    m_groupsLoaded = true;
    emit groupsChanged(groupSet);
}

void FolderInstanceProvider::groupChanged()
{
    // save the groups. save all of them.
    auto instance = (BaseInstance *) QObject::sender();
    auto id = instance->id();
    groupMap[id] = instance->group();
    emit groupsChanged({instance->group()});
    saveGroupList();
}


void FolderInstanceProvider::instanceDirContentsChanged(const QString& path)
{
    Q_UNUSED(path);
    emit instancesChanged();
}

void FolderInstanceProvider::on_InstFolderChanged(const Setting &setting, QVariant value)
{
    QString newInstDir = QDir(value.toString()).canonicalPath();
    if(newInstDir != m_instDir)
    {
        if(m_groupsLoaded)
        {
            saveGroupList();
        }
        m_instDir = newInstDir;
        m_groupsLoaded = false;
        emit instancesChanged();
    }
}

template <typename T>
static void clamp(T& current, T min, T max)
{
    if (current < min)
    {
        current = min;
    }
    else if(current > max)
    {
        current = max;
    }
}

// List of numbers from min to max. Next is exponent times bigger than previous.
class ExponentialSeries
{
public:
    ExponentialSeries(unsigned min, unsigned max, unsigned exponent = 2)
    {
        m_current = m_min = min;
        m_max = max;
        m_exponent = exponent;
    }
    void reset()
    {
        m_current = m_min;
    }
    unsigned operator()()
    {
        unsigned retval = m_current;
        m_current *= m_exponent;
        clamp(m_current, m_min, m_max);
        return retval;
    }
    unsigned m_current;
    unsigned m_min;
    unsigned m_max;
    unsigned m_exponent;
};

/*
 * WHY: the whole reason why this uses an exponential backoff retry scheme is antivirus on Windows.
 * Basically, it starts messing things up while MultiMC is extracting/creating instances
 * and causes that horrible failure that is NTFS to lock files in place because they are open.
 */
class FolderInstanceStaging : public Task
{
Q_OBJECT
    const unsigned minBackoff = 1;
    const unsigned maxBackoff = 16;
public:
    FolderInstanceStaging (
        FolderInstanceProvider * parent,
        Task * child,
        const QString & stagingPath,
        const QString& instanceName,
        const QString& groupName )
    : backoff(minBackoff, maxBackoff)
    {
        m_parent = parent;
        m_child.reset(child);
        connect(child, &Task::succeeded, this, &FolderInstanceStaging::childSucceded);
        connect(child, &Task::failed, this, &FolderInstanceStaging::childFailed);
        connect(child, &Task::status, this, &FolderInstanceStaging::setStatus);
        connect(child, &Task::progress, this, &FolderInstanceStaging::setProgress);
        m_instanceName = instanceName;
        m_groupName = groupName;
        m_stagingPath = stagingPath;
        m_backoffTimer.setSingleShot(true);
        connect(&m_backoffTimer, &QTimer::timeout, this, &FolderInstanceStaging::childSucceded);
    }

    virtual ~FolderInstanceStaging() {};

protected:
    virtual void executeTask() override
    {
        m_child->start();
    }
    QStringList warnings() const override
    {
        return m_child->warnings();
    }

private slots:
    void childSucceded()
    {
        unsigned sleepTime = backoff();
        if(m_parent->commitStagedInstance(m_stagingPath, m_instanceName, m_groupName))
        {
            emitSucceeded();
            return;
        }
        // we actually failed, retry?
        if(sleepTime == maxBackoff)
        {
            emitFailed(tr("Failed to commit instance, even after multiple retries. It is being blocked by something."));
            return;
        }
        qDebug() << "Failed to commit instance" << m_instanceName << "Initiating backoff:" << sleepTime;
        m_backoffTimer.start(sleepTime * 500);
    }
    void childFailed(const QString & reason)
    {
        m_parent->destroyStagingPath(m_stagingPath);
        emitFailed(reason);
    }

private:
    ExponentialSeries backoff;
    QString m_stagingPath;
    FolderInstanceProvider * m_parent;
    unique_qobject_ptr<Task> m_child;
    QString m_instanceName;
    QString m_groupName;
    QTimer m_backoffTimer;
};

#include "InstanceTask.h"
Task * FolderInstanceProvider::wrapInstanceTask(InstanceTask * task)
{
    auto stagingPath = getStagedInstancePath();
    task->setStagingPath(stagingPath);
    task->setParentSettings(m_globalSettings);
    return new FolderInstanceStaging(this, task, stagingPath, task->name(), task->group());
}

QString FolderInstanceProvider::getStagedInstancePath()
{
    QString key = QUuid::createUuid().toString();
    QString relPath = FS::PathCombine("_MMC_TEMP/" , key);
    QDir rootPath(m_instDir);
    auto path = FS::PathCombine(m_instDir, relPath);
    if(!rootPath.mkpath(relPath))
    {
        return QString();
    }
    return path;
}

bool FolderInstanceProvider::commitStagedInstance(const QString& path, const QString& instanceName, const QString& groupName)
{
    QDir dir;
    QString instID = FS::DirNameFromString(instanceName, m_instDir);
    {
        WatchLock lock(m_watcher, m_instDir);
        QString destination = FS::PathCombine(m_instDir, instID);
        if(!dir.rename(path, destination))
        {
            qWarning() << "Failed to move" << path << "to" << destination;
            return false;
        }
        groupMap[instID] = groupName;
        emit groupsChanged({groupName});
        emit instancesChanged();
    }
    saveGroupList();
    return true;
}

bool FolderInstanceProvider::destroyStagingPath(const QString& keyPath)
{
    return FS::deletePath(keyPath);
}

#include "FolderInstanceProvider.moc"