GH-352 Make OneSix instance update downloads cancellable

32 files changed, 773 insertions, 337 deletions

diff --git a/api/logic/BaseInstance.h b/api/logic/BaseInstance.h
index 9a6976cb..ebaaeb83 100644
--- a/api/logic/BaseInstance.h
+++ b/api/logic/BaseInstance.h
@@ -16,6 +16,7 @@
 #pragma once
 
 #include <QObject>
+#include "QObjectPtr.h"
 #include <QDateTime>
 #include <QSet>
 #include <QProcess>
@@ -152,7 +153,7 @@ public:
 	virtual SettingsObjectPtr settings() const;
 
 	/// returns a valid update task
-	virtual std::shared_ptr<Task> createUpdateTask() = 0;
+	virtual shared_qobject_ptr<Task> createUpdateTask() = 0;
 
 	/// returns a valid launcher (task container)
 	virtual std::shared_ptr<LaunchTask> createLaunchTask(AuthSessionPtr account) = 0;
diff --git a/api/logic/CMakeLists.txt b/api/logic/CMakeLists.txt
index 4514d8c3..415584fc 100644
--- a/api/logic/CMakeLists.txt
+++ b/api/logic/CMakeLists.txt
@@ -200,6 +200,14 @@ set(MINECRAFT_SOURCES
 	minecraft/onesix/OneSixProfileStrategy.h
 	minecraft/onesix/OneSixVersionFormat.cpp
 	minecraft/onesix/OneSixVersionFormat.h
+	minecraft/onesix/update/AssetUpdateTask.h
+	minecraft/onesix/update/AssetUpdateTask.cpp
+	minecraft/onesix/update/FMLLibrariesTask.cpp
+	minecraft/onesix/update/FMLLibrariesTask.h
+	minecraft/onesix/update/FoldersTask.cpp
+	minecraft/onesix/update/FoldersTask.h
+	minecraft/onesix/update/LibrariesTask.cpp
+	minecraft/onesix/update/LibrariesTask.h
 	minecraft/launch/CreateServerResourcePacksFolder.cpp
 	minecraft/launch/CreateServerResourcePacksFolder.h
 	minecraft/launch/ModMinecraftJar.cpp
diff --git a/api/logic/NullInstance.h b/api/logic/NullInstance.h
index d87fb6f7..4fb31854 100644
--- a/api/logic/NullInstance.h
+++ b/api/logic/NullInstance.h
@@ -48,7 +48,7 @@ public:
 	{
 		return nullptr;
 	}
-	virtual std::shared_ptr< Task > createUpdateTask() override
+	virtual shared_qobject_ptr< Task > createUpdateTask() override
 	{
 		return nullptr;
 	}
diff --git a/api/logic/QObjectPtr.h b/api/logic/QObjectPtr.h
index b81b3234..000d228d 100644
--- a/api/logic/QObjectPtr.h
+++ b/api/logic/QObjectPtr.h
@@ -48,6 +48,10 @@ public:
 		using namespace std::placeholders;
 		m_ptr.reset(wrap, std::bind(&QObject::deleteLater, _1));
 	}
+	void reset(const shared_qobject_ptr<T> &other)
+	{
+		m_ptr = other.m_ptr;
+	}
 	void reset()
 	{
 		m_ptr.reset();
diff --git a/api/logic/launch/steps/Update.cpp b/api/logic/launch/steps/Update.cpp
index 4901f001..ad0c4fc4 100644
--- a/api/logic/launch/steps/Update.cpp
+++ b/api/logic/launch/steps/Update.cpp
@@ -18,7 +18,12 @@
 
 void Update::executeTask()
 {
-	m_updateTask = m_parent->instance()->createUpdateTask();
+	if(m_aborted)
+	{
+		emitFailed(tr("Task aborted."));
+		return;
+	}
+	m_updateTask.reset(m_parent->instance()->createUpdateTask());
 	if(m_updateTask)
 	{
 		connect(m_updateTask.get(), SIGNAL(finished()), this, SLOT(updateFinished()));
@@ -39,12 +44,37 @@ void Update::updateFinished()
 {
 	if(m_updateTask->successful())
 	{
+		m_updateTask.reset();
 		emitSucceeded();
 	}
 	else
 	{
 		QString reason = tr("Instance update failed because: %1.\n\n").arg(m_updateTask->failReason());
+		m_updateTask.reset();
 		emit logLine(reason, MessageLevel::Fatal);
 		emitFailed(reason);
 	}
 }
+
+bool Update::canAbort() const
+{
+	if(m_updateTask)
+	{
+		return m_updateTask->canAbort();
+	}
+	return true;
+}
+
+
+bool Update::abort()
+{
+	m_aborted = true;
+	if(m_updateTask)
+	{
+		if(m_updateTask->canAbort())
+		{
+			return m_updateTask->abort();
+		}
+	}
+	return true;
+}
diff --git a/api/logic/launch/steps/Update.h b/api/logic/launch/steps/Update.h
index 14928253..1739de47 100644
--- a/api/logic/launch/steps/Update.h
+++ b/api/logic/launch/steps/Update.h
@@ -16,6 +16,7 @@
 #pragma once
 
 #include <launch/LaunchStep.h>
+#include <QObjectPtr.h>
 #include <launch/LoggedProcess.h>
 #include <java/JavaChecker.h>
 
@@ -27,15 +28,16 @@ public:
 	explicit Update(LaunchTask *parent):LaunchStep(parent) {};
 	virtual ~Update() {};
 
-	virtual void executeTask();
-	virtual bool canAbort() const
-	{
-		return false;
-	}
-	virtual void proceed();
+	void executeTask() override;
+	bool canAbort() const override;
+	void proceed() override;
+public slots:
+	bool abort() override;
+
 private slots:
 	void updateFinished();
 
 private:
-	std::shared_ptr<Task> m_updateTask;
+	shared_qobject_ptr<Task> m_updateTask;
+	bool m_aborted = false;
 };
diff --git a/api/logic/minecraft/MinecraftVersionList.cpp b/api/logic/minecraft/MinecraftVersionList.cpp
index 4e4eafbc..e3f416d9 100644
--- a/api/logic/minecraft/MinecraftVersionList.cpp
+++ b/api/logic/minecraft/MinecraftVersionList.cpp
@@ -61,6 +61,10 @@ public:
 	explicit MCVListVersionUpdateTask(MinecraftVersionList *vlist, std::shared_ptr<MinecraftVersion> updatedVersion);
 	virtual ~MCVListVersionUpdateTask() override{};
 	virtual void executeTask() override;
+	bool canAbort() const override;
+
+public slots:
+	bool abort() override;
 
 protected
 slots:
@@ -71,6 +75,7 @@ protected:
 	QByteArray versionIndexData;
 	std::shared_ptr<MinecraftVersion> updatedVersion;
 	MinecraftVersionList *m_list;
+	bool m_aborted = false;
 };
 
 class ListLoadError : public Exception
@@ -410,6 +415,11 @@ MCVListVersionUpdateTask::MCVListVersionUpdateTask(MinecraftVersionList *vlist,
 
 void MCVListVersionUpdateTask::executeTask()
 {
+	if(m_aborted)
+	{
+		emitFailed(tr("Task aborted."));
+		return;
+	}
 	auto job = new NetJob("Version index");
 	job->addNetAction(Net::Download::makeByteArray(QUrl(updatedVersion->getUrl()), &versionIndexData));
 	specificVersionDownloadJob.reset(job);
@@ -419,6 +429,21 @@ void MCVListVersionUpdateTask::executeTask()
 	specificVersionDownloadJob->start();
 }
 
+bool MCVListVersionUpdateTask::canAbort() const
+{
+	return true;
+}
+
+bool MCVListVersionUpdateTask::abort()
+{
+	m_aborted = true;
+	if(specificVersionDownloadJob)
+	{
+		return specificVersionDownloadJob->abort();
+	}
+	return true;
+}
+
 void MCVListVersionUpdateTask::json_downloaded()
 {
 	specificVersionDownloadJob.reset();
diff --git a/api/logic/minecraft/forge/ForgeXzDownload.cpp b/api/logic/minecraft/forge/ForgeXzDownload.cpp
index adf96552..8b762866 100644
--- a/api/logic/minecraft/forge/ForgeXzDownload.cpp
+++ b/api/logic/minecraft/forge/ForgeXzDownload.cpp
@@ -35,6 +35,12 @@ ForgeXzDownload::ForgeXzDownload(QString relative_path, MetaEntryPtr entry) : Ne
 
 void ForgeXzDownload::start()
 {
+	if(m_status == Job_Aborted)
+	{
+		qWarning() << "Attempt to start an aborted Download:" << m_url.toString();
+		emit aborted(m_index_within_job);
+		return;
+	}
 	m_status = Job_InProgress;
 	if (!m_entry->isStale())
 	{
@@ -76,9 +82,17 @@ void ForgeXzDownload::downloadProgress(qint64 bytesReceived, qint64 bytesTotal)
 
 void ForgeXzDownload::downloadError(QNetworkReply::NetworkError error)
 {
-	// error happened during download.
-	// TODO: log the reason why
-	m_status = Job_Failed;
+	if(error == QNetworkReply::OperationCanceledError)
+	{
+		qCritical() << "Aborted " << m_url.toString();
+		m_status = Job_Aborted;
+	}
+	else
+	{
+		// error happened during download.
+		qCritical() << "Failed " << m_url.toString() << " with reason " << error;
+		m_status = Job_Failed;
+	}
 }
 
 void ForgeXzDownload::failAndTryNextMirror()
@@ -90,7 +104,7 @@ void ForgeXzDownload::failAndTryNextMirror()
 void ForgeXzDownload::downloadFinished()
 {
 	// if the download succeeded
-	if (m_status != Job_Failed)
+	if (m_status != Job_Failed && m_status != Job_Aborted)
 	{
 		// nothing went wrong...
 		m_status = Job_Finished;
@@ -110,6 +124,14 @@ void ForgeXzDownload::downloadFinished()
 			return;
 		}
 	}
+	else if(m_status == Job_Aborted)
+	{
+		m_pack200_xz_file.remove();
+		m_reply.reset();
+		emit failed(m_index_within_job);
+		emit aborted(m_index_within_job);
+		return;
+	}
 	// else the download failed
 	else
 	{
@@ -147,6 +169,7 @@ void ForgeXzDownload::downloadReadyRead()
 
 const size_t buffer_size = 8196;
 
+// NOTE: once this gets here, it can't be aborted anymore. we don't care.
 void ForgeXzDownload::decompressAndInstall()
 {
 	// rewind the downloaded temp file
@@ -356,3 +379,16 @@ void ForgeXzDownload::decompressAndInstall()
 	m_reply.reset();
 	emit succeeded(m_index_within_job);
 }
+
+bool ForgeXzDownload::abort()
+{
+	if(m_reply)
+		m_reply->abort();
+	m_status = Job_Aborted;
+	return true;
+}
+
+bool ForgeXzDownload::canAbort()
+{
+	return true;
+}
diff --git a/api/logic/minecraft/forge/ForgeXzDownload.h b/api/logic/minecraft/forge/ForgeXzDownload.h
index 67524405..e51ff9e5 100644
--- a/api/logic/minecraft/forge/ForgeXzDownload.h
+++ b/api/logic/minecraft/forge/ForgeXzDownload.h
@@ -41,17 +41,19 @@ public:
 		return ForgeXzDownloadPtr(new ForgeXzDownload(relative_path, entry));
 	}
 	virtual ~ForgeXzDownload(){};
+	bool canAbort() override;
 
 protected
 slots:
-	virtual void downloadProgress(qint64 bytesReceived, qint64 bytesTotal);
-	virtual void downloadError(QNetworkReply::NetworkError error);
-	virtual void downloadFinished();
-	virtual void downloadReadyRead();
+	void downloadProgress(qint64 bytesReceived, qint64 bytesTotal) override;
+	void downloadError(QNetworkReply::NetworkError error) override;
+	void downloadFinished() override;
+	void downloadReadyRead() override;
 
 public
 slots:
-	virtual void start();
+	void start() override;
+	bool abort() override;
 
 private:
 	void decompressAndInstall();
diff --git a/api/logic/minecraft/ftb/OneSixFTBInstance.cpp b/api/logic/minecraft/ftb/OneSixFTBInstance.cpp
index 81e939a1..5edad080 100644
--- a/api/logic/minecraft/ftb/OneSixFTBInstance.cpp
+++ b/api/logic/minecraft/ftb/OneSixFTBInstance.cpp
@@ -125,7 +125,7 @@ void OneSixFTBInstance::createProfile()
 	m_profile.reset(new MinecraftProfile(new FTBProfileStrategy(this)));
 }
 
-std::shared_ptr<Task> OneSixFTBInstance::createUpdateTask()
+shared_qobject_ptr<Task> OneSixFTBInstance::createUpdateTask()
 {
 	return OneSixInstance::createUpdateTask();
 }
diff --git a/api/logic/minecraft/ftb/OneSixFTBInstance.h b/api/logic/minecraft/ftb/OneSixFTBInstance.h
index e7f8f485..a5621685 100644
--- a/api/logic/minecraft/ftb/OneSixFTBInstance.h
+++ b/api/logic/minecraft/ftb/OneSixFTBInstance.h
@@ -13,7 +13,7 @@ public:
 
 	virtual void createProfile() override;
 
-	virtual std::shared_ptr<Task> createUpdateTask() override;
+	virtual shared_qobject_ptr<Task> createUpdateTask() override;
 
 	virtual QString id() const override;
 
diff --git a/api/logic/minecraft/legacy/LegacyInstance.cpp b/api/logic/minecraft/legacy/LegacyInstance.cpp
index 7c552369..7ed2041c 100644
--- a/api/logic/minecraft/legacy/LegacyInstance.cpp
+++ b/api/logic/minecraft/legacy/LegacyInstance.cpp
@@ -87,12 +87,12 @@ bool LegacyInstance::shouldUseCustomBaseJar() const
 }
 
 
-std::shared_ptr<Task> LegacyInstance::createUpdateTask()
+shared_qobject_ptr<Task> LegacyInstance::createUpdateTask()
 {
 	// make sure the jar mods list is initialized by asking for it.
 	auto list = jarModList();
 	// create an update task
-	return std::shared_ptr<Task>(new LegacyUpdate(this, this));
+	return shared_qobject_ptr<Task>(new LegacyUpdate(this, this));
 }
 
 std::shared_ptr<Task> LegacyInstance::createJarModdingTask()
diff --git a/api/logic/minecraft/legacy/LegacyInstance.h b/api/logic/minecraft/legacy/LegacyInstance.h
index f1cefbcc..1d95340b 100644
--- a/api/logic/minecraft/legacy/LegacyInstance.h
+++ b/api/logic/minecraft/legacy/LegacyInstance.h
@@ -113,7 +113,7 @@ public:
 
 	virtual bool shouldUpdate() const override;
 	virtual void setShouldUpdate(bool val) override;
-	virtual std::shared_ptr<Task> createUpdateTask() override;
+	virtual shared_qobject_ptr<Task> createUpdateTask() override;
 	virtual std::shared_ptr<Task> createJarModdingTask() override;
 	virtual QString createLaunchScript(AuthSessionPtr session) override;
 
diff --git a/api/logic/minecraft/onesix/OneSixInstance.cpp b/api/logic/minecraft/onesix/OneSixInstance.cpp
index 8b5491e2..1bf75bdb 100644
--- a/api/logic/minecraft/onesix/OneSixInstance.cpp
+++ b/api/logic/minecraft/onesix/OneSixInstance.cpp
@@ -60,9 +60,9 @@ QSet<QString> OneSixInstance::traits()
 	}
 }
 
-std::shared_ptr<Task> OneSixInstance::createUpdateTask()
+shared_qobject_ptr<Task> OneSixInstance::createUpdateTask()
 {
-	return std::shared_ptr<Task>(new OneSixUpdate(this));
+	return shared_qobject_ptr<Task>(new OneSixUpdate(this));
 }
 
 QString replaceTokensIn(QString text, QMap<QString, QString> with)
diff --git a/api/logic/minecraft/onesix/OneSixInstance.h b/api/logic/minecraft/onesix/OneSixInstance.h
index 1a917e79..c857075f 100644
--- a/api/logic/minecraft/onesix/OneSixInstance.h
+++ b/api/logic/minecraft/onesix/OneSixInstance.h
@@ -52,7 +52,7 @@ public:
 	QString worldDir() const;
 	virtual QString instanceConfigFolder() const override;
 
-	virtual std::shared_ptr<Task> createUpdateTask() override;
+	virtual shared_qobject_ptr<Task> createUpdateTask() override;
 	virtual std::shared_ptr<Task> createJarModdingTask() override;
 	virtual QString createLaunchScript(AuthSessionPtr session) override;
 	QStringList verboseDescription(AuthSessionPtr session) override;
diff --git a/api/logic/minecraft/onesix/OneSixUpdate.cpp b/api/logic/minecraft/onesix/OneSixUpdate.cpp
index d3cd197d..02a6f561 100644
--- a/api/logic/minecraft/onesix/OneSixUpdate.cpp
+++ b/api/logic/minecraft/onesix/OneSixUpdate.cpp
@@ -18,332 +18,138 @@
 #include "OneSixUpdate.h"
 #include "OneSixInstance.h"
 
-#include <QtNetwork>
-
 #include <QFile>
 #include <QFileInfo>
 #include <QTextStream>
 #include <QDataStream>
-#include <JlCompress.h>
 
 #include "BaseInstance.h"
 #include "minecraft/MinecraftVersionList.h"
 #include "minecraft/MinecraftProfile.h"
 #include "minecraft/Library.h"
 #include "net/URLConstants.h"
-#include "net/ChecksumValidator.h"
-#include "minecraft/AssetsUtils.h"
-#include "Exception.h"
-#include "MMCZip.h"
 #include <FileSystem.h>
 
-OneSixUpdate::OneSixUpdate(OneSixInstance *inst, QObject *parent) : Task(parent), m_inst(inst)
-{
-}
+#include "update/FoldersTask.h"
+#include "update/LibrariesTask.h"
+#include "update/FMLLibrariesTask.h"
+#include "update/AssetUpdateTask.h"
 
-void OneSixUpdate::executeTask()
+OneSixUpdate::OneSixUpdate(OneSixInstance *inst, QObject *parent) : Task(parent), m_inst(inst)
 {
-	// Make directories
-	QDir mcDir(m_inst->minecraftRoot());
-	if (!mcDir.exists() && !mcDir.mkpath("."))
+	// create folders
 	{
-		emitFailed(tr("Failed to create folder for minecraft binaries."));
-		return;
+		m_tasks.append(std::make_shared<FoldersTask>(m_inst));
 	}
 
-	// Get a pointer to the version object that corresponds to the instance's version.
-	targetVersion = std::dynamic_pointer_cast<MinecraftVersion>(ENV.getVersion("net.minecraft", m_inst->intendedVersionId()));
-	if (targetVersion == nullptr)
-	{
-		// don't do anything if it was invalid
-		emitFailed(tr("The specified Minecraft version is invalid. Choose a different one."));
-		return;
-	}
-	if (m_inst->providesVersionFile() || !targetVersion->needsUpdate())
+	// add a version update task, if necessary
 	{
-		qDebug() << "Instance either provides a version file or doesn't need an update.";
-		jarlibStart();
-		return;
+		auto list = std::dynamic_pointer_cast<MinecraftVersionList>(ENV.getVersionList("net.minecraft"));
+		auto version = std::dynamic_pointer_cast<MinecraftVersion>(list->findVersion(m_inst->intendedVersionId()));
+		if (version == nullptr)
+		{
+			// don't do anything if it was invalid
+			m_preFailure = tr("The specified Minecraft version is invalid. Choose a different one.");
+		}
+		else if (m_inst->providesVersionFile() || !version->needsUpdate())
+		{
+			qDebug() << "Instance either provides a version file or doesn't need an update.";
+		}
+		else
+		{
+			auto versionUpdateTask = list->createUpdateTask(m_inst->intendedVersionId());
+			if (!versionUpdateTask)
+			{
+				qDebug() << "Didn't spawn an update task.";
+			}
+			else
+			{
+				m_tasks.append(versionUpdateTask);
+			}
+		}
 	}
-	versionUpdateTask = std::dynamic_pointer_cast<MinecraftVersionList>(ENV.getVersionList("net.minecraft"))->createUpdateTask(m_inst->intendedVersionId());
-	if (!versionUpdateTask)
+
+	// libraries download
 	{
-		qDebug() << "Didn't spawn an update task.";
-		jarlibStart();
-		return;
+		m_tasks.append(std::make_shared<LibrariesTask>(m_inst));
 	}
-	connect(versionUpdateTask.get(), SIGNAL(succeeded()), SLOT(jarlibStart()));
-	connect(versionUpdateTask.get(), &NetJob::failed, this, &OneSixUpdate::versionUpdateFailed);
-	connect(versionUpdateTask.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
-	setStatus(tr("Getting the version files from Mojang..."));
-	versionUpdateTask->start();
-}
 
-void OneSixUpdate::versionUpdateFailed(QString reason)
-{
-	emitFailed(reason);
-}
-
-void OneSixUpdate::assetIndexStart()
-{
-	setStatus(tr("Updating assets index..."));
-	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	auto profile = inst->getMinecraftProfile();
-	auto assets = profile->getMinecraftAssets();
-	QUrl indexUrl = assets->url;
-	QString localPath = assets->id + ".json";
-	auto job = new NetJob(tr("Asset index for %1").arg(inst->name()));
-
-	auto metacache = ENV.metacache();
-	auto entry = metacache->resolveEntry("asset_indexes", localPath);
-	entry->setStale(true);
-	auto hexSha1 = assets->sha1.toLatin1();
-	qDebug() << "Asset index SHA1:" << hexSha1;
-	auto dl = Net::Download::makeCached(indexUrl, entry);
-	auto rawSha1 = QByteArray::fromHex(assets->sha1.toLatin1());
-	dl->addValidator(new Net::ChecksumValidator(QCryptographicHash::Sha1, rawSha1));
-	job->addNetAction(dl);
-
-	jarlibDownloadJob.reset(job);
-
-	connect(jarlibDownloadJob.get(), SIGNAL(succeeded()), SLOT(assetIndexFinished()));
-	connect(jarlibDownloadJob.get(), &NetJob::failed, this, &OneSixUpdate::assetIndexFailed);
-	connect(jarlibDownloadJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
-
-	qDebug() << m_inst->name() << ": Starting asset index download";
-	jarlibDownloadJob->start();
-}
-
-void OneSixUpdate::assetIndexFinished()
-{
-	AssetsIndex index;
-	qDebug() << m_inst->name() << ": Finished asset index download";
-
-	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	auto profile = inst->getMinecraftProfile();
-	auto assets = profile->getMinecraftAssets();
-
-	QString asset_fname = "assets/indexes/" + assets->id + ".json";
-	// FIXME: this looks like a job for a generic validator based on json schema?
-	if (!AssetsUtils::loadAssetsIndexJson(assets->id, asset_fname, &index))
+	// FML libraries download and copy into the instance
 	{
-		auto metacache = ENV.metacache();
-		auto entry = metacache->resolveEntry("asset_indexes", assets->id + ".json");
-		metacache->evictEntry(entry);
-		emitFailed(tr("Failed to read the assets index!"));
+		m_tasks.append(std::make_shared<FMLLibrariesTask>(m_inst));
 	}
 
-	auto job = index.getDownloadJob();
-	if(job)
+	// assets update
 	{
-		setStatus(tr("Getting the assets files from Mojang..."));
-		jarlibDownloadJob = job;
-		connect(jarlibDownloadJob.get(), SIGNAL(succeeded()), SLOT(assetsFinished()));
-		connect(jarlibDownloadJob.get(), &NetJob::failed, this, &OneSixUpdate::assetsFailed);
-		connect(jarlibDownloadJob.get(), SIGNAL(progress(qint64, qint64)), SIGNAL(progress(qint64, qint64)));
-		jarlibDownloadJob->start();
-		return;
+		m_tasks.append(std::make_shared<AssetUpdateTask>(m_inst));
 	}
-	assetsFinished();
-}
-
-void OneSixUpdate::assetIndexFailed(QString reason)
-{
-	qDebug() << m_inst->name() << ": Failed asset index download";
-	emitFailed(tr("Failed to download the assets index:\n%1").arg(reason));
-}
-
-void OneSixUpdate::assetsFinished()
-{
-	emitSucceeded();
-}
-
-void OneSixUpdate::assetsFailed(QString reason)
-{
-	emitFailed(tr("Failed to download assets:\n%1").arg(reason));
 }
 
-void OneSixUpdate::jarlibStart()
+void OneSixUpdate::executeTask()
 {
-	setStatus(tr("Getting the library files from Mojang..."));
-	qDebug() << m_inst->name() << ": downloading libraries";
-	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	inst->reloadProfile();
-	if(inst->flags() & BaseInstance::VersionBrokenFlag)
+	if(!m_preFailure.isEmpty())
 	{
-		emitFailed(tr("Failed to load the version description files - check the instance for errors."));
+		emitFailed(m_preFailure);
 		return;
 	}
+	next();
+}
 
-	// Build a list of URLs that will need to be downloaded.
-	std::shared_ptr<MinecraftProfile> profile = inst->getMinecraftProfile();
-	// minecraft.jar for this version
+void OneSixUpdate::next()
+{
+	if(m_abort)
 	{
-		QString version_id = profile->getMinecraftVersion();
-		QString localPath = version_id + "/" + version_id + ".jar";
-		QString urlstr = profile->getMainJarUrl();
-
-		auto job = new NetJob(tr("Libraries for instance %1").arg(inst->name()));
-
-		auto metacache = ENV.metacache();
-		auto entry = metacache->resolveEntry("versions", localPath);
-		job->addNetAction(Net::Download::makeCached(QUrl(urlstr), entry));
-		jarlibDownloadJob.reset(job);
+		emitFailed(tr("Aborted by user."));
+		return;
 	}
-
-	auto libs = profile->getLibraries();
-
-	auto metacache = ENV.metacache();
-	QList<LibraryPtr> brokenLocalLibs;
-
-	QStringList failedFiles;
-	for (auto lib : libs)
+	m_currentTask ++;
+	if(m_currentTask > 0)
 	{
-		auto dls = lib->getDownloads(currentSystem, metacache.get(), failedFiles);
-		for(auto dl : dls)
-		{
-			jarlibDownloadJob->addNetAction(dl);
-		}
+		auto task = m_tasks[m_currentTask - 1];
+		disconnect(task.get(), &Task::succeeded, this, &OneSixUpdate::subtaskSucceeded);
+		disconnect(task.get(), &Task::failed, this, &OneSixUpdate::subtaskFailed);
+		disconnect(task.get(), &Task::progress, this, &OneSixUpdate::progress);
+		disconnect(task.get(), &Task::status, this, &OneSixUpdate::setStatus);
 	}
-	if (!brokenLocalLibs.empty())
+	if(m_currentTask == m_tasks.size())
 	{
-		jarlibDownloadJob.reset();
-
-		QString failed_all = failedFiles.join("\n");
-		emitFailed(tr("Some libraries marked as 'local' are missing their jar "
-					  "files:\n%1\n\nYou'll have to correct this problem manually. If this is "
-					  "an externally tracked instance, make sure to run it at least once "
-					  "outside of MultiMC.").arg(failed_all));
+		emitSucceeded();
 		return;
 	}
-
-	connect(jarlibDownloadJob.get(), SIGNAL(succeeded()), SLOT(jarlibFinished()));
-	connect(jarlibDownloadJob.get(), &NetJob::failed, this, &OneSixUpdate::jarlibFailed);
-	connect(jarlibDownloadJob.get(), SIGNAL(progress(qint64, qint64)),
-			SIGNAL(progress(qint64, qint64)));
-
-	jarlibDownloadJob->start();
+	auto task = m_tasks[m_currentTask];
+	connect(task.get(), &Task::succeeded, this, &OneSixUpdate::subtaskSucceeded);
+	connect(task.get(), &Task::failed, this, &OneSixUpdate::subtaskFailed);
+	connect(task.get(), &Task::progress, this, &OneSixUpdate::progress);
+	connect(task.get(), &Task::status, this, &OneSixUpdate::setStatus);
+	task->start();
 }
 
-void OneSixUpdate::jarlibFinished()
+void OneSixUpdate::subtaskSucceeded()
 {
-	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	std::shared_ptr<MinecraftProfile> profile = inst->getMinecraftProfile();
-
-	if (profile->hasTrait("legacyFML"))
-	{
-		fmllibsStart();
-	}
-	else
-	{
-		assetIndexStart();
-	}
+	next();
 }
 
-void OneSixUpdate::jarlibFailed(QString reason)
+void OneSixUpdate::subtaskFailed(QString error)
 {
-	QStringList failed = jarlibDownloadJob->getFailedFiles();
-	QString failed_all = failed.join("\n");
-	emitFailed(
-		tr("Failed to download the following files:\n%1\n\nReason:%2\nPlease try again.").arg(failed_all, reason));
+	emitFailed(error);
 }
 
-void OneSixUpdate::fmllibsStart()
-{
-	// Get the mod list
-	OneSixInstance *inst = (OneSixInstance *)m_inst;
-	std::shared_ptr<MinecraftProfile> profile = inst->getMinecraftProfile();
-	bool forge_present = false;
-
-	QString version = inst->intendedVersionId();
-	auto &fmlLibsMapping = g_VersionFilterData.fmlLibsMapping;
-	if (!fmlLibsMapping.contains(version))
-	{
-		assetIndexStart();
-		return;
-	}
-
-	auto &libList = fmlLibsMapping[version];
-
-	// determine if we need some libs for FML or forge
-	setStatus(tr("Checking for FML libraries..."));
-	forge_present = (profile->versionPatch("net.minecraftforge") != nullptr);
-	// we don't...
-	if (!forge_present)
-	{
-		assetIndexStart();
-		return;
-	}
-
-	// now check the lib folder inside the instance for files.
-	for (auto &lib : libList)
-	{
-		QFileInfo