Fix "Too many open files" error.

The current code did create all files in advance, exceeding the
open file limit on big downloads. Now we create the file once we
write to it.

Task-number: QTIFW-662
Change-Id: I9fe019e08342cbfb14bf564ad00b045cc03b6661
Reviewed-by: Jarek Kobus <jaroslaw.kobus@theqtcompany.com>

1 files changed, 48 insertions, 58 deletions

diff --git a/src/libs/installer/downloadfiletask.cpp b/src/libs/installer/downloadfiletask.cpp
index d5ab2acda..f308315c9 100644
--- a/src/libs/installer/downloadfiletask.cpp
+++ b/src/libs/installer/downloadfiletask.cpp
@@ -1,3 +1,4 @@
+
 /**************************************************************************
 **
 ** Copyright (C) 2015 The Qt Company Ltd.
@@ -34,11 +35,9 @@
 #include "downloadfiletask.h"
 
 #include "downloadfiletask_p.h"
-#include "observer.h"
 
 #include <QCoreApplication>
 #include <QEventLoop>
-#include <QFile>
 #include <QFileInfo>
 #include <QNetworkProxyFactory>
 #include <QSslError>
@@ -62,16 +61,10 @@ Downloader::Downloader()
 Downloader::~Downloader()
 {
     m_nam.disconnect();
-    foreach (QNetworkReply *const reply, m_downloads.keys()) {
-        reply->disconnect();
-        reply->abort();
-        reply->deleteLater();
-    }
-
-    foreach (const Data &data, m_downloads.values()) {
-        data.file->close();
-        delete data.file;
-        delete data.observer;
+    for (const auto &pair : m_downloads) {
+        pair.first->disconnect();
+        pair.first->abort();
+        pair.first->deleteLater();
     }
 }
 
@@ -119,7 +112,34 @@ void Downloader::onReadyRead()
     if (!reply)
         return;
 
-    const Data &data = m_downloads[reply];
+    Data &data = *m_downloads[reply];
+    if (!data.file) {
+        std::unique_ptr<QFile> file = Q_NULLPTR;
+        const QString target = data.taskItem.target();
+        if (target.isEmpty()) {
+            std::unique_ptr<QTemporaryFile> tmp(new QTemporaryFile);
+            tmp->setAutoRemove(false);
+            file = std::move(tmp);
+        } else {
+            std::unique_ptr<QFile> tmp(new QFile(target));
+            file = std::move(tmp);
+        }
+
+        if (file->exists() && (!QFileInfo(file->fileName()).isFile())) {
+            m_futureInterface->reportException(TaskException(tr("Target file '%1' already exists "
+                "but is not a file.").arg(file->fileName())));
+            return;
+        }
+
+        if (!file->open(QIODevice::WriteOnly | QIODevice::Truncate)) {
+            //: %2 is a sentence describing the error
+            m_futureInterface->reportException(TaskException(tr("Could not open target '%1' for "
+                "write. Error: %2.").arg(file->fileName(), file->errorString())));
+            return;
+        }
+        data.file = std::move(file);
+    }
+
     if (!data.file->isOpen()) {
         //: %2 is a sentence describing the error.
         m_futureInterface->reportException(
@@ -154,8 +174,8 @@ void Downloader::onReadyRead()
         data.observer->addCheckSumData(buffer.data(), read);
 
         int progress = m_finished * 100;
-        foreach (const Data &data, m_downloads.values())
-            progress += data.observer->progressValue();
+        for (const auto &pair : m_downloads)
+            progress += pair.second->observer->progressValue();
         if (!reply->attribute(QNetworkRequest::RedirectionTargetAttribute).isValid()) {
             m_futureInterface->setProgressValueAndText(progress / m_items.count(),
                 data.observer->progressText());
@@ -165,18 +185,16 @@ void Downloader::onReadyRead()
 
 void Downloader::onFinished(QNetworkReply *reply)
 {
-    const Data &data = m_downloads[reply];
-    const QString filename = data.file->fileName();
+    Data &data = *m_downloads[reply];
+    const QString filename = data.file ? data.file->fileName() : QString();
     if (!m_futureInterface->isCanceled()) {
         if (reply->attribute(QNetworkRequest::RedirectionTargetAttribute).isValid()) {
             const QUrl url = reply->url()
                 .resolved(reply->attribute(QNetworkRequest::RedirectionTargetAttribute).toUrl());
             const QList<QUrl> redirects = m_redirects.values(reply);
             if (!redirects.contains(url)) {
-                data.file->close();
-                data.file->remove();
-                delete data.file;
-                delete data.observer;
+                if (data.file)
+                    data.file->remove();
 
                 FileTaskItem taskItem = data.taskItem;
                 taskItem.insert(TaskRole::SourceFile, url.toString());
@@ -186,7 +204,7 @@ void Downloader::onFinished(QNetworkReply *reply)
                     m_redirects.insertMulti(redirectReply, redirect);
                 m_redirects.insertMulti(redirectReply, url);
 
-                m_downloads.remove(reply);
+                m_downloads.erase(reply);
                 m_redirects.remove(reply);
                 reply->deleteLater();
                 return;
@@ -214,16 +232,12 @@ void Downloader::onFinished(QNetworkReply *reply)
     }
     m_futureInterface->reportResult(FileTaskResult(filename, data.observer->checkSum(), data.taskItem));
 
-    data.file->close();
-    delete data.file;
-    delete data.observer;
-
-    m_downloads.remove(reply);
+    m_downloads.erase(reply);
     m_redirects.remove(reply);
     reply->deleteLater();
 
     m_finished++;
-    if (m_downloads.isEmpty() || m_futureInterface->isCanceled()) {
+    if (m_downloads.empty() || m_futureInterface->isCanceled()) {
         m_futureInterface->reportFinished();
         emit finished();    // emit finished, so the event loop can shutdown
     }
@@ -239,7 +253,7 @@ void Downloader::onError(QNetworkReply::NetworkError error)
         return; // already handled by onAuthenticationRequired
 
     if (reply) {
-        const Data &data = m_downloads[reply];
+        const Data &data = *m_downloads[reply];
         //: %2 is a sentence describing the error
         m_futureInterface->reportException(
                     TaskException(tr("Network error while downloading '%1': %2.").arg(
@@ -266,17 +280,17 @@ void Downloader::onDownloadProgress(qint64 bytesReceived, qint64 bytesTotal)
     Q_UNUSED(bytesReceived)
     QNetworkReply *const reply = qobject_cast<QNetworkReply *>(sender());
     if (reply) {
-        const Data &data = m_downloads[reply];
+        const Data &data = *m_downloads[reply];
         data.observer->setBytesToTransfer(bytesTotal);
     }
 }
 
 void Downloader::onAuthenticationRequired(QNetworkReply *reply, QAuthenticator *authenticator)
 {
-    if (!authenticator || !reply || !m_downloads.contains(reply))
+    if (!authenticator || !reply || m_downloads.find(reply) == m_downloads.cend())
         return;
 
-    FileTaskItem *item = &m_downloads[reply].taskItem;
+    FileTaskItem *item = &m_downloads[reply]->taskItem;
     const QAuthenticator auth = item->value(TaskRole::Authenticator).value<QAuthenticator>();
     if (auth.user().isEmpty()) {
         AuthenticationRequiredException e(AuthenticationRequiredException::Type::Server,
@@ -327,33 +341,9 @@ QNetworkReply *Downloader::startDownload(const FileTaskItem &item)
         return 0;
     }
 
-    QScopedPointer<QFile> file;
-    const QString target = item.target();
-    if (target.isEmpty()) {
-        QTemporaryFile *tmp = new QTemporaryFile;
-        tmp->setAutoRemove(false);
-        file.reset(tmp);
-    } else {
-        file.reset(new QFile(target));
-    }
-
-    if (file->exists() && (!QFileInfo(file->fileName()).isFile())) {
-        m_futureInterface->reportException(
-                    TaskException(tr("Target file '%1' already exists but is not a file.").arg(
-                                          file->fileName())));
-        return 0;
-    }
-
-    if (!file->open(QIODevice::WriteOnly | QIODevice::Truncate)) {
-        //: %2 is a sentence describing the error
-        m_futureInterface->reportException(
-                    TaskException(tr("Could not open target '%1' for write. Error: %2.").arg(
-                                          file->fileName(), file->errorString())));
-        return 0;
-    }
-
     QNetworkReply *reply = m_nam.get(QNetworkRequest(source));
-    m_downloads.insert(reply, Data(file.take(), new FileTaskObserver(QCryptographicHash::Sha1), item));
+    std::unique_ptr<Data> data(new Data(item));
+    m_downloads[reply] = std::move(data);
 
     connect(reply, SIGNAL(readyRead()), this, SLOT(onReadyRead()));
     connect(reply, SIGNAL(error(QNetworkReply::NetworkError)), this,