Drop file-engine abstraction from public API

This abstraction imposed serious performance penalties and is being
dropped from the public API.

In particular, by allowing file names to be arbitrarily hijacked by
different file engines, and requiring engines to be instantiated in
order to decide, it imposed unnecessary overhead on all file operations.

Another flaw in the design with direct impact on performance is how
engines have no way to provide (or retain) additional information
obtained when querying the filesystem. In many places this has meant
repeated operations on the file system, where useful information is
immediately discarded to be queried again subsequently.

For Qt 4.8 a major refactoring of the code base took place to allow
bypassing the file-engine abstraction in select places, with
considerable performance gains observed. In Qt 5 it is expected we'll be
able to take this further, reaping even more benefits, but the
abstraction has to go.

[Dropping this now does not preclude that virtual file systems make an
appearance in Qt at a later point in Qt 5's lifecycle. Hopefully with a
new and improved abstraction.]

Forward declarations for QFileExtension(Result) were dropped, as the
classes were never used or defined.

Tests using "internalized" classes will only fully run on developer
builds. QFSFileEngine was removed altogether from exception safety test,
as it isn't its intent to test internal API.

Change-Id: Ie910e6c2628be202ea9e05366b091d6d529b246b
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

1 files changed, 63 insertions, 2 deletions

diff --git a/src/corelib/io/qfsfileengine_p.h b/src/corelib/io/qfsfileengine_p.h
index c06f662380..f403706479 100644
--- a/src/corelib/io/qfsfileengine_p.h
+++ b/src/corelib/io/qfsfileengine_p.h
@@ -54,8 +54,7 @@
 //
 
 #include "qplatformdefs.h"
-#include "QtCore/qfsfileengine.h"
-#include "private/qabstractfileengine_p.h"
+#include "QtCore/private/qabstractfileengine_p.h"
 #include <QtCore/private/qfilesystementry_p.h>
 #include <QtCore/private/qfilesystemmetadata_p.h>
 #include <qhash.h>
@@ -68,6 +67,68 @@ QT_BEGIN_NAMESPACE
 #define Q_USE_DEPRECATED_MAP_API 1
 #endif
 
+class QFSFileEnginePrivate;
+
+class Q_AUTOTEST_EXPORT QFSFileEngine : public QAbstractFileEngine
+{
+    Q_DECLARE_PRIVATE(QFSFileEngine)
+public:
+    QFSFileEngine();
+    explicit QFSFileEngine(const QString &file);
+    ~QFSFileEngine();
+
+    bool open(QIODevice::OpenMode openMode);
+    bool open(QIODevice::OpenMode flags, FILE *fh);
+    bool close();
+    bool flush();
+    qint64 size() const;
+    qint64 pos() const;
+    bool seek(qint64);
+    bool isSequential() const;
+    bool remove();
+    bool copy(const QString &newName);
+    bool rename(const QString &newName);
+    bool link(const QString &newName);
+    bool mkdir(const QString &dirName, bool createParentDirectories) const;
+    bool rmdir(const QString &dirName, bool recurseParentDirectories) const;
+    bool setSize(qint64 size);
+    bool caseSensitive() const;
+    bool isRelativePath() const;
+    QStringList entryList(QDir::Filters filters, const QStringList &filterNames) const;
+    FileFlags fileFlags(FileFlags type) const;
+    bool setPermissions(uint perms);
+    QString fileName(FileName file) const;
+    uint ownerId(FileOwner) const;
+    QString owner(FileOwner) const;
+    QDateTime fileTime(FileTime time) const;
+    void setFileName(const QString &file);
+    int handle() const;
+
+    Iterator *beginEntryList(QDir::Filters filters, const QStringList &filterNames);
+    Iterator *endEntryList();
+
+    qint64 read(char *data, qint64 maxlen);
+    qint64 readLine(char *data, qint64 maxlen);
+    qint64 write(const char *data, qint64 len);
+
+    bool extension(Extension extension, const ExtensionOption *option = 0, ExtensionReturn *output = 0);
+    bool supportsExtension(Extension extension) const;
+
+    //FS only!!
+    bool open(QIODevice::OpenMode flags, int fd);
+    bool open(QIODevice::OpenMode flags, int fd, QFile::FileHandleFlags handleFlags);
+    bool open(QIODevice::OpenMode flags, FILE *fh, QFile::FileHandleFlags handleFlags);
+    static bool setCurrentPath(const QString &path);
+    static QString currentPath(const QString &path = QString());
+    static QString homePath();
+    static QString rootPath();
+    static QString tempPath();
+    static QFileInfoList drives();
+
+protected:
+    QFSFileEngine(QFSFileEnginePrivate &dd);
+};
+
 class Q_AUTOTEST_EXPORT QFSFileEnginePrivate : public QAbstractFileEnginePrivate
 {
     Q_DECLARE_PUBLIC(QFSFileEngine)