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>

2 files changed, 15 insertions, 5 deletions

diff --git a/tests/auto/corelib/io/qfile/test/test.pro b/tests/auto/corelib/io/qfile/test/test.pro
index 2611ff39bd..dab5e4a3a5 100644
--- a/tests/auto/corelib/io/qfile/test/test.pro
+++ b/tests/auto/corelib/io/qfile/test/test.pro
@@ -1,5 +1,5 @@
 CONFIG += testcase
-QT = core network testlib
+QT = core-private core network testlib
 TARGET = ../tst_qfile
 SOURCES = ../tst_qfile.cpp
 RESOURCES += ../qfile.qrc ../rename-fallback.qrc ../copy-fallback.qrc
diff --git a/tests/auto/corelib/io/qfile/tst_qfile.cpp b/tests/auto/corelib/io/qfile/tst_qfile.cpp
index d1a0debf4d..87d2cf83f7 100644
--- a/tests/auto/corelib/io/qfile/tst_qfile.cpp
+++ b/tests/auto/corelib/io/qfile/tst_qfile.cpp
@@ -42,13 +42,15 @@
 #include <QtTest/QtTest>
 #include <qplatformdefs.h>
 
-#include <QAbstractFileEngine>
-#include <QFSFileEngine>
 #include <QCoreApplication>
 #include <QDebug>
 #include <QDir>
 #include <QFile>
 #include <QFileInfo>
+
+#include <private/qabstractfileengine_p.h>
+#include <private/qfsfileengine_p.h>
+
 #if !defined(Q_OS_WINCE)
 #include <QHostInfo>
 #endif
@@ -70,7 +72,6 @@
 # include <sys/statfs.h>
 #elif defined(Q_OS_WINCE)
 # include <qplatformdefs.h>
-# include <private/qfsfileengine_p.h>
 #endif
 
 #include <stdio.h>
@@ -1943,6 +1944,7 @@ void tst_QFile::longFileName()
     QVERIFY(QFile::remove(newName));
 }
 
+#ifdef QT_BUILD_INTERNAL
 class MyEngine : public QAbstractFileEngine
 {
 public:
@@ -1998,6 +2000,7 @@ public:
         return new MyEngine(2);
     }
 };
+#endif
 
 void tst_QFile::fileEngineHandler()
 {
@@ -2006,6 +2009,7 @@ void tst_QFile::fileEngineHandler()
     QFile file("ole.bull");
     QCOMPARE(file.size(), qint64(0));
 
+#ifdef QT_BUILD_INTERNAL
     // Instantiating our handler will enable the new engine.
     MyHandler handler;
     file.setFileName("ole.bull");
@@ -2015,9 +2019,10 @@ void tst_QFile::fileEngineHandler()
     MyHandler2 handler2;
     file.setFileName("ole.bull");
     QCOMPARE(file.size(), qint64(125));
-
+#endif
 }
 
+#ifdef QT_BUILD_INTERNAL
 class MyRecursiveHandler : public QAbstractFileEngineHandler
 {
 public:
@@ -2032,13 +2037,18 @@ public:
         return 0;
     }
 };
+#endif
 
 void tst_QFile::useQFileInAFileHandler()
 {
+#ifdef QT_BUILD_INTERNAL
     // This test should not dead-lock
     MyRecursiveHandler handler;
     QFile file(":!tst_qfile.cpp");
     QVERIFY(file.exists());
+#else
+    QSKIP("This test requires -developer-build.");
+#endif
 }
 
 void tst_QFile::getCharFF()