QIODevice: add infrastructure for multistreaming

Some sequential devices allow data to be partitioned into several
channels that have the property of independently sequenced delivery.
Supporting such devices uniformly requires a unified API which provides
the user with a uniform concept of multistreaming.

This patch is based on QProcess's multiplexing model and introduces
the following features:

 - ability to get the number of channels;
 - multiple internal read/write buffers;
 - channel selection functions;
 - notification signals on channel activity.

To keep the source code compatible with single-channel implementations,
introduce a private class that references the current read buffer and
hides multistreaming internals from the user.

Bump the TypeInformationVersion field in qtHookData, to notify the
Qt Creator developers that the offset of QFilePrivate::fileName was
changed and dumpers should be adapted.

[ChangeLog][QtCore] Added multistreaming to QIODevice.

Change-Id: Idcaa6a618927c101c4c7284d2a633913be6a6ee2
Reviewed-by: Allan Sandfeld Jensen <allan.jensen@theqtcompany.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

1 files changed, 9 insertions, 0 deletions

diff --git a/src/corelib/io/qiodevice.h b/src/corelib/io/qiodevice.h
index 7840b8500c..162480d22f 100644
--- a/src/corelib/io/qiodevice.h
+++ b/src/corelib/io/qiodevice.h
@@ -96,6 +96,13 @@ public:
     bool isWritable() const;
     virtual bool isSequential() const;
 
+    int readChannelCount() const;
+    int writeChannelCount() const;
+    int currentReadChannel() const;
+    void setCurrentReadChannel(int channel);
+    int currentWriteChannel() const;
+    void setCurrentWriteChannel(int channel);
+
     virtual bool open(OpenMode mode);
     virtual void close();
 
@@ -142,7 +149,9 @@ public:
 #ifndef QT_NO_QOBJECT
 Q_SIGNALS:
     void readyRead();
+    void channelReadyRead(int channel);
     void bytesWritten(qint64 bytes);
+    void channelBytesWritten(int channel, qint64 bytes);
     void aboutToClose();
     void readChannelFinished();
 #endif