Fixes two issues with the browser refresh

elpaso · elpaso · commit bcb48f2bdc8f · 2017-08-09T08:59:17.000+02:00
1. endless loop when a sqlite-based layer is opened, and
   wal+shm files are created. This triggers a loop because
   the directoryChanged signal is emitted again and again ...
   This was the real blocker.

2. when a new files appears in a directory
   the directoryChanged is emitted and OGR/GDAL may fail
   to open the file because the file copy was not yet
   finished.

This commit fixes 1 but the fix for 2 is only a best effort using
a 100 ms timer: I could not find a definitive solution to this issue,
a file could be legitimately opened in streaming mode and it will
always triggers an error, there is apparently no way to get
the QFileSystemWatcher emit a signal when new files are closed
flusehd and not when they are just created.
diff --git a/python/core/qgsdataitem.sip b/python/core/qgsdataitem.sip
@@ -525,6 +525,7 @@ Check if the given path is hidden from the browser model
  :rtype: bool
 %End
 
+
   public slots:
     virtual void childrenCreated();
     void directoryChanged();
diff --git a/src/core/qgsdataitem.cpp b/src/core/qgsdataitem.cpp
@@ -238,6 +238,7 @@ void QgsDataItem::populate( bool foreground )
     {
       mFutureWatcher = new QFutureWatcher< QVector <QgsDataItem *> >( this );
     }
+
     connect( mFutureWatcher, &QFutureWatcherBase::finished, this, &QgsDataItem::childrenCreated );
     mFutureWatcher->setFuture( QtConcurrent::run( runCreateChildren, this ) );
   }
@@ -791,12 +792,22 @@ void QgsDirectoryItem::directoryChanged()
 {
   if ( state() == Populating )
   {
-    // schedule to refresh later, because refres() simply returns if Populating
+    // schedule to refresh later, because refresh() simply returns if Populating
     mRefreshLater = true;
   }
   else
   {
-    refresh();
+    // We definintely don't want the temporary files created by sqlite
+    // to re-trigger a refresh in an infinite loop.
+    disconnect( mFileSystemWatcher, &QFileSystemWatcher::directoryChanged, this, &QgsDirectoryItem::directoryChanged );
+    // QFileSystemWhatcher::directoryChanged is emitted when a
+    // file is created and not when it is closed/flushed.
+    //
+    // Delay to give to OS the time to complete writing the file
+    // this happens when a new file appears in the directory and
+    // the item's children thread will try to open the file with
+    // GDAL or OGR even if it is still being written.
+    QTimer::singleShot( 100, this, SLOT( refresh() ) );
   }
 }
 
@@ -809,6 +820,7 @@ bool QgsDirectoryItem::hiddenPath( const QString &path )
   return ( idx > -1 );
 }
 
+
 void QgsDirectoryItem::childrenCreated()
 {
   QgsDebugMsgLevel( QString( "mRefreshLater = %1" ).arg( mRefreshLater ), 3 );
@@ -824,6 +836,8 @@ void QgsDirectoryItem::childrenCreated()
   {
     QgsDataCollectionItem::childrenCreated();
   }
+  // Re-connect the file watcher after all children have been created
+  connect( mFileSystemWatcher, &QFileSystemWatcher::directoryChanged, this, &QgsDirectoryItem::directoryChanged );
 }
 
 bool QgsDirectoryItem::equal( const QgsDataItem *other )
diff --git a/src/core/qgsdataitem.h b/src/core/qgsdataitem.h
@@ -468,6 +468,7 @@ class CORE_EXPORT QgsDirectoryItem : public QgsDataCollectionItem
     //! Check if the given path is hidden from the browser model
     static bool hiddenPath( const QString &path );
 
+
   public slots:
     virtual void childrenCreated() override;
     void directoryChanged();

Original file line number	Diff line number	Diff line change
`@@ -238,6 +238,7 @@ void QgsDataItem::populate( bool foreground )`
`238`	`238`	`{`
`239`	`239`	`mFutureWatcher = new QFutureWatcher< QVector <QgsDataItem *> >( this );`
`240`	`240`	`}`
	`241`	`+`
`241`	`242`	`connect( mFutureWatcher, &QFutureWatcherBase::finished, this, &QgsDataItem::childrenCreated );`
`242`	`243`	`mFutureWatcher->setFuture( QtConcurrent::run( runCreateChildren, this ) );`
`243`	`244`	`}`
`@@ -791,12 +792,22 @@ void QgsDirectoryItem::directoryChanged()`
`791`	`792`	`{`
`792`	`793`	`if ( state() == Populating )`
`793`	`794`	`{`
`794`		`- // schedule to refresh later, because refres() simply returns if Populating`
	`795`	`+ // schedule to refresh later, because refresh() simply returns if Populating`
`795`	`796`	`mRefreshLater = true;`
`796`	`797`	`}`
`797`	`798`	`else`
`798`	`799`	`{`
`799`		`- refresh();`
	`800`	`+ // We definintely don't want the temporary files created by sqlite`
	`801`	`+ // to re-trigger a refresh in an infinite loop.`
	`802`	`+ disconnect( mFileSystemWatcher, &QFileSystemWatcher::directoryChanged, this, &QgsDirectoryItem::directoryChanged );`
	`803`	`+ // QFileSystemWhatcher::directoryChanged is emitted when a`
	`804`	`+ // file is created and not when it is closed/flushed.`
	`805`	`+ //`
	`806`	`+ // Delay to give to OS the time to complete writing the file`
	`807`	`+ // this happens when a new file appears in the directory and`
	`808`	`+ // the item's children thread will try to open the file with`
	`809`	`+ // GDAL or OGR even if it is still being written.`
	`810`	`+ QTimer::singleShot( 100, this, SLOT( refresh() ) );`
`800`	`811`	`}`
`801`	`812`	`}`
`802`	`813`
`@@ -809,6 +820,7 @@ bool QgsDirectoryItem::hiddenPath( const QString &path )`
`809`	`820`	`return ( idx > -1 );`
`810`	`821`	`}`
`811`	`822`
	`823`	`+`
`812`	`824`	`void QgsDirectoryItem::childrenCreated()`
`813`	`825`	`{`
`814`	`826`	`QgsDebugMsgLevel( QString( "mRefreshLater = %1" ).arg( mRefreshLater ), 3 );`
`@@ -824,6 +836,8 @@ void QgsDirectoryItem::childrenCreated()`
`824`	`836`	`{`
`825`	`837`	`QgsDataCollectionItem::childrenCreated();`
`826`	`838`	`}`
	`839`	`+ // Re-connect the file watcher after all children have been created`
	`840`	`+ connect( mFileSystemWatcher, &QFileSystemWatcher::directoryChanged, this, &QgsDirectoryItem::directoryChanged );`
`827`	`841`	`}`
`828`	`842`
`829`	`843`	`bool QgsDirectoryItem::equal( const QgsDataItem *other )`