Fixes two issues with the browser refresh

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.
qgis · Aug 9, 2017 · bcb48f2 · bcb48f2
1 parent a2d4e82
commit bcb48f2
Show file tree

Hide file tree

Showing 3 changed files with 18 additions and 2 deletions.
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();