What triggers the release of file locks in pyQGISPyQGIS?
I am trying to delete a few data sources (used temporarily) by calling QgsVectorFileWriter.deleteShapeFile, but I have to quit QGIS before I can do that. I have loaded the sources into QgsVectorLayer objects.
Must all of these objects and references to them be garbage collected before I can delete the source?
Is there a way to force this?
I've managed to create a minimal code sample that fails. Make sure temp dir is empty before running.
from qgis.core import *
import processing, os, gc
project_temp_dir = "C:/Path/To/My/Dir/"
layer1_path = project_temp_dir + "layer1.shp"
layer2_path = project_temp_dir + "layer2.shp"
input_layer = QgsMapLayerRegistry.instance().mapLayersByName('in_layer')[0]
if not input_layer.isValid(): raise Exception("Failed to grab input layer")
# Create layer 1
err = QgsVectorFileWriter.writeAsVectorFormat(input_layer, layer1_path, "utf-8", input_layer.crs())
if err != QgsVectorFileWriter.NoError: raise Exception("Failed to write layer 1")
# Load layer 1
layer1 = QgsVectorLayer(layer1_path, "lyr1", "ogr")
if not layer1.isValid(): raise Exception("Failed to load layer 1")
# Use layer 1 to create layer 2, read-only makes no difference
# if not layer1.setReadOnly(): raise Exception("Could not set layer 1 to read-only")
processing.runalg("qgis:reprojectlayer", layer1, "EPSG:54030", layer2_path)
# Load layer 2
layer2 = QgsVectorLayer(layer2_path, "lyr2", "ogr")
if not layer2.isValid(): raise Exception("Failed to load layer 2")
del layer1
del layer2
del input_layer
gc.collect()
print "Garbage: " + str(gc.garbage) # Empty
# Remove data sources for layers - FAILS!!
for f in os.listdir(project_temp_dir):
if f.endswith(".shp") and not os.path.isdir(project_temp_dir + f):
if not QgsVectorFileWriter.deleteShapeFile(project_temp_dir + f):
# F*%&ing locks.
print "Failed to clear project temp directory."
I found that it works if I use QgsVectorFileWriter to create layer2, instead of the processing algorithm. I get the same error if try the qgis:clip algorithm.
Is this a bug in processing?
Am I using it wrong?
