def committedFeaturesAdded(a, b):
    QgsMessageLog.logMessage( 'committedFeaturesAdded was triggered' )

def committedFeaturesRemoved(a, b):
    QgsMessageLog.logMessage( 'committedFeaturesRemoved was triggered' )

def committedAttributeValuesChanges(a, b):
    QgsMessageLog.logMessage( 'committedAttributeValuesChanges was triggered' )

def committedGeometriesChanges(a, b):
    QgsMessageLog.logMessage( 'committedGeometriesChanges was triggered' )

iface.activeLayer().committedFeaturesAdded.connect( committedFeaturesAdded )
iface.activeLayer().committedFeaturesRemoved.connect( committedFeaturesRemoved )
iface.activeLayer().committedAttributeValuesChanges.connect( committedAttributeValuesChanges )
iface.activeLayer().committedGeometriesChanges.connect( committedGeometriesChanges )