Add close_dataset() to pybind Raster.cpp (#863)

* add close_dataset() to pybind Raster.cpp

* Update python/extensions/pybind_isce3/io/Raster.cpp

Co-authored-by: Geoffrey M Gunter <[email protected]>

* only call GDALClose from Raster destructor if attribute _dataset is not null

* check GDAL dataset ownership before deleting it

Co-authored-by: Geoffrey M Gunter <[email protected]>

Author: 2 people

cxx/isce3/io/Raster.cpp

@@ -233,7 +233,7 @@ int isce3::io::Raster::setEPSG(int epsgcode)
 // Destructor. When GDALOpenShared() is used the dataset is dereferenced
 // and closed only if the referenced count is less than 1.
 isce3::io::Raster::~Raster() {
-    if (_owner) {
+    if (_owner and _dataset != nullptr) {
         GDALClose( _dataset );
     }
 }

cxx/isce3/io/Raster.h

@@ -132,6 +132,9 @@ class isce3::io::Raster {
        * @param[in] ds GDALDataset pointer*/
       inline void         dataset(GDALDataset* ds) { _dataset=ds; }
 
+      /** GDALDataset owner getter*/
+      inline bool dataset_owner()  const { return _owner; }
+
       /** Return GDALDatatype of specified band
        *
        * @param[in] band Band number in 1-index*/

python/extensions/pybind_isce3/io/Raster.cpp

@@ -93,6 +93,24 @@ void addbinding(py::class_<Raster> & pyRaster)
             "Create a VRT raster dataset from list of rasters",
             py::arg("path"),
             py::arg("raster_list"))
+        .def("close_dataset", [](Raster & self)
+            {
+                if (self.dataset_owner()) {
+                    auto gdal_ds = self.dataset();
+                    delete gdal_ds;
+                }
+                self.dataset(nullptr);
+            },
+            R"(
+            Close the dataset.
+
+            Decrements the reference count of the underlying `GDALDataset`, which,
+            if this was the last open instance, causes the dataset to be closed
+            and any cached changes to be flushed to disk.
+
+            This invalidates the `Raster` instance -- it cannot be used after closing
+            the underlying dataset.
+            )")
         .def(py::init([](std::uintptr_t py_ds_ptr)
             {
                 auto gdal_ds = reinterpret_cast<GDALDataset*>(py_ds_ptr);