Re: [Libguestfs] [PATCH nbdkit] python: Implement can_extents + extents.

--- plugins/python/nbdkit-python-plugin.pod | 19 ++++++- plugins/python/python.c | 75 +++++++++++++++++++++++++ tests/test-python-plugin.py | 8 ++- tests/test_python.py | 73 +++++++++++++++++++++++- 4 files changed, 169 insertions(+), 6 deletions(-) diff --git a/plugins/python/nbdkit-python-plugin.pod b/plugins/python/nbdkit-python-plugin.pod index b20f51f7..d7b6033f 100644 --- a/plugins/python/nbdkit-python-plugin.pod +++ b/plugins/python/nbdkit-python-plugin.pod @@ -271,6 +271,13 @@ contents will be garbage collected. # return nbdkit.CACHE_NONE or nbdkit.CACHE_EMULATE # or nbdkit.CACHE_NATIVE

+++ b/plugins/python/python.c @@ -1020,6 +1020,79 @@ py_can_cache (void *handle) return NBDKIT_CACHE_NONE; } +static int +py_can_extents (void *handle) +{ + ACQUIRE_PYTHON_GIL_FOR_CURRENT_SCOPE; + return boolean_callback (handle, "can_extents", "extents"); +} + +static int +py_extents (void *handle, uint32_t count, uint64_t offset, + uint32_t flags, struct nbdkit_extents *extents) +{ + ACQUIRE_PYTHON_GIL_FOR_CURRENT_SCOPE; + struct handle *h = handle; + PyObject *fn; + PyObject *r; + Py_ssize_t i, size; + + if (callback_defined ("extents", &fn)) { + PyErr_Clear (); + + r = PyObject_CallFunction (fn, "OiLI", h->py_h, count, offset, flags); + Py_DECREF (fn); + if (check_python_failure ("extents") == -1) + return -1; + + /* We expect a list of extents to be returned. Each extent is a + * tuple (offset, length, type). + */ + if (!PyList_Check (r)) { + nbdkit_error ("extents method did not return a list"); + Py_DECREF (r); + return -1; + } + + size = PyList_Size (r); + for (i = 0; i < size; ++i) { + PyObject *t, *py_offset, *py_length, *py_type; + uint64_t extent_offset, extent_length; + uint32_t extent_type; + + t = PyList_GetItem (r, i); + if (!PyTuple_Check (t) || PyTuple_Size (t) != 3) { + nbdkit_error ("extents method did not return a list of 3-tuples"); + Py_DECREF (r); + return -1; + } + py_offset = PyTuple_GetItem (t, 0); + py_length = PyTuple_GetItem (t, 1); + py_type = PyTuple_GetItem (t, 2); + extent_offset = PyLong_AsUnsignedLongLong (py_offset); + extent_length = PyLong_AsUnsignedLongLong (py_length); + extent_type = PyLong_AsUnsignedLong (py_type); + if (check_python_failure ("PyLong") == -1) {

+ Py_DECREF (r); + return -1; + } + if (nbdkit_add_extent (extents, + extent_offset, extent_length, extent_type) == -1) { + Py_DECREF (r); + return -1; + } + } + + Py_DECREF (r); + } + else { + nbdkit_error ("%s not implemented", "extents"); + return -1;

+++ b/tests/test_python.py

@@ -220,3 +232,60 @@ class Test (unittest.TestCase): """Test cache.""" self.connect ({"size": 512, "can_cache": "native"}) self.h.cache (512, 0) + + # We don't have access to the magic constants defined in the + # nbdkit module, so redefine them here. + EXTENT_HOLE = 1 + EXTENT_ZERO = 2