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...n.c index 20e05e0..9445343 100644 --- a/plugins/python/python.c +++ b/plugins/python/python.c @@ -684,110 +684,56 @@ py_zero (void *handle, uint32_t count, uint64_t offset, uint32_t flags) } static int -py_can_write (void *handle) +boolean_callback (void *handle, const char *can_fn, const char *plain_fn) { PyObject *obj = handle; PyObject *fn; PyObject *r; int ret; - if (callback_defined ("can_write", &fn)) { + if (callback_defined (can_fn, &fn)) { PyErr_Clear (); r = PyObject_CallFunctionObjArgs (fn, obj, NULL); Py_DECREF (fn); - if (check_py...

On 3/18/20 8:21 PM, Eric Blake wrote: > In commit c306fa93ab and neighbors (v1.15.1), a concerted effort went > into caching the results of .can_FOO callbacks, with commit messages > demonstrating that a plugin with a slow callback should not have that > delay magnified multiple times. But nothing was added to the > testsuite at the time, and with the sh and eval plugins, we still

And fill out most of the missing bits of the API. Rich.

As mentioned in my reviews, I wonder if we should make our python callbacks look a bit more Pythonic by having kwargs added for each new flag that we want to expose. The idea was first floated here: https://www.redhat.com/archives/libguestfs/2018-April/msg00108.html Note that with my proposal, there is no need for a python script to expose a global API_VERSION variable; new flags are added

...+ if (check_python_failure ("cache") == -1) + return -1; + Py_DECREF (r); + } + else { + nbdkit_error ("%s not implemented", "cache"); + return -1; + } + + return 0; +} + static int boolean_callback (void *handle, const char *can_fn, const char *plain_fn) { @@ -768,6 +801,7 @@ static struct nbdkit_plugin plugin = { .flush = py_flush, .trim = py_trim, .zero = py_zero, + .cache = py_cache, }; NBDKIT_REGISTER_PLUGIN (plugin) -- 2.23.0

...+ if (check_python_failure ("cache") == -1) + return -1; + Py_DECREF (r); + } + else { + nbdkit_error ("%s not implemented", "cache"); + return -1; + } + + return 0; +} + static int boolean_callback (void *handle, const char *can_fn, const char *plain_fn) { @@ -736,6 +769,12 @@ py_can_trim (void *handle) return boolean_callback (handle, "can_trim", "trim"); } +static int +py_can_cache (void *handle) +{ + return boolean_callback (handle, "can_cache", "cache"); +} + #define py_config_help \ "sc...

v1: https://www.redhat.com/archives/libguestfs/2019-November/msg00153.html v2: - Fix implementation of can_cache. - Add implementation of can_fua. - Add a very thorough test suite which tests every command + flag combination.

When I added .can_FOO caching in 1.16, I missed the case that the sh plugin itself was calling .can_flush twice in some situations (in order to default .can_fua). Then right after, I regressed it to call .can_zero twice (in order to default .can_fast_zero). I also missed that .thread_model could use better caching, because at the time, I did not add testsuite coverage. Fix that now. Eric Blake

This is working for me now, although possibly only on Python 3.9. Dan suggested PyEval_InitThreads but that was deprecated in Python 3.7. Rich.

v3 was here: https://www.redhat.com/archives/libguestfs/2019-November/msg00209.html In v4: - Rebase on top of current master. Includes various fixes and updates required because of Nir's patches that went into master. - Fix api_version() -> API_VERSION in patch 2 noted previously on the mailing list. Rich.

v2 was here: https://www.redhat.com/archives/libguestfs/2019-November/msg00163.html I pushed patch 1 (with spelling fix), patch 4 and patch 5 since those were previously ACKed on the list. Differences in v3: - Add error checking to PyModule_AddIntConstant. - Use API_VERSION constant instead of function. - Add max API version supported to --dump-plugin output. - Print API_VERSION selected by