Re: [Libguestfs] [PATCH 0/3] Cleanups for ovirt 4.4

By the way if you happen to be looking at the Python plugin, then there are two changes that may be worth using. API_VERSION = 2: https://libguestfs.org/nbdkit-python-plugin.3.html#API-versions and multi-thread support: https://libguestfs.org/nbdkit-python-plugin.3.html#Threads These were both added (by you) and are both available in nbdkit >= 1.22, which is now available in RHEL AV >= 8.3.0 so there's no reason why we can't use them now. I don't think there's any advantage to API_VERSION = 2 because the plugin is very (exclusively?) write-heavy. But a more parallel thread model is surely advantageous? For API_VERSION = 2, the changes are: * pread signature changes to: def pread(h, buf, offset, flags) -> returns nothing - You have to write the result directly into the buf parameter, avoiding the extra copy. * pwrite adds flags parameter: def pwrite(h, buf, offset, flags) -> returns nothing * flush, trim also add flags parameter. * zero changes signature completely, removing the may_trim parameter and adding a general flags parameter in its place. For threads: * Add a thread_model() function with no parameters which returns nbdkit.THREAD_MODEL_PARALLEL or nbdkit.THREAD_MODEL_SERIALIZE_REQUESTS. Of course locking will need to be introduced (especially for PARALLEL) to protect internal data structures. See nbdkit-plugin(3) for an explanation of the thread models. You'll also have to change the minimum version of nbdkit so that older versions get rejected, here: https://github.com/libguestfs/virt-v2v/blob/1d5fc257765c444644e5bfc6525e8... Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com libguestfs lets you edit virtual machines. Supports shell scripting, bindings from many languages. http://libguestfs.org