similar to: [nbdkit PATCH] ocaml: Support .preconnect callback

Allow plugins to affect the handling of the new NBD_CMD_FLAG_FAST_ZERO flag, then update affected plugins. In particular, in-memory plugins are always fast; the full plugin is better served by omitting .zero and relying on .pwrite fallback; nbd takes advantage of libnbd extensions proposed in parallel to pass through support; and v2 language bindings expose the choice to their scripts. The

Fairly straightforward. I'd love for type export to be a bit more flexible to make description optional, but could not figure out how to decode that from the C side of things, so for now this just requires the caller to supply a description for all exports during .list_exports. Signed-off-by: Eric Blake <eblake at redhat.com> --- plugins/ocaml/NBDKit.mli | 9 ++++

Fairly straightforward. A user can supply { "name"; None } or { "name"; Some "description" } as desired. Signed-off-by: Eric Blake <eblake@redhat.com> --- plugins/ocaml/NBDKit.mli | 9 ++++ plugins/ocaml/NBDKit.ml | 17 ++++++++ plugins/ocaml/example.ml | 33 +++++++++----- plugins/ocaml/ocaml.c | 92 +++++++++++++++++++++++++++++++++++++++- 4 files

I like this change. I think we were overloading the config_complete method before to do two different things (complete configuration; do any allocation/housekeeping necessary before we can start serving). The only questions in my mind are whether we want this before 1.18, and whether the name ("get_ready") is a good one. Rich.

This picks up python and ocaml. Some of our languages are lacking a number of bindings (for example, lua and perl lack .extents, so I didn't have anything to copy from), and I felt less comfortable with golang and rust. But for python and ocaml, I was able to test a working implementation. Eric Blake (2): python: Implement .list_exports and friends ocaml: Implement .list_exports and

I will be following up to this email with four separate threads each addressed to the appropriate single list, with proposed changes to: - the NBD protocol - qemu: both server and client - libnbd: client - nbdkit: server The feature in question adds a new optional NBD_INFO_ packet to the NBD_OPT_GO portion of handshake, adding up to 16 bits of information that the server can advertise to the

We do not promise API stability for non-C languages; this is an API break as follows: instead of calling 'NBDKit.register_plugin model plugin' with a static model, you can now add .thread_model :(unit -> thread_model) to plugin or default to PARALLEL. Since all existing OCaml plugins will have already thought about thread models, they can convert their existing model into the new

If you have a plugin which either creates background threads itself or uses a library that creates background threads, it turns out you cannot create these in .get_ready (or earlier). The reason is that nbdkit forks when either daemonizing itself or using the --run option, and fork cancels all the background threads in the child process (the daemonized or captive nbdkit). The only good solution

With our recent cleanups to nxdata, the only remaining difference between functions like backend_open() and next_open() was the signature (one used void*, the other struct backend *); the API is compatible. All of our filters are in-tree, and we don't promise API/ABI stability, but it is still a lot of files to touch, so the simplest solution to avoid the redundant hop through wrapper

I'm about to add an 'exportname' filter, and in the process, I noticed a few shortcomings in our API. Having .default_export makes it easy to answer NBD_INFO_NAME in response to a client request during NBD_OPT_GO, but answering NBD_INFO_DESCRIPTION is awkward - there's no guarantee the export name was given with a description in .list_exports. Note, however, that while we map

This happened on s390 in Koji, once. The key lines from the log are: + start_t=0 nbdkit: sh[1]: debug: retry 1: waiting 1 seconds before retrying nbdkit: sh[1]: debug: retry 1: waiting 1 seconds before retrying + end_t=1 Somehow nbdkit did wait 2 seconds (or at least, nbdkit_nanosleep (1, 0) was called twice by the retry filter). But in the bash script, time (as measured by $SECONDS) advanced

This was previously used as ‘nxdata’ and stored a tuple of ’b->next’ and the real filter handle. However after recent changes we don't need it. We can use ‘b->next’ as nxdata, and the handle is passed to us by the calling functions. Inspired by Eric Blakes observations in this email: https://www.redhat.com/archives/libguestfs/2020-February/msg00092.html --- server/filters.c | 217

It's confusing to use the same terminology for a single backend as for the linked list of backends. In particular it's often not clear if we're calling the next backend or the whole chain of backends. --- server/internal.h | 14 ++++++++++-- server/connections.c | 20 ++++++++--------- server/locks.c | 2 +- server/main.c

This is a cover letter to a series of patches being proposed in tandem to four different projects: - nbd: Document a new NBD_CMD_FLAG_FAST_ZERO command flag - qemu: Implement the flag for both clients and server - libnbd: Implement the flag for clients - nbdkit: Implement the flag for servers, including the nbd passthrough client If you want to test the patches together, I've pushed a

hi is it possible to have asterisk connect to mysql with a username/password in some config file and then, afterwards, just use a global handle to the db? I don't see the point of connecting every time I need to query it ... roy

Eric: Did you want to take this one any further? It might be one that we save for > 1.18: https://www.redhat.com/archives/libguestfs/2020-February/thread.html#00206 Another thing I've been thinking about for some time is splitting .config_complete into .config_complete + .get_ready (new name TBD). At the moment .config_complete is both the place where we finish processing config, and

For example if .preconnect fails, it printed the debug messages: debug: preconnect: ... debug: close: ... This confused me into thinking that the close callback was actually being called without a corresponding open. In fact it is not called in this case. Suppress the debug message unless the callback is actually being called. --- server/backend.c | 2 +- 1 file changed, 1 insertion(+), 1

On Sat, Feb 22, 2020 at 05:11:01AM -0600, Eric Blake wrote: > On 2/22/20 4:37 AM, Richard W.M. Jones wrote: > >Another thing I've been thinking about for some time is splitting > >.config_complete into .config_complete + .get_ready (new name TBD). > >At the moment .config_complete is both the place where we finish > >processing config, and also the last chance we get

It's been several weeks since I posted v2 (I got distracted by improving libnbd to better test things, which in turn surfaced some major memory leak problems in nbdsh that are now fixed). Many of the patches are minor rebases from v2, with the biggest changes being fallout from: - patch 2: rename nbdkit_add_default_export to nbdkit_use_default_export - overall: this missed 1.22, so update

Qemu was able to demonstrate that knowing whether a zero operation is fast is useful when copying from one image to another: there is a choice between bulk pre-zeroing and then revisiting the data sections (fewer transactions, but depends on the zeroing to be fast), vs. visiting every portion of the disk only once (more transactions, but no time lost to duplicated I/O due to slow zeroes). As