search for: nbd_aio_pread_structur

...aio_FOO command based on its cookie. That solves the race for the callback ever being fired before the user has had a chance to track the cookie, and makes it so that only one command has to register callback functions (rather than one counterpart per aio_FOO command). Or maybe even three parts: nbd_aio_pread_structured() => creates cookie, called once nbd_aio_add_callback(cookie, callback, user_data) - called 0 or more times before submit; callbacks run in LIFO order at command completion nbd_aio_submit(cookie) => kicks off the command Why do it this way? Because in the Python bindings, right now we ha...

Rich recently patched things to generate one man page per function rather than libnbd-api.3 (nice), but in doing so got stumped by a problem with a fresh git clone (automake fails for any 'include' directive that does not already exist). I've figured out how to hack around it, but the hack requires GNU make. We already use GNU make constructs elsewhere (such as $(wildcard)), but

On 7/17/19 8:00 AM, Richard W.M. Jones wrote: > --- > .gitignore | 1 + > README | 2 + > configure.ac | 9 + > examples/Makefile.am | 22 ++ > examples/glib-main-loop.c | 511 ++++++++++++++++++++++++++++++++++++++ > 5 files changed, 545 insertions(+) Looks good. > > + revents = g_source_query_unix_fd

This is my proposal for fixing the documentation to match practice (namely, that completion.callback is not invoked in the cases where the aio call itself reports errors); we could instead try to go the other direction and tweak the generator to guarantee that both completion.callback and completion.free are reached no matter what, but that felt more invasive to me. Eric Blake (2): api: Tighten

...tional free function' > +this function when the callback will not be called again by libnbd. > > -=over 4 > +This can be used to free associated C<user_data>. For example: > > -=item C<LIBNBD_CALLBACK_VALID> > + void *my_data = malloc (...); > + > + nbd_aio_pread_structured (nbd, buf, sizeof buf, offset, > + (nbd_chunk_callback) { .callback = my_fn, > + .user_data = my_data, > + .free = free }, > + NBD_NULL_CALLBACK(completion), Needs rebasing based...

...const char *context, const char *msg), > void *user_data); Would the 'valid_flag' be presented to non-C bindings, or is it only needed for C code? At any rate, the idea makes sense as a lighter-weight way for libnbd to always inform the callback about the last invocation. For nbd_aio_pread_structured and nbd_aio_block_status, the chunk/extent callback can either match server state (if the server replies replies with NBD_REPLY_FLAG_DONE on an OFFSET_DATA/BLOCK_STATUS reply, we could set VALID|FREE; if the server defers NBD_REPLY_FLAG_DONE to an NBD_REPLY_TYPE_NONE packet then the two flags wil...

Obvious change given the previous patch, so ACK. I do wonder if we should make the notify parameter mandatory (and therefore avoid the duplicate functions). Another trick you might do if feeling really keen is to programmatically generate the notify variants of commands, something like this: let make_notify_variant_of_call ({ args; longdesc } as call) = let args = List.rev args in let

...f: +You can associate a free function with callbacks. Libnbd will call +this function when the callback will not be called again by libnbd. -=over 4 +This can be used to free associated C<user_data>. For example: -=item C<LIBNBD_CALLBACK_VALID> + void *my_data = malloc (...); + + nbd_aio_pread_structured (nbd, buf, sizeof buf, offset, + (nbd_chunk_callback) { .callback = my_fn, + .user_data = my_data, + .free = free }, + NBD_NULL_CALLBACK(completion), + 0); -The callback para...

...- nbd_pread \ - nbd_pread_structured \ - nbd_pwrite \ - nbd_shutdown \ - nbd_flush \ - nbd_trim \ - nbd_cache \ - nbd_zero \ - nbd_block_status \ - nbd_poll \ - nbd_aio_connect \ - nbd_aio_connect_uri \ - nbd_aio_connect_unix \ - nbd_aio_connect_tcp \ - nbd_aio_connect_command \ - nbd_aio_pread \ - nbd_aio_pread_structured \ - nbd_aio_pwrite \ - nbd_aio_disconnect \ - nbd_aio_flush \ - nbd_aio_trim \ - nbd_aio_cache \ - nbd_aio_zero \ - nbd_aio_block_status \ - nbd_aio_get_fd \ - nbd_aio_get_direction \ - nbd_aio_notify_read \ - nbd_aio_notify_write \ - nbd_aio_is_created \ - nbd_aio_is_connecting \ - nbd_aio_is_re...

...+ nbd_pread \ + nbd_pread_structured \ + nbd_pwrite \ + nbd_shutdown \ + nbd_flush \ + nbd_trim \ + nbd_cache \ + nbd_zero \ + nbd_block_status \ + nbd_poll \ + nbd_aio_connect \ + nbd_aio_connect_uri \ + nbd_aio_connect_unix \ + nbd_aio_connect_tcp \ + nbd_aio_connect_command \ + nbd_aio_pread \ + nbd_aio_pread_structured \ + nbd_aio_pwrite \ + nbd_aio_disconnect \ + nbd_aio_flush \ + nbd_aio_trim \ + nbd_aio_cache \ + nbd_aio_zero \ + nbd_aio_block_status \ + nbd_aio_get_fd \ + nbd_aio_get_direction \ + nbd_aio_notify_read \ + nbd_aio_notify_write \ + nbd_aio_is_created \ + nbd_aio_is_connecting \ + nbd_aio_is_re...

Patches 1 & 2 are rather complex, but the end result is that we pass closures + user_data + free function in single struct parameters as I described previously in this email: https://www.redhat.com/archives/libguestfs/2019-August/msg00210.html Patch 3 adds a convenient FREE_CALLBACK macro which seems a worthwhile simplification if you buy into 1 & 2. Patch 4 adds another macro which is

...to complete, and then a separate thread can gather the final completion status using just libnbd's locking, making the polling loop more efficient. This also provides an opportunity to clean up any opaque data and/or change the final command status (for example, writing a strict validator for nbd_aio_pread_structured can change the command from success to failure if the server violated protocol by not returning chunks to cover the entire read). We also want the client to be aware of any issued/in-flight commands that failed because they were stranded when the state machine moved to CLOSED or DEAD. Previousl...

...s.c +++ b/examples/strict-structured-reads.c @@ -235,9 +235,9 @@ main (int argc, char *argv[]) *r = (struct range) { .first = offset, .last = offset + maxsize, }; *d = (struct data) { .offset = offset, .count = maxsize, .flags = flags, .remaining = r, }; - if (nbd_aio_pread_structured_callback (nbd, buf, sizeof buf, offset, - read_chunk, d, read_verify, d, - flags) == -1) { + if (nbd_aio_pread_structured (nbd, buf, sizeof buf, offset, + read_chunk, d, read_ve...

On Mon, Jul 22, 2019 at 10:08:25AM +0100, Richard W.M. Jones wrote: > On Sat, Jul 20, 2019 at 07:38:45AM +0100, Richard W.M. Jones wrote: > > More thoughts on callbacks, etc. following on from: > > https://www.redhat.com/archives/libguestfs/2019-July/thread.html#00184 > > > > Closure lifetimes > > ----------------- Here's a possibly better idea which still

...all with + args = []; ret = RBool; + shortdesc = "does the server support the don't fragment flag to pread?"; + longdesc = "\ +Returns true if the server supports structured reads with an +ability to request a non-fragmented read (see C<nbd_pread_structured>, +C<nbd_aio_pread_structured>). Returns false if the server either lacks +structured reads or if it does not support a non-fragmented read request."; + }; + "can_multi_conn", { default_call with args = []; ret = RBool; @@ -1306,7 +1317,8 @@ at C<offset> and ending at C<offset> + C...

This applies on top of the OClosure v2 series posted a few minutes ago. Rich.

...ads.c index 4bc63b8..d7c3e1b 100644 --- a/examples/strict-structured-reads.c +++ b/examples/strict-structured-reads.c @@ -236,7 +236,8 @@ main (int argc, char *argv[]) *d = (struct data) { .offset = offset, .count = maxsize, .flags = flags, .remaining = r, }; if (nbd_aio_pread_structured (nbd, buf, sizeof buf, offset, - read_chunk, d, read_verify, d, + (nbd_chunk_callback) { .callback = read_chunk, .user_data = d }, + (nbd_completion_callback) { .callback = read_verify, .user_data =...

One API change, some small documentation changes.

This replaces 13/13 of my v2 series; and now that it has pretty good testsuite coverage and demonstrable performance improvement to nbdinfo, I'm going ahead and pushing this now. We may still want to add further nbd_opt_* commands for other fine-grained tuning of negotiation, but for now, I think things have stabilized on this end, and I can return to polishing .list_exports on the nbdkit

I still need to wire in the use of *_notify functions into nbdkit to prove whether it makes the code any faster or easier to maintain, but at least the added example shows one good use case for the new API. Eric Blake (6): api: Add nbd_aio_in_flight generator: Allow DEAD state actions to run generator: Allow Int64 in callbacks states: Prepare for aio notify callback api: Add new