search for: myfilter_config

...8YbkCBd9ye7Cvs Content-Type: text/x-pod; charset=utf-8 Content-Disposition: attachment; filename="nbdkit-filter.pod" Content-Transfer-Encoding: 8bit =encoding utf8 =head1 NAME nbdkit-filter - How to write nbdkit filters =head1 SYNOPSIS #include <nbdkit-filter.h> static int myfilter_config (nbdkit_next_config *next, void *nxdata, const char *key, const char *value) { if (strcmp (key, "myparameter") == 0) { // ... return 0; } else { // pass through to next filter or plugin return next (nxdata, key, value); } } static str...

...nbdkit-filter.pod b/docs/nbdkit-filter.pod new file mode 100644 index 0000000..75157ef --- /dev/null +++ b/docs/nbdkit-filter.pod @@ -0,0 +1,501 @@ +=encoding utf8 + +=head1 NAME + +nbdkit-filter - How to write nbdkit filters + +=head1 SYNOPSIS + + #include <nbdkit-filter.h> + + static int + myfilter_config (nbdkit_next_config *next, void *nxdata, + const char *key, const char *value) + { + if (strcmp (key, "myparameter") == 0) { + // ... + return 0; + } + else { + // pass through to next filter or plugin + return next (nxdata, key, value); + } + } +...

...nbdkit-filter.pod b/docs/nbdkit-filter.pod new file mode 100644 index 0000000..cec60c6 --- /dev/null +++ b/docs/nbdkit-filter.pod @@ -0,0 +1,510 @@ +=encoding utf8 + +=head1 NAME + +nbdkit-filter - How to write nbdkit filters + +=head1 SYNOPSIS + + #include <nbdkit-filter.h> + + static int + myfilter_config (nbdkit_next_config *next, void *nxdata, + const char *key, const char *value) + { + if (strcmp (key, "myparameter") == 0) { + // ... + return 0; + } + else { + // pass through to next filter or plugin + return next (nxdata, key, value); + } + } +...

This patch isn't complete (patch 6/6 isn't finished) so it's just for discussion, although it does compile and run. This introduces to nbdkit a concept of "filters" which can be placed in front of plugins to modify their behaviour. Some examples where you might use filters: * Serve a subset of the data, such as (offset, range) or a single partition from a disk image.

...nbdkit-filter.pod b/docs/nbdkit-filter.pod index 4033789..86894f1 100644 --- a/docs/nbdkit-filter.pod +++ b/docs/nbdkit-filter.pod @@ -6,8 +6,6 @@ nbdkit-filter - how to write nbdkit filters #include <nbdkit-filter.h> - #define THREAD_MODEL NBDKIT_THREAD_MODEL_PARALLEL - static int myfilter_config (nbdkit_next_config *next, void *nxdata, const char *key, const char *value) @@ -107,24 +105,6 @@ should not expect to distribute filters separately from nbdkit. All filters should start by including this header file. -=head1 C<#define THREAD_MODEL> - -All filters must d...

This is still tentative and needs a lot of work, but: - partition filter works, supporting MBR & GPT - prepare and finalize methods fixed - open method can now be changed (allowing readonly flag to be modified) - thread_model can be limited I believe I made most of the changes which were previously suggested in email. I think the only one I didn't was preventing inclusion of both

Rebased filters patch. Requires current git master + the locks / thread model fix (https://www.redhat.com/archives/libguestfs/2018-January/msg00128.html) So a few changes here since last time: The "introduce filters" and "implement filters" patches are squashed together. I introduced a concept of .prepare and .finalize. These run before and after the data serving phase

The first three patches are identical to: https://www.redhat.com/archives/libguestfs/2018-January/msg00079.html "[PATCH nbdkit v2 0/3] Refactor plugin_* functions into a backend" The rest of the patches add filters using the new filter API previously described here: https://www.redhat.com/archives/libguestfs/2018-January/msg00073.html This needs a lot more testing -- and tests --

A combination of the work that both Rich and I have been doing lately, where filters use only the new API with flags on every command that the client can send over the wire (we can then add support for more flags in nbdkit without having to add new callbacks, as NBD adds more flags upstream). Eric Blake (4): protocol: Split flags from cmd field in requests backend: Pass flags argument through

Being able to programmatically force nbdkit to be less parallel can be useful during testing. I was less sure about patch 3, but if you like it, I'm inclined to instead squash it into patch 1. This patch is written to apply after my NBD_CMD_CACHE work (since I touched the nocache filter); but can be rearranged if we think this series should go in first while that one undergoes any adjustments