We only use Eq ranges

CAS predicates should always contain the current raft term, because this
is what's explicitly checked in proc_cas.

Note that this will sometimes result in a EntryTermMismatch error
because the latest applied entry may have a different term in case the
election has started but not finished yet.

We could add this check to all the client cas precondition checks, but
it's not a big deal, because we handle the situation correctly anyways.

Close #635

Reasons:
- it's not safe to split raft entries as atomicness is lost
- the original feature was not tested

godzie44 authored 11 months ago and Yaroslav Dynnikov committed 10 months ago

Plugin topology is a mapping plugin service to tiers.

Introduce new `pico.update_plugin_tiers` API.
This function may be used for control
where plugin services must be running and where not.

Plugin integration tests have also been refactored.

godzie44 authored 11 months ago and Yaroslav Dynnikov committed 11 months ago

Now for installation and enable plugin, there are two steps instead of one
(`pico.load_plugin` previously).
1. Install plugin (`pico.install_plugin`):
validate plugin, create system tables.
2. Enable plugin (`pico.enable_plugin`):
loads plugin into instances memory, call `on_start` callback.

Same for a plugin removing process (`pico.remove_plugin` previously):
1. Disable plugin (`pico.disable_plugin`): call `on_stop` callbacks, drop
plugin from instances.
2. Remove plugin (`pico.remove_plugin`):
remove plugin meta from system tables.

godzie44 authored 11 months ago and Yaroslav Dynnikov committed 11 months ago

Introduce a plugin system for picodata cluster.
Plugin system contains:
- `picoplugin` crate with plugin interfaces.
This crate exposes plugin interfaces for user implementation and API
that used by picodata to interact with plugin as with a code from dynamic library.
- Support for plugin work cycle in picodata instance work cycle.
Picodata instance interacts with running plugin by `PluginManager`
component.
Typically, plugins react to events that occur in instance or whole cluster.
- New lua API with plugin CRUD actions.
    - pico.create_plugin - load a new plugin into picodata cluster
    - pico.remove_plugin - remove plugin from picodata cluster
    - pico.update_plugin_config - update plugin service configuration