The next patch will use these to order the hooks.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Changelog-Added: plugins: hooks can now specify that they must be called 'before' or 'after' other plugins.
One is called on every plugin return, and tells us whether to continue;
the other is only called if every plugin says ok.
This works for things like payload replacement, where we need to process
the results from each plugin, not just the final one!
We should probably turn everything into a chained callback next
release.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
They callback must take ownership of the payload (almost all do, but
now it's explicit).
And since the payload and cb_arg arguments to plugin_hook_call_() are
always identical, make them a single parameter.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Switch from having a single plugin to a list of plugins. If the hook is of
type single we will enforce that constraint on the number of registered
plugins when attempting to add.
The newly introduced type is used to determine what the call semantics of the
hook are. We have `single` corresponding to the old behavior, as well as
`chain` which allows multiple plugins to register for the hook, and they are
then called sequentially (if all plugins return `{"result": "continue"}`) or
exit the chain if the hook event was handled.
This adds 'plugin_unregister_hook' and 'plugin_unregister_hook_all'
functions to unregister a given hook a plugin registered, or all hooks a
plugin registered for. Since hooks can only be registered once, it's
useful in the case a new plugin is added which would be prefered for
hook registration over an already loaded plugin.
This seems like overkill, at least for now. Handling the JSON
inline is clearer, for the existing examples at least.
We also remove the dummy hook, rather than fix it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
I started by trying to change the current infrastructure, but this is
really the only completely sync hook which makes sense; it needs to avoid
doing the db_transation, as well as waiting, and using a callback is just
overkill.
So with some regret, I open coded it.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This is the first use of the `hooks` autodata field, and it required a
dummy element in order for the section not to be dropped, it'll be
removed once we have actual hooks.
I might have gone a bit overboard with the type-checking, but
typesafe_cb_cast is quite nice to use, so why not. The macro to
register a new hook encapsulates the entire flow from param
serialization, to dispatch, parsing and callback dispatch in one
bundle. I was tempted to have the callback outside of the
registration, but it's unlikely that we'll have two calls to the same
hook with different callbacks.
Signed-off-by: Christian Decker <decker.christian@gmail.com>
