Creates an example package that subscribes to all notifications and logs
them. This is useful for testing the behavior of subscribing to "*".
I've also edited the Makefile to ensure that `make` builds the example
and that `make clean` removes the example
In the old version requesting the config-value of an option
was a little bit tricky.
Let's say we want to have a plugin which uses a default
port of 1234.
```rust
let value = plugin.option("plugin-port");
match value {
Some(Value::Integer(_)) => {},
Some(Value::String(_)) => {}, // Can never happen
Some(Value::Boolean(_)) => {}, // Can never happen
None => {}, // Can never happen
}
```
Many users of the `cln_plugin` crate are overly cautious
and handle all these error scenario's. Which is completely unneeded.
Core Lightning will complain if you put a `String` where an `Integer` is
expected and will never send the value to the plug-in.
This change makes the API much more ergonomical and actually motivates
some of the changes in previous commits.
```
const MY_OPTION : ConfigOption<i64> = ConfigOption::new_i64_with_default(
"plugin-port',
1235,
"Description");
let value : Result<i64> = plugin.option(MY_OPTION);
```
The result will provide a proper error-message.
It is also safe to `unwrap` the result because it will
only be triggered if the user neglected to provide the
option to the `Builder`.
This is the first part of two commits that attempts to simplify
the API that is used to retrieve configuration values.
Previously, we encouraged the following pattern to build a plugin.
```rust
let configured_plugin =
Builder::new(
tokio::io::stdin(),
tokio::io::stdout())
.option(ConfigOption::new_i64_with_default("some-option", 0, "Description"))
.configure();
let value = configured_plugion.option("some-option");
match value {
Some(Integer(i)) => {}, // Config provided
None => {}, // No config set
_ => {}, // This should never happened
}
```
This commit helps to move to the following pattern
```rust
const SOME_OPTION : ConfigOption<i64> = ConfigOption::new_i64_with_default(
"some-option",
"description");
async fn main() -> Result<()> {
let plugin = Builder::new(tokio::io::stdin(), tokio::io::stdoout())
.option(SOME_OPTION)
.configure()
.await?;
let value : i64 = plugin.option(SOME_OPTION)?;
}
```
Breaking changes here.
This improves the semantics of `ConfigOption` and `options::Value`
drastically.
We've been using `options::Value` for 2 purposes
1. To specify the type and default value of an option
2. Coummunicate how a user configured an option
We fall here in the pit-fall of being poor at both purposes.
I've edited the code to ensure
- `options::Value` -> To read or specify the value of an option
- `option::ValueType` -> To specify the type of an option
**Configure an option**
Let's create an string-typed option create an option named `"required-string-opt"` the
developer has to use the following code.
```rust
let option = ConfigOption::new("required-string", Value::OptString, "description");
```
The semantics of `OptString` might falsely suggest that it is optional to specify the config.
However, we use `OptString` to say we are not providing a default-value.
After this commit we can use instead
```rust
let option = ConfigOption::new_str_no_default("required-string", "description");
```
For reading a configured value the `option::Value` is somewhat
cumbersome. The old version of had 6 different types of value
```rust
let value = plugin.option("required-string");
match value {
String(s) => {}, // User has configured string value or default
Integer(i) => {}, // User has configured int value or default
Boolean(b) => {}, // User has configured bool value or default
OptString => {}, // User has not configured value and no default
OptInteger = {}, // User has not configured value and no default
OptBOolean => {}, // User has not configured value and no default
}
```
This has been changed to
```rust
let value = plugin.option("required-string");
match value {
Some(String(s)) => {},
Some(Integer(i)) => {},
Some(Boolean(b)) => {},
None => {},
}
```
This was pointed out by Daywalker [1]: we are synchronously processing
events from `lightningd` which means that if processing one of the
hooks or requests was slow or delayed, we would not get notifications,
hooks, or RPC requests, massively impacting the flexbility.
This highlights the issue with a failing test (it times out), and in
the next commit we will isolate event processing into their own task,
so to free the event loop from having to wait for an eventual
response.
[1] https://community.corelightning.org/c/developers/hold-invoice-plugin#comment_wrapper_16754493
We had a bit of a chicken-and-egg problem, where we instantiated the
`state` to be managed by the `Plugin` during the very first step when
creating the `Builder`, but then the state might depend on the
configuration we only get later. This would force developers to add
placeholders in the form of `Option` into the state, when really
they'd never be none after configuring.
This defers the binding until after we get the configuration and
cleans up the semantics:
- `Builder`: declare options, hooks, etc
- `ConfiguredPlugin`: we have exchanged the handshake with
`lightningd`, now we can construct the `state` accordingly
- `Plugin`: Running instance of the plugin
Changelog-Changed: cln-plugin: Moved the state binding to the plugin until after the configuration step
We now have ternary outcomes for `Builder.configure()` and
`Builder.start()`:
- Ok(Some(p)) means we were configured correctly, and can continue
with our work normally
- Ok(None) means that `lightningd` was invoked with `--help`, we
weren't configured (which is not an error since the `lightningd` just
implicitly told us to shut down) and user code should clean up and
exit as well
- Err(e) something went wrong, user code may report an error and exit.
Mostly comments and docs: some places are actually paths, which
I have avoided changing. We may migrate them slowly, particularly
when they're user-visible.
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
For now hooks are treated identically to rpcmethods, with the
exception of not being returned in the `getmanifest` call. Later on we
can add typed handlers as well.
