Add rocksdb

[igalshilman]

This PR adds an initial storage and wires it.
The api in the storage_api is a low level one, we need to iterate few more times once we will learn more about the domain objects that we need to persist.

Here is an example:

#[cfg(test)]
mod tests {
    use super::*;

    #[derive(Debug, Eq, PartialEq, Clone)]
    struct MyMessage(String);

    impl From<&str> for MyMessage {
        fn from(value: &str) -> Self {
            MyMessage(value.to_string())
        }
    }

    impl StorageDeserializer for MyMessage {
        fn from_bytes(bytes: impl AsRef<[u8]>) -> Self {
            let b = bytes.as_ref().to_vec();
            MyMessage(String::from_utf8(b).unwrap())
        }
    }

    impl AsRef<[u8]> for MyMessage {
        fn as_ref(&self) -> &[u8] {
            self.0.as_bytes()
        }
    }

    fn usage_example<S: Storage>(storage: S) {
        let mut txn = storage.transaction();

        txn.put(State, "abcc-a", "1");
        txn.put(State, "abcc-b", "2");

        txn.put(State, "abcd-a", "a");
        txn.put(State, "abcd-b", "b");
        txn.put(State, "abcd-c", "c");

        txn.put(State, "abce-d", "d");
        txn.put(State, "abce-a", "3");
        txn.put(State, "abce-b", "4");

        txn.commit();

        let mut vec: Vec<(MyMessage, MyMessage)> = vec![];
        storage.copy_prefix_into(State, "abcd-b", 4, &mut vec);

        assert_eq!(vec.len(), 2);
        assert_eq!(vec.get(0).cloned().unwrap(), ("abcd-b".into(), "b".into()));
        assert_eq!(vec.get(1).cloned().unwrap(), ("abcd-c".into(), "c".into()));
    }

    #[test]
    fn test_usage_example() {
        let opts = Options {
            path: "db/".to_string(),
        };
        let storage = RocksDBStorage::new(opts);
        usage_example(storage);
    }
}

[tillrohrmann]

Great work @igalshilman. The changes look good to me. I think we need to add BSD-3-Clause and ISC to the list of allowed licenses in deny.toml. I think both licenses are ok to be used by Restate. I guess we need to check licenses for build-dependencies because they might output code that is included in the final product that is licensed with their respective license. +1 for merging afterwards.

[tillrohrmann]

Suggested change

	/// async fn main() { /// use tracing_instrumentation::TokioRuntime;
	/// async fn main() {

[tillrohrmann]

What is ignore used for?

[igalshilman]

Without ignore doc-test couldn't run since tracing_instrumentation does not depend on Tokio.
I couldn't run cargo test without it. Let me know if I've made here something silly?

[igalshilman]

ok, I've tried just test instead of cargo test and it worked without the ignore.
I'm not sure I understand what is going on there, but let me revert the ignore.

[igalshilman]

Great work @igalshilman. The changes look good to me. I think we need to add BSD-3-Clause and ISC to the list of allowed licenses in deny.toml. I think both licenses are ok to be used by Restate. I guess we need to check licenses for build-dependencies because they might output code that is included in the final product that is licensed with their respective license. +1 for merging afterwards.

okay Till :-) thanks for the review! I'll squash and merge.

[slinkydeveloper]

Just left some comments for future :)

[slinkydeveloper]

Perhaps this can be a macro? You could use stringify

[slinkydeveloper]

Perhaps the bound should be at impl level here

[slinkydeveloper]

Reason is that I see this impl block evolving like:

• on_apply (parent apply function)
• on_message_x
• on_message_y

All of these will need the same storage bound, as the entrypoint is still on_apply