emissary-core 0.4.0

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#![allow(unused)]

use ethbloom::{Bloom, Input};

/// Tunnel message bloom filter.
///
/// Idea taken from `ire` which is licensed under MIT.
///
/// Credits to str4d.
#[derive(Default)]
pub struct BloomFilter {
    /// Current filter.
    current: Bloom,

    /// Previous filter.
    previous: Bloom,
}

impl BloomFilter {
    /// Attempt to insert `bytes` into [`BloomFilter`].
    ///
    /// Returns `true` if `bytes` doesn't exist in the filter and `false` if it does.
    pub fn insert(&mut self, bytes: &[u8]) -> bool {
        if self.current.contains_input(Input::Raw(bytes))
            || self.previous.contains_input(Input::Raw(bytes))
        {
            return false;
        }

        self.current.accrue(Input::Raw(bytes));
        true
    }

    /// Decay [`BloomFilter`].
    pub fn decay(&mut self) {
        self.previous = core::mem::take(&mut self.current);
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::runtime::{mock::MockRuntime, Runtime};
    use rand::Rng;

    #[test]
    fn insert_and_decay() {
        let messages = (0..5)
            .map(|_| {
                let mut message = [0u8; 1008];
                MockRuntime::rng().fill_bytes(&mut message);

                message
            })
            .collect::<Vec<_>>();

        let mut bloom = BloomFilter::default();

        // insert all messages and verify they're all in the bloom filter
        assert!(messages.iter().all(|message| bloom.insert(message.as_ref())));
        assert!(messages.iter().all(|message| !bloom.insert(message.as_ref())));

        // deacy the filter and verify that all the messages are still part of the bloom filter
        bloom.decay();
        assert!(messages.iter().all(|message| !bloom.insert(message.as_ref())));

        // decay filter again and verify that the messages are no longer part of it
        bloom.decay();
        assert!(messages.iter().all(|message| bloom.insert(message.as_ref())));
        assert!(messages.iter().all(|message| !bloom.insert(message.as_ref())));
    }
}