Add a simple kv database for cfilters

Use a kv bucket to store all filters on disk

crates/floresta-compact-filters/src/kv_filter_database.rs

@@ -0,0 +1,55 @@
+use std::path::PathBuf;
+
+use bitcoin::util::bip158::BlockFilter;
+use kv::{Bucket, Integer, Config};
+
+use crate::BlockFilterStore;
+
+/// Stores the block filters insinde a kv database
+pub struct KvFilterStore<'a> {
+    bucket: Bucket<'a, Integer, Vec<u8>>,
+}
+
+impl KvFilterStore<'_> {
+    /// Creates a new [KvFilterStore] that stores it's content in `datadir`.
+    ///
+    /// If the path does't exist it'll be created. This store uses compression by default, if you
+    /// want to make more granular configuration over the underlying Kv database, use `with_config`
+    /// instead.
+    pub fn new(datadir: &PathBuf) -> Self {
+        let store = kv::Store::new(kv::Config {
+            path: datadir.to_owned(),
+            temporary: false,
+            use_compression: true,
+            flush_every_ms: None,
+            cache_capacity: None,
+            segment_size: None,
+        }).expect("Could not open store");
+
+        let bucket = store.bucket(Some("cfilters")).unwrap();
+        KvFilterStore { bucket }
+
+    }
+    /// Creates a new [KvFilterStore] that stores it's content with a given config
+    pub fn with_config(config: Config) -> Self {
+        let store = kv::Store::new(config).expect("Could not open database");
+        let bucket = store.bucket(Some("cffilters")).unwrap();
+        KvFilterStore { bucket }
+    }
+}
+
+impl BlockFilterStore for KvFilterStore<'_> {
+    fn get_filter(&self, block_height: u64) -> Option<bitcoin::util::bip158::BlockFilter> {
+        let value = self
+            .bucket
+            .get(&Integer::from(block_height))
+            .ok()
+            .flatten()?;
+        Some(BlockFilter::new(&value))
+    }
+    fn put_filter(&self, block_height: u64, block_filter: bitcoin::util::bip158::BlockFilter) {
+        self.bucket
+            .set(&Integer::from(block_height), &block_filter.content)
+            .expect("Bucket should be open");
+    }
+}

crates/floresta-compact-filters/src/lib.rs

@@ -197,7 +197,7 @@ impl BlockFilterBackend {
                 ser_input[0..32].clone_from_slice(&input.previous_output.txid);
                 ser_input[32..].clone_from_slice(&input.previous_output.vout.to_be_bytes());
                 filter.put(&ser_input);
-            });
+            })
         }
     }
     fn write_tx_outs(&self, tx: &Transaction, filter: &mut FilterBuilder) {