WIP: use a separate RocksDB for status caching

Cargo.lock

@@ -65,6 +65,15 @@ version = "0.8.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf9ff0bbfd639f15c74af777d81383cf53efb7c93613f6cab67c6c11e05bbf8b"
 
+[[package]]
+name = "bincode"
+version = "1.3.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b1f45e9417d87227c7a56d22e471c6206462cba514c7590c09aff4cf6d1ddcad"
+dependencies = [
+ "serde",
+]
+
 [[package]]
 name = "bindgen"
 version = "0.55.1"
@@ -334,6 +343,7 @@ name = "electrs"
 version = "0.9.4"
 dependencies = [
  "anyhow",
+ "bincode",
  "bitcoin",
  "bitcoincore-rpc",
  "configure_me",

Cargo.toml

@@ -23,6 +23,7 @@ spec = "internal/config_specification.toml"
 
 [dependencies]
 anyhow = "1.0"
+bincode = "=1.3.3"
 bitcoin = { version = "0.27.1", features = ["use-serde", "rand"] }
 bitcoincore-rpc = "0.14.0"
 configure_me = "0.4"

internal/config_specification.toml

@@ -130,3 +130,8 @@ default = "concat!(\"Welcome to electrs \", env!(\"CARGO_PKG_VERSION\"), \" (Ele
 name = "log_filters"
 type = "String"
 doc = "Logging filters, overriding `RUST_LOG` environment variable (see https://docs.rs/env_logger/ for details)"
+
+[[param]]
+name = "cache_db_dir"
+type = "std::path::PathBuf"
+doc = "Directory to store server-side cache database (default: disabled for privacy considerations)"

src/cache.rs

@@ -1,22 +1,32 @@
-use bitcoin::{Transaction, Txid};
+use anyhow::Result;
+use bitcoin::{BlockHash, Transaction, Txid};
+use electrs_rocksdb as rocksdb;
 use parking_lot::RwLock;
 
 use std::collections::HashMap;
+use std::io::{Cursor, Write};
+use std::path::{Path, PathBuf};
 use std::sync::Arc;
 
-use crate::metrics::{self, Histogram, Metrics};
+use crate::{
+    metrics::{self, Histogram, Metrics},
+    status::TxEntry,
+    types::ScriptHash,
+};
 
 pub(crate) struct Cache {
     txs: Arc<RwLock<HashMap<Txid, Transaction>>>,
+    db: Option<CacheDB>,
 
     // stats
     txs_size: Histogram,
 }
 
 impl Cache {
-    pub fn new(metrics: &Metrics) -> Self {
+    pub fn new(metrics: &Metrics, cache_db_path: Option<&PathBuf>) -> Self {
         Cache {
             txs: Default::default(),
+            db: cache_db_path.map(|path| CacheDB::open(path).unwrap()),
             txs_size: metrics.histogram_vec(
                 "cache_txs_size",
                 "Cached transactions' size (in bytes)",
@@ -40,4 +50,66 @@ impl Cache {
     {
         self.txs.read().get(txid).map(f)
     }
+
+    pub fn add_status_entry(
+        &self,
+        scripthash: ScriptHash,
+        blockhash: BlockHash,
+        entries: &[TxEntry],
+    ) {
+        if let Some(db) = &self.db {
+            db.add(scripthash, blockhash, entries);
+        }
+    }
+
+    pub fn get_status_entries(&self, scripthash: ScriptHash) -> HashMap<BlockHash, Vec<TxEntry>> {
+        self.db
+            .as_ref()
+            .map(|db| db.scan(scripthash))
+            .unwrap_or_default()
+    }
+}
+
+struct CacheDB {
+    db: rocksdb::DB,
+}
+
+impl CacheDB {
+    fn open(path: &Path) -> Result<Self> {
+        let db = rocksdb::DB::open_default(path)?;
+        let live_files = db.live_files()?;
+        info!(
+            "{:?}: {} SST files, {} GB, {} Grows",
+            path,
+            live_files.len(),
+            live_files.iter().map(|f| f.size).sum::<usize>() as f64 / 1e9,
+            live_files.iter().map(|f| f.num_entries).sum::<u64>() as f64 / 1e9
+        );
+        Ok(CacheDB { db })
+    }
+
+    fn add(&self, scripthash: ScriptHash, blockhash: BlockHash, entries: &[TxEntry]) {
+        let mut cursor = Cursor::new(Vec::with_capacity(1024));
+        cursor.write_all(&scripthash).unwrap();
+        bincode::serialize_into(&mut cursor, &blockhash).unwrap();
+        bincode::serialize_into(&mut cursor, entries).unwrap();
+        let mut batch = rocksdb::WriteBatch::default();
+        batch.put(cursor.into_inner(), b"");
+        self.db.write_without_wal(batch).unwrap(); // best-effort write
+    }
+
+    fn scan(&self, scripthash: ScriptHash) -> HashMap<BlockHash, Vec<TxEntry>> {
+        let mode = rocksdb::IteratorMode::From(&scripthash, rocksdb::Direction::Forward);
+        self.db
+            .iterator(mode)
+            .map(|(key, _)| key)
+            .take_while(|key| key.starts_with(&scripthash))
+            .map(|key| {
+                let mut cursor = &key[scripthash.len()..];
+                let blockhash: BlockHash = bincode::deserialize_from(&mut cursor).unwrap();
+                let entries: Vec<TxEntry> = bincode::deserialize_from(&mut cursor).unwrap();
+                (blockhash, entries)
+            })
+            .collect()
+    }
 }

src/config.rs

@@ -144,6 +144,7 @@ pub struct Config {
     pub sync_once: bool,
     pub disable_electrum_rpc: bool,
     pub server_banner: String,
+    pub cache_db_path: Option<PathBuf>,
     pub args: Vec<String>,
 }
 
@@ -201,7 +202,7 @@ impl Config {
     pub fn from_args() -> Config {
         use internal::ResultExt;
 
-        let (mut config, args) =
+        let (config, args) =
             internal::Config::including_optional_config_files(default_config_files())
                 .unwrap_or_exit();
 
@@ -212,7 +213,10 @@ impl Config {
             Network::Signet => "signet",
         };
 
-        config.db_dir.push(db_subdir);
+        let db_path = config.db_dir.join(db_subdir);
+        let cache_db_path = config
+            .cache_db_dir
+            .map(|d| d.join(format!("{}-cache", db_subdir)));
 
         let default_daemon_rpc_port = match config.network {
             Network::Bitcoin => 8332,
@@ -263,14 +267,13 @@ impl Config {
             ResolvAddr::resolve_or_exit,
         );
 
-        match config.network {
-            Network::Bitcoin => (),
-            Network::Testnet => config.daemon_dir.push("testnet3"),
-            Network::Regtest => config.daemon_dir.push("regtest"),
-            Network::Signet => config.daemon_dir.push("signet"),
-        }
+        let daemon_dir = match config.network {
+            Network::Bitcoin => config.daemon_dir.clone(),
+            Network::Testnet => config.daemon_dir.join("testnet3"),
+            Network::Regtest => config.daemon_dir.join("regtest"),
+            Network::Signet => config.daemon_dir.join("signet"),
+        };
 
-        let daemon_dir = &config.daemon_dir;
         let daemon_auth = SensitiveAuth(match (config.auth, config.cookie_file) {
             (None, None) => Auth::CookieFile(daemon_dir.join(".cookie")),
             (None, Some(cookie_file)) => Auth::CookieFile(cookie_file),
@@ -314,8 +317,8 @@ impl Config {
 
         let config = Config {
             network: config.network,
-            db_path: config.db_dir,
-            daemon_dir: config.daemon_dir,
+            db_path,
+            daemon_dir,
             daemon_auth,
             daemon_rpc_addr,
             daemon_p2p_addr,
@@ -331,6 +334,7 @@ impl Config {
             sync_once: config.sync_once,
             disable_electrum_rpc: config.disable_electrum_rpc,
             server_banner: config.server_banner,
+            cache_db_path,
             args: args.map(|a| a.into_string().unwrap()).collect(),
         };
         eprintln!(

src/electrum.rs

@@ -140,7 +140,7 @@ impl Rpc {
         let tracker = Tracker::new(config, metrics)?;
         let signal = Signal::new();
         let daemon = Daemon::connect(config, signal.exit_flag(), tracker.metrics())?;
-        let cache = Cache::new(tracker.metrics());
+        let cache = Cache::new(tracker.metrics(), config.cache_db_path.as_ref());
         Ok(Self {
             tracker,
             cache,
@@ -340,7 +340,7 @@ impl Rpc {
     }
 
     fn new_status(&self, scripthash: ScriptHash) -> Result<ScriptHashStatus> {
-        let mut status = ScriptHashStatus::new(scripthash);
+        let mut status = ScriptHashStatus::load(scripthash, &self.cache);
         self.tracker
             .update_scripthash_status(&mut status, &self.daemon, &self.cache)?;
         Ok(status)

src/status.rs

@@ -19,14 +19,17 @@ use crate::{
 };
 
 /// Given a scripthash, store relevant inputs and outputs of a specific transaction
-struct TxEntry {
+#[derive(Clone, Serialize, Deserialize)]
+pub(crate) struct TxEntry {
     txid: Txid,
     outputs: Vec<TxOutput>, // relevant funded outputs and their amounts
     spent: Vec<OutPoint>,   // relevant spent outpoints
 }
 
+#[derive(Clone, Serialize, Deserialize)]
 struct TxOutput {
     index: u32,
+    #[serde(with = "bitcoin::util::amount::serde::as_sat")]
     value: Amount,
 }
 
@@ -230,6 +233,20 @@ impl ScriptHashStatus {
         }
     }
 
+    /// Return non-synced (empty) status for a given script hash.
+    pub(crate) fn load(scripthash: ScriptHash, cache: &Cache) -> Self {
+        let mut result = Self::new(scripthash);
+        result.confirmed = cache.get_status_entries(scripthash);
+        if !result.confirmed.is_empty() {
+            debug!(
+                "{} status transaction entries loaded from {} blocks",
+                result.confirmed.values().map(Vec::len).sum::<usize>(),
+                result.confirmed.len()
+            );
+        }
+        result
+    }
+
     /// Iterate through confirmed TxEntries with their corresponding block heights.
     /// Skip entries from stale blocks.
     fn confirmed_height_entries<'a>(
@@ -370,7 +387,7 @@ impl ScriptHashStatus {
         })?;
 
         Ok(result
-            .into_iter()
+            .into_par_iter()
             .map(|(blockhash, entries_map)| {
                 // sort transactions by their position in a block
                 let sorted_entries = entries_map
@@ -379,6 +396,7 @@ impl ScriptHashStatus {
                     .into_iter()
                     .map(|(_pos, entry)| entry)
                     .collect::<Vec<TxEntry>>();
+                cache.add_status_entry(self.scripthash, blockhash, &sorted_entries);
                 (blockhash, sorted_entries)
             })
             .collect())