Use LRU cache (instead of an unbounded HashMap) for transaction caching

6 years ago · 42ab247776
6 changed files with 41 additions and 21 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -290,6 +290,7 @@ dependencies = [
 "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
 "libc 0.2.43 (registry+https://github.com/rust-lang/crates.io-index)",
 "log 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)",
+ "lru 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)",
 "num_cpus 1.8.0 (registry+https://github.com/rust-lang/crates.io-index)",
 "page_size 0.4.1 (registry+https://github.com/rust-lang/crates.io-index)",
 "prometheus 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
@ -512,6 +513,11 @@ dependencies = [
 "cfg-if 0.1.5 (registry+https://github.com/rust-lang/crates.io-index)",
 ]

+[[package]]
+name = "lru"
+version = "0.1.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "make-cmd"
 version = "0.1.0"
@ -1094,6 +1100,7 @@ dependencies = [
 "checksum libloading 0.5.0 (registry+https://github.com/rust-lang/crates.io-index)" = "9c3ad660d7cb8c5822cd83d10897b0f1f1526792737a179e73896152f85b88c2"
 "checksum librocksdb-sys 5.14.2 (registry+https://github.com/rust-lang/crates.io-index)" = "474d805d72e23a06310fa5201dfe182dc4b80ab1f18bb2823c1ac17ff9dcbaa2"
 "checksum log 0.4.5 (registry+https://github.com/rust-lang/crates.io-index)" = "d4fcce5fa49cc693c312001daf1d13411c4a5283796bac1084299ea3e567113f"
+"checksum lru 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "5fb41c1934bda881f2ab7ad8afa2ec25b8e0453563bfb09854bf3c319b1c96c3"
 "checksum make-cmd 0.1.0 (registry+https://github.com/rust-lang/crates.io-index)" = "a8ca8afbe8af1785e09636acb5a41e08a765f5f0340568716c18a8700ba3c0d3"
 "checksum matches 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "7ffc5c5338469d4d3ea17d269fa8ea3512ad247247c30bd2df69e68309ed0a08"
 "checksum memchr 1.0.2 (registry+https://github.com/rust-lang/crates.io-index)" = "148fab2e51b4f1cfc66da2a7c32981d1d3c083a803978268bb11fe4b86925e7a"
--- a/Cargo.toml
+++ b/Cargo.toml
@ -24,6 +24,7 @@ glob = "0.2"
 hex = "0.3"
 libc = "0.2"
 log = "0.4"
+lru = "0.1"
 num_cpus = "1.0"
 page_size = "0.4"
 prometheus = "0.4"
--- a/src/bin/electrs.rs
+++ b/src/bin/electrs.rs
@ -16,7 +16,7 @@ use electrs::{
    errors::*,
    index::Index,
    metrics::Metrics,
-    query::Query,
+    query::{Query, TransactionCache},
    rpc::RPC,
    signal::Waiter,
    store::{full_compaction, is_fully_compacted, DBStore},
@ -54,7 +54,8 @@ fn run_server(config: &Config) -> Result<()> {
    }.enable_compaction(); // enable auto compactions before starting incremental index updates.

    let app = App::new(store, index, daemon)?;
-    let query = Query::new(app.clone(), &metrics);
+    let tx_cache = TransactionCache::new(config.tx_cache_size);
+    let query = Query::new(app.clone(), &metrics, tx_cache);

    let mut server = None; // Electrum RPC server
    loop {
--- a/src/config.rs
+++ b/src/config.rs
@ -14,17 +14,19 @@ use errors::*;

 #[derive(Debug)]
 pub struct Config {
+    // See below for the documentation of each field:
    pub log: stderrlog::StdErrLog,
-    pub network_type: Network,         // bitcoind JSONRPC endpoint
-    pub db_path: PathBuf,              // RocksDB directory path
-    pub daemon_dir: PathBuf,           // Bitcoind data directory
-    pub daemon_rpc_addr: SocketAddr,   // for connecting Bitcoind JSONRPC
-    pub cookie: Option<String>,        // for bitcoind JSONRPC authentication ("USER:PASSWORD")
-    pub electrum_rpc_addr: SocketAddr, // for serving Electrum clients
-    pub monitoring_addr: SocketAddr,   // for Prometheus monitoring
-    pub jsonrpc_import: bool,          // slower initial indexing, for low-memory systems
-    pub index_batch_size: usize,       // number of blocks to index in parallel
-    pub bulk_index_threads: usize,     // number of threads to use for bulk indexing
+    pub network_type: Network,
+    pub db_path: PathBuf,
+    pub daemon_dir: PathBuf,
+    pub daemon_rpc_addr: SocketAddr,
+    pub cookie: Option<String>,
+    pub electrum_rpc_addr: SocketAddr,
+    pub monitoring_addr: SocketAddr,
+    pub jsonrpc_import: bool,
+    pub index_batch_size: usize,
+    pub bulk_index_threads: usize,
+    pub tx_cache_size: usize,
 }

 impl Config {
@ -101,6 +103,12 @@ impl Config {
                    .help("Number of threads used for bulk indexing (default: use the # of CPUs)")
                    .default_value("0")
            )
+            .arg(
+                Arg::with_name("tx_cache_size")
+                    .long("tx-cache-size")
+                    .help("Number of transactions to keep in for query LRU cache")
+                    .default_value("10000")  // should be enough for a small wallet.
+            )
            .get_matches();

        let network_name = m.value_of("network").unwrap_or("mainnet");
@ -184,6 +192,7 @@ impl Config {
            jsonrpc_import: m.is_present("jsonrpc_import"),
            index_batch_size: value_t_or_exit!(m, "index_batch_size", usize),
            bulk_index_threads,
+            tx_cache_size: value_t_or_exit!(m, "tx_cache_size", usize),
        };
        eprintln!("{:?}", config);
        config
--- a/src/lib.rs
+++ b/src/lib.rs
@ -9,6 +9,7 @@ extern crate dirs;
 extern crate glob;
 extern crate hex;
 extern crate libc;
+extern crate lru;
 extern crate num_cpus;
 extern crate page_size;
 extern crate prometheus;
--- a/src/query.rs
+++ b/src/query.rs
@ -4,8 +4,9 @@ use bitcoin::network::serialize::deserialize;
 use bitcoin::util::hash::Sha256dHash;
 use crypto::digest::Digest;
 use crypto::sha2::Sha256;
+use lru::LruCache;
 use std::collections::HashMap;
-use std::sync::{Arc, RwLock};
+use std::sync::{Arc, Mutex, RwLock};

 use app::App;
 use index::{compute_script_hash, TxInRow, TxOutRow, TxRow};
@ -155,14 +156,14 @@ fn txids_by_funding_output(
        .collect()
 }

-struct TransactionCache {
-    map: RwLock<HashMap<Sha256dHash, Transaction>>,
+pub struct TransactionCache {
+    map: Mutex<LruCache<Sha256dHash, Transaction>>,
 }

 impl TransactionCache {
-    fn new() -> TransactionCache {
+    pub fn new(capacity: usize) -> TransactionCache {
        TransactionCache {
-            map: RwLock::new(HashMap::new()),
+            map: Mutex::new(LruCache::new(capacity)),
        }
    }

@ -170,11 +171,11 @@ impl TransactionCache {
    where
        F: FnOnce() -> Result<Transaction>,
    {
-        if let Some(txn) = self.map.read().unwrap().get(txid) {
+        if let Some(txn) = self.map.lock().unwrap().get(txid) {
            return Ok(txn.clone());
        }
        let txn = load_txn_func()?;
-        self.map.write().unwrap().insert(*txid, txn.clone());
+        self.map.lock().unwrap().put(*txid, txn.clone());
        Ok(txn)
    }
 }
@ -186,11 +187,11 @@ pub struct Query {
 }

 impl Query {
-    pub fn new(app: Arc<App>, metrics: &Metrics) -> Arc<Query> {
+    pub fn new(app: Arc<App>, metrics: &Metrics, tx_cache: TransactionCache) -> Arc<Query> {
        Arc::new(Query {
            app,
            tracker: RwLock::new(Tracker::new(metrics)),
-            tx_cache: TransactionCache::new(),
+            tx_cache,
        })
    }