Add a 'blocks_dir' option analogous to bitcoind's '-blocksdir'

The '-blocksdir' startup option allows one to store blk*.dat on an
external disk, while keeping the index (blocks/index/) on the same disk.

This makes electrs aware of such an option, while still keeping the same
default behaviour (blk*.dat in '<config_dir>/blocks/').

Signed-off-by: Antoine Poinsot <darosior@protonmail.com>

config_spec.toml

@@ -29,6 +29,11 @@ type = "std::path::PathBuf"
 doc = "Data directory of Bitcoind (default: ~/.bitcoin/)"
 default = "crate::config::default_daemon_dir()"
 
+[[param]]
+name = "blocks_dir"
+type = "std::path::PathBuf"
+doc = "Analogous to bitcoind's -blocksdir option, this specifies the directory containing the raw blocks files (blk*.dat)"
+
 [[param]]
 name = "cookie"
 type = "String"

examples/index.rs

@@ -21,6 +21,7 @@ fn run() -> Result<()> {
 
     let daemon = Daemon::new(
         &config.daemon_dir,
+        &config.blocks_dir,
         config.daemon_rpc_addr,
         config.cookie_getter(),
         config.network_type,

src/bin/electrs.rs

@@ -31,6 +31,7 @@ fn run_server(config: &Config) -> Result<()> {
 
     let daemon = Daemon::new(
         &config.daemon_dir,
+        &config.blocks_dir,
         config.daemon_rpc_addr,
         config.cookie_getter(),
         config.network_type,

src/config.rs

@@ -128,6 +128,7 @@ pub struct Config {
     pub network_type: Network,
     pub db_path: PathBuf,
     pub daemon_dir: PathBuf,
+    pub blocks_dir: PathBuf,
     pub daemon_rpc_addr: SocketAddr,
     pub electrum_rpc_addr: SocketAddr,
     pub monitoring_addr: SocketAddr,
@@ -152,6 +153,10 @@ fn default_daemon_dir() -> PathBuf {
     home
 }
 
+fn default_blocks_dir(daemon_dir: &Path) -> PathBuf {
+    daemon_dir.join("blocks")
+}
+
 fn create_cookie_getter(
     cookie: Option<String>,
     cookie_file: Option<PathBuf>,
@@ -230,6 +235,10 @@ impl Config {
             Network::Regtest => config.daemon_dir.push("regtest"),
         }
 
+        let blocks_dir = config.blocks_dir.unwrap_or(
+            default_blocks_dir(&config.daemon_dir)
+        );
+
         let cookie_getter =
             create_cookie_getter(config.cookie, config.cookie_file, &config.daemon_dir);
 
@@ -260,6 +269,7 @@ impl Config {
             network_type: config.network,
             db_path: config.db_dir,
             daemon_dir: config.daemon_dir,
+            blocks_dir,
             daemon_rpc_addr,
             electrum_rpc_addr,
             monitoring_addr,
@@ -302,6 +312,7 @@ debug_struct! { Config,
     network_type,
     db_path,
     daemon_dir,
+    blocks_dir,
     daemon_rpc_addr,
     electrum_rpc_addr,
     monitoring_addr,

src/daemon.rs

@@ -288,6 +288,7 @@ impl Counter {
 
 pub struct Daemon {
     daemon_dir: PathBuf,
+    blocks_dir: PathBuf,
     network: Network,
     conn: Mutex<Connection>,
     message_id: Counter, // for monotonic JSONRPC 'id'
@@ -302,6 +303,7 @@ pub struct Daemon {
 impl Daemon {
     pub fn new(
         daemon_dir: &PathBuf,
+        blocks_dir: &PathBuf,
         daemon_rpc_addr: SocketAddr,
         cookie_getter: Arc<dyn CookieGetter>,
         network: Network,
@@ -311,6 +313,7 @@ impl Daemon {
     ) -> Result<Daemon> {
         let daemon = Daemon {
             daemon_dir: daemon_dir.clone(),
+            blocks_dir: blocks_dir.clone(),
             network,
             conn: Mutex::new(Connection::new(
                 daemon_rpc_addr,
@@ -360,6 +363,7 @@ impl Daemon {
     pub fn reconnect(&self) -> Result<Daemon> {
         Ok(Daemon {
             daemon_dir: self.daemon_dir.clone(),
+            blocks_dir: self.blocks_dir.clone(),
             network: self.network,
             conn: Mutex::new(self.conn.lock().unwrap().reconnect()?),
             message_id: Counter::new(),
@@ -371,9 +375,7 @@ impl Daemon {
     }
 
     pub fn list_blk_files(&self) -> Result<Vec<PathBuf>> {
-        let mut path = self.daemon_dir.clone();
-        path.push("blocks");
-        path.push("blk*.dat");
+        let path = self.blocks_dir.join("blk*.dat");
         info!("listing block files at {:?}", path);
         let mut paths: Vec<PathBuf> = glob::glob(path.to_str().unwrap())
             .chain_err(|| "failed to list blk*.dat files")?