Added purge subcommand to purge beacon chain db (#971)

beacon_node/beacon_chain/src/builder.rs

@@ -221,7 +221,7 @@ where
             .get::<PersistedBeaconChain>(&Hash256::from_slice(&BEACON_CHAIN_DB_KEY))
             .map_err(|e| format!("DB error when reading persisted beacon chain: {:?}", e))?
             .ok_or_else(|| {
-                "No persisted beacon chain found in store. Try deleting the .lighthouse/beacon dir."
+                "No persisted beacon chain found in store. Try purging the beacon chain database."
                     .to_string()
             })?;
 

beacon_node/client/src/config.rs

@@ -1,3 +1,4 @@
+use beacon_chain::builder::PUBKEY_CACHE_FILENAME;
 use network::NetworkConfig;
 use serde_derive::{Deserialize, Serialize};
 use std::fs;
@@ -11,6 +12,9 @@ const TESTNET_SPEC_CONSTANTS: &str = "minimal";
 /// Default directory name for the freezer database under the top-level data dir.
 const DEFAULT_FREEZER_DB_DIR: &str = "freezer_db";
 
+/// Trap file indicating if chain_db was purged
+const CHAIN_DB_PURGED_TRAP_FILE: &str = ".db_purged";
+
 /// Defines how the client should initialize the `BeaconChain` and other components.
 #[derive(PartialEq, Debug, Clone, Serialize, Deserialize)]
 pub enum ClientGenesis {
@@ -97,6 +101,68 @@ impl Config {
             .map(|data_dir| data_dir.join(&self.db_name))
     }
 
+    /// Get the path of the chain db purged trap file
+    pub fn get_db_purged_trap_file_path(&self) -> Option<PathBuf> {
+        self.get_data_dir()
+            .map(|data_dir| data_dir.join(CHAIN_DB_PURGED_TRAP_FILE))
+    }
+
+    /// returns whether chain_db was recently purged
+    pub fn chain_db_was_purged(&self) -> bool {
+        self.get_db_purged_trap_file_path()
+            .map_or(false, |trap_file| trap_file.exists())
+    }
+
+    /// purges the chain_db and creates trap file
+    pub fn purge_chain_db(&self) -> Result<(), String> {
+        // create the trap file
+        let trap_file = self
+            .get_db_purged_trap_file_path()
+            .ok_or("Failed to get trap file path".to_string())?;
+        fs::File::create(trap_file)
+            .map_err(|err| format!("Failed to create trap file: {}", err))?;
+
+        // remove the chain_db
+        fs::remove_dir_all(
+            self.get_db_path()
+                .ok_or("Failed to get db_path".to_string())?,
+        )
+        .map_err(|err| format!("Failed to remove chain_db: {}", err))?;
+
+        // remove the freezer db
+        fs::remove_dir_all(
+            self.get_freezer_db_path()
+                .ok_or("Failed to get freezer db path".to_string())?,
+        )
+        .map_err(|err| format!("Failed to remove chain_db: {}", err))?;
+
+        // also need to remove pubkey cache file if it exists
+        let pubkey_cache_file = self
+            .get_data_dir()
+            .map(|data_dir| data_dir.join(PUBKEY_CACHE_FILENAME))
+            .ok_or("Failed to get pubkey cache file path".to_string())?;
+        if !pubkey_cache_file.exists() {
+            return Ok(());
+        }
+        fs::remove_file(pubkey_cache_file)
+            .map_err(|err| format!("Failed to remove pubkey cache: {}", err))?;
+
+        Ok(())
+    }
+
+    /// cleans up purge_db trap file
+    pub fn cleanup_after_purge_db(&self) -> Result<(), String> {
+        let trap_file = self
+            .get_db_purged_trap_file_path()
+            .ok_or("Failed to get trap file path".to_string())?;
+        if !trap_file.exists() {
+            return Ok(());
+        }
+        fs::remove_file(trap_file).map_err(|err| format!("Failed to remove trap file: {}", err))?;
+
+        Ok(())
+    }
+
     /// Get the database path, creating it if necessary.
     pub fn create_db_path(&self) -> Result<PathBuf, String> {
         let db_path = self

beacon_node/src/cli.rs

@@ -309,4 +309,12 @@ pub fn cli_app<'a, 'b>() -> App<'a, 'b> {
                     .help("A file from which to read the state"))
             )
         )
+        /*
+         * The "purge" sub-command.
+         *
+         * Allows user to purge beacon database
+         */
+        .subcommand(SubCommand::with_name("purge")
+            .about("Purge the beacon chain database.")
+        )
 }

beacon_node/src/config.rs

@@ -189,15 +189,27 @@ pub fn get_config<E: EthSpec>(
         ("testnet", Some(sub_cmd_args)) => {
             process_testnet_subcommand(&mut client_config, &eth2_config, sub_cmd_args)?
         }
+        ("purge", _) => {
+            client_config.purge_chain_db()?;
+            println!("Successfully purged chain db");
+            std::process::exit(0);
+        }
         // No sub-command assumes a resume operation.
         _ => {
             // If no primary subcommand was given, start the beacon chain from an existing
             // database.
             client_config.genesis = ClientGenesis::Resume;
 
+            let db_path_exists: bool = match client_config.get_db_path() {
+                Some(path) => path.exists(),
+                None => false,
+            };
+
             // Whilst there is no large testnet or mainnet force the user to specify how they want
             // to start a new chain (e.g., from a genesis YAML file, another node, etc).
-            if !client_config.data_dir.exists() {
+            if !client_config.data_dir.exists()
+                || (!db_path_exists && client_config.chain_db_was_purged())
+            {
                 info!(
                     log,
                     "Starting from an empty database";
@@ -392,7 +404,8 @@ fn init_new_client<E: EthSpec>(
 ///
 /// Returns an error if `self.data_dir` already exists.
 pub fn create_new_datadir(client_config: &ClientConfig, eth2_config: &Eth2Config) -> Result<()> {
-    if client_config.data_dir.exists() {
+    let rebuild_db = client_config.chain_db_was_purged();
+    if client_config.data_dir.exists() && !rebuild_db {
         return Err(format!(
             "Data dir already exists at {:?}",
             client_config.data_dir
@@ -407,7 +420,9 @@ pub fn create_new_datadir(client_config: &ClientConfig, eth2_config: &Eth2Config
         ($file: ident, $variable: ident) => {
             let file = client_config.data_dir.join($file);
             if file.exists() {
-                return Err(format!("Datadir is not clean, {} exists.", $file));
+                if !rebuild_db {
+                    return Err(format!("Datadir is not clean, {} exists.", $file));
+                }
             } else {
                 // Write the onfig to a TOML file in the datadir.
                 write_to_file(client_config.data_dir.join($file), $variable)
@@ -418,6 +433,7 @@ pub fn create_new_datadir(client_config: &ClientConfig, eth2_config: &Eth2Config
 
     write_to_file!(CLIENT_CONFIG_FILENAME, client_config);
     write_to_file!(ETH2_CONFIG_FILENAME, eth2_config);
+    client_config.cleanup_after_purge_db()?;
 
     Ok(())
 }