feat(state): delete old database directories

zebra-state/src/config.rs

@@ -57,6 +57,13 @@ pub struct Config {
     ///
     /// Set to `None` by default: Zebra continues syncing indefinitely.
     pub debug_stop_at_height: Option<u32>,
+
+    /// Whether to delete the old database directories when present.
+    ///
+    /// Set to `true` by default. If this is set to `false`,
+    /// no check for old database versions will be made and nothing will be
+    /// deleted.
+    pub delete_old_database: bool,
 }
 
 fn gen_temp_path(prefix: &str) -> PathBuf {
@@ -108,6 +115,7 @@ impl Default for Config {
             cache_dir,
             ephemeral: false,
             debug_stop_at_height: None,
+            delete_old_database: true,
         }
     }
 }

zebrad/src/commands/start.rs

@@ -59,7 +59,7 @@
 //!    * answers RPC client requests using the State Service and Mempool Service
 //!    * submits client transactions to the node's mempool
 
-use std::{cmp::max, ops::Add, time::Duration};
+use std::{cmp::max, fs::remove_dir_all, ops::Add, path::PathBuf, time::Duration};
 
 use abscissa_core::{config, Command, FrameworkError, Options, Runnable};
 use chrono::Utc;
@@ -105,6 +105,11 @@ impl StartCmd {
         let config = app_config().clone();
         info!(?config);
 
+        if config.state.delete_old_database {
+            info!("checking old database versions");
+            check_and_delete_old_databases(config.state.cache_dir.clone())?;
+        }
+
         info!("initializing node state");
         let (state_service, read_only_state_service, latest_chain_tip, chain_tip_change) =
             zebra_state::init(config.state.clone(), config.network.network);
@@ -601,3 +606,43 @@ impl config::Override<ZebradConfig> for StartCmd {
         Ok(config)
     }
 }
+
+/// Check if there are old database folders and delete them from the filesystem.
+///
+/// Iterate over the files and directories in the databases folder and delete if:
+/// - The entry is a directory.
+/// - The directory name has a lenght of at least 2 characters.
+/// - The directory name has a prefix `v`.
+/// - The directory name without the prefix can be parsed as an unsigned number.
+/// - The parsed number is lower than the hardcoded `DATABASE_FORMAT_VERSION`.
+fn check_and_delete_old_databases(cache_dir: PathBuf) -> Result<(), Report> {
+    let cache_dir = cache_dir.join("state");
+    for entry in (cache_dir.read_dir()?).flatten() {
+        if entry.file_type()?.is_dir() {
+            let dir_name = entry
+                .file_name()
+                .into_string()
+                .expect("conversion from osstring to string should work.");
+            if dir_name.len() >= 2 && dir_name.starts_with('v') {
+                let potential_version_number_string = dir_name
+                    .strip_prefix('v')
+                    .expect("should not panic as we know there is a `v` prefix.")
+                    .to_string();
+                let version_number: u32 =
+                    potential_version_number_string.parse().unwrap_or(u32::MAX);
+                if version_number < zebra_state::constants::DATABASE_FORMAT_VERSION {
+                    let delete_path = cache_dir.join(dir_name);
+                    info!(
+                        "deleting {}",
+                        delete_path
+                            .to_str()
+                            .expect("path is valid, should not panic")
+                    );
+                    remove_dir_all(delete_path)?;
+                }
+            }
+        }
+    }
+
+    Ok(())
+}