change(state): Allow opening the database in a read-only mode

zebra-scan/src/init.rs

@@ -33,7 +33,7 @@ pub async fn init(
     state: scan::State,
     chain_tip_change: ChainTipChange,
 ) -> Result<(), Report> {
-    let storage = tokio::task::spawn_blocking(move || Storage::new(&config, network))
+    let storage = tokio::task::spawn_blocking(move || Storage::new(&config, network, false))
         .wait_for_panics()
         .await;
 

zebra-scan/src/storage.rs

@@ -55,8 +55,8 @@ impl Storage {
     ///
     /// This method can block while creating or reading database files, so it must be inside
     /// spawn_blocking() in async code.
-    pub fn new(config: &Config, network: Network) -> Self {
-        let mut storage = Self::new_db(config, network);
+    pub fn new(config: &Config, network: Network, read_only: bool) -> Self {
+        let mut storage = Self::new_db(config, network, read_only);
 
         for (sapling_key, birthday) in config.sapling_keys_to_scan.iter() {
             storage.add_sapling_key(sapling_key, Some(zebra_chain::block::Height(*birthday)));

zebra-scan/src/storage/db.rs

@@ -49,11 +49,11 @@ impl Storage {
     /// If there is no existing database, creates a new database on disk.
     ///
     /// New keys in `config` are not inserted into the database.
-    pub(crate) fn new_db(config: &Config, network: Network) -> Self {
+    pub(crate) fn new_db(config: &Config, network: Network, read_only: bool) -> Self {
         Self::new_with_debug(
             config, network,
-            // TODO: make format upgrades work with any database, then change this to `false`
-            true,
+            // TODO: make format upgrades work with any database, then change debug_skip_format_upgrades to `false`
+            true, read_only,
         )
     }
 
@@ -67,6 +67,7 @@ impl Storage {
         config: &Config,
         network: Network,
         debug_skip_format_upgrades: bool,
+        read_only: bool,
     ) -> Self {
         let db = ScannerDb::new(
             config.db_config(),
@@ -77,6 +78,7 @@ impl Storage {
             SCANNER_COLUMN_FAMILIES_IN_CODE
                 .iter()
                 .map(ToString::to_string),
+            read_only,
         );
 
         let new_storage = Self { db };

zebra-scan/src/storage/db/tests.rs

@@ -20,7 +20,7 @@ mod snapshot;
 
 /// Returns an empty `Storage` suitable for testing.
 pub fn new_test_storage(network: Network) -> Storage {
-    Storage::new(&Config::ephemeral(), network)
+    Storage::new(&Config::ephemeral(), network, false)
 }
 
 /// Add fake keys to `storage` for testing purposes.

zebra-scan/src/tests/vectors.rs

@@ -22,7 +22,7 @@
 use zebra_state::{SaplingScannedResult, TransactionIndex};
 
 use crate::{
     config::Config,
     scan::{block_to_compact, scan_block},
     tests::{fake_block, ZECPAGES_SAPLING_VIEWING_KEY},
 };
@@ -157,7 +157,7 @@
         zcash_client_backend::encoding::encode_extended_full_viewing_key("zxviews", &extfvk);
 
     // Create a database
-    let mut s = crate::storage::Storage::new(&Config::ephemeral(), Network::Mainnet);
+    let mut s = crate::storage::tests::new_test_storage(Network::Mainnet);
 
     // Insert the generated key to the database
     s.add_sapling_key(&key_to_be_stored, None);

zebra-state/src/service/finalized_state.rs

@@ -146,6 +146,7 @@ impl FinalizedState {
             false,
             #[cfg(feature = "elasticsearch")]
             elastic_db,
+            false,
         )
     }
 
@@ -158,6 +159,7 @@ impl FinalizedState {
         network: Network,
         debug_skip_format_upgrades: bool,
         #[cfg(feature = "elasticsearch")] elastic_db: Option<elasticsearch::Elasticsearch>,
+        read_only: bool,
     ) -> Self {
         let db = ZebraDb::new(
             config,
@@ -168,6 +170,7 @@ impl FinalizedState {
             STATE_COLUMN_FAMILIES_IN_CODE
                 .iter()
                 .map(ToString::to_string),
+            read_only,
         );
 
         #[cfg(feature = "elasticsearch")]

zebra-state/src/service/finalized_state/disk_db.rs

@@ -622,6 +622,7 @@ impl DiskDb {
         format_version_in_code: &Version,
         network: Network,
         column_families_in_code: impl IntoIterator<Item = String>,
+        read_only: bool,
     ) -> DiskDb {
         let db_kind = db_kind.as_ref();
         let path = config.db_path(db_kind, format_version_in_code.major, network);
@@ -644,7 +645,11 @@ impl DiskDb {
             .unique()
             .map(|cf_name| rocksdb::ColumnFamilyDescriptor::new(cf_name, db_options.clone()));
 
-        let db_result = DB::open_cf_descriptors(&db_options, &path, column_families);
+        let db_result = if read_only {
+            DB::open_cf_descriptors_read_only(&db_options, &path, column_families, false)
+        } else {
+            DB::open_cf_descriptors(&db_options, &path, column_families)
+        };
 
         match db_result {
             Ok(db) => {

zebra-state/src/service/finalized_state/zebra_db.rs

@@ -96,6 +96,7 @@ impl ZebraDb {
         network: Network,
         debug_skip_format_upgrades: bool,
         column_families_in_code: impl IntoIterator<Item = String>,
+        read_only: bool,
     ) -> ZebraDb {
         let disk_version = database_format_version_on_disk(
             config,
@@ -108,16 +109,20 @@ impl ZebraDb {
         // Log any format changes before opening the database, in case opening fails.
         let format_change = DbFormatChange::open_database(format_version_in_code, disk_version);
 
-        // Always do format upgrades in production, but allow them to be skipped by the scanner
-        // (because it doesn't support them yet).
+        // Format upgrades try to write to the database, so we always skip them if `read_only` is
+        // `true`.
+        //
+        // We allow skipping the upgrades by the scanner because it doesn't support them yet and we
+        // also allow skipping them when we are running tests.
         //
         // TODO: Make scanner support format upgrades, then remove `shielded-scan` here.
-        let can_skip_format_upgrades = cfg!(test) || cfg!(feature = "shielded-scan");
+        let debug_skip_format_upgrades = read_only
+            || ((cfg!(test) || cfg!(feature = "shielded-scan")) && debug_skip_format_upgrades);
 
         // Open the database and do initial checks.
         let mut db = ZebraDb {
             config: Arc::new(config.clone()),
-            debug_skip_format_upgrades: can_skip_format_upgrades && debug_skip_format_upgrades,
+            debug_skip_format_upgrades,
             format_change_handle: None,
             // After the database directory is created, a newly created database temporarily
             // changes to the default database version. Then we set the correct version in the
@@ -129,6 +134,7 @@ impl ZebraDb {
                 format_version_in_code,
                 network,
                 column_families_in_code,
+                read_only,
             ),
         };
 

zebra-state/src/service/finalized_state/zebra_db/block/tests/vectors.rs

@@ -89,6 +89,7 @@ fn test_block_db_round_trip_with(
         STATE_COLUMN_FAMILIES_IN_CODE
             .iter()
             .map(ToString::to_string),
+        false,
     );
 
     // Check that each block round-trips to the database

zebra-state/src/service/read/tests/vectors.rs

@@ -377,5 +377,6 @@ fn new_ephemeral_db() -> ZebraDb {
         STATE_COLUMN_FAMILIES_IN_CODE
             .iter()
             .map(ToString::to_string),
+        false,
     )
 }

zebra-state/src/tests/setup.rs

@@ -99,6 +99,7 @@ pub(crate) fn new_state_with_mainnet_genesis(
         true,
         #[cfg(feature = "elasticsearch")]
         None,
+        false,
     );
     let non_finalized_state = NonFinalizedState::new(network);