feat: allow using SafeNoSync for MDBX (#18945)

Co-authored-by: Alexey Shekhirin <5773434+shekhirin@users.noreply.github.com>

Author: eabz

crates/node/core/src/args/database.rs

@@ -6,9 +6,12 @@ use crate::version::default_client_version;
 use clap::{
     builder::{PossibleValue, TypedValueParser},
     error::ErrorKind,
-    Arg, Args, Command, Error,
+    value_parser, Arg, Args, Command, Error,
+};
+use reth_db::{
+    mdbx::{MaxReadTransactionDuration, SyncMode},
+    ClientVersion,
 };
-use reth_db::{mdbx::MaxReadTransactionDuration, ClientVersion};
 use reth_storage_errors::db::LogLevel;
 
 /// Parameters for database configuration
@@ -34,6 +37,12 @@ pub struct DatabaseArgs {
     /// Maximum number of readers allowed to access the database concurrently.
     #[arg(long = "db.max-readers")]
     pub max_readers: Option<u64>,
+    /// Controls how aggressively the database synchronizes data to disk.
+    #[arg(
+        long = "db.sync-mode",
+        value_parser = value_parser!(SyncMode),
+    )]
+    pub sync_mode: Option<SyncMode>,
 }
 
 impl DatabaseArgs {
@@ -61,6 +70,7 @@ impl DatabaseArgs {
             .with_geometry_max_size(self.max_size)
             .with_growth_step(self.growth_step)
             .with_max_readers(self.max_readers)
+            .with_sync_mode(self.sync_mode)
     }
 }
 
@@ -340,4 +350,36 @@ mod tests {
         let cmd = CommandParser::<DatabaseArgs>::try_parse_from(["reth"]).unwrap();
         assert_eq!(cmd.args.log_level, None);
     }
+
+    #[test]
+    fn test_command_parser_with_valid_default_sync_mode() {
+        let cmd = CommandParser::<DatabaseArgs>::try_parse_from(["reth"]).unwrap();
+        assert!(cmd.args.sync_mode.is_none());
+    }
+
+    #[test]
+    fn test_command_parser_with_valid_sync_mode_durable() {
+        let cmd =
+            CommandParser::<DatabaseArgs>::try_parse_from(["reth", "--db.sync-mode", "durable"])
+                .unwrap();
+        assert!(matches!(cmd.args.sync_mode, Some(SyncMode::Durable)));
+    }
+
+    #[test]
+    fn test_command_parser_with_valid_sync_mode_safe_no_sync() {
+        let cmd = CommandParser::<DatabaseArgs>::try_parse_from([
+            "reth",
+            "--db.sync-mode",
+            "safe-no-sync",
+        ])
+        .unwrap();
+        assert!(matches!(cmd.args.sync_mode, Some(SyncMode::SafeNoSync)));
+    }
+
+    #[test]
+    fn test_command_parser_with_invalid_sync_mode() {
+        let result =
+            CommandParser::<DatabaseArgs>::try_parse_from(["reth", "--db.sync-mode", "ultra-fast"]);
+        assert!(result.is_err());
+    }
 }

crates/storage/db/src/implementation/mdbx/mod.rs

@@ -103,6 +103,22 @@ pub struct DatabaseArguments {
     /// MDBX allows up to 32767 readers (`MDBX_READERS_LIMIT`). This arg is to configure the max
     /// readers.
     max_readers: Option<u64>,
+    /// Defines the synchronization strategy used by the MDBX database when writing data to disk.
+    ///
+    /// This determines how aggressively MDBX ensures data durability versus prioritizing
+    /// performance. The available modes are:
+    ///
+    /// - [`SyncMode::Durable`]: Ensures all transactions are fully flushed to disk before they are
+    ///   considered committed.   This provides the highest level of durability and crash safety
+    ///   but may have a performance cost.
+    /// - [`SyncMode::SafeNoSync`]: Skips certain fsync operations to improve write performance.
+    ///   This mode still maintains database integrity but may lose the most recent transactions if
+    ///   the system crashes unexpectedly.
+    ///
+    /// Choose `Durable` if consistency and crash safety are critical (e.g., production
+    /// environments). Choose `SafeNoSync` if performance is more important and occasional data
+    /// loss is acceptable (e.g., testing or ephemeral data).
+    sync_mode: SyncMode,
 }
 
 impl Default for DatabaseArguments {
@@ -126,6 +142,7 @@ impl DatabaseArguments {
             max_read_transaction_duration: None,
             exclusive: None,
             max_readers: None,
+            sync_mode: SyncMode::Durable,
         }
     }
 
@@ -137,6 +154,15 @@ impl DatabaseArguments {
         self
     }
 
+    /// Sets the database sync mode.
+    pub const fn with_sync_mode(mut self, sync_mode: Option<SyncMode>) -> Self {
+        if let Some(sync_mode) = sync_mode {
+            self.sync_mode = sync_mode;
+        }
+
+        self
+    }
+
     /// Configures the database growth step in bytes.
     pub const fn with_growth_step(mut self, growth_step: Option<usize>) -> Self {
         if let Some(growth_step) = growth_step {
@@ -329,7 +355,7 @@ impl DatabaseEnv {
             DatabaseEnvKind::RW => {
                 // enable writemap mode in RW mode
                 inner_env.write_map();
-                Mode::ReadWrite { sync_mode: SyncMode::Durable }
+                Mode::ReadWrite { sync_mode: args.sync_mode }
             }
         };
 

crates/storage/libmdbx-rs/src/flags.rs

@@ -1,8 +1,10 @@
+use std::str::FromStr;
+
 use bitflags::bitflags;
 use ffi::*;
 
 /// MDBX sync mode
-#[derive(Clone, Copy, Debug, Default)]
+#[derive(PartialEq, Eq, Clone, Copy, Debug, Default)]
 pub enum SyncMode {
     /// Default robust and durable sync mode.
     /// Metadata is written and flushed to disk after a data is written and flushed, which
@@ -119,6 +121,21 @@ impl From<Mode> for EnvironmentFlags {
     }
 }
 
+impl FromStr for SyncMode {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        let val = s.trim().to_ascii_lowercase();
+        match val.as_str() {
+            "durable" => Ok(Self::Durable),
+            "safe-no-sync" | "safenosync" | "safe_no_sync" => Ok(Self::SafeNoSync),
+            _ => Err(format!(
+                "invalid value '{s}' for sync mode. valid values: durable, safe-no-sync"
+            )),
+        }
+    }
+}
+
 #[derive(Clone, Copy, Debug, Default)]
 pub struct EnvironmentFlags {
     pub no_sub_dir: bool,

docs/vocs/docs/pages/cli/reth/db.mdx

@@ -83,6 +83,9 @@ Database:
       --db.max-readers <MAX_READERS>
           Maximum number of readers allowed to access the database concurrently
 
+      --db.sync-mode <SYNC_MODE>
+          Controls how aggressively the database synchronizes data to disk
+
 Logging:
       --log.stdout.format <FORMAT>
           The format to use for logs written to stdout

docs/vocs/docs/pages/cli/reth/db/diff.mdx

@@ -46,6 +46,9 @@ Database:
       --db.max-readers <MAX_READERS>
           Maximum number of readers allowed to access the database concurrently
 
+      --db.sync-mode <SYNC_MODE>
+          Controls how aggressively the database synchronizes data to disk
+
       --table <TABLE>
           The table name to diff. If not specified, all tables are diffed.
 

docs/vocs/docs/pages/cli/reth/download.mdx

@@ -70,6 +70,9 @@ Database:
       --db.max-readers <MAX_READERS>
           Maximum number of readers allowed to access the database concurrently
 
+      --db.sync-mode <SYNC_MODE>
+          Controls how aggressively the database synchronizes data to disk
+
   -u, --url <URL>
           Specify a snapshot URL or let the command propose a default one.
 

docs/vocs/docs/pages/cli/reth/export-era.mdx

@@ -70,6 +70,9 @@ Database:
       --db.max-readers <MAX_READERS>
           Maximum number of readers allowed to access the database concurrently
 
+      --db.sync-mode <SYNC_MODE>
+          Controls how aggressively the database synchronizes data to disk
+
       --first-block-number <first-block-number>
           Optional first block number to export from the db.
           It is by default 0.

docs/vocs/docs/pages/cli/reth/import-era.mdx

@@ -70,6 +70,9 @@ Database:
       --db.max-readers <MAX_READERS>
           Maximum number of readers allowed to access the database concurrently
 
+      --db.sync-mode <SYNC_MODE>
+          Controls how aggressively the database synchronizes data to disk
+
       --path <IMPORT_ERA_PATH>
           The path to a directory for import.
 

docs/vocs/docs/pages/cli/reth/import.mdx

@@ -70,6 +70,9 @@ Database:
       --db.max-readers <MAX_READERS>
           Maximum number of readers allowed to access the database concurrently
 
+      --db.sync-mode <SYNC_MODE>
+          Controls how aggressively the database synchronizes data to disk
+
       --no-state
           Disables stages that require state.
 

docs/vocs/docs/pages/cli/reth/init-state.mdx

@@ -70,6 +70,9 @@ Database:
       --db.max-readers <MAX_READERS>
           Maximum number of readers allowed to access the database concurrently
 
+      --db.sync-mode <SYNC_MODE>
+          Controls how aggressively the database synchronizes data to disk
+
       --without-evm
           Specifies whether to initialize the state without relying on EVM historical data.