feat: Add atomic_write for atomic file writing (#245)

Introduces atomic file writes for all SPV storage operations with a tempfile + rename pattern to ensure files dont get corrupted if a crash happens during write.

  - Adds `atomic_write` function
  - Updates all file writes: headers, filter headers, index, chain state, sync state, checkpoints, chainlocks, metadata, peers, peer-reputation

Author: xdustinface

dash-spv/src/network/persist.rs

@@ -5,6 +5,7 @@ use serde::{Deserialize, Serialize};
 use std::path::PathBuf;
 
 use crate::error::{SpvError as Error, StorageError};
+use crate::storage::disk::io::atomic_write;
 
 /// Peer persistence for saving and loading known peer addresses
 pub struct PeerStore {
@@ -61,9 +62,7 @@ impl PeerStore {
         let json = serde_json::to_string_pretty(&saved)
             .map_err(|e| Error::Storage(StorageError::Serialization(e.to_string())))?;
 
-        tokio::fs::write(&self.path, json)
-            .await
-            .map_err(|e| Error::Storage(StorageError::WriteFailed(e.to_string())))?;
+        atomic_write(&self.path, json.as_bytes()).await.map_err(Error::Storage)?;
 
         log::debug!("Saved {} peers to {:?}", saved.peers.len(), self.path);
         Ok(())

dash-spv/src/network/reputation.rs

@@ -12,6 +12,8 @@ use std::sync::Arc;
 use std::time::{Duration, Instant};
 use tokio::sync::RwLock;
 
+use crate::storage::disk::io::atomic_write;
+
 /// Maximum misbehavior score before a peer is banned
 const MAX_MISBEHAVIOR_SCORE: i32 = 100;
 
@@ -424,7 +426,7 @@ impl PeerReputationManager {
             .collect();
 
         let json = serde_json::to_string_pretty(&data)?;
-        tokio::fs::write(path, json).await
+        atomic_write(path, json.as_bytes()).await.map_err(std::io::Error::other)
     }
 
     /// Load reputation data from persistent storage

dash-spv/src/storage/disk/filters.rs

@@ -7,6 +7,7 @@ use dashcore_hashes::Hash;
 
 use crate::error::StorageResult;
 
+use super::io::atomic_write;
 use super::manager::DiskStorageManager;
 use super::segments::SegmentState;
 
@@ -185,8 +186,7 @@ impl DiskStorageManager {
     /// Store a compact filter.
     pub async fn store_filter(&mut self, height: u32, filter: &[u8]) -> StorageResult<()> {
         let path = self.base_path.join(format!("filters/{}.dat", height));
-        tokio::fs::write(path, filter).await?;
-        Ok(())
+        atomic_write(&path, filter).await
     }
 
     /// Load a compact filter.