Add autoremoving expired snapshot feature

Author: foriequal0

codechain/config/mod.rs

@@ -284,6 +284,8 @@ fn default_enable_devel_api() -> bool {
 pub struct Snapshot {
     pub disable: Option<bool>,
     pub path: Option<String>,
+    // Snapshot's age in blocks
+    pub expiration: Option<u64>,
 }
 
 #[derive(Deserialize)]
@@ -679,6 +681,9 @@ impl Snapshot {
         if other.path.is_some() {
             self.path = other.path.clone();
         }
+        if other.expiration.is_some() {
+            self.expiration = other.expiration;
+        }
     }
 
     pub fn overwrite_with(&mut self, matches: &clap::ArgMatches) -> Result<(), String> {

codechain/config/presets/config.dev.toml

@@ -52,6 +52,7 @@ max_connections = 100
 [snapshot]
 disable = false
 path = "snapshot"
+expiration = 100000 # blocks. About a week
 
 [stratum]
 disable = false

codechain/config/presets/config.prod.toml

@@ -52,6 +52,7 @@ max_connections = 100
 [snapshot]
 disable = true
 path = "snapshot"
+expiration = 100000 # blocks. About a week
 
 [stratum]
 disable = true

codechain/run_node.rs

@@ -371,7 +371,8 @@ pub fn run_node(matches: &ArgMatches) -> Result<(), String> {
         client.engine().register_snapshot_notify_sender(tx);
 
         if !config.snapshot.disable.unwrap() {
-            let service = Arc::new(SnapshotService::new(client, rx, config.snapshot.path.unwrap()));
+            let service =
+                Arc::new(SnapshotService::new(client, rx, config.snapshot.path.unwrap(), config.snapshot.expiration));
             Some(service)
         } else {
             None

sync/src/snapshot/mod.rs

@@ -14,18 +14,19 @@
 // You should have received a copy of the GNU Affero General Public License
 // along with this program.  If not, see <https://www.gnu.org/licenses/>.
 
-use std::fs::{create_dir_all, File};
+
+use std::fs;
 use std::path::PathBuf;
+use std::str::FromStr;
 use std::sync::Arc;
 use std::thread::{spawn, JoinHandle};
 
 use ccore::snapshot_notify::{NotifyReceiverSource, ReceiverCanceller};
-use ccore::{BlockChainTrait, BlockId, Client};
+use ccore::{BlockChainClient, BlockChainTrait, BlockId, Client};
 use cmerkle::snapshot::{ChunkCompressor, Error as SnapshotError, Snapshot};
 use ctypes::BlockHash;
 use hashdb::{AsHashDB, HashDB};
 use primitives::H256;
-use std::ops::Deref;
 
 pub struct Service {
     join_handle: Option<JoinHandle<()>>,
@@ -35,7 +36,7 @@ pub struct Service {
 pub fn snapshot_dir(root_dir: &str, block: &BlockHash) -> PathBuf {
     let mut path = PathBuf::new();
     path.push(root_dir);
-    path.push(format!("{:x}", block.deref()));
+    path.push(format!("{:x}", **block));
     path
 }
 
@@ -46,7 +47,12 @@ pub fn snapshot_path(root_dir: &str, block: &BlockHash, chunk_root: &H256) -> Pa
 }
 
 impl Service {
-    pub fn new(client: Arc<Client>, notify_receiver_source: NotifyReceiverSource, root_dir: String) -> Self {
+    pub fn new(
+        client: Arc<Client>,
+        notify_receiver_source: NotifyReceiverSource,
+        root_dir: String,
+        expiration: Option<u64>,
+    ) -> Self {
         let NotifyReceiverSource(canceller, receiver) = notify_receiver_source;
         let join_handle = spawn(move || {
             cinfo!(SYNC, "Snapshot service is on");
@@ -58,19 +64,26 @@ impl Service {
                     cerror!(SYNC, "There isn't corresponding header for the requested block hash: {}", block_hash,);
                     continue
                 };
-                let db_lock = client.state_db().read();
-                if let Some(err) = snapshot(db_lock.as_hashdb(), block_hash, state_root, &root_dir).err() {
-                    cerror!(
-                        SYNC,
-                        "Snapshot request failed for block: {}, chunk_root: {}, err: {}",
-                        block_hash,
-                        state_root,
-                        err
-                    );
-                } else {
-                    cinfo!(SYNC, "Snapshot is ready for block: {}", block_hash)
+                {
+                    let db_lock = client.state_db().read();
+                    if let Err(err) = snapshot(db_lock.as_hashdb(), block_hash, state_root, &root_dir) {
+                        cerror!(
+                            SYNC,
+                            "Snapshot request failed for block: {}, chunk_root: {}, err: {}",
+                            block_hash,
+                            state_root,
+                            err
+                        );
+                    } else {
+                        cinfo!(SYNC, "Snapshot is ready for block: {}", block_hash)
+                    }
+                }
+
+                if let Some(expiration) = expiration {
+                    if let Err(err) = cleanup_expired(&client, &root_dir, expiration) {
+                        cerror!(SYNC, "Snapshot cleanup error after block hash {}, err: {}", block_hash, err);
+                    }
                 }
-                // TODO: Prune old snapshots
             }
             cinfo!(SYNC, "Snapshot service is stopped")
         });
@@ -84,18 +97,80 @@ impl Service {
 
 fn snapshot(db: &dyn HashDB, block_hash: BlockHash, chunk_root: H256, root_dir: &str) -> Result<(), SnapshotError> {
     let snapshot_dir = snapshot_dir(root_dir, &block_hash);
-    create_dir_all(snapshot_dir)?;
+    fs::create_dir_all(snapshot_dir)?;
 
     for chunk in Snapshot::from_hashdb(db, chunk_root) {
         let chunk_path = snapshot_path(root_dir, &block_hash, &chunk.root);
-        let chunk_file = File::create(chunk_path)?;
+        let chunk_file = fs::File::create(chunk_path)?;
         let compressor = ChunkCompressor::new(chunk_file);
         compressor.compress_chunk(&chunk)?;
     }
 
     Ok(())
 }
 
+fn cleanup_expired(client: &Client, root_dir: &str, expiration: u64) -> Result<(), SnapshotError> {
+    for entry in fs::read_dir(root_dir)? {
+        let entry = match entry {
+            Ok(entry) => entry,
+            Err(err) => {
+                cerror!(SYNC, "Snapshot cleanup can't retrieve entry. err: {}", err);
+                continue
+            }
+        };
+        let path = entry.path();
+
+        match entry.file_type().map(|x| x.is_dir()) {
+            Ok(true) => {}
+            Ok(false) => continue,
+            Err(err) => {
+                cerror!(SYNC, "Snapshot cleanup can't retrieve file info: {}, err: {}", path.to_string_lossy(), err);
+                continue
+            }
+        }
+
+        let name = match path.file_name().expect("Directories always have file name").to_str() {
+            Some(n) => n,
+            None => continue,
+        };
+        let hash = match H256::from_str(name) {
+            Ok(h) => BlockHash::from(h),
+            Err(_) => continue,
+        };
+        let number = if let Some(number) = client.block_number(&BlockId::Hash(hash)) {
+            number
+        } else {
+            cerror!(SYNC, "Snapshot cleanup can't retrieve block number for block_hash: {}", hash);
+            continue
+        };
+
+        if number + expiration < client.best_block_header().number() {
+            cleanup_snapshot(root_dir, hash)
+        }
+    }
+    Ok(())
+}
+
+/// Remove all files in `root_dir/block_hash`
+fn cleanup_snapshot(root_dir: &str, block_hash: BlockHash) {
+    let path = snapshot_dir(root_dir, &block_hash);
+    let rename_to = PathBuf::from(root_dir).join(format!("{:x}.old", *block_hash));
+    // It is okay to ignore errors. We just wanted them to be removed.
+    match fs::rename(path, &rename_to) {
+        Ok(()) => {}
+        Err(err) => {
+            cerror!(SYNC, "Snapshot cleanup: renaming {} failed, reason: {}", block_hash, err);
+        }
+    }
+    // Ignore the error. Cleanup failure is not a critical error.
+    match fs::remove_dir_all(rename_to) {
+        Ok(()) => {}
+        Err(err) => {
+            cerror!(SYNC, "Snapshot cleanup: removing {} failed, reason: {}", block_hash, err);
+        }
+    }
+}
+
 impl Drop for Service {
     fn drop(&mut self) {
         if let Some(canceller) = self.canceller.take() {