Freeze pruning while creating snapshot (#205)

* Freeze pruning while creating snapshot
* Use scopeguard for snapshot generation
* Snapshot 1k blocks
* Snapshot number correction

Cargo.lock

@@ -572,7 +572,7 @@ dependencies = [
  "crossbeam-utils 0.6.6",
  "lazy_static",
  "memoffset",
- "scopeguard 1.0.0",
+ "scopeguard 1.1.0",
 ]
 
 [[package]]
@@ -1014,6 +1014,7 @@ dependencies = [
  "rlp_compress",
  "rlp_derive",
  "rustc-hex 1.0.0",
+ "scopeguard 1.1.0",
  "serde",
  "serde_derive",
  "serde_json",
@@ -1871,7 +1872,7 @@ version = "0.5.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a3753954f7bd71f0e671afb8b5a992d1724cf43b7f95a563cd4a0bde94659ca8"
 dependencies = [
- "scopeguard 1.0.0",
+ "scopeguard 1.1.0",
  "winapi 0.3.8",
 ]
 
@@ -2436,7 +2437,7 @@ version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c4da24a77a3d8a6d4862d95f72e6fdb9c09a643ecdb402d754004a557f2bec75"
 dependencies = [
- "scopeguard 1.0.0",
+ "scopeguard 1.1.0",
 ]
 
 [[package]]
@@ -4126,9 +4127,9 @@ checksum = "94258f53601af11e6a49f722422f6e3425c52b06245a5cf9bc09908b174f5e27"
 
 [[package]]
 name = "scopeguard"
-version = "1.0.0"
+version = "1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b42e15e59b18a828bbf5c58ea01debb36b9b096346de35d941dcb89009f24a0d"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 
 [[package]]
 name = "scrypt"

bin/oe/run.rs

@@ -60,11 +60,11 @@ use signer;
 use sync::{self, SyncConfig};
 use user_defaults::UserDefaults;
 
-// how often to take periodic snapshots.
+// How often we attempt to take a snapshot: only snapshot on blocknumbers that are multiples of this.
-const SNAPSHOT_PERIOD: u64 = 5000;
+const SNAPSHOT_PERIOD: u64 = 20000;
 
-// how many blocks to wait before starting a periodic snapshot.
+// Start snapshoting from `tip`-`history, with this we want to bypass reorgs. Should be smaller than prunning history.
-const SNAPSHOT_HISTORY: u64 = 100;
+const SNAPSHOT_HISTORY: u64 = 50;
 
 // Full client number of DNS threads
 const FETCH_FULL_NUM_DNS_THREADS: usize = 4;

crates/ethcore/Cargo.toml

@@ -74,6 +74,7 @@ using_queue = { path = "../concensus/miner/using-queue" }
 vm = { path = "../vm/vm" }
 walkdir = "2.3"
 wasm = { path = "../vm/wasm" }
+scopeguard = "1.1.0"
 
 [dev-dependencies]
 blooms-db = { path = "../db/blooms-db" }

crates/ethcore/src/client/client.rs

@@ -21,7 +21,7 @@ use std::{
     io::{BufRead, BufReader},
     str::{from_utf8, FromStr},
     sync::{
-        atomic::{AtomicBool, AtomicI64, Ordering as AtomicOrdering},
+        atomic::{AtomicBool, AtomicI64, AtomicU64, Ordering as AtomicOrdering},
         Arc, Weak,
     },
     time::{Duration, Instant},
@@ -209,6 +209,9 @@ pub struct Client {
     /// Database pruning strategy to use for StateDB
     pruning: journaldb::Algorithm,
 
+    /// Don't prune the state we're currently snapshotting
+    snapshotting_at: AtomicU64,
+
     /// Client uses this to store blocks, traces, etc.
     db: RwLock<Arc<dyn BlockChainDB>>,
 
@@ -946,6 +949,7 @@ impl Client {
             tracedb,
             engine,
             pruning: config.pruning.clone(),
+            snapshotting_at: AtomicU64::new(0),
             db: RwLock::new(db.clone()),
             state_db: RwLock::new(state_db),
             report: RwLock::new(Default::default()),
@@ -1137,7 +1141,7 @@ impl Client {
         mut state_db: StateDB,
         chain: &BlockChain,
     ) -> Result<(), ::error::Error> {
-        let number = match state_db.journal_db().latest_era() {
+        let latest_era = match state_db.journal_db().latest_era() {
             Some(n) => n,
             None => return Ok(()),
         };
@@ -1152,16 +1156,27 @@ impl Client {
                 break;
             }
             match state_db.journal_db().earliest_era() {
-                Some(era) if era + self.history <= number => {
+                Some(earliest_era) if earliest_era + self.history <= latest_era => {
-                    trace!(target: "client", "Pruning state for ancient era {}", era);
+                    let freeze_at = self.snapshotting_at.load(AtomicOrdering::SeqCst);
-                    match chain.block_hash(era) {
+                    if freeze_at > 0 && freeze_at == earliest_era {
+                        // Note: journal_db().mem_used() can be used for a more accurate memory
+                        // consumption measurement but it can be expensive so sticking with the
+                        // faster `journal_size()` instead.
+                        trace!(target: "pruning", "Pruning is paused at era {} (snapshot under way); earliest era={}, latest era={}, journal_size={} – Not pruning.",
+						       freeze_at, earliest_era, latest_era, state_db.journal_db().journal_size());
+                        break;
+                    }
+                    trace!(target: "client", "Pruning state for ancient era {}", earliest_era);
+                    match chain.block_hash(earliest_era) {
                         Some(ancient_hash) => {
                             let mut batch = DBTransaction::new();
-                            state_db.mark_canonical(&mut batch, era, &ancient_hash)?;
+                            state_db.mark_canonical(&mut batch, earliest_era, &ancient_hash)?;
                             self.db.read().key_value().write_buffered(batch);
                             state_db.journal_db().flush();
                         }
-                        None => debug!(target: "client", "Missing expected hash for block {}", era),
+                        None => {
+                            debug!(target: "client", "Missing expected hash for block {}", earliest_era)
+                        }
                     }
                 }
                 _ => break, // means that every era is kept, no pruning necessary.
@@ -1349,7 +1364,6 @@ impl Client {
         p: &snapshot::Progress,
     ) -> Result<(), EthcoreError> {
         let db = self.state_db.read().journal_db().boxed_clone();
-        let best_block_number = self.chain_info().best_block_number;
         let block_number = self
             .block_number(at)
             .ok_or_else(|| snapshot::Error::InvalidStartingBlock(at))?;
@@ -1360,19 +1374,23 @@ impl Client {
 
         let history = ::std::cmp::min(self.history, 1000);
 
-        let start_hash = match at {
+        let (snapshot_block_number, start_hash) = match at {
             BlockId::Latest => {
+                let best_block_number = self.chain_info().best_block_number;
                 let start_num = match db.earliest_era() {
                     Some(era) => ::std::cmp::max(era, best_block_number.saturating_sub(history)),
                     None => best_block_number.saturating_sub(history),
                 };
 
-                self.block_hash(BlockId::Number(start_num))
+                match self.block_hash(BlockId::Number(start_num)) {
-                    .ok_or_else(|| snapshot::Error::InvalidStartingBlock(at))?
+                    Some(h) => (start_num, h),
+                    None => return Err(snapshot::Error::InvalidStartingBlock(at).into()),
                 }
-            _ => self
+            }
-                .block_hash(at)
+            _ => match self.block_hash(at) {
-                .ok_or_else(|| snapshot::Error::InvalidStartingBlock(at))?,
+                Some(hash) => (block_number, hash),
+                None => return Err(snapshot::Error::InvalidStartingBlock(at).into()),
+            },
         };
 
         let processing_threads = self.config.snapshot.processing_threads;
@@ -1380,6 +1398,13 @@ impl Client {
             .engine
             .snapshot_components()
             .ok_or(snapshot::Error::SnapshotsUnsupported)?;
+        self.snapshotting_at
+            .store(snapshot_block_number, AtomicOrdering::SeqCst);
+        {
+            scopeguard::defer! {{
+                info!(target: "snapshot", "Re-enabling pruning.");
+                self.snapshotting_at.store(0, AtomicOrdering::SeqCst)
+            }};
             snapshot::take_snapshot(
                 chunker,
                 &self.chain.read(),
@@ -1389,6 +1414,7 @@ impl Client {
                 p,
                 processing_threads,
             )?;
+        }
         Ok(())
     }
 

crates/ethcore/src/ethereum/ethash.rs

@@ -38,9 +38,9 @@ use machine::EthereumMachine;
 
 /// Number of blocks in an ethash snapshot.
 // make dependent on difficulty incrment divisor?
-const SNAPSHOT_BLOCKS: u64 = 5000;
+const SNAPSHOT_BLOCKS: u64 = 1000;
 /// Maximum number of blocks allowed in an ethash snapshot.
-const MAX_SNAPSHOT_BLOCKS: u64 = 30000;
+const MAX_SNAPSHOT_BLOCKS: u64 = 10000;
 
 /// Ethash specific seal
 #[derive(Debug, PartialEq)]

crates/ethcore/src/snapshot/service.rs

@@ -530,6 +530,10 @@ impl Service {
             .store(num as usize, Ordering::SeqCst);
 
         info!("Taking snapshot at #{}", num);
+        {
+            scopeguard::defer! {{
+                self.taking_snapshot.store(false, Ordering::SeqCst);
+            }}
             self.progress.reset();
 
             let temp_dir = self.temp_snapshot_dir();
@@ -541,7 +545,6 @@ impl Service {
 
             let guard = Guard::new(temp_dir.clone());
             let res = client.take_snapshot(writer, BlockId::Number(num), &self.progress);
-        self.taking_snapshot.store(false, Ordering::SeqCst);
             if let Err(e) = res {
                 if client.chain_info().best_block_number >= num + client.pruning_history() {
                     // The state we were snapshotting was pruned before we could finish.
@@ -570,6 +573,7 @@ impl Service {
             guard.disarm();
             Ok(())
         }
+    }
 
     /// Initialize the restoration synchronously.
     /// The recover flag indicates whether to recover the restored snapshot.