Create bank snapshots (#3671)

* Be able to create bank snapshots

* fix clippy

* load snapshot on start

* regenerate account index from the storage

* Remove rc feature dependency

* cleanup

* save snapshot for slot 0

core/src/bank_forks.rs

@@ -1,10 +1,16 @@
 //! The `bank_forks` module implments BankForks a DAG of checkpointed Banks
 
-use hashbrown::{HashMap, HashSet};
+use bincode::{deserialize_from, serialize_into};
 use solana_metrics::counter::Counter;
-use solana_runtime::bank::Bank;
+use solana_runtime::bank::{Bank, BankRc};
 use solana_sdk::timing;
+use std::collections::{HashMap, HashSet};
+use std::env;
+use std::fs;
+use std::fs::File;
+use std::io::{BufReader, BufWriter, Error, ErrorKind};
 use std::ops::Index;
+use std::path::{Path, PathBuf};
 use std::sync::Arc;
 use std::time::Instant;
 
@@ -12,6 +18,8 @@ pub struct BankForks {
     banks: HashMap<u64, Arc<Bank>>,
     working_bank: Arc<Bank>,
     root: u64,
+    slots: HashSet<u64>,
+    use_snapshot: bool,
 }
 
 impl Index<u64> for BankForks {
@@ -30,6 +38,8 @@ impl BankForks {
             banks,
             working_bank,
             root: 0,
+            slots: HashSet::new(),
+            use_snapshot: false,
         }
     }
 
@@ -45,6 +55,7 @@ impl BankForks {
     }
 
     /// Create a map of bank slot id to the set of all of its descendants
+    #[allow(clippy::or_fun_call)]
     pub fn descendants(&self) -> HashMap<u64, HashSet<u64>> {
         let mut descendants = HashMap::new();
         for bank in self.banks.values() {
@@ -91,6 +102,8 @@ impl BankForks {
             root,
             banks,
             working_bank,
+            slots: HashSet::new(),
+            use_snapshot: false,
         }
     }
 
@@ -128,9 +141,162 @@ impl BankForks {
     }
 
     fn prune_non_root(&mut self, root: u64) {
+        let slots: HashSet<u64> = self
+            .banks
+            .iter()
+            .filter(|(_, b)| b.is_frozen())
+            .map(|(k, _)| *k)
+            .collect();
         let descendants = self.descendants();
         self.banks
-            .retain(|slot, _| descendants[&root].contains(slot))
+            .retain(|slot, _| descendants[&root].contains(slot));
+        if self.use_snapshot {
+            let diff: HashSet<_> = slots.symmetric_difference(&self.slots).collect();
+            trace!("prune non root {} - {:?}", root, diff);
+            for slot in diff.iter() {
+                if **slot > root {
+                    let _ = self.add_snapshot(**slot, root);
+                } else if **slot > 0 {
+                    self.remove_snapshot(**slot);
+                }
+            }
+        }
+        self.slots = slots.clone();
+    }
+
+    fn get_io_error(error: &str) -> Error {
+        Error::new(ErrorKind::Other, error)
+    }
+
+    fn get_snapshot_path() -> PathBuf {
+        let out_dir = env::var("OUT_DIR").unwrap_or_else(|_| "target".to_string());
+        let snapshot_dir = format!("{}/snapshots/", out_dir);
+        Path::new(&snapshot_dir).to_path_buf()
+    }
+
+    pub fn add_snapshot(&self, slot: u64, root: u64) -> Result<(), Error> {
+        let path = BankForks::get_snapshot_path();
+        fs::create_dir_all(path.clone())?;
+        let bank_file = format!("{}", slot);
+        let bank_file_path = path.join(bank_file);
+        trace!("path: {:?}", bank_file_path);
+        let file = File::create(bank_file_path)?;
+        let mut stream = BufWriter::new(file);
+        let bank = self.get(slot).unwrap().clone();
+        serialize_into(&mut stream, &*bank)
+            .map_err(|_| BankForks::get_io_error("serialize bank error"))?;
+        let mut parent_slot: u64 = 0;
+        if let Some(parent_bank) = bank.parent() {
+            parent_slot = parent_bank.slot();
+        }
+        serialize_into(&mut stream, &parent_slot)
+            .map_err(|_| BankForks::get_io_error("serialize bank parent error"))?;
+        serialize_into(&mut stream, &bank.rc)
+            .map_err(|_| BankForks::get_io_error("serialize bank rc error"))?;
+        serialize_into(&mut stream, &root)
+            .map_err(|_| BankForks::get_io_error("serialize root error"))?;
+        Ok(())
+    }
+
+    pub fn remove_snapshot(&self, slot: u64) {
+        let path = BankForks::get_snapshot_path();
+        let bank_file = format!("{}", slot);
+        let bank_file_path = path.join(bank_file);
+        let _ = fs::remove_file(bank_file_path);
+    }
+
+    pub fn set_snapshot_config(&mut self, use_snapshot: bool) {
+        self.use_snapshot = use_snapshot;
+    }
+
+    fn setup_banks(
+        bank_maps: &mut Vec<(u64, u64, Bank)>,
+        bank_rc: &BankRc,
+    ) -> (HashMap<u64, Arc<Bank>>, HashSet<u64>, u64) {
+        let mut banks = HashMap::new();
+        let mut slots = HashSet::new();
+        let (last_slot, last_parent_slot, mut last_bank) = bank_maps.remove(0);
+        last_bank.set_bank_rc(&bank_rc);
+
+        while let Some((slot, parent_slot, mut bank)) = bank_maps.pop() {
+            bank.set_bank_rc(&bank_rc);
+            if parent_slot != 0 {
+                if let Some(parent) = banks.get(&parent_slot) {
+                    bank.set_parent(parent);
+                }
+            }
+            banks.insert(slot, Arc::new(bank));
+            slots.insert(slot);
+        }
+        if last_parent_slot != 0 {
+            if let Some(parent) = banks.get(&last_parent_slot) {
+                last_bank.set_parent(parent);
+            }
+        }
+        banks.insert(last_slot, Arc::new(last_bank));
+        slots.insert(last_slot);
+
+        (banks, slots, last_slot)
+    }
+
+    pub fn load_from_snapshot() -> Result<Self, Error> {
+        let path = BankForks::get_snapshot_path();
+        let paths = fs::read_dir(path.clone())?;
+        let mut names = paths
+            .filter_map(|entry| {
+                entry.ok().and_then(|e| {
+                    e.path()
+                        .file_name()
+                        .and_then(|n| n.to_str().map(|s| s.parse::<u64>().unwrap()))
+                })
+            })
+            .collect::<Vec<u64>>();
+
+        names.sort();
+        let mut bank_maps = vec![];
+        let mut bank_rc: Option<BankRc> = None;
+        let mut root: u64 = 0;
+        for bank_slot in names.iter().rev() {
+            let bank_path = format!("{}", bank_slot);
+            let bank_file_path = path.join(bank_path.clone());
+            info!("Load from {:?}", bank_file_path);
+            let file = File::open(bank_file_path)?;
+            let mut stream = BufReader::new(file);
+            let bank: Result<Bank, std::io::Error> = deserialize_from(&mut stream)
+                .map_err(|_| BankForks::get_io_error("deserialize bank error"));
+            let slot: Result<u64, std::io::Error> = deserialize_from(&mut stream)
+                .map_err(|_| BankForks::get_io_error("deserialize bank parent error"));
+            let parent_slot = if slot.is_ok() { slot.unwrap() } else { 0 };
+            if bank_rc.is_none() {
+                let rc: Result<BankRc, std::io::Error> = deserialize_from(&mut stream)
+                    .map_err(|_| BankForks::get_io_error("deserialize bank rc error"));
+                if rc.is_ok() {
+                    bank_rc = Some(rc.unwrap());
+                    let r: Result<u64, std::io::Error> = deserialize_from(&mut stream)
+                        .map_err(|_| BankForks::get_io_error("deserialize root error"));
+                    if r.is_ok() {
+                        root = r.unwrap();
+                    }
+                }
+            }
+            match bank {
+                Ok(v) => bank_maps.push((*bank_slot, parent_slot, v)),
+                Err(_) => warn!("Load snapshot failed for {}", bank_slot),
+            }
+        }
+        if bank_maps.is_empty() || bank_rc.is_none() {
+            return Err(Error::new(ErrorKind::Other, "no snapshots loaded"));
+        }
+
+        let (banks, slots, last_slot) = BankForks::setup_banks(&mut bank_maps, &bank_rc.unwrap());
+        let working_bank = banks[&last_slot].clone();
+        Ok(BankForks {
+            banks,
+            working_bank,
+            root,
+            slots,
+            use_snapshot: true,
+        })
     }
 }
 
@@ -140,6 +306,10 @@ mod tests {
     use crate::genesis_utils::create_genesis_block;
     use solana_sdk::hash::Hash;
     use solana_sdk::pubkey::Pubkey;
+    use solana_sdk::signature::{Keypair, KeypairUtil};
+    use solana_sdk::system_transaction;
+    use std::env;
+    use std::fs::remove_dir_all;
 
     #[test]
     fn test_bank_forks() {
@@ -164,8 +334,8 @@ mod tests {
         let bank = Bank::new_from_parent(&bank0, &Pubkey::default(), 2);
         bank_forks.insert(bank);
         let descendants = bank_forks.descendants();
-        let children: Vec<u64> = descendants[&0].iter().cloned().collect();
-        assert_eq!(children, vec![1, 2]);
+        let children: HashSet<u64> = [1u64, 2u64].to_vec().into_iter().collect();
+        assert_eq!(children, *descendants.get(&0).unwrap());
         assert!(descendants[&1].is_empty());
         assert!(descendants[&2].is_empty());
     }
@@ -209,4 +379,89 @@ mod tests {
         assert_eq!(bank_forks.active_banks(), vec![1]);
     }
 
+    struct TempPaths {
+        pub paths: String,
+    }
+
+    #[macro_export]
+    macro_rules! tmp_bank_accounts_name {
+        () => {
+            &format!("{}-{}", file!(), line!())
+        };
+    }
+
+    #[macro_export]
+    macro_rules! get_tmp_bank_accounts_path {
+        () => {
+            get_tmp_bank_accounts_path(tmp_bank_accounts_name!())
+        };
+    }
+
+    impl Drop for TempPaths {
+        fn drop(&mut self) {
+            let paths: Vec<String> = self.paths.split(',').map(|s| s.to_string()).collect();
+            paths.iter().for_each(|p| {
+                let _ignored = remove_dir_all(p);
+            });
+        }
+    }
+
+    fn get_paths_vec(paths: &str) -> Vec<String> {
+        paths.split(',').map(|s| s.to_string()).collect()
+    }
+
+    fn get_tmp_bank_accounts_path(paths: &str) -> TempPaths {
+        let vpaths = get_paths_vec(paths);
+        let out_dir = env::var("OUT_DIR").unwrap_or_else(|_| "target".to_string());
+        let vpaths: Vec<_> = vpaths
+            .iter()
+            .map(|path| format!("{}/{}", out_dir, path))
+            .collect();
+        TempPaths {
+            paths: vpaths.join(","),
+        }
+    }
+
+    fn save_and_load_snapshot(bank_forks: &BankForks) {
+        for (slot, _) in bank_forks.banks.iter() {
+            bank_forks.add_snapshot(*slot, 0).unwrap();
+        }
+
+        let new = BankForks::load_from_snapshot().unwrap();
+        for (slot, _) in bank_forks.banks.iter() {
+            let bank = bank_forks.banks.get(slot).unwrap().clone();
+            let new_bank = new.banks.get(slot).unwrap();
+            bank.compare_bank(&new_bank);
+        }
+        for (slot, _) in new.banks.iter() {
+            new.remove_snapshot(*slot);
+        }
+    }
+
+    #[test]
+    fn test_bank_forks_snapshot_n() {
+        solana_logger::setup();
+        let path = get_tmp_bank_accounts_path!();
+        let (genesis_block, mint_keypair) = create_genesis_block(10_000);
+        let bank0 = Bank::new_with_paths(&genesis_block, Some(path.paths.clone()));
+        bank0.freeze();
+        let mut bank_forks = BankForks::new(0, bank0);
+        bank_forks.set_snapshot_config(true);
+        for index in 0..10 {
+            let bank = Bank::new_from_parent(&bank_forks[index], &Pubkey::default(), index + 1);
+            let key1 = Keypair::new().pubkey();
+            let tx = system_transaction::create_user_account(
+                &mint_keypair,
+                &key1,
+                1,
+                genesis_block.hash(),
+                0,
+            );
+            assert_eq!(bank.process_transaction(&tx), Ok(()));
+            bank.freeze();
+            bank_forks.insert(bank);
+            save_and_load_snapshot(&bank_forks);
+        }
+        assert_eq!(bank_forks.working_bank().slot(), 10);
+    }
 }