use std::convert::TryInto; use std::path::{Path, PathBuf}; use std::sync::Arc; use std::time::Duration; use arc_swap::ArcSwapOption; use async_trait::async_trait; use serde::{Deserialize, Serialize}; use zstd::stream::{decode_all as zstd_decode, Encoder}; use futures::future::*; use futures::select; use tokio::fs; use tokio::io::{AsyncReadExt, AsyncWriteExt}; use tokio::sync::{watch, Mutex, Notify}; use opentelemetry::{ trace::{FutureExt as OtelFutureExt, TraceContextExt, Tracer}, Context, KeyValue, }; use garage_util::data::*; use garage_util::error::*; use garage_util::metrics::RecordDuration; use garage_util::sled_counter::SledCountedTree; use garage_util::time::*; use garage_util::tranquilizer::Tranquilizer; use garage_rpc::system::System; use garage_rpc::*; use garage_table::replication::{TableReplication, TableShardedReplication}; use crate::block_metrics::*; use crate::block_ref_table::*; use crate::garage::Garage; /// Size under which data will be stored inlined in database instead of as files pub const INLINE_THRESHOLD: usize = 3072; pub const BACKGROUND_TRANQUILITY: u32 = 2; // Timeout for RPCs that read and write blocks to remote nodes const BLOCK_RW_TIMEOUT: Duration = Duration::from_secs(30); // Timeout for RPCs that ask other nodes whether they need a copy // of a given block before we delete it locally const NEED_BLOCK_QUERY_TIMEOUT: Duration = Duration::from_secs(5); // The delay between the time where a resync operation fails // and the time when it is retried, with exponential backoff // (multiplied by 2, 4, 8, 16, etc. for every consecutive failure). const RESYNC_RETRY_DELAY: Duration = Duration::from_secs(60); // The delay between the moment when the reference counter // drops to zero, and the moment where we allow ourselves // to delete the block locally. const BLOCK_GC_DELAY: Duration = Duration::from_secs(600); /// RPC messages used to share blocks of data between nodes #[derive(Debug, Serialize, Deserialize)] pub enum BlockRpc { Ok, /// Message to ask for a block of data, by hash GetBlock(Hash), /// Message to send a block of data, either because requested, of for first delivery of new /// block PutBlock { hash: Hash, data: DataBlock, }, /// Ask other node if they should have this block, but don't actually have it NeedBlockQuery(Hash), /// Response : whether the node do require that block NeedBlockReply(bool), } /// A possibly compressed block of data #[derive(Debug, Serialize, Deserialize)] pub enum DataBlock { /// Uncompressed data Plain(#[serde(with = "serde_bytes")] Vec), /// Data compressed with zstd Compressed(#[serde(with = "serde_bytes")] Vec), } impl DataBlock { /// Query whether this block is compressed pub fn is_compressed(&self) -> bool { matches!(self, DataBlock::Compressed(_)) } /// Get the inner, possibly compressed buffer. You should probably use [`DataBlock::verify_get`] /// instead pub fn inner_buffer(&self) -> &[u8] { use DataBlock::*; let (Plain(ref res) | Compressed(ref res)) = self; res } /// Get the buffer, possibly decompressing it, and verify it's integrity. /// For Plain block, data is compared to hash, for Compressed block, zstd checksumming system /// is used instead. pub fn verify_get(self, hash: Hash) -> Result, Error> { match self { DataBlock::Plain(data) => { if blake2sum(&data) == hash { Ok(data) } else { Err(Error::CorruptData(hash)) } } DataBlock::Compressed(data) => { zstd_decode(&data[..]).map_err(|_| Error::CorruptData(hash)) } } } /// Verify data integrity. Allocate less than [`DataBlock::verify_get`] and don't consume self, but /// does not return the buffer content. pub fn verify(&self, hash: Hash) -> Result<(), Error> { match self { DataBlock::Plain(data) => { if blake2sum(data) == hash { Ok(()) } else { Err(Error::CorruptData(hash)) } } DataBlock::Compressed(data) => zstd::stream::copy_decode(&data[..], std::io::sink()) .map_err(|_| Error::CorruptData(hash)), } } pub fn from_buffer(data: Vec, level: Option) -> DataBlock { if let Some(level) = level { if let Ok(data) = zstd_encode(&data[..], level) { return DataBlock::Compressed(data); } } DataBlock::Plain(data) } } impl Rpc for BlockRpc { type Response = Result; } /// The block manager, handling block exchange between nodes, and block storage on local node pub struct BlockManager { /// Replication strategy, allowing to find on which node blocks should be located pub replication: TableShardedReplication, /// Directory in which block are stored pub data_dir: PathBuf, mutation_lock: Mutex, rc: sled::Tree, resync_queue: SledCountedTree, resync_notify: Notify, resync_errors: SledCountedTree, system: Arc, endpoint: Arc>, pub(crate) garage: ArcSwapOption, metrics: BlockManagerMetrics, } // This custom struct contains functions that must only be ran // when the lock is held. We ensure that it is the case by storing // it INSIDE a Mutex. struct BlockManagerLocked(); impl BlockManager { pub fn new( db: &sled::Db, data_dir: PathBuf, replication: TableShardedReplication, system: Arc, ) -> Arc { let rc = db .open_tree("block_local_rc") .expect("Unable to open block_local_rc tree"); let resync_queue = db .open_tree("block_local_resync_queue") .expect("Unable to open block_local_resync_queue tree"); let resync_queue = SledCountedTree::new(resync_queue); let resync_errors = db .open_tree("block_local_resync_errors") .expect("Unable to open block_local_resync_errors tree"); let resync_errors = SledCountedTree::new(resync_errors); let endpoint = system .netapp .endpoint("garage_model/block.rs/Rpc".to_string()); let manager_locked = BlockManagerLocked(); let metrics = BlockManagerMetrics::new(resync_queue.clone(), resync_errors.clone()); let block_manager = Arc::new(Self { replication, data_dir, mutation_lock: Mutex::new(manager_locked), rc, resync_queue, resync_notify: Notify::new(), resync_errors, system, endpoint, garage: ArcSwapOption::from(None), metrics, }); block_manager.endpoint.set_handler(block_manager.clone()); block_manager } /// Ask nodes that might have a (possibly compressed) block for it async fn rpc_get_raw_block(&self, hash: &Hash) -> Result { let who = self.replication.read_nodes(hash); let resps = self .system .rpc .try_call_many( &self.endpoint, &who[..], BlockRpc::GetBlock(*hash), RequestStrategy::with_priority(PRIO_NORMAL) .with_quorum(1) .with_timeout(BLOCK_RW_TIMEOUT) .interrupt_after_quorum(true), ) .await?; for resp in resps { if let BlockRpc::PutBlock { data, .. } = resp { return Ok(data); } } Err(Error::Message(format!( "Unable to read block {:?}: no valid blocks returned", hash ))) } // ---- Public interface ---- /// Ask nodes that might have a block for it pub async fn rpc_get_block(&self, hash: &Hash) -> Result, Error> { self.rpc_get_raw_block(hash).await?.verify_get(*hash) } /// Send block to nodes that should have it pub async fn rpc_put_block(&self, hash: Hash, data: Vec) -> Result<(), Error> { let who = self.replication.write_nodes(&hash); let compression_level = self .garage .load() .as_ref() .unwrap() .config .compression_level; let data = DataBlock::from_buffer(data, compression_level); self.system .rpc .try_call_many( &self.endpoint, &who[..], BlockRpc::PutBlock { hash, data }, RequestStrategy::with_priority(PRIO_NORMAL) .with_quorum(self.replication.write_quorum()) .with_timeout(BLOCK_RW_TIMEOUT), ) .await?; Ok(()) } /// Launch the repair procedure on the data store /// /// This will list all blocks locally present, as well as those /// that are required because of refcount > 0, and will try /// to fix any mismatch between the two. pub async fn repair_data_store(&self, must_exit: &watch::Receiver) -> Result<(), Error> { // 1. Repair blocks from RC table. let garage = self.garage.load_full().unwrap(); let mut last_hash = None; for (i, entry) in garage.block_ref_table.data.store.iter().enumerate() { let (_k, v_bytes) = entry?; let block_ref = rmp_serde::decode::from_read_ref::<_, BlockRef>(v_bytes.as_ref())?; if Some(&block_ref.block) == last_hash.as_ref() { continue; } if !block_ref.deleted.get() { last_hash = Some(block_ref.block); self.put_to_resync(&block_ref.block, Duration::from_secs(0))?; } if i & 0xFF == 0 && *must_exit.borrow() { return Ok(()); } } // 2. Repair blocks actually on disk // Lists all blocks on disk and adds them to the resync queue. // This allows us to find blocks we are storing but don't actually need, // so that we can offload them if necessary and then delete them locally. self.for_each_file( (), move |_, hash| async move { self.put_to_resync(&hash, Duration::from_secs(0)) }, must_exit, ) .await } /// Verify integrity of each block on disk. Use `speed_limit` to limit the load generated by /// this function. pub async fn scrub_data_store( &self, must_exit: &watch::Receiver, tranquility: u32, ) -> Result<(), Error> { let tranquilizer = Tranquilizer::new(30); self.for_each_file( tranquilizer, move |mut tranquilizer, hash| async move { let _ = self.read_block(&hash).await; tranquilizer.tranquilize(tranquility).await; Ok(tranquilizer) }, must_exit, ) .await } /// Get lenght of resync queue pub fn resync_queue_len(&self) -> usize { self.resync_queue.len() } /// Get number of items in the refcount table pub fn rc_len(&self) -> usize { self.rc.len() } //// ----- Managing the reference counter ---- /// Increment the number of time a block is used, putting it to resynchronization if it is /// required, but not known pub fn block_incref(&self, hash: &Hash) -> Result<(), Error> { let old_rc = self .rc .fetch_and_update(&hash, |old| RcEntry::parse_opt(old).increment().serialize())?; let old_rc = RcEntry::parse_opt(old_rc); if old_rc.is_zero() { // When the reference counter is incremented, there is // normally a node that is responsible for sending us the // data of the block. However that operation may fail, // so in all cases we add the block here to the todo list // to check later that it arrived correctly, and if not // we will fecth it from someone. self.put_to_resync(hash, 2 * BLOCK_RW_TIMEOUT)?; } Ok(()) } /// Decrement the number of time a block is used pub fn block_decref(&self, hash: &Hash) -> Result<(), Error> { let new_rc = self .rc .update_and_fetch(&hash, |old| RcEntry::parse_opt(old).decrement().serialize())?; let new_rc = RcEntry::parse_opt(new_rc); if let RcEntry::Deletable { .. } = new_rc { self.put_to_resync(hash, BLOCK_GC_DELAY + Duration::from_secs(10))?; } Ok(()) } /// Read a block's reference count fn get_block_rc(&self, hash: &Hash) -> Result { Ok(RcEntry::parse_opt(self.rc.get(hash.as_ref())?)) } /// Delete an entry in the RC table if it is deletable and the /// deletion time has passed fn clear_deleted_block_rc(&self, hash: &Hash) -> Result<(), Error> { let now = now_msec(); self.rc.update_and_fetch(&hash, |rcval| { let updated = match RcEntry::parse_opt(rcval) { RcEntry::Deletable { at_time } if now > at_time => RcEntry::Absent, v => v, }; updated.serialize() })?; Ok(()) } // ---- Reading and writing blocks locally ---- /// Write a block to disk async fn write_block(&self, hash: &Hash, data: &DataBlock) -> Result { let write_size = data.inner_buffer().len() as u64; let res = self .mutation_lock .lock() .await .write_block(hash, data, self) .bound_record_duration(&self.metrics.block_write_duration) .await?; self.metrics.bytes_written.add(write_size); Ok(res) } /// Read block from disk, verifying it's integrity async fn read_block(&self, hash: &Hash) -> Result { let data = self .read_block_internal(hash) .bound_record_duration(&self.metrics.block_read_duration) .await?; self.metrics .bytes_read .add(data.inner_buffer().len() as u64); Ok(BlockRpc::PutBlock { hash: *hash, data }) } async fn read_block_internal(&self, hash: &Hash) -> Result { let mut path = self.block_path(hash); let compressed = match self.is_block_compressed(hash).await { Ok(c) => c, Err(e) => { // Not found but maybe we should have had it ?? self.put_to_resync(hash, 2 * BLOCK_RW_TIMEOUT)?; return Err(Into::into(e)); } }; if compressed { path.set_extension("zst"); } let mut f = fs::File::open(&path).await?; let mut data = vec![]; f.read_to_end(&mut data).await?; drop(f); let data = if compressed { DataBlock::Compressed(data) } else { DataBlock::Plain(data) }; if data.verify(*hash).is_err() { self.metrics.corruption_counter.add(1); self.mutation_lock .lock() .await .move_block_to_corrupted(hash, self) .await?; self.put_to_resync(hash, Duration::from_millis(0))?; return Err(Error::CorruptData(*hash)); } Ok(data) } /// Check if this node should have a block, but don't actually have it async fn need_block(&self, hash: &Hash) -> Result { let BlockStatus { exists, needed } = self .mutation_lock .lock() .await .check_block_status(hash, self) .await?; Ok(needed.is_nonzero() && !exists) } /// Utility: gives the path of the directory in which a block should be found fn block_dir(&self, hash: &Hash) -> PathBuf { let mut path = self.data_dir.clone(); path.push(hex::encode(&hash.as_slice()[0..1])); path.push(hex::encode(&hash.as_slice()[1..2])); path } /// Utility: give the full path where a block should be found, minus extension if block is /// compressed fn block_path(&self, hash: &Hash) -> PathBuf { let mut path = self.block_dir(hash); path.push(hex::encode(hash.as_ref())); path } /// Utility: check if block is stored compressed. Error if block is not stored async fn is_block_compressed(&self, hash: &Hash) -> Result { let mut path = self.block_path(hash); path.set_extension("zst"); if fs::metadata(&path).await.is_ok() { return Ok(true); } path.set_extension(""); fs::metadata(&path).await.map(|_| false).map_err(Into::into) } // ---- Resync loop ---- pub fn spawn_background_worker(self: Arc) { // Launch a background workers for background resync loop processing let background = self.system.background.clone(); tokio::spawn(async move { tokio::time::sleep(Duration::from_secs(10)).await; background.spawn_worker("block resync worker".into(), move |must_exit| { self.resync_loop(must_exit) }); }); } fn put_to_resync(&self, hash: &Hash, delay: Duration) -> Result<(), Error> { let when = now_msec() + delay.as_millis() as u64; self.put_to_resync_at(hash, when) } fn put_to_resync_at(&self, hash: &Hash, when: u64) -> Result<(), Error> { trace!("Put resync_queue: {} {:?}", when, hash); let mut key = u64::to_be_bytes(when).to_vec(); key.extend(hash.as_ref()); self.resync_queue.insert(key, hash.as_ref())?; self.resync_notify.notify_waiters(); Ok(()) } async fn resync_loop(self: Arc, mut must_exit: watch::Receiver) { let mut tranquilizer = Tranquilizer::new(30); while !*must_exit.borrow() { match self.resync_iter(&mut must_exit).await { Ok(true) => { tranquilizer.tranquilize(BACKGROUND_TRANQUILITY).await; } Ok(false) => { tranquilizer.reset(); } Err(e) => { // The errors that we have here are only Sled errors // We don't really know how to handle them so just ¯\_(ツ)_/¯ // (there is kind of an assumption that Sled won't error on us, // if it does there is not much we can do -- TODO should we just panic?) error!( "Could not do a resync iteration: {} (this is a very bad error)", e ); tranquilizer.reset(); } } } } async fn resync_iter(&self, must_exit: &mut watch::Receiver) -> Result { if let Some(first_pair_res) = self.resync_queue.iter().next() { let (time_bytes, hash_bytes) = first_pair_res?; let time_msec = u64::from_be_bytes(time_bytes[0..8].try_into().unwrap()); let now = now_msec(); if now >= time_msec { let hash = Hash::try_from(&hash_bytes[..]).unwrap(); if let Some(ec) = self.resync_errors.get(hash.as_slice())? { let ec = ErrorCounter::decode(ec); if now < ec.next_try() { // if next retry after an error is not yet, // don't do resync and return early, but still // make sure the item is still in queue at expected time self.put_to_resync_at(&hash, ec.next_try())?; // ec.next_try() > now >= time_msec, so this remove // is not removing the one we added just above self.resync_queue.remove(time_bytes)?; return Ok(false); } } let tracer = opentelemetry::global::tracer("garage"); let trace_id = gen_uuid(); let span = tracer .span_builder("Resync block") .with_trace_id( opentelemetry::trace::TraceId::from_hex(&hex::encode( &trace_id.as_slice()[..16], )) .unwrap(), ) .with_attributes(vec![KeyValue::new("block", format!("{:?}", hash))]) .start(&tracer); let res = self .resync_block(&hash) .with_context(Context::current_with_span(span)) .bound_record_duration(&self.metrics.resync_duration) .await; self.metrics.resync_counter.add(1); if let Err(e) = &res { self.metrics.resync_error_counter.add(1); warn!("Error when resyncing {:?}: {}", hash, e); let err_counter = match self.resync_errors.get(hash.as_slice())? { Some(ec) => ErrorCounter::decode(ec).add1(now + 1), None => ErrorCounter::new(now + 1), }; self.resync_errors .insert(hash.as_slice(), err_counter.encode())?; self.put_to_resync_at(&hash, err_counter.next_try())?; // err_counter.next_try() >= now + 1 > now, // the entry we remove from the queue is not // the entry we inserted with put_to_resync_at self.resync_queue.remove(time_bytes)?; } else { self.resync_errors.remove(hash.as_slice())?; self.resync_queue.remove(time_bytes)?; } Ok(true) } else { let delay = tokio::time::sleep(Duration::from_millis(time_msec - now)); select! { _ = delay.fuse() => {}, _ = self.resync_notify.notified().fuse() => {}, _ = must_exit.changed().fuse() => {}, } Ok(false) } } else { select! { _ = self.resync_notify.notified().fuse() => {}, _ = must_exit.changed().fuse() => {}, } Ok(false) } } async fn resync_block(&self, hash: &Hash) -> Result<(), Error> { let BlockStatus { exists, needed } = self .mutation_lock .lock() .await .check_block_status(hash, self) .await?; if exists != needed.is_needed() || exists != needed.is_nonzero() { debug!( "Resync block {:?}: exists {}, nonzero rc {}, deletable {}", hash, exists, needed.is_nonzero(), needed.is_deletable(), ); } if exists && needed.is_deletable() { info!("Resync block {:?}: offloading and deleting", hash); let mut who = self.replication.write_nodes(hash); if who.len() < self.replication.write_quorum() { return Err(Error::Message("Not trying to offload block because we don't have a quorum of nodes to write to".to_string())); } who.retain(|id| *id != self.system.id); let msg = Arc::new(BlockRpc::NeedBlockQuery(*hash)); let who_needs_fut = who.iter().map(|to| { self.system.rpc.call_arc( &self.endpoint, *to, msg.clone(), RequestStrategy::with_priority(PRIO_BACKGROUND) .with_timeout(NEED_BLOCK_QUERY_TIMEOUT), ) }); let who_needs_resps = join_all(who_needs_fut).await; let mut need_nodes = vec![]; for (node, needed) in who.iter().zip(who_needs_resps.into_iter()) { match needed.err_context("NeedBlockQuery RPC")? { BlockRpc::NeedBlockReply(needed) => { if needed { need_nodes.push(*node); } } m => { return Err(Error::unexpected_rpc_message(m)); } } } if !need_nodes.is_empty() { trace!( "Block {:?} needed by {} nodes, sending", hash, need_nodes.len() ); for node in need_nodes.iter() { self.metrics .resync_send_counter .add(1, &[KeyValue::new("to", format!("{:?}", node))]); } let put_block_message = self.read_block(hash).await?; self.system .rpc .try_call_many( &self.endpoint, &need_nodes[..], put_block_message, RequestStrategy::with_priority(PRIO_BACKGROUND) .with_quorum(need_nodes.len()) .with_timeout(BLOCK_RW_TIMEOUT), ) .await .err_context("PutBlock RPC")?; } info!( "Deleting unneeded block {:?}, offload finished ({} / {})", hash, need_nodes.len(), who.len() ); self.mutation_lock .lock() .await .delete_if_unneeded(hash, self) .await?; self.clear_deleted_block_rc(hash)?; } if needed.is_nonzero() && !exists { info!( "Resync block {:?}: fetching absent but needed block (refcount > 0)", hash ); let block_data = self.rpc_get_raw_block(hash).await?; self.metrics.resync_recv_counter.add(1); self.write_block(hash, &block_data).await?; } Ok(()) } // ---- Utility: iteration on files in the data directory ---- async fn for_each_file( &self, state: State, mut f: F, must_exit: &watch::Receiver, ) -> Result<(), Error> where F: FnMut(State, Hash) -> Fut + Send, Fut: Future> + Send, State: Send, { self.for_each_file_rec(&self.data_dir, state, &mut f, must_exit) .await .map(|_| ()) } fn for_each_file_rec<'a, F, Fut, State>( &'a self, path: &'a Path, mut state: State, f: &'a mut F, must_exit: &'a watch::Receiver, ) -> BoxFuture<'a, Result> where F: FnMut(State, Hash) -> Fut + Send, Fut: Future> + Send, State: Send + 'a, { async move { let mut ls_data_dir = fs::read_dir(path).await?; while let Some(data_dir_ent) = ls_data_dir.next_entry().await? { if *must_exit.borrow() { break; } let name = data_dir_ent.file_name(); let name = if let Ok(n) = name.into_string() { n } else { continue; }; let ent_type = data_dir_ent.file_type().await?; let name = name.strip_suffix(".zst").unwrap_or(&name); if name.len() == 2 && hex::decode(&name).is_ok() && ent_type.is_dir() { state = self .for_each_file_rec(&data_dir_ent.path(), state, f, must_exit) .await?; } else if name.len() == 64 { let hash_bytes = if let Ok(h) = hex::decode(&name) { h } else { continue; }; let mut hash = [0u8; 32]; hash.copy_from_slice(&hash_bytes[..]); state = f(state, hash.into()).await?; } } Ok(state) } .boxed() } } #[async_trait] impl EndpointHandler for BlockManager { async fn handle( self: &Arc, message: &BlockRpc, _from: NodeID, ) -> Result { match message { BlockRpc::PutBlock { hash, data } => self.write_block(hash, data).await, BlockRpc::GetBlock(h) => self.read_block(h).await, BlockRpc::NeedBlockQuery(h) => self.need_block(h).await.map(BlockRpc::NeedBlockReply), m => Err(Error::unexpected_rpc_message(m)), } } } struct BlockStatus { exists: bool, needed: RcEntry, } impl BlockManagerLocked { async fn check_block_status( &self, hash: &Hash, mgr: &BlockManager, ) -> Result { let exists = mgr.is_block_compressed(hash).await.is_ok(); let needed = mgr.get_block_rc(hash)?; Ok(BlockStatus { exists, needed }) } async fn write_block( &self, hash: &Hash, data: &DataBlock, mgr: &BlockManager, ) -> Result { let compressed = data.is_compressed(); let data = data.inner_buffer(); let mut path = mgr.block_dir(hash); let directory = path.clone(); path.push(hex::encode(hash)); fs::create_dir_all(&directory).await?; let to_delete = match (mgr.is_block_compressed(hash).await, compressed) { (Ok(true), _) => return Ok(BlockRpc::Ok), (Ok(false), false) => return Ok(BlockRpc::Ok), (Ok(false), true) => { let path_to_delete = path.clone(); path.set_extension("zst"); Some(path_to_delete) } (Err(_), compressed) => { if compressed { path.set_extension("zst"); } None } }; let mut path2 = path.clone(); path2.set_extension("tmp"); let mut f = fs::File::create(&path2).await?; f.write_all(data).await?; f.sync_all().await?; drop(f); fs::rename(path2, path).await?; if let Some(to_delete) = to_delete { fs::remove_file(to_delete).await?; } // We want to ensure that when this function returns, data is properly persisted // to disk. The first step is the sync_all above that does an fsync on the data file. // Now, we do an fsync on the containing directory, to ensure that the rename // is persisted properly. See: // http://thedjbway.b0llix.net/qmail/syncdir.html let dir = fs::OpenOptions::new() .read(true) .mode(0) .open(directory) .await?; dir.sync_all().await?; drop(dir); Ok(BlockRpc::Ok) } async fn move_block_to_corrupted(&self, hash: &Hash, mgr: &BlockManager) -> Result<(), Error> { warn!( "Block {:?} is corrupted. Renaming to .corrupted and resyncing.", hash ); let mut path = mgr.block_path(hash); let mut path2 = path.clone(); if mgr.is_block_compressed(hash).await? { path.set_extension("zst"); path2.set_extension("zst.corrupted"); } else { path2.set_extension("corrupted"); } fs::rename(path, path2).await?; Ok(()) } async fn delete_if_unneeded(&self, hash: &Hash, mgr: &BlockManager) -> Result<(), Error> { let BlockStatus { exists, needed } = self.check_block_status(hash, mgr).await?; if exists && needed.is_deletable() { let mut path = mgr.block_path(hash); if mgr.is_block_compressed(hash).await? { path.set_extension("zst"); } fs::remove_file(path).await?; mgr.metrics.delete_counter.add(1); } Ok(()) } } /// Describes the state of the reference counter for a block #[derive(Clone, Copy, Debug)] enum RcEntry { /// Present: the block has `count` references, with `count` > 0. /// /// This is stored as u64::to_be_bytes(count) Present { count: u64 }, /// Deletable: the block has zero references, and can be deleted /// once time (returned by now_msec) is larger than at_time /// (in millis since Unix epoch) /// /// This is stored as [0u8; 8] followed by u64::to_be_bytes(at_time), /// (this allows for the data format to be backwards compatible with /// previous Garage versions that didn't have this intermediate state) Deletable { at_time: u64 }, /// Absent: the block has zero references, and can be deleted /// immediately Absent, } impl RcEntry { fn parse(bytes: &[u8]) -> Self { if bytes.len() == 8 { RcEntry::Present { count: u64::from_be_bytes(bytes.try_into().unwrap()), } } else if bytes.len() == 16 { RcEntry::Deletable { at_time: u64::from_be_bytes(bytes[8..16].try_into().unwrap()), } } else { panic!("Invalid RC entry: {:?}, database is corrupted. This is an error Garage is currently unable to recover from. Sorry, and also please report a bug.", bytes ) } } fn parse_opt>(bytes: Option) -> Self { bytes .map(|b| Self::parse(b.as_ref())) .unwrap_or(Self::Absent) } fn serialize(self) -> Option> { match self { RcEntry::Present { count } => Some(u64::to_be_bytes(count).to_vec()), RcEntry::Deletable { at_time } => { Some([u64::to_be_bytes(0), u64::to_be_bytes(at_time)].concat()) } RcEntry::Absent => None, } } fn increment(self) -> Self { let old_count = match self { RcEntry::Present { count } => count, _ => 0, }; RcEntry::Present { count: old_count + 1, } } fn decrement(self) -> Self { match self { RcEntry::Present { count } => { if count > 1 { RcEntry::Present { count: count - 1 } } else { RcEntry::Deletable { at_time: now_msec() + BLOCK_GC_DELAY.as_millis() as u64, } } } del => del, } } fn is_zero(&self) -> bool { matches!(self, RcEntry::Deletable { .. } | RcEntry::Absent) } fn is_nonzero(&self) -> bool { !self.is_zero() } fn is_deletable(&self) -> bool { match self { RcEntry::Present { .. } => false, RcEntry::Deletable { at_time } => now_msec() > *at_time, RcEntry::Absent => true, } } fn is_needed(&self) -> bool { !self.is_deletable() } } /// Counts the number of errors when resyncing a block, /// and the time of the last try. /// Used to implement exponential backoff. #[derive(Clone, Copy, Debug)] struct ErrorCounter { errors: u64, last_try: u64, } impl ErrorCounter { fn new(now: u64) -> Self { Self { errors: 1, last_try: now, } } fn decode(data: sled::IVec) -> Self { Self { errors: u64::from_be_bytes(data[0..8].try_into().unwrap()), last_try: u64::from_be_bytes(data[8..16].try_into().unwrap()), } } fn encode(&self) -> Vec { [ u64::to_be_bytes(self.errors), u64::to_be_bytes(self.last_try), ] .concat() } fn add1(self, now: u64) -> Self { Self { errors: self.errors + 1, last_try: now, } } fn delay_msec(&self) -> u64 { (RESYNC_RETRY_DELAY.as_millis() as u64) << std::cmp::min(self.errors - 1, 10) } fn next_try(&self) -> u64 { self.last_try + self.delay_msec() } } fn zstd_encode(mut source: R, level: i32) -> std::io::Result> { let mut result = Vec::::new(); let mut encoder = Encoder::new(&mut result, level)?; encoder.include_checksum(true)?; std::io::copy(&mut source, &mut encoder)?; encoder.finish()?; Ok(result) }