garage/src/model/block.rs

682 lines
18 KiB
Rust

use std::path::{Path, PathBuf};
use std::sync::Arc;
use std::time::Duration;
use arc_swap::ArcSwapOption;
use async_trait::async_trait;
use futures::future::*;
use futures::select;
use serde::{Deserialize, Serialize};
use tokio::fs;
use tokio::io::{AsyncReadExt, AsyncWriteExt};
use tokio::sync::{watch, Mutex, Notify};
use garage_util::data::*;
use garage_util::error::*;
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_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_WORKERS: u64 = 1;
pub const BACKGROUND_TRANQUILITY: u32 = 3;
const BLOCK_RW_TIMEOUT: Duration = Duration::from_secs(42);
const BLOCK_GC_TIMEOUT: Duration = Duration::from_secs(60);
const NEED_BLOCK_QUERY_TIMEOUT: Duration = Duration::from_secs(5);
const RESYNC_RETRY_TIMEOUT: Duration = Duration::from_secs(10);
/// 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(PutBlockMessage),
/// 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),
}
/// Structure used to send a block
#[derive(Debug, Serialize, Deserialize)]
pub struct PutBlockMessage {
/// Hash of the block
pub hash: Hash,
/// Content of the block
#[serde(with = "serde_bytes")]
pub data: Vec<u8>,
}
impl Rpc for BlockRpc {
type Response = Result<BlockRpc, Error>;
}
/// 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<BlockManagerLocked>,
rc: sled::Tree,
resync_queue: sled::Tree,
resync_notify: Notify,
system: Arc<System>,
endpoint: Arc<Endpoint<BlockRpc, Self>>,
pub(crate) garage: ArcSwapOption<Garage>,
}
// 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<System>,
) -> Arc<Self> {
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 endpoint = system
.netapp
.endpoint("garage_model/block.rs/Rpc".to_string());
let manager_locked = BlockManagerLocked();
let block_manager = Arc::new(Self {
replication,
data_dir,
mutation_lock: Mutex::new(manager_locked),
rc,
resync_queue,
resync_notify: Notify::new(),
system,
endpoint,
garage: ArcSwapOption::from(None),
});
block_manager.endpoint.set_handler(block_manager.clone());
block_manager
}
// ---- Public interface ----
/// Ask nodes that might have a block for it
pub async fn rpc_get_block(&self, hash: &Hash) -> Result<Vec<u8>, Error> {
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(msg) = resp {
return Ok(msg.data);
}
}
Err(Error::Message(format!(
"Unable to read block {:?}: no valid blocks returned",
hash
)))
}
/// Send block to nodes that should have it
pub async fn rpc_put_block(&self, hash: Hash, data: Vec<u8>) -> Result<(), Error> {
let who = self.replication.write_nodes(&hash);
self.system
.rpc
.try_call_many(
&self.endpoint,
&who[..],
BlockRpc::PutBlock(PutBlockMessage { 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<bool>) -> 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<bool>,
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| {
let old_v = old.map(u64_from_be_bytes).unwrap_or(0);
Some(u64::to_be_bytes(old_v + 1).to_vec())
})?;
let old_rc = old_rc.map(u64_from_be_bytes).unwrap_or(0);
if old_rc == 0 {
self.put_to_resync(hash, 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| {
let old_v = old.map(u64_from_be_bytes).unwrap_or(0);
if old_v > 1 {
Some(u64::to_be_bytes(old_v - 1).to_vec())
} else {
None
}
})?;
if new_rc.is_none() {
self.put_to_resync(hash, BLOCK_GC_TIMEOUT)?;
}
Ok(())
}
/// Read a block's reference count
pub fn get_block_rc(&self, hash: &Hash) -> Result<u64, Error> {
Ok(self
.rc
.get(hash.as_ref())?
.map(u64_from_be_bytes)
.unwrap_or(0))
}
// ---- Reading and writing blocks locally ----
/// Write a block to disk
async fn write_block(&self, hash: &Hash, data: &[u8]) -> Result<BlockRpc, Error> {
self.mutation_lock
.lock()
.await
.write_block(hash, data, self)
.await
}
/// Read block from disk, verifying it's integrity
async fn read_block(&self, hash: &Hash) -> Result<BlockRpc, Error> {
let path = self.block_path(hash);
let mut f = match fs::File::open(&path).await {
Ok(f) => f,
Err(e) => {
// Not found but maybe we should have had it ??
self.put_to_resync(hash, Duration::from_millis(0))?;
return Err(Into::into(e));
}
};
let mut data = vec![];
f.read_to_end(&mut data).await?;
drop(f);
if blake2sum(&data[..]) != *hash {
self.mutation_lock
.lock()
.await
.move_block_to_corrupted(hash, self)
.await?;
return Err(Error::CorruptData(*hash));
}
Ok(BlockRpc::PutBlock(PutBlockMessage { hash: *hash, data }))
}
/// Check if this node should have a block, but don't actually have it
async fn need_block(&self, hash: &Hash) -> Result<bool, Error> {
let BlockStatus { exists, needed } = self
.mutation_lock
.lock()
.await
.check_block_status(hash, self)
.await?;
Ok(needed && !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
fn block_path(&self, hash: &Hash) -> PathBuf {
let mut path = self.block_dir(hash);
path.push(hex::encode(hash.as_ref()));
path
}
// ---- Resync loop ----
pub fn spawn_background_worker(self: Arc<Self>) {
// Launch 2 simultaneous workers for background resync loop preprocessing
for i in 0..BACKGROUND_WORKERS {
let bm2 = self.clone();
let background = self.system.background.clone();
tokio::spawn(async move {
tokio::time::sleep(Duration::from_secs(10 * (i + 1))).await;
background.spawn_worker(format!("block resync worker {}", i), move |must_exit| {
bm2.resync_loop(must_exit)
});
});
}
}
fn put_to_resync(&self, hash: &Hash, delay: Duration) -> Result<(), Error> {
let when = now_msec() + delay.as_millis() as u64;
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<Self>, mut must_exit: watch::Receiver<bool>) {
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<bool>) -> Result<bool, Error> {
if let Some((time_bytes, hash_bytes)) = self.resync_queue.pop_min()? {
let time_msec = u64_from_be_bytes(&time_bytes[0..8]);
let now = now_msec();
if now >= time_msec {
let hash = Hash::try_from(&hash_bytes[..]).unwrap();
let res = self.resync_block(&hash).await;
if let Err(e) = &res {
warn!("Error when resyncing {:?}: {}", hash, e);
self.put_to_resync(&hash, RESYNC_RETRY_TIMEOUT)?;
}
Ok(true)
} else {
self.resync_queue.insert(time_bytes, hash_bytes)?;
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 {
info!(
"Resync block {:?}: exists {}, needed {}",
hash, exists, needed
);
}
if exists && !needed {
trace!("Offloading block {:?}", 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);
}
}
_ => {
return Err(Error::Message(
"Unexpected response to NeedBlockQuery RPC".to_string(),
));
}
}
}
if !need_nodes.is_empty() {
trace!(
"Block {:?} needed by {} nodes, sending",
hash,
need_nodes.len()
);
let put_block_message = self.read_block(hash).await.err_context("PutBlock RPC")?;
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?;
}
info!(
"Deleting block {:?}, offload finished ({} / {})",
hash,
need_nodes.len(),
who.len()
);
self.mutation_lock
.lock()
.await
.delete_if_unneeded(hash, self)
.await?;
}
if needed && !exists {
// TODO find a way to not do this if they are sending it to us
// Let's suppose this isn't an issue for now with the BLOCK_RW_TIMEOUT delay
// between the RC being incremented and this part being called.
let block_data = self.rpc_get_block(hash).await?;
self.write_block(hash, &block_data[..]).await?;
}
Ok(())
}
async fn for_each_file<F, Fut, State>(
&self,
state: State,
mut f: F,
must_exit: &watch::Receiver<bool>,
) -> Result<(), Error>
where
F: FnMut(State, Hash) -> Fut + Send,
Fut: Future<Output = Result<State, Error>> + 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<bool>,
) -> BoxFuture<'a, Result<State, Error>>
where
F: FnMut(State, Hash) -> Fut + Send,
Fut: Future<Output = Result<State, Error>> + 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?;
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<BlockRpc> for BlockManager {
async fn handle(
self: &Arc<Self>,
message: &BlockRpc,
_from: NodeID,
) -> Result<BlockRpc, Error> {
match message {
BlockRpc::PutBlock(m) => self.write_block(&m.hash, &m.data).await,
BlockRpc::GetBlock(h) => self.read_block(h).await,
BlockRpc::NeedBlockQuery(h) => self.need_block(h).await.map(BlockRpc::NeedBlockReply),
_ => Err(Error::BadRpc("Unexpected RPC message".to_string())),
}
}
}
struct BlockStatus {
exists: bool,
needed: bool,
}
impl BlockManagerLocked {
async fn check_block_status(
&self,
hash: &Hash,
mgr: &BlockManager,
) -> Result<BlockStatus, Error> {
let path = mgr.block_path(hash);
let exists = fs::metadata(&path).await.is_ok();
let needed = mgr.get_block_rc(hash)? > 0;
Ok(BlockStatus { exists, needed })
}
async fn write_block(
&self,
hash: &Hash,
data: &[u8],
mgr: &BlockManager,
) -> Result<BlockRpc, Error> {
let mut path = mgr.block_dir(hash);
fs::create_dir_all(&path).await?;
path.push(hex::encode(hash));
if fs::metadata(&path).await.is_ok() {
return Ok(BlockRpc::Ok);
}
let mut path2 = path.clone();
path2.set_extension("tmp");
let mut f = fs::File::create(&path2).await?;
f.write_all(data).await?;
drop(f);
fs::rename(path2, path).await?;
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 path = mgr.block_path(hash);
let mut path2 = path.clone();
path2.set_extension("corrupted");
fs::rename(path, path2).await?;
mgr.put_to_resync(hash, Duration::from_millis(0))?;
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 {
let path = mgr.block_path(hash);
fs::remove_file(path).await?;
}
Ok(())
}
}
fn u64_from_be_bytes<T: AsRef<[u8]>>(bytes: T) -> u64 {
assert!(bytes.as_ref().len() == 8);
let mut x8 = [0u8; 8];
x8.copy_from_slice(bytes.as_ref());
u64::from_be_bytes(x8)
}