garage/src/block/manager.rs

1104 lines
32 KiB
Rust

use std::convert::TryInto;
use std::path::PathBuf;
use std::pin::Pin;
use std::sync::Arc;
use std::time::Duration;
use arc_swap::ArcSwapOption;
use async_trait::async_trait;
use bytes::Bytes;
use serde::{Deserialize, Serialize};
use futures::{Stream, TryStreamExt};
use futures_util::stream::StreamExt;
use tokio::fs;
use tokio::io::{AsyncReadExt, AsyncWriteExt, BufReader};
use tokio::select;
use tokio::sync::{mpsc, watch, Mutex, Notify};
use opentelemetry::{
trace::{FutureExt as OtelFutureExt, TraceContextExt, Tracer},
Context, KeyValue,
};
use garage_rpc::rpc_helper::netapp::stream::{stream_asyncread, ByteStream};
use garage_db as db;
use garage_db::counted_tree_hack::CountedTree;
use garage_util::background::*;
use garage_util::data::*;
use garage_util::error::*;
use garage_util::metrics::RecordDuration;
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::*;
use crate::metrics::*;
use crate::rc::*;
use crate::repair::*;
/// Size under which data will be stored inlined in database instead of as files
pub const INLINE_THRESHOLD: usize = 3072;
// 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 minimum retry delay is 60 seconds = 1 minute
// The maximum retry delay is 60 seconds * 2^6 = 60 seconds << 6 = 64 minutes (~1 hour)
const RESYNC_RETRY_DELAY_MAX_BACKOFF_POWER: u64 = 6;
// The delay between the moment when the reference counter
// drops to zero, and the moment where we allow ourselves
// to delete the block locally.
pub(crate) 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,
header: DataBlockHeader,
},
/// 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),
}
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,
compression_level: Option<i32>,
background_tranquility: u32,
mutation_lock: [Mutex<BlockManagerLocked>; 256],
pub(crate) rc: BlockRc,
resync_queue: CountedTree,
resync_notify: Notify,
resync_errors: CountedTree,
pub(crate) system: Arc<System>,
endpoint: Arc<Endpoint<BlockRpc, Self>>,
metrics: BlockManagerMetrics,
tx_scrub_command: ArcSwapOption<mpsc::Sender<ScrubWorkerCommand>>,
}
// 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();
enum ResyncIterResult {
BusyDidSomething,
BusyDidNothing,
IdleFor(Duration),
}
impl BlockManager {
pub fn new(
db: &db::Db,
data_dir: PathBuf,
compression_level: Option<i32>,
background_tranquility: u32,
replication: TableShardedReplication,
system: Arc<System>,
) -> Arc<Self> {
let rc = db
.open_tree("block_local_rc")
.expect("Unable to open block_local_rc tree");
let rc = BlockRc::new(rc);
let resync_queue = db
.open_tree("block_local_resync_queue")
.expect("Unable to open block_local_resync_queue tree");
let resync_queue =
CountedTree::new(resync_queue).expect("Could not count block_local_resync_queue");
let resync_errors = db
.open_tree("block_local_resync_errors")
.expect("Unable to open block_local_resync_errors tree");
let resync_errors =
CountedTree::new(resync_errors).expect("Could not count block_local_resync_errors");
let endpoint = system
.netapp
.endpoint("garage_block/manager.rs/Rpc".to_string());
let metrics = BlockManagerMetrics::new(resync_queue.clone(), resync_errors.clone());
let block_manager = Arc::new(Self {
replication,
data_dir,
compression_level,
background_tranquility,
mutation_lock: [(); 256].map(|_| Mutex::new(BlockManagerLocked())),
rc,
resync_queue,
resync_notify: Notify::new(),
resync_errors,
system,
endpoint,
metrics,
tx_scrub_command: ArcSwapOption::new(None),
});
block_manager.endpoint.set_handler(block_manager.clone());
block_manager.clone().spawn_background_workers();
block_manager
}
/// Ask nodes that might have a (possibly compressed) block for it
/// Return it as a stream with a header
async fn rpc_get_raw_block_streaming(
&self,
hash: &Hash,
) -> Result<(DataBlockHeader, ByteStream), Error> {
let who = self.replication.read_nodes(hash);
for node in who.iter() {
let node_id = NodeID::from(*node);
let rpc =
self.endpoint
.call_streaming(&node_id, BlockRpc::GetBlock(*hash), PRIO_NORMAL);
tokio::select! {
res = rpc => {
let res = match res {
Ok(res) => res,
Err(e) => {
debug!("Node {:?} returned error: {}", node, e);
continue;
}
};
let (header, stream) = match res.into_parts() {
(Ok(BlockRpc::PutBlock { hash: _, header }), Some(stream)) => (header, stream),
_ => {
debug!("Node {:?} returned a malformed response", node);
continue;
}
};
return Ok((header, stream));
}
_ = tokio::time::sleep(BLOCK_RW_TIMEOUT) => {
debug!("Node {:?} didn't return block in time, trying next.", node);
}
};
}
Err(Error::Message(format!(
"Unable to read block {:?}: no node returned a valid block",
hash
)))
}
/// Ask nodes that might have a (possibly compressed) block for it
/// Return its entire body
async fn rpc_get_raw_block(&self, hash: &Hash) -> Result<DataBlock, Error> {
let who = self.replication.read_nodes(hash);
for node in who.iter() {
let node_id = NodeID::from(*node);
let rpc =
self.endpoint
.call_streaming(&node_id, BlockRpc::GetBlock(*hash), PRIO_NORMAL);
tokio::select! {
res = rpc => {
let res = match res {
Ok(res) => res,
Err(e) => {
debug!("Node {:?} returned error: {}", node, e);
continue;
}
};
let (header, stream) = match res.into_parts() {
(Ok(BlockRpc::PutBlock { hash: _, header }), Some(stream)) => (header, stream),
_ => {
debug!("Node {:?} returned a malformed response", node);
continue;
}
};
match read_stream_to_end(stream).await {
Ok(bytes) => return Ok(DataBlock::from_parts(header, bytes)),
Err(e) => {
debug!("Error reading stream from node {:?}: {}", node, e);
}
}
}
_ = tokio::time::sleep(BLOCK_RW_TIMEOUT) => {
debug!("Node {:?} didn't return block in time, trying next.", node);
}
};
}
Err(Error::Message(format!(
"Unable to read block {:?}: no node returned a valid block",
hash
)))
}
// ---- Public interface ----
/// Ask nodes that might have a block for it,
/// return it as a stream
pub async fn rpc_get_block_streaming(
&self,
hash: &Hash,
) -> Result<
Pin<Box<dyn Stream<Item = Result<Bytes, std::io::Error>> + Send + Sync + 'static>>,
Error,
> {
let (header, stream) = self.rpc_get_raw_block_streaming(hash).await?;
match header {
DataBlockHeader::Plain => Ok(Box::pin(stream.map_err(|_| {
std::io::Error::new(std::io::ErrorKind::Other, "netapp stream error")
}))),
DataBlockHeader::Compressed => {
// Too many things, I hate it.
let reader = stream_asyncread(stream);
let reader = BufReader::new(reader);
let reader = async_compression::tokio::bufread::ZstdDecoder::new(reader);
Ok(Box::pin(tokio_util::io::ReaderStream::new(reader)))
}
}
}
/// Ask nodes that might have a block for it
pub async fn rpc_get_block(&self, hash: &Hash) -> Result<Bytes, 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: Bytes) -> Result<(), Error> {
let who = self.replication.write_nodes(&hash);
let (header, bytes) = DataBlock::from_buffer(data, self.compression_level)
.await
.into_parts();
let put_block_rpc =
Req::new(BlockRpc::PutBlock { hash, header })?.with_stream_from_buffer(bytes);
self.system
.rpc
.try_call_many(
&self.endpoint,
&who[..],
put_block_rpc,
RequestStrategy::with_priority(PRIO_NORMAL)
.with_quorum(self.replication.write_quorum())
.with_timeout(BLOCK_RW_TIMEOUT),
)
.await?;
Ok(())
}
/// Get lenght of resync queue
pub fn resync_queue_len(&self) -> Result<usize, Error> {
// This currently can't return an error because the CountedTree hack
// doesn't error on .len(), but this will change when we remove the hack
// (hopefully someday!)
Ok(self.resync_queue.len())
}
/// Get number of blocks that have an error
pub fn resync_errors_len(&self) -> Result<usize, Error> {
// (see resync_queue_len comment)
Ok(self.resync_errors.len())
}
/// Get number of items in the refcount table
pub fn rc_len(&self) -> Result<usize, Error> {
Ok(self.rc.rc.len()?)
}
/// Send command to start/stop/manager scrub worker
pub async fn send_scrub_command(&self, cmd: ScrubWorkerCommand) {
let _ = self
.tx_scrub_command
.load()
.as_ref()
.unwrap()
.send(cmd)
.await;
}
//// ----- 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: &Arc<Self>,
tx: &mut db::Transaction,
hash: Hash,
) -> db::TxOpResult<()> {
if self.rc.block_incref(tx, &hash)? {
// 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.
let this = self.clone();
tokio::spawn(async move {
if let Err(e) = this.put_to_resync(&hash, 2 * BLOCK_RW_TIMEOUT) {
error!("Block {:?} could not be put in resync queue: {}.", hash, e);
}
});
}
Ok(())
}
/// Decrement the number of time a block is used
pub fn block_decref(
self: &Arc<Self>,
tx: &mut db::Transaction,
hash: Hash,
) -> db::TxOpResult<()> {
if self.rc.block_decref(tx, &hash)? {
// When the RC is decremented, it might drop to zero,
// indicating that we don't need the block.
// There is a delay before we garbage collect it;
// make sure that it is handled in the resync loop
// after that delay has passed.
let this = self.clone();
tokio::spawn(async move {
if let Err(e) = this.put_to_resync(&hash, BLOCK_GC_DELAY + Duration::from_secs(10))
{
error!("Block {:?} could not be put in resync queue: {}.", hash, e);
}
});
}
Ok(())
}
// ---- Reading and writing blocks locally ----
async fn handle_put_block(
&self,
hash: Hash,
header: DataBlockHeader,
stream: Option<ByteStream>,
) -> Result<(), Error> {
let stream = stream.ok_or_message("missing stream")?;
let bytes = read_stream_to_end(stream).await?;
let data = DataBlock::from_parts(header, bytes);
self.write_block(&hash, &data).await
}
/// Write a block to disk
async fn write_block(&self, hash: &Hash, data: &DataBlock) -> Result<(), Error> {
let tracer = opentelemetry::global::tracer("garage");
let write_size = data.inner_buffer().len() as u64;
self.mutation_lock[hash.as_slice()[0] as usize]
.lock()
.with_context(Context::current_with_span(
tracer.start("Acquire mutation_lock"),
))
.await
.write_block(hash, data, self)
.bound_record_duration(&self.metrics.block_write_duration)
.with_context(Context::current_with_span(
tracer.start("BlockManagerLocked::write_block"),
))
.await?;
self.metrics.bytes_written.add(write_size);
Ok(())
}
async fn handle_get_block(&self, hash: &Hash) -> Resp<BlockRpc> {
let block = match self.read_block(hash).await {
Ok(data) => data,
Err(e) => return Resp::new(Err(e)),
};
let (header, data) = block.into_parts();
self.metrics.bytes_read.add(data.len() as u64);
Resp::new(Ok(BlockRpc::PutBlock {
hash: *hash,
header,
}))
.with_stream_from_buffer(data)
}
/// Read block from disk, verifying it's integrity
pub(crate) async fn read_block(&self, hash: &Hash) -> Result<DataBlock, Error> {
self.read_block_internal(hash)
.bound_record_duration(&self.metrics.block_read_duration)
.await
}
async fn read_block_internal(&self, hash: &Hash) -> Result<DataBlock, Error> {
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.into())
} else {
DataBlock::Plain(data.into())
};
if data.verify(*hash).is_err() {
self.metrics.corruption_counter.add(1);
self.mutation_lock[hash.as_slice()[0] as usize]
.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<bool, Error> {
let BlockStatus { exists, needed } = self.mutation_lock[hash.as_slice()[0] as usize]
.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<bool, Error> {
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 ----
// This part manages a queue of blocks that need to be
// "resynchronized", i.e. that need to have a check that
// they are at present if we need them, or that they are
// deleted once the garbage collection delay has passed.
//
// Here are some explanations on how the resync queue works.
// There are two Sled trees that are used to have information
// about the status of blocks that need to be resynchronized:
//
// - resync_queue: a tree that is ordered first by a timestamp
// (in milliseconds since Unix epoch) that is the time at which
// the resync must be done, and second by block hash.
// The key in this tree is just:
// concat(timestamp (8 bytes), hash (32 bytes))
// The value is the same 32-byte hash.
//
// - resync_errors: a tree that indicates for each block
// if the last resync resulted in an error, and if so,
// the following two informations (see the ErrorCounter struct):
// - how many consecutive resync errors for this block?
// - when was the last try?
// These two informations are used to implement an
// exponential backoff retry strategy.
// The key in this tree is the 32-byte hash of the block,
// and the value is the encoded ErrorCounter value.
//
// We need to have these two trees, because the resync queue
// is not just a queue of items to process, but a set of items
// that are waiting a specific delay until we can process them
// (the delay being necessary both internally for the exponential
// backoff strategy, and exposed as a parameter when adding items
// to the queue, e.g. to wait until the GC delay has passed).
// This is why we need one tree ordered by time, and one
// ordered by identifier of item to be processed (block hash).
//
// When the worker wants to process an item it takes from
// resync_queue, it checks in resync_errors that if there is an
// exponential back-off delay to await, it has passed before we
// process the item. If not, the item in the queue is skipped
// (but added back for later processing after the time of the
// delay).
//
// An alternative that would have seemed natural is to
// only add items to resync_queue with a processing time that is
// after the delay, but there are several issues with this:
// - This requires to synchronize updates to resync_queue and
// resync_errors (with the current model, there is only one thread,
// the worker thread, that accesses resync_errors,
// so no need to synchronize) by putting them both in a lock.
// This would mean that block_incref might need to take a lock
// before doing its thing, meaning it has much more chances of
// not completing successfully if something bad happens to Garage.
// Currently Garage is not able to recover from block_incref that
// doesn't complete successfully, because it is necessary to ensure
// the consistency between the state of the block manager and
// information in the BlockRef table.
// - If a resync fails, we put that block in the resync_errors table,
// and also add it back to resync_queue to be processed after
// the exponential back-off delay,
// but maybe the block is already scheduled to be resynced again
// at another time that is before the exponential back-off delay,
// and we have no way to check that easily. This means that
// in all cases, we need to check the resync_errors table
// in the resync loop at the time when a block is popped from
// the resync_queue.
// Overall, the current design is therefore simpler and more robust
// because it tolerates inconsistencies between the resync_queue
// and resync_errors table (items being scheduled in resync_queue
// for times that are earlier than the exponential back-off delay
// is a natural condition that is handled properly).
fn spawn_background_workers(self: Arc<Self>) {
// Launch a background workers for background resync loop processing
let background = self.system.background.clone();
let worker = ResyncWorker::new(self.clone());
tokio::spawn(async move {
tokio::time::sleep(Duration::from_secs(10)).await;
background.spawn_worker(worker);
});
// Launch a background worker for data store scrubs
let (scrub_tx, scrub_rx) = mpsc::channel(1);
self.tx_scrub_command.store(Some(Arc::new(scrub_tx)));
let scrub_worker = ScrubWorker::new(self.clone(), scrub_rx);
self.system.background.spawn_worker(scrub_worker);
}
pub(crate) fn put_to_resync(&self, hash: &Hash, delay: Duration) -> db::Result<()> {
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) -> db::Result<()> {
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_iter(&self) -> Result<ResyncIterResult, db::Error> {
if let Some((time_bytes, hash_bytes)) = self.resync_queue.first()? {
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
// (we want to do the remove after the insert to ensure
// that the item is not lost if we crash in-between)
self.resync_queue.remove(time_bytes)?;
return Ok(ResyncIterResult::BusyDidNothing);
}
}
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(ResyncIterResult::BusyDidSomething)
} else {
Ok(ResyncIterResult::IdleFor(Duration::from_millis(
time_msec - now,
)))
}
} else {
// Here we wait either for a notification that an item has been
// added to the queue, or for a constant delay of 10 secs to expire.
// The delay avoids a race condition where the notification happens
// between the time we checked the queue and the first poll
// to resync_notify.notified(): if that happens, we'll just loop
// back 10 seconds later, which is fine.
Ok(ResyncIterResult::IdleFor(Duration::from_secs(10)))
}
}
async fn resync_block(&self, hash: &Hash) -> Result<(), Error> {
let BlockStatus { exists, needed } = self.mutation_lock[hash.as_slice()[0] as usize]
.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 who_needs_resps = self
.system
.rpc
.call_many(
&self.endpoint,
&who,
BlockRpc::NeedBlockQuery(*hash),
RequestStrategy::with_priority(PRIO_BACKGROUND)
.with_timeout(NEED_BLOCK_QUERY_TIMEOUT),
)
.await?;
let mut need_nodes = vec![];
for (node, needed) in 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 block = self.read_block(hash).await?;
let (header, bytes) = block.into_parts();
let put_block_message = Req::new(BlockRpc::PutBlock {
hash: *hash,
header,
})?
.with_stream_from_buffer(bytes);
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[hash.as_slice()[0] as usize]
.lock()
.await
.delete_if_unneeded(hash, self)
.await?;
self.rc.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(())
}
}
#[async_trait]
impl StreamingEndpointHandler<BlockRpc> for BlockManager {
async fn handle(self: &Arc<Self>, mut message: Req<BlockRpc>, _from: NodeID) -> Resp<BlockRpc> {
match message.msg() {
BlockRpc::PutBlock { hash, header } => Resp::new(
self.handle_put_block(*hash, *header, message.take_stream())
.await
.map(|_| BlockRpc::Ok),
),
BlockRpc::GetBlock(h) => self.handle_get_block(h).await,
BlockRpc::NeedBlockQuery(h) => {
Resp::new(self.need_block(h).await.map(BlockRpc::NeedBlockReply))
}
m => Resp::new(Err(Error::unexpected_rpc_message(m))),
}
}
}
struct ResyncWorker {
manager: Arc<BlockManager>,
tranquilizer: Tranquilizer,
next_delay: Duration,
}
impl ResyncWorker {
fn new(manager: Arc<BlockManager>) -> Self {
Self {
manager,
tranquilizer: Tranquilizer::new(30),
next_delay: Duration::from_secs(10),
}
}
}
#[async_trait]
impl Worker for ResyncWorker {
fn name(&self) -> String {
"Block resync worker".into()
}
fn info(&self) -> Option<String> {
let mut ret = vec![];
let qlen = self.manager.resync_queue_len().unwrap_or(0);
let elen = self.manager.resync_errors_len().unwrap_or(0);
if qlen > 0 {
ret.push(format!("{} blocks in queue", qlen));
}
if elen > 0 {
ret.push(format!("{} blocks in error state", elen));
}
if !ret.is_empty() {
Some(ret.join(", "))
} else {
None
}
}
async fn work(&mut self, _must_exit: &mut watch::Receiver<bool>) -> Result<WorkerState, Error> {
self.tranquilizer.reset();
match self.manager.resync_iter().await {
Ok(ResyncIterResult::BusyDidSomething) => Ok(self
.tranquilizer
.tranquilize_worker(self.manager.background_tranquility)),
Ok(ResyncIterResult::BusyDidNothing) => Ok(WorkerState::Busy),
Ok(ResyncIterResult::IdleFor(delay)) => {
self.next_delay = delay;
Ok(WorkerState::Idle)
}
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?)
// Here we just give the error to the worker manager,
// it will print it to the logs and increment a counter
Err(e.into())
}
}
}
async fn wait_for_work(&mut self, _must_exit: &watch::Receiver<bool>) -> WorkerState {
select! {
_ = tokio::time::sleep(self.next_delay) => (),
_ = self.manager.resync_notify.notified() => (),
};
WorkerState::Busy
}
}
struct BlockStatus {
exists: bool,
needed: RcEntry,
}
impl BlockManagerLocked {
async fn check_block_status(
&self,
hash: &Hash,
mgr: &BlockManager,
) -> Result<BlockStatus, Error> {
let exists = mgr.is_block_compressed(hash).await.is_ok();
let needed = mgr.rc.get_block_rc(hash)?;
Ok(BlockStatus { exists, needed })
}
async fn write_block(
&self,
hash: &Hash,
data: &DataBlock,
mgr: &BlockManager,
) -> Result<(), Error> {
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(()),
(Ok(false), false) => return 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(())
}
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(())
}
}
/// 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: &[u8]) -> 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<u8> {
[
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, RESYNC_RETRY_DELAY_MAX_BACKOFF_POWER)
}
fn next_try(&self) -> u64 {
self.last_try + self.delay_msec()
}
}
async fn read_stream_to_end(mut stream: ByteStream) -> Result<Bytes, Error> {
let mut parts: Vec<Bytes> = vec![];
while let Some(part) = stream.next().await {
parts.push(part.ok_or_message("error in stream")?);
}
Ok(parts
.iter()
.map(|x| &x[..])
.collect::<Vec<_>>()
.concat()
.into())
}