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|
use std::path::PathBuf;
use std::sync::Arc;
use std::time::Duration;
use futures::stream::*;
use tokio::fs;
use tokio::prelude::*;
use tokio::sync::{watch, Mutex};
use crate::data;
use crate::data::*;
use crate::error::Error;
use crate::membership::System;
use crate::proto::*;
use crate::rpc_client::*;
pub struct BlockManager {
pub data_dir: PathBuf,
pub rc: sled::Tree,
pub resync_queue: sled::Tree,
pub lock: Mutex<()>,
pub system: Arc<System>,
}
impl BlockManager {
pub async fn new(db: &sled::Db, data_dir: PathBuf, system: Arc<System>) -> Arc<Self> {
let rc = db
.open_tree("block_local_rc")
.expect("Unable to open block_local_rc tree");
rc.set_merge_operator(rc_merge);
let resync_queue = db
.open_tree("block_local_resync_queue")
.expect("Unable to open block_local_resync_queue tree");
let block_manager = Arc::new(Self {
rc,
resync_queue,
data_dir,
lock: Mutex::new(()),
system,
});
let bm2 = block_manager.clone();
block_manager
.system
.background
.spawn_worker(move |must_exit| bm2.resync_loop(must_exit))
.await;
block_manager
}
pub async fn write_block(&self, hash: &Hash, data: &[u8]) -> Result<Message, Error> {
let _lock = self.lock.lock().await;
let mut path = self.block_dir(hash);
fs::create_dir_all(&path).await?;
path.push(hex::encode(hash));
if fs::metadata(&path).await.is_ok() {
return Ok(Message::Ok);
}
let mut f = fs::File::create(path).await?;
f.write_all(data).await?;
drop(f);
Ok(Message::Ok)
}
pub async fn read_block(&self, hash: &Hash) -> Result<Message, Error> {
let mut path = self.block_dir(hash);
path.push(hex::encode(hash));
let mut f = fs::File::open(&path).await?;
let mut data = vec![];
f.read_to_end(&mut data).await?;
drop(f);
if data::hash(&data[..]) != *hash {
let _lock = self.lock.lock().await;
eprintln!("Block {:?} is corrupted. Deleting and resyncing.", hash);
fs::remove_file(path).await?;
self.resync_queue.insert(hash.to_vec(), vec![1u8])?;
return Err(Error::CorruptData(hash.clone()));
}
Ok(Message::PutBlock(PutBlockMessage {
hash: hash.clone(),
data,
}))
}
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
}
pub fn block_incref(&self, hash: &Hash) -> Result<(), Error> {
self.rc.merge(&hash, vec![1])?;
Ok(())
}
pub fn block_decref(&self, hash: &Hash) -> Result<(), Error> {
if self.rc.merge(&hash, vec![0])?.is_none() {
self.resync_queue.insert(hash.to_vec(), vec![1u8])?;
}
Ok(())
}
async fn resync_loop(self: Arc<Self>, must_exit: watch::Receiver<bool>) -> Result<(), Error> {
while !*must_exit.borrow() {
if let Some((hash_bytes, _v)) = self.resync_queue.get_gt(&[])? {
let mut hash = [0u8; 32];
hash.copy_from_slice(hash_bytes.as_ref());
let hash = Hash::from(hash);
match self.resync_iter(&hash).await {
Ok(_) => {
self.resync_queue.remove(&hash_bytes)?;
}
Err(e) => {
eprintln!(
"Failed to resync hash {:?}, leaving it in queue: {}",
hash, e
);
}
}
} else {
tokio::time::delay_for(Duration::from_secs(1)).await;
}
}
Ok(())
}
async fn resync_iter(&self, hash: &Hash) -> Result<(), Error> {
let mut path = self.data_dir.clone();
path.push(hex::encode(hash.as_ref()));
let exists = fs::metadata(&path).await.is_ok();
let needed = self
.rc
.get(hash.as_ref())?
.map(|x| u64_from_bytes(x.as_ref()) > 0)
.unwrap_or(false);
if exists && !needed {
// TODO: verify that other nodes that might need it have it ?
fs::remove_file(path).await?;
self.resync_queue.remove(&hash)?;
}
if needed && !exists {
// TODO find a way to not do this if they are sending it to us
let block_data = rpc_get_block(&self.system, &hash).await?;
self.write_block(hash, &block_data[..]).await?;
}
Ok(())
}
}
fn u64_from_bytes(bytes: &[u8]) -> u64 {
assert!(bytes.len() == 8);
let mut x8 = [0u8; 8];
x8.copy_from_slice(bytes);
u64::from_be_bytes(x8)
}
fn rc_merge(_key: &[u8], old: Option<&[u8]>, new: &[u8]) -> Option<Vec<u8>> {
let old = old.map(u64_from_bytes).unwrap_or(0);
assert!(new.len() == 1);
let new = match new[0] {
0 => {
if old > 0 {
old - 1
} else {
0
}
}
1 => old + 1,
_ => unreachable!(),
};
if new == 0 {
None
} else {
Some(u64::to_be_bytes(new).to_vec())
}
}
pub async fn rpc_get_block(system: &Arc<System>, hash: &Hash) -> Result<Vec<u8>, Error> {
let who = system
.ring
.borrow()
.clone()
.walk_ring(&hash, system.config.data_replication_factor);
let msg = Message::GetBlock(hash.clone());
let mut resp_stream = who
.iter()
.map(|to| rpc_call(system.clone(), to, &msg, BLOCK_RW_TIMEOUT))
.collect::<FuturesUnordered<_>>();
while let Some(resp) = resp_stream.next().await {
if let Ok(Message::PutBlock(msg)) = resp {
if data::hash(&msg.data[..]) == *hash {
return Ok(msg.data);
}
}
}
Err(Error::Message(format!(
"Unable to read block {:?}: no valid blocks returned",
hash
)))
}
pub async fn rpc_put_block(system: &Arc<System>, hash: Hash, data: Vec<u8>) -> Result<(), Error> {
let who = system
.ring
.borrow()
.clone()
.walk_ring(&hash, system.config.data_replication_factor);
rpc_try_call_many(
system.clone(),
&who[..],
Message::PutBlock(PutBlockMessage { hash, data }),
(system.config.data_replication_factor + 1) / 2,
BLOCK_RW_TIMEOUT,
)
.await?;
Ok(())
}
|
