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Prevent database corruption on OOM (#2832)

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* Prevent database corruption on OOM

* Renamed write_flushing
This commit is contained in:
Arkadiy Paronyan 2016-10-24 18:32:06 +02:00 committed by Gav Wood
parent 1b42e9a9af
commit edbd667696
1 changed files with 19 additions and 5 deletions
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24
util/src/kvdb.rs
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@ -277,7 +277,8 @@ pub struct Database {
// Values currently being flushed. Cleared when `flush` completes. // Values currently being flushed. Cleared when `flush` completes.
flushing: RwLock<Vec<HashMap<ElasticArray32<u8>, KeyState>>>, flushing: RwLock<Vec<HashMap<ElasticArray32<u8>, KeyState>>>,
// Prevents concurrent flushes. // Prevents concurrent flushes.
flushing_lock: Mutex<()>, // Value indicates if a flush is in progress.
flushing_lock: Mutex<bool>,
} }
impl Database { impl Database {
@ -379,7 +380,7 @@ impl Database {
write_opts: write_opts, write_opts: write_opts,
overlay: RwLock::new((0..(num_cols + 1)).map(|_| HashMap::new()).collect()), overlay: RwLock::new((0..(num_cols + 1)).map(|_| HashMap::new()).collect()),
flushing: RwLock::new((0..(num_cols + 1)).map(|_| HashMap::new()).collect()), flushing: RwLock::new((0..(num_cols + 1)).map(|_| HashMap::new()).collect()),
flushing_lock: Mutex::new(()), flushing_lock: Mutex::new((false)),
path: path.to_owned(), path: path.to_owned(),
read_opts: read_opts, read_opts: read_opts,
}) })
@ -417,11 +418,10 @@ impl Database {
}; };
} }
/// Commit buffered changes to database. /// Commit buffered changes to database. Must be called under `flush_lock`
pub fn flush(&self) -> Result<(), String> { fn write_flushing_with_lock(&self, _lock: &mut MutexGuard<bool>) -> Result<(), String> {
match *self.db.read() { match *self.db.read() {
Some(DBAndColumns { ref db, ref cfs }) => { Some(DBAndColumns { ref db, ref cfs }) => {
let _lock = self.flushing_lock.lock();
let batch = WriteBatch::new(); let batch = WriteBatch::new();
mem::swap(&mut *self.overlay.write(), &mut *self.flushing.write()); mem::swap(&mut *self.overlay.write(), &mut *self.flushing.write());
{ {
@ -464,6 +464,20 @@ impl Database {
} }
} }
/// Commit buffered changes to database.
pub fn flush(&self) -> Result<(), String> {
let mut lock = self.flushing_lock.lock();
// If RocksDB batch allocation fails the thread gets terminated and the lock is released.
// The value inside the lock is used to detect that.
if *lock {
// This can only happen if another flushing thread is terminated unexpectedly.
return Err("Database write failure. Running low on memory perhaps?".to_owned());
}
*lock = true;
let result = self.write_flushing_with_lock(&mut lock);
*lock = false;
result
}
/// Commit transaction to database. /// Commit transaction to database.
pub fn write(&self, tr: DBTransaction) -> Result<(), String> { pub fn write(&self, tr: DBTransaction) -> Result<(), String> {