continuwuity/src/database/abstraction/sqlite.rs
2022-10-10 14:09:11 +02:00

349 lines
10 KiB
Rust

use super::{watchers::Watchers, KeyValueDatabaseEngine, KvTree};
use crate::{database::Config, Result};
use parking_lot::{Mutex, MutexGuard};
use rusqlite::{Connection, DatabaseName::Main, OptionalExtension};
use std::{
cell::RefCell,
future::Future,
path::{Path, PathBuf},
pin::Pin,
sync::Arc,
};
use thread_local::ThreadLocal;
use tracing::debug;
thread_local! {
static READ_CONNECTION: RefCell<Option<&'static Connection>> = RefCell::new(None);
static READ_CONNECTION_ITERATOR: RefCell<Option<&'static Connection>> = RefCell::new(None);
}
struct PreparedStatementIterator<'a> {
pub iterator: Box<dyn Iterator<Item = TupleOfBytes> + 'a>,
pub _statement_ref: NonAliasingBox<rusqlite::Statement<'a>>,
}
impl Iterator for PreparedStatementIterator<'_> {
type Item = TupleOfBytes;
fn next(&mut self) -> Option<Self::Item> {
self.iterator.next()
}
}
struct NonAliasingBox<T>(*mut T);
impl<T> Drop for NonAliasingBox<T> {
fn drop(&mut self) {
unsafe { Box::from_raw(self.0) };
}
}
pub struct Engine {
writer: Mutex<Connection>,
read_conn_tls: ThreadLocal<Connection>,
read_iterator_conn_tls: ThreadLocal<Connection>,
path: PathBuf,
cache_size_per_thread: u32,
}
impl Engine {
fn prepare_conn(path: &Path, cache_size_kb: u32) -> Result<Connection> {
let conn = Connection::open(path)?;
conn.pragma_update(Some(Main), "page_size", 2048)?;
conn.pragma_update(Some(Main), "journal_mode", "WAL")?;
conn.pragma_update(Some(Main), "synchronous", "NORMAL")?;
conn.pragma_update(Some(Main), "cache_size", -i64::from(cache_size_kb))?;
conn.pragma_update(Some(Main), "wal_autocheckpoint", 0)?;
Ok(conn)
}
fn write_lock(&self) -> MutexGuard<'_, Connection> {
self.writer.lock()
}
fn read_lock(&self) -> &Connection {
self.read_conn_tls
.get_or(|| Self::prepare_conn(&self.path, self.cache_size_per_thread).unwrap())
}
fn read_lock_iterator(&self) -> &Connection {
self.read_iterator_conn_tls
.get_or(|| Self::prepare_conn(&self.path, self.cache_size_per_thread).unwrap())
}
pub fn flush_wal(self: &Arc<Self>) -> Result<()> {
self.write_lock()
.pragma_update(Some(Main), "wal_checkpoint", "RESTART")?;
Ok(())
}
}
impl KeyValueDatabaseEngine for Arc<Engine> {
fn open(config: &Config) -> Result<Self> {
let path = Path::new(&config.database_path).join("conduit.db");
// calculates cache-size per permanent connection
// 1. convert MB to KiB
// 2. divide by permanent connections + permanent iter connections + write connection
// 3. round down to nearest integer
let cache_size_per_thread: u32 = ((config.db_cache_capacity_mb * 1024.0)
/ ((num_cpus::get().max(1) * 2) + 1) as f64)
as u32;
let writer = Mutex::new(Engine::prepare_conn(&path, cache_size_per_thread)?);
let arc = Arc::new(Engine {
writer,
read_conn_tls: ThreadLocal::new(),
read_iterator_conn_tls: ThreadLocal::new(),
path,
cache_size_per_thread,
});
Ok(arc)
}
fn open_tree(&self, name: &str) -> Result<Arc<dyn KvTree>> {
self.write_lock().execute(&format!("CREATE TABLE IF NOT EXISTS {} ( \"key\" BLOB PRIMARY KEY, \"value\" BLOB NOT NULL )", name), [])?;
Ok(Arc::new(SqliteTable {
engine: Arc::clone(self),
name: name.to_owned(),
watchers: Watchers::default(),
}))
}
fn flush(&self) -> Result<()> {
// we enabled PRAGMA synchronous=normal, so this should not be necessary
Ok(())
}
fn cleanup(&self) -> Result<()> {
self.flush_wal()
}
}
pub struct SqliteTable {
engine: Arc<Engine>,
name: String,
watchers: Watchers,
}
type TupleOfBytes = (Vec<u8>, Vec<u8>);
impl SqliteTable {
fn get_with_guard(&self, guard: &Connection, key: &[u8]) -> Result<Option<Vec<u8>>> {
//dbg!(&self.name);
Ok(guard
.prepare(format!("SELECT value FROM {} WHERE key = ?", self.name).as_str())?
.query_row([key], |row| row.get(0))
.optional()?)
}
fn insert_with_guard(&self, guard: &Connection, key: &[u8], value: &[u8]) -> Result<()> {
//dbg!(&self.name);
guard.execute(
format!(
"INSERT OR REPLACE INTO {} (key, value) VALUES (?, ?)",
self.name
)
.as_str(),
[key, value],
)?;
Ok(())
}
pub fn iter_with_guard<'a>(
&'a self,
guard: &'a Connection,
) -> Box<dyn Iterator<Item = TupleOfBytes> + 'a> {
let statement = Box::leak(Box::new(
guard
.prepare(&format!(
"SELECT key, value FROM {} ORDER BY key ASC",
&self.name
))
.unwrap(),
));
let statement_ref = NonAliasingBox(statement);
//let name = self.name.clone();
let iterator = Box::new(
statement
.query_map([], |row| Ok((row.get_unwrap(0), row.get_unwrap(1))))
.unwrap()
.map(move |r| {
//dbg!(&name);
r.unwrap()
}),
);
Box::new(PreparedStatementIterator {
iterator,
_statement_ref: statement_ref,
})
}
}
impl KvTree for SqliteTable {
fn get(&self, key: &[u8]) -> Result<Option<Vec<u8>>> {
self.get_with_guard(self.engine.read_lock(), key)
}
fn insert(&self, key: &[u8], value: &[u8]) -> Result<()> {
let guard = self.engine.write_lock();
self.insert_with_guard(&guard, key, value)?;
drop(guard);
self.watchers.wake(key);
Ok(())
}
fn insert_batch<'a>(&self, iter: &mut dyn Iterator<Item = (Vec<u8>, Vec<u8>)>) -> Result<()> {
let guard = self.engine.write_lock();
guard.execute("BEGIN", [])?;
for (key, value) in iter {
self.insert_with_guard(&guard, &key, &value)?;
}
guard.execute("COMMIT", [])?;
drop(guard);
Ok(())
}
fn increment_batch<'a>(&self, iter: &mut dyn Iterator<Item = Vec<u8>>) -> Result<()> {
let guard = self.engine.write_lock();
guard.execute("BEGIN", [])?;
for key in iter {
let old = self.get_with_guard(&guard, &key)?;
let new = crate::utils::increment(old.as_deref())
.expect("utils::increment always returns Some");
self.insert_with_guard(&guard, &key, &new)?;
}
guard.execute("COMMIT", [])?;
drop(guard);
Ok(())
}
fn remove(&self, key: &[u8]) -> Result<()> {
let guard = self.engine.write_lock();
guard.execute(
format!("DELETE FROM {} WHERE key = ?", self.name).as_str(),
[key],
)?;
Ok(())
}
fn iter<'a>(&'a self) -> Box<dyn Iterator<Item = TupleOfBytes> + 'a> {
let guard = self.engine.read_lock_iterator();
self.iter_with_guard(guard)
}
fn iter_from<'a>(
&'a self,
from: &[u8],
backwards: bool,
) -> Box<dyn Iterator<Item = TupleOfBytes> + 'a> {
let guard = self.engine.read_lock_iterator();
let from = from.to_vec(); // TODO change interface?
//let name = self.name.clone();
if backwards {
let statement = Box::leak(Box::new(
guard
.prepare(&format!(
"SELECT key, value FROM {} WHERE key <= ? ORDER BY key DESC",
&self.name
))
.unwrap(),
));
let statement_ref = NonAliasingBox(statement);
let iterator = Box::new(
statement
.query_map([from], |row| Ok((row.get_unwrap(0), row.get_unwrap(1))))
.unwrap()
.map(move |r| {
//dbg!(&name);
r.unwrap()
}),
);
Box::new(PreparedStatementIterator {
iterator,
_statement_ref: statement_ref,
})
} else {
let statement = Box::leak(Box::new(
guard
.prepare(&format!(
"SELECT key, value FROM {} WHERE key >= ? ORDER BY key ASC",
&self.name
))
.unwrap(),
));
let statement_ref = NonAliasingBox(statement);
let iterator = Box::new(
statement
.query_map([from], |row| Ok((row.get_unwrap(0), row.get_unwrap(1))))
.unwrap()
.map(move |r| {
//dbg!(&name);
r.unwrap()
}),
);
Box::new(PreparedStatementIterator {
iterator,
_statement_ref: statement_ref,
})
}
}
fn increment(&self, key: &[u8]) -> Result<Vec<u8>> {
let guard = self.engine.write_lock();
let old = self.get_with_guard(&guard, key)?;
let new =
crate::utils::increment(old.as_deref()).expect("utils::increment always returns Some");
self.insert_with_guard(&guard, key, &new)?;
Ok(new)
}
fn scan_prefix<'a>(&'a self, prefix: Vec<u8>) -> Box<dyn Iterator<Item = TupleOfBytes> + 'a> {
Box::new(
self.iter_from(&prefix, false)
.take_while(move |(key, _)| key.starts_with(&prefix)),
)
}
fn watch_prefix<'a>(&'a self, prefix: &[u8]) -> Pin<Box<dyn Future<Output = ()> + Send + 'a>> {
self.watchers.watch(prefix)
}
fn clear(&self) -> Result<()> {
debug!("clear: running");
self.engine
.write_lock()
.execute(format!("DELETE FROM {}", self.name).as_str(), [])?;
debug!("clear: ran");
Ok(())
}
}