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#![feature(try_trait)]
#[macro_use]
extern crate failure;
extern crate futures_locks;
#[macro_use]
extern crate err_convert_macro;
extern crate cxmr_exchanges;
extern crate cxmr_snapshots;
use std::cell::Cell;
use std::collections::HashMap;
use std::sync::Arc;
use futures_locks::RwLock;
use cxmr_exchanges::Market;
use cxmr_snapshots::Snapshot;
#[derive(Debug, Fail)]
pub enum Error {
#[fail(display = "option none")]
OptionNone,
#[fail(display = "snapshot error: {:?}", _0)]
Snapshot(#[cause] cxmr_snapshots::Error),
}
err_converter!(Snapshot, cxmr_snapshots::Error);
err_converter_no_args!(OptionNone, std::option::NoneError);
pub struct Options {
pub maximum_snapshots: usize,
}
impl Default for Options {
fn default() -> Self {
Options {
maximum_snapshots: 10,
}
}
}
pub type SharedSnapshot = Arc<RwLock<Snapshot>>;
#[derive(Clone)]
pub struct SnapshotCache {
inner: Arc<RwLock<CacheImpl>>,
}
impl SnapshotCache {
pub fn new(options: Options) -> Self {
SnapshotCache {
inner: Arc::new(RwLock::new(CacheImpl::new(options))),
}
}
pub async fn open(
&mut self,
path: &str,
market: Market,
timestamp: u64,
interval: u64,
) -> Result<SharedSnapshot, Error> {
self.inner
.read()
.await
.open(path, market, timestamp, interval)
.await
}
pub async fn open_and_compress(
&mut self,
path: &str,
market: Market,
timestamp: u64,
interval: u64,
) -> Result<SharedSnapshot, Error> {
self.inner
.read()
.await
.open(path, market, timestamp, interval)
.await
}
}
#[derive(Hash, PartialEq, Eq)]
struct CacheKey {
market: Market,
timestamp: u64,
interval: u64,
}
struct CacheImpl {
options: Options,
snapshots: RwLock<HashMap<CacheKey, CachedSnapshot>>,
}
impl CacheImpl {
fn new(options: Options) -> Self {
CacheImpl {
options,
snapshots: RwLock::new(HashMap::default()),
}
}
async fn open(
&self,
path: &str,
market: Market,
timestamp: u64,
interval: u64,
) -> Result<SharedSnapshot, Error> {
let cache_key = CacheKey {
market,
timestamp,
interval,
};
let mut cached = self
.snapshots
.write()
.await
.entry(cache_key)
.or_default()
.clone();
cached.open(path, interval).await
}
}
#[derive(Default, Clone)]
struct CachedSnapshot {
inner: Arc<RwLock<Cell<Option<SharedSnapshot>>>>,
}
impl CachedSnapshot {
async fn open(&mut self, path: &str, interval: u64) -> Result<SharedSnapshot, Error> {
let mut inner = self.inner.write().await;
if let Some(snapshot) = inner.get_mut() {
return Ok(snapshot.clone());
}
let snapshot = Arc::new(RwLock::new(Snapshot::open(path, interval)?));
inner.set(Some(snapshot.clone()));
Ok(snapshot)
}
}