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//! The core module
use rayon::iter::{ParallelBridge, ParallelIterator};
use std::{collections::BTreeMap, sync::Arc};
use crate::{
basic::{Delta, PropTag, Value, EID},
error::Error,
method::{MergeFn, TickFn},
};
use moka::sync::Cache;
pub use sled::Config;
use sled::Db;
use typed_sled::Tree;
/// As the name says.
pub struct Database {
db: Db,
props: BTreeMap<PropTag, Arc<Prop>>,
}
impl Database {
/// Create a new database.
///
/// Using sled config. See more in [`Config`]
pub fn new(conf: Config) -> Result<Self, Error> {
Ok(Database {
db: conf.open()?,
props: BTreeMap::default(),
})
}
}
impl Default for Database {
fn default() -> Database {
Database {
db: Config::default()
.path("db/default")
.cache_capacity(1_000_000_000)
.flush_every_ms(Some(1000))
.open()
.expect("Error when open default db"),
props: BTreeMap::default(),
}
}
}
impl Database {
/// Get Prop reference from Database.
///
/// Return None if not exist.
pub fn get_prop(&self, prop: &PropTag) -> Option<Arc<Prop>> {
self.props.get(prop).map(|x| x.clone())
}
/// If already exists, return the old data but register new method.
pub fn create_prop(
&mut self,
prop_name: PropTag,
merge: impl MergeFn,
tick: impl TickFn,
) -> Arc<Prop> {
let prop = self
.props
.entry(prop_name.clone())
.or_insert_with(|| Arc::new(Prop::new(&self.db, prop_name, tick, merge)))
.clone();
prop
}
}
/// The level-2 storage beneath Database
pub struct Prop {
name: PropTag,
tree: Tree<EID, Value>,
tick_method: Arc<dyn TickFn>,
cache: Cache<EID, Option<Value>>,
}
impl Prop {
/// Create a new Prop.
///
/// Note that the merge method is necessary,
/// if not used, just invoke an empty closure like `|_,_,_|None`.
pub fn new(db: &Db, name: PropTag, tick: impl TickFn, merge: impl MergeFn) -> Self {
let mut rtn = Self {
name: name.clone(),
tree: Tree::<EID, Value>::open::<PropTag>(db, name),
tick_method: Arc::new(tick),
cache: Cache::builder().max_capacity(1024 * 1024).build(),
};
rtn.register_merge(merge);
rtn
}
}
impl Prop {
/// Return the name of this Prop.
pub fn name(&self) -> PropTag {
self.name
}
/// Get a value for a eid in Prop.
///
/// # Example
/// ```rust
/// use retable::{Database, Config, basic::{EID, Value}};
///
/// // create a temporary database to avoid old disk file polution.
/// let mut db = Database::new(Config::default().temporary(true)).unwrap();
/// // create a prop with non-bound method.
/// let prop = db.create_prop("test_int".into(), |_, _, _| None, |_,_,_|None);
///
/// // Example eid is 1.
/// let eid = EID::new(1);
///
/// // Get a non-exist value, it's a None.
/// assert_eq!(prop.get(&eid), None);
///
/// // Set a Int(8) for eid(1) and get it.
/// prop.set(&eid, Value::Int(8), false);
/// assert_eq!(prop.get(&eid), Some(Value::Int(8)));
/// ```
///
pub fn get(&self, eid: &EID) -> Option<Value> {
// 访问缓存
if let Some(result) = self.cache.get(&eid) {
// 缓存命中
return result;
}
// 缓存未命中
let rtn = self
.tree
.get(&eid)
.expect(format!("Error when get {:?}", &eid).as_str());
// 更新缓存
// 对于None值，也会缓存
self.cache.insert(*eid, rtn);
rtn
}
/// Set a value for a eid in Prop.
/// If retrieve is true, return old value.
///
/// # Example
/// ```rust
/// use retable::{Database, Config, basic::{EID, Value}};
///
///
/// // create a temporary database to avoid old disk file polution.
/// let mut db = Database::new(Config::default().temporary(true)).unwrap();
/// // create a prop with non-bound method.
/// let prop = db.create_prop("test_int".into(), |_, _, _| None, |_,_,_|None);
///
/// let eid = EID::new(1);
/// // Set a Int(8) for eid(1) and get it.
/// let old = prop.set(&eid, Value::Int(42), true);
/// assert_eq!(old, None);
/// assert_eq!(prop.get(&eid), Some(Value::Int(42)));
///
/// // Return the old value if retrieve is true.
/// let old = prop.set(&eid, Value::Int(43), true);
/// assert_eq!(old, Some(Value::Int(42)));
/// assert_eq!(prop.get(&eid), Some(Value::Int(43)));
///
/// // Always return a None if retrieve is false.
/// let old = prop.set(&eid, Value::Int(2001), false);
/// assert_eq!(old, None);
/// assert_eq!(prop.get(&eid), Some(Value::Int(2001)));
/// ```
///
pub fn set(&self, eid: &EID, value: Value, retrieve: bool) -> Option<Value> {
self.cache.insert(*eid, Some(value));
let old = self
.tree
.insert(&eid, &value)
.expect(format!("Error when set {:?} to {:?}", eid, value).as_str());
if retrieve {
old
} else {
None
}
}
/// Remove entry from Prop.
/// If retrieve is true, return old value.
///
/// # Example
/// ```rust
/// use retable::{Database, Config, basic::{EID, Value}};
///
/// // create a temporary database to avoid old disk file polution.
/// let mut db = Database::new(Config::default().temporary(true)).unwrap();
/// // create a prop with non-bound method.
/// let prop = db.create_prop("test_int".into(), |_, _, _| None, |_,_,_| None);
///
/// // Set a value for eid(1) and eid(2) in prop.
/// prop.set(&EID::new(1), Value::Int(42), false);
/// prop.set(&EID::new(2), Value::Int(42), false);
/// // Let's remove it, and fetch the old value, just like "pop".
/// let value = prop.remove(&EID::new(1), true);
/// assert_eq!(value, Some(Value::Int(42)));
///
/// // Remove the value without retrieve will always return a None.
/// let value = prop.remove(&EID::new(2), false);
/// assert_eq!(value, None);
///
/// // Now we lost eid(1) and eid(2) forever.
/// assert!(prop.get(&EID::new(1)).is_none());
/// assert!(prop.get(&EID::new(2)).is_none());
/// ```
pub fn remove(&self, eid: &EID, retrieve: bool) -> Option<Value> {
self.cache.insert(*eid, None);
if let Some(v) = self
.tree
.remove(&eid)
.expect(format!("Error when remove prop {:?}", eid).as_str())
{
if retrieve {
Some(v)
} else {
None
}
} else {
None
}
}
/// Register a merge function for Prop.
/// See [Prop::merge] for more.
pub fn register_merge(&mut self, f: impl MergeFn) -> () {
self.tree.set_merge_operator(f); // 使用typed_sled的merge方法
}
/// Merge a delta to a value(index by given eid) in Prop.
///
/// # Example
/// ```rust
/// use retable::{Database, Config, basic::{EID, Value, Delta}};
///
/// // First define a merge function,
/// // which merge a delta value int into the old value by addition, and return the new value.
/// //
/// // the old one is called "old", the new one is called "delta".
/// //
/// // Return None if either value is not int. Return Some(Value) if both values are int.
/// // Do nothing if old value is None.
/// // Method signature is defined by [`crate::MergeFn`]
/// const fn int_add_merge(_: EID, old: Option<Value>, delta: Delta) -> Option<Value> {
/// if let Some(old) = old {
/// match (old, delta) {
/// (Value::Int(v), Delta::Int(d)) => {
/// Some(Value::Int(v + d))
/// }
/// _ => {
/// None
/// }
/// }
/// } else {
/// None
/// }
/// }
///
/// // create a temporary database to avoid old disk file polution.
/// let mut db = Database::new(Config::default().temporary(true)).unwrap();
/// // create a prop with int_add_merge and non-tick method.
/// let prop = db.create_prop("test_int".into(), int_add_merge, |_,_,_| None);
///
/// // Set some value first.
/// prop.set(&EID::new(1), Value::Int(42), false);
/// prop.set(&EID::new(2), Value::Int(2023), false);
///
/// // The delta that should be merged
/// let delta = Delta::Int(666);
/// // Merge it.
/// // Note that the prop is immutable, the Sync and Send traits is garenteed by inner design.
/// // So **DO NOT** use a Mutex (or any other lock) to protect the prop.
/// prop.merge(&EID::new(1), delta);
/// prop.merge(&EID::new(2), delta);
///
/// // Check the result.
/// assert_eq!(prop.get(&EID::new(1)), Some(Value::Int(708)));
/// assert_eq!(prop.get(&EID::new(2)), Some(Value::Int(2689)));
///
/// // The None value merged function is fully defined by the Merge Function
/// // In our scenery, it will do nothing. You can modify the merge method to implement more complex logic.
/// prop.merge(&EID::new(3), delta);
/// assert_eq!(prop.get(&EID::new(3)), None);
/// ```
///
pub fn merge(&self, eid: &EID, delta: Delta) -> () {
let new = self.tree.merge(&eid, &delta).unwrap();
self.cache.insert(*eid, new);
}
/// See more in [`crate::method::TickFn`]
pub fn register_tick(&mut self, f: impl TickFn) -> () {
self.tick_method = Arc::new(f);
}
/// Tick all entity.
///
/// Tick actions is launched in parellar, by calling tick method using (&EID, Value, &Self)
/// The result delta of every tick is auto merged.
///
/// See more in [`crate::method::TickFn`]
pub fn tick(&self) {
self.tree.iter().par_bridge().for_each(|i| {
if let Ok((eid, value)) = i {
let result = (self.tick_method)(&eid, value, self);
if let Some(delta) = result {
self.merge(&eid, delta);
}
}
})
}
}