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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -1,40 +1,117 @@ | ||
| //! The implementation for Etcd cache. | ||
| use super::KeyValue; | ||
| use super::OverflowArithmetic; | ||
| use crate::watch::EtcdWatchRequest; | ||
| use lockfree_cuckoohash::{pin, LockFreeCuckooHash}; | ||
| use priority_queue::PriorityQueue; | ||
| use smol::channel::Sender; | ||
| use smol::lock::Mutex; | ||
| use std::sync::Arc; | ||
| use std::time::{SystemTime, UNIX_EPOCH}; | ||
| use utilities::Cast; | ||
|
|
||
| /// Cache struct contains a lock-free hashTable. | ||
| #[derive(Clone)] | ||
| pub struct Cache { | ||
| /// map to store key value | ||
| hashtable: Arc<LockFreeCuckooHash<Vec<u8>, KeyValue>>, | ||
| /// lru queue to store the keys in hashtable. | ||
| lru_queue: Arc<Mutex<PriorityQueue<Vec<u8>, u64>>>, | ||
| /// map to store key and watch id | ||
| watch_id_table: Arc<LockFreeCuckooHash<Vec<u8>, i64>>, | ||
| /// Etcd watch request sender. | ||
| watch_sender: Sender<EtcdWatchRequest>, | ||
| } | ||
|
|
||
| impl Cache { | ||
| /// Create a new `Cache` with specified size. | ||
| pub fn new(size: usize) -> Self { | ||
| pub fn new(size: usize, sender: Sender<EtcdWatchRequest>) -> Self { | ||
| Self { | ||
| hashtable: Arc::new(LockFreeCuckooHash::with_capacity(size)), | ||
| lru_queue: Arc::new(Mutex::new(PriorityQueue::new())), | ||
| watch_id_table: Arc::new(LockFreeCuckooHash::with_capacity(size)), | ||
| watch_sender: sender, | ||
| } | ||
| } | ||
|
|
||
| /// Searches a `key` from the cache. | ||
| pub fn search(&self, key: &[u8]) -> Option<KeyValue> { | ||
| let guard = pin(); | ||
| let search_result = self.hashtable.search_with_guard(&key.to_vec(), &guard); | ||
| pub async fn search(&self, key: Vec<u8>) -> Option<KeyValue> { | ||
| let search_result = { | ||
| let guard = pin(); | ||
| self.hashtable.search_with_guard(&key, &guard).cloned() | ||
| }; | ||
| match search_result { | ||
| Some(value) => Some(value.clone()), | ||
| Some(value) => { | ||
| self.lru_queue.lock().await.push(key, Self::get_priority()); | ||
| Some(value.clone()) | ||
| } | ||
| None => None, | ||
| } | ||
| } | ||
|
|
||
| /// Inserts a `key` from the cache. | ||
| pub fn insert(&self, key: Vec<u8>, value: KeyValue) { | ||
| self.hashtable.insert(key, value); | ||
| pub async fn insert(&self, key: Vec<u8>, value: KeyValue) { | ||
| self.hashtable.insert(key.clone(), value); | ||
| self.lru_queue.lock().await.push(key, Self::get_priority()); | ||
| self.adjust_cache_size().await; | ||
| } | ||
|
|
||
| /// Deletes a `key` from the cache. | ||
| pub fn delete(&self, key: &[u8]) { | ||
| self.hashtable.remove(&key.to_vec()); | ||
| pub async fn delete(&self, key: Vec<u8>, cancel_watch: bool) { | ||
| if cancel_watch { | ||
| let watch_id = self | ||
| .search_watch_id(&key.clone()) | ||
| .unwrap_or_else(|| panic!("Fail to get watch id for a key")); | ||
| // Remove watch for this key. | ||
| self.watch_sender | ||
| .send(EtcdWatchRequest::cancel(watch_id.cast())) | ||
| .await | ||
| .unwrap_or_else(|e| panic!("Fail to send watch request, the error is {}", e)); | ||
| } else { | ||
| self.delete_watch_id(&key); | ||
| } | ||
|
|
||
| self.hashtable.remove(&key); | ||
| self.lru_queue.lock().await.remove(&key); | ||
| } | ||
|
|
||
| /// Deletes a watch id from the cache. | ||
| pub fn delete_watch_id(&self, key: &[u8]) { | ||
| self.watch_id_table.remove(&key.to_vec()); | ||
| } | ||
|
|
||
| /// Inserts a watch id to the cache. | ||
| pub fn insert_watch_id(&self, key: Vec<u8>, value: i64) { | ||
| self.watch_id_table.insert(key, value); | ||
| } | ||
|
|
||
| /// Searches a watch id for a specific key. | ||
| pub fn search_watch_id(&self, key: &[u8]) -> Option<i64> { | ||
| let guard = pin(); | ||
| let search_result = self.watch_id_table.search_with_guard(&key.to_vec(), &guard); | ||
| match search_result { | ||
| Some(value) => Some(*value), | ||
| None => None, | ||
| } | ||
| } | ||
|
|
||
| /// Gets the priority of a key in lru queue. | ||
| fn get_priority() -> u64 { | ||
| let current_time = SystemTime::now(); | ||
| let since_the_epoch = current_time | ||
| .duration_since(UNIX_EPOCH) | ||
| .unwrap_or_else(|e| panic!("Fail to get the time since the epoch, the error is {}", e)); | ||
|
|
||
| u64::MAX.overflow_sub(since_the_epoch.as_secs()) | ||
| } | ||
|
|
||
| /// Adjusts cache size if the number of value in cache has exceed the threshold(0.6). | ||
| async fn adjust_cache_size(&self) { | ||
| if self.hashtable.size() > self.hashtable.capacity().overflow_mul(6).overflow_div(10) { | ||
| let queue = self.lru_queue.lock().await; | ||
| if let Some(pop_value) = queue.peek() { | ||
| self.delete(pop_value.0.to_vec().clone(), false).await; | ||
| } | ||
| } | ||
| } | ||
| } |
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