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use super::{
base_cache::{BaseCache, HouseKeeperArc, MAX_SYNC_REPEATS, WRITE_RETRY_INTERVAL_MICROS},
housekeeper::InnerSync,
value_initializer::ValueInitializer,
CacheBuilder, ConcurrentCacheExt, PredicateId, Weigher, WriteOp,
};
use crate::{sync::value_initializer::InitResult, PredicateError};
use crossbeam_channel::{Sender, TrySendError};
use std::{
any::TypeId,
borrow::Borrow,
collections::hash_map::RandomState,
hash::{BuildHasher, Hash},
sync::Arc,
time::Duration,
};
/// A thread-safe concurrent in-memory cache.
///
/// `Cache` supports full concurrency of retrievals and a high expected concurrency
/// for updates.
///
/// `Cache` utilizes a lock-free concurrent hash table `SegmentedHashMap` from the
/// [moka-cht][moka-cht-crate] crate for the central key-value storage. `Cache`
/// performs a best-effort bounding of the map using an entry replacement algorithm
/// to determine which entries to evict when the capacity is exceeded.
///
/// [moka-cht-crate]: https://crates.io/crates/moka-cht
///
/// # Examples
///
/// Cache entries are manually added using [`insert`](#method.insert) or
/// [`get_or_insert_with`](#method.get_or_insert_with) method, and are stored in the
/// cache until either evicted or manually invalidated.
///
/// Here's an example of reading and updating a cache by using multiple threads:
///
/// ```rust
/// use moka::sync::Cache;
///
/// use std::thread;
///
/// fn value(n: usize) -> String {
/// format!("value {}", n)
/// }
///
/// const NUM_THREADS: usize = 16;
/// const NUM_KEYS_PER_THREAD: usize = 64;
///
/// // Create a cache that can store up to 10,000 entries.
/// let cache = Cache::new(10_000);
///
/// // Spawn threads and read and update the cache simultaneously.
/// let threads: Vec<_> = (0..NUM_THREADS)
/// .map(|i| {
/// // To share the same cache across the threads, clone it.
/// // This is a cheap operation.
/// let my_cache = cache.clone();
/// let start = i * NUM_KEYS_PER_THREAD;
/// let end = (i + 1) * NUM_KEYS_PER_THREAD;
///
/// thread::spawn(move || {
/// // Insert 64 entries. (NUM_KEYS_PER_THREAD = 64)
/// for key in start..end {
/// my_cache.insert(key, value(key));
/// // get() returns Option<String>, a clone of the stored value.
/// assert_eq!(my_cache.get(&key), Some(value(key)));
/// }
///
/// // Invalidate every 4 element of the inserted entries.
/// for key in (start..end).step_by(4) {
/// my_cache.invalidate(&key);
/// }
/// })
/// })
/// .collect();
///
/// // Wait for all threads to complete.
/// threads.into_iter().for_each(|t| t.join().expect("Failed"));
///
/// // Verify the result.
/// for key in 0..(NUM_THREADS * NUM_KEYS_PER_THREAD) {
/// if key % 4 == 0 {
/// assert_eq!(cache.get(&key), None);
/// } else {
/// assert_eq!(cache.get(&key), Some(value(key)));
/// }
/// }
/// ```
///
/// If you want to atomically initialize and insert a value when the key is not
/// present, you might want to check other insertion methods
/// [`get_or_insert_with`](#method.get_or_insert_with) and
/// [`get_or_try_insert_with`](#method.get_or_try_insert_with).
///
/// # Avoiding to clone the value at `get`
///
/// The return type of `get` method is `Option<V>` instead of `Option<&V>`. Every
/// time `get` is called for an existing key, it creates a clone of the stored value
/// `V` and returns it. This is because the `Cache` allows concurrent updates from
/// threads so a value stored in the cache can be dropped or replaced at any time by
/// any other thread. `get` cannot return a reference `&V` as it is impossible to
/// guarantee the value outlives the reference.
///
/// If you want to store values that will be expensive to clone, wrap them by
/// `std::sync::Arc` before storing in a cache. [`Arc`][rustdoc-std-arc] is a
/// thread-safe reference-counted pointer and its `clone()` method is cheap.
///
/// [rustdoc-std-arc]: https://doc.rust-lang.org/stable/std/sync/struct.Arc.html
///
/// # Size-based Eviction
///
/// ```rust
/// use std::convert::TryInto;
/// use moka::sync::Cache;
///
/// // Evict based on the number of entries in the cache.
/// let cache = Cache::builder()
/// // Up to 10,000 entries.
/// .max_capacity(10_000)
/// // Create the cache.
/// .build();
/// cache.insert(1, "one".to_string());
///
/// // Evict based on the byte length of strings in the cache.
/// let cache = Cache::builder()
/// // A weigher closure takes &K and &V and returns a u32
/// // representing the relative size of the entry.
/// .weigher(|_key, value: &String| -> u32 {
/// value.len().try_into().unwrap_or(u32::MAX)
/// })
/// // This cache will hold up to 32MiB of values.
/// .max_capacity(32 * 1024 * 1024)
/// .build();
/// cache.insert(2, "two".to_string());
/// ```
///
/// If your cache should not grow beyond a certain size, use the `max_capacity`
/// method of the [`CacheBuilder`][builder-struct] to set the upper bound. The cache
/// will try to evict entries that have not been used recently or very often.
///
/// At the cache creation time, a weigher closure can be set by the `weigher` method
/// of the `CacheBuilder`. A weigher closure takes `&K` and `&V` as the arguments and
/// returns a `u32` representing the relative size of the entry:
///
/// - If the `weigher` is _not_ set, the cache will treat each entry has the same
/// size of `1`. This means the cache will be bounded by the number of entries.
/// - If the `weigher` is set, the cache will call the weigher to calculate the
/// weighted size (relative size) on an entry. This means the cache will be bounded
/// by the total weighted size of entries.
///
/// Note that weighted sizes are not used when making eviction selections.
///
/// [builder-struct]: ./struct.CacheBuilder.html
///
/// # Time-based Expirations
///
/// `Cache` supports the following expiration policies:
///
/// - **Time to live**: A cached entry will be expired after the specified duration
/// past from `insert`.
/// - **Time to idle**: A cached entry will be expired after the specified duration
/// past from `get` or `insert`.
///
/// ```rust
/// use moka::sync::Cache;
/// use std::time::Duration;
///
/// let cache = Cache::builder()
/// // Time to live (TTL): 30 minutes
/// .time_to_live(Duration::from_secs(30 * 60))
/// // Time to idle (TTI): 5 minutes
/// .time_to_idle(Duration::from_secs( 5 * 60))
/// // Create the cache.
/// .build();
///
/// // This entry will expire after 5 minutes (TTI) if there is no get().
/// cache.insert(0, "zero");
///
/// // This get() will extend the entry life for another 5 minutes.
/// cache.get(&0);
///
/// // Even though we keep calling get(), the entry will expire
/// // after 30 minutes (TTL) from the insert().
/// ```
///
/// # Thread Safety
///
/// All methods provided by the `Cache` are considered thread-safe, and can be safely
/// accessed by multiple concurrent threads.
///
/// - `Cache<K, V, S>` requires trait bounds `Send`, `Sync` and `'static` for `K`
/// (key), `V` (value) and `S` (hasher state).
/// - `Cache<K, V, S>` will implement `Send` and `Sync`.
///
/// # Sharing a cache across threads
///
/// To share a cache across threads, do one of the followings:
///
/// - Create a clone of the cache by calling its `clone` method and pass it to other
/// thread.
/// - Wrap the cache by a `sync::OnceCell` or `sync::Lazy` from
/// [once_cell][once-cell-crate] create, and set it to a `static` variable.
///
/// Cloning is a cheap operation for `Cache` as it only creates thread-safe
/// reference-counted pointers to the internal data structures.
///
/// [once-cell-crate]: https://crates.io/crates/once_cell
///
/// # Hashing Algorithm
///
/// By default, `Cache` uses a hashing algorithm selected to provide resistance
/// against HashDoS attacks. It will be the same one used by
/// `std::collections::HashMap`, which is currently SipHash 1-3.
///
/// While SipHash's performance is very competitive for medium sized keys, other
/// hashing algorithms will outperform it for small keys such as integers as well as
/// large keys such as long strings. However those algorithms will typically not
/// protect against attacks such as HashDoS.
///
/// The hashing algorithm can be replaced on a per-`Cache` basis using the
/// [`build_with_hasher`][build-with-hasher-method] method of the
/// `CacheBuilder`. Many alternative algorithms are available on crates.io, such
/// as the [aHash][ahash-crate] crate.
///
/// [build-with-hasher-method]: ./struct.CacheBuilder.html#method.build_with_hasher
/// [ahash-crate]: https://crates.io/crates/ahash
///
#[derive(Clone)]
pub struct Cache<K, V, S = RandomState> {
base: BaseCache<K, V, S>,
value_initializer: Arc<ValueInitializer<K, V, S>>,
}
// TODO: https://github.com/moka-rs/moka/issues/54
#[allow(clippy::non_send_fields_in_send_ty)]
unsafe impl<K, V, S> Send for Cache<K, V, S>
where
K: Send + Sync,
V: Send + Sync,
S: Send,
{
}
unsafe impl<K, V, S> Sync for Cache<K, V, S>
where
K: Send + Sync,
V: Send + Sync,
S: Sync,
{
}
impl<K, V> Cache<K, V, RandomState>
where
K: Hash + Eq + Send + Sync + 'static,
V: Clone + Send + Sync + 'static,
{
/// Constructs a new `Cache<K, V>` that will store up to the `max_capacity`.
///
/// To adjust various configuration knobs such as `initial_capacity` or
/// `time_to_live`, use the [`CacheBuilder`][builder-struct].
///
/// [builder-struct]: ./struct.CacheBuilder.html
pub fn new(max_capacity: u64) -> Self {
let build_hasher = RandomState::default();
Self::with_everything(
Some(max_capacity),
None,
build_hasher,
None,
None,
None,
false,
)
}
/// Returns a [`CacheBuilder`][builder-struct], which can builds a `Cache` or
/// `SegmentedCache` with various configuration knobs.
///
/// [builder-struct]: ./struct.CacheBuilder.html
pub fn builder() -> CacheBuilder<K, V, Cache<K, V, RandomState>> {
CacheBuilder::default()
}
}
impl<K, V, S> Cache<K, V, S>
where
K: Hash + Eq + Send + Sync + 'static,
V: Clone + Send + Sync + 'static,
S: BuildHasher + Clone + Send + Sync + 'static,
{
pub(crate) fn with_everything(
max_capacity: Option<u64>,
initial_capacity: Option<usize>,
build_hasher: S,
weigher: Option<Weigher<K, V>>,
time_to_live: Option<Duration>,
time_to_idle: Option<Duration>,
invalidator_enabled: bool,
) -> Self {
Self {
base: BaseCache::new(
max_capacity,
initial_capacity,
build_hasher.clone(),
weigher,
time_to_live,
time_to_idle,
invalidator_enabled,
),
value_initializer: Arc::new(ValueInitializer::with_hasher(build_hasher)),
}
}
/// Returns a _clone_ of the value corresponding to the key.
///
/// If you want to store values that will be expensive to clone, wrap them by
/// `std::sync::Arc` before storing in a cache. [`Arc`][rustdoc-std-arc] is a
/// thread-safe reference-counted pointer and its `clone()` method is cheap.
///
/// The key may be any borrowed form of the cache's key type, but `Hash` and `Eq`
/// on the borrowed form _must_ match those for the key type.
///
/// [rustdoc-std-arc]: https://doc.rust-lang.org/stable/std/sync/struct.Arc.html
pub fn get<Q>(&self, key: &Q) -> Option<V>
where
Arc<K>: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
self.base.get_with_hash(key, self.base.hash(key))
}
pub(crate) fn get_with_hash<Q>(&self, key: &Q, hash: u64) -> Option<V>
where
Arc<K>: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
self.base.get_with_hash(key, hash)
}
/// Ensures the value of the key exists by inserting the result of the init
/// function if not exist, and returns a _clone_ of the value.
///
/// This method prevents to evaluate the init closure multiple times on the same
/// key even if the method is concurrently called by many threads; only one of
/// the calls evaluates its closure, and other calls wait for that closure to
/// complete.
///
/// # Example
///
/// ```rust
/// use moka::sync::Cache;
/// use std::{sync::Arc, thread, time::Duration};
///
/// const TEN_MIB: usize = 10 * 1024 * 1024; // 10MiB
/// let cache = Cache::new(100);
///
/// // Spawn four threads.
/// let threads: Vec<_> = (0..4_u8)
/// .map(|task_id| {
/// let my_cache = cache.clone();
/// thread::spawn(move || {
/// println!("Thread {} started.", task_id);
///
/// // Try to insert and get the value for key1. Although all four
/// // threads will call `get_or_insert_with` at the same time, the
/// // `init` closure must be evaluated only once.
/// let value = my_cache.get_or_insert_with("key1", || {
/// println!("Thread {} inserting a value.", task_id);
/// Arc::new(vec![0u8; TEN_MIB])
/// });
///
/// // Ensure the value exists now.
/// assert_eq!(value.len(), TEN_MIB);
/// thread::sleep(Duration::from_millis(10));
/// assert!(my_cache.get(&"key1").is_some());
///
/// println!("Thread {} got the value. (len: {})", task_id, value.len());
/// })
/// })
/// .collect();
///
/// // Wait all threads to complete.
/// threads
/// .into_iter()
/// .for_each(|t| t.join().expect("Thread failed"));
/// ```
///
/// **Result**
///
/// - The `init` closure was called exactly once by thread 1.
/// - Other threads were blocked until thread 1 inserted the value.
///
/// ```console
/// Thread 1 started.
/// Thread 0 started.
/// Thread 3 started.
/// Thread 2 started.
/// Thread 1 inserting a value.
/// Thread 2 got the value. (len: 10485760)
/// Thread 1 got the value. (len: 10485760)
/// Thread 0 got the value. (len: 10485760)
/// Thread 3 got the value. (len: 10485760)
/// ```
///
/// # Panics
///
/// This method panics when the `init` closure has been panicked. When it
/// happens, only the caller whose `init` closure panicked will get the panic
/// (e.g. only thread 1 in the above sample). If there are other calls in
/// progress (e.g. thread 0, 2 and 3 above), this method will restart and resolve
/// one of the remaining `init` closure.
///
pub fn get_or_insert_with(&self, key: K, init: impl FnOnce() -> V) -> V {
let hash = self.base.hash(&key);
let key = Arc::new(key);
self.get_or_insert_with_hash_and_fun(key, hash, init)
}
pub(crate) fn get_or_insert_with_hash_and_fun(
&self,
key: Arc<K>,
hash: u64,
init: impl FnOnce() -> V,
) -> V {
if let Some(v) = self.get_with_hash(&key, hash) {
return v;
}
match self.value_initializer.init_or_read(Arc::clone(&key), init) {
InitResult::Initialized(v) => {
self.insert_with_hash(Arc::clone(&key), hash, v.clone());
self.value_initializer
.remove_waiter(&key, TypeId::of::<()>());
v
}
InitResult::ReadExisting(v) => v,
InitResult::InitErr(_) => unreachable!(),
}
}
/// Try to ensure the value of the key exists by inserting an `Ok` result of the
/// init closure if not exist, and returns a _clone_ of the value or the `Err`
/// returned by the closure.
///
/// This method prevents to evaluate the init closure multiple times on the same
/// key even if the method is concurrently called by many threads; only one of
/// the calls evaluates its closure (as long as these closures return the same
/// error type), and other calls wait for that closure to complete.
///
/// # Example
///
/// ```rust
/// use moka::sync::Cache;
/// use std::{path::Path, time::Duration, thread};
///
/// /// This function tries to get the file size in bytes.
/// fn get_file_size(thread_id: u8, path: impl AsRef<Path>) -> Result<u64, std::io::Error> {
/// println!("get_file_size() called by thread {}.", thread_id);
/// Ok(std::fs::metadata(path)?.len())
/// }
///
/// let cache = Cache::new(100);
///
/// // Spawn four threads.
/// let threads: Vec<_> = (0..4_u8)
/// .map(|thread_id| {
/// let my_cache = cache.clone();
/// thread::spawn(move || {
/// println!("Thread {} started.", thread_id);
///
/// // Try to insert and get the value for key1. Although all four
/// // threads will call `get_or_try_insert_with` at the same time,
/// // get_file_size() must be called only once.
/// let value = my_cache.get_or_try_insert_with(
/// "key1",
/// || get_file_size(thread_id, "./Cargo.toml"),
/// );
///
/// // Ensure the value exists now.
/// assert!(value.is_ok());
/// thread::sleep(Duration::from_millis(10));
/// assert!(my_cache.get(&"key1").is_some());
///
/// println!(
/// "Thread {} got the value. (len: {})",
/// thread_id,
/// value.unwrap()
/// );
/// })
/// })
/// .collect();
///
/// // Wait all threads to complete.
/// threads
/// .into_iter()
/// .for_each(|t| t.join().expect("Thread failed"));
/// ```
///
/// **Result**
///
/// - `get_file_size()` was called exactly once by thread 1.
/// - Other threads were blocked until thread 1 inserted the value.
///
/// ```console
/// Thread 1 started.
/// Thread 2 started.
/// get_file_size() called by thread 1.
/// Thread 3 started.
/// Thread 0 started.
/// Thread 2 got the value. (len: 1466)
/// Thread 0 got the value. (len: 1466)
/// Thread 1 got the value. (len: 1466)
/// Thread 3 got the value. (len: 1466)
/// ```
///
/// # Panics
///
/// This method panics when the `init` closure has been panicked. When it
/// happens, only the caller whose `init` closure panicked will get the panic
/// (e.g. only thread 1 in the above sample). If there are other calls in
/// progress (e.g. thread 0, 2 and 3 above), this method will restart and resolve
/// one of the remaining `init` closure.
///
pub fn get_or_try_insert_with<F, E>(&self, key: K, init: F) -> Result<V, Arc<E>>
where
F: FnOnce() -> Result<V, E>,
E: Send + Sync + 'static,
{
let hash = self.base.hash(&key);
let key = Arc::new(key);
self.get_or_try_insert_with_hash_and_fun(key, hash, init)
}
pub(crate) fn get_or_try_insert_with_hash_and_fun<F, E>(
&self,
key: Arc<K>,
hash: u64,
init: F,
) -> Result<V, Arc<E>>
where
F: FnOnce() -> Result<V, E>,
E: Send + Sync + 'static,
{
if let Some(v) = self.get_with_hash(&key, hash) {
return Ok(v);
}
match self
.value_initializer
.try_init_or_read(Arc::clone(&key), init)
{
InitResult::Initialized(v) => {
self.insert_with_hash(Arc::clone(&key), hash, v.clone());
self.value_initializer
.remove_waiter(&key, TypeId::of::<E>());
Ok(v)
}
InitResult::ReadExisting(v) => Ok(v),
InitResult::InitErr(e) => Err(e),
}
}
/// Inserts a key-value pair into the cache.
///
/// If the cache has this key present, the value is updated.
pub fn insert(&self, key: K, value: V) {
let hash = self.base.hash(&key);
let key = Arc::new(key);
self.insert_with_hash(key, hash, value)
}
pub(crate) fn insert_with_hash(&self, key: Arc<K>, hash: u64, value: V) {
let op = self.base.do_insert_with_hash(key, hash, value);
let hk = self.base.housekeeper.as_ref();
Self::schedule_write_op(&self.base.write_op_ch, op, hk).expect("Failed to insert");
}
/// Discards any cached value for the key.
///
/// The key may be any borrowed form of the cache's key type, but `Hash` and `Eq`
/// on the borrowed form _must_ match those for the key type.
pub fn invalidate<Q>(&self, key: &Q)
where
Arc<K>: Borrow<Q>,
Q: Hash + Eq + ?Sized,
{
if let Some(kv) = self.base.remove_entry(key) {
let op = WriteOp::Remove(kv);
let hk = self.base.housekeeper.as_ref();
Self::schedule_write_op(&self.base.write_op_ch, op, hk).expect("Failed to remove");
}
}
/// Discards all cached values.
///
/// This method returns immediately and a background thread will evict all the
/// cached values inserted before the time when this method was called. It is
/// guaranteed that the `get` method must not return these invalidated values
/// even if they have not been evicted.
///
/// Like the `invalidate` method, this method does not clear the historic
/// popularity estimator of keys so that it retains the client activities of
/// trying to retrieve an item.
pub fn invalidate_all(&self) {
self.base.invalidate_all();
}
/// Discards cached values that satisfy a predicate.
///
/// `invalidate_entries_if` takes a closure that returns `true` or `false`. This
/// method returns immediately and a background thread will apply the closure to
/// each cached value inserted before the time when `invalidate_entries_if` was
/// called. If the closure returns `true` on a value, that value will be evicted
/// from the cache.
///
/// Also the `get` method will apply the closure to a value to determine if it
/// should have been invalidated. Therefore, it is guaranteed that the `get`
/// method must not return invalidated values.
///
/// Note that you must call
/// [`CacheBuilder::support_invalidation_closures`][support-invalidation-closures]
/// at the cache creation time as the cache needs to maintain additional internal
/// data structures to support this method. Otherwise, calling this method will
/// fail with a
/// [`PredicateError::InvalidationClosuresDisabled`][invalidation-disabled-error].
///
/// Like the `invalidate` method, this method does not clear the historic
/// popularity estimator of keys so that it retains the client activities of
/// trying to retrieve an item.
///
/// [support-invalidation-closures]: ./struct.CacheBuilder.html#method.support_invalidation_closures
/// [invalidation-disabled-error]: ../enum.PredicateError.html#variant.InvalidationClosuresDisabled
pub fn invalidate_entries_if<F>(&self, predicate: F) -> Result<PredicateId, PredicateError>
where
F: Fn(&K, &V) -> bool + Send + Sync + 'static,
{
self.base.invalidate_entries_if(Arc::new(predicate))
}
pub(crate) fn invalidate_entries_with_arc_fun<F>(
&self,
predicate: Arc<F>,
) -> Result<PredicateId, PredicateError>
where
F: Fn(&K, &V) -> bool + Send + Sync + 'static,
{
self.base.invalidate_entries_if(predicate)
}
/// Returns the `max_capacity` of this cache.
pub fn max_capacity(&self) -> Option<usize> {
self.base.max_capacity()
}
/// Returns the `time_to_live` of this cache.
pub fn time_to_live(&self) -> Option<Duration> {
self.base.time_to_live()
}
/// Returns the `time_to_idle` of this cache.
pub fn time_to_idle(&self) -> Option<Duration> {
self.base.time_to_idle()
}
/// Returns the number of internal segments of this cache.
///
/// `Cache` always returns `1`.
pub fn num_segments(&self) -> usize {
1
}
#[cfg(test)]
pub(crate) fn estimated_entry_count(&self) -> u64 {
self.base.estimated_entry_count()
}
#[cfg(test)]
pub(crate) fn weighted_size(&self) -> u64 {
self.base.weighted_size()
}
}
impl<K, V, S> ConcurrentCacheExt<K, V> for Cache<K, V, S>
where
K: Hash + Eq + Send + Sync + 'static,
V: Send + Sync + 'static,
S: BuildHasher + Clone + Send + Sync + 'static,
{
fn sync(&self) {
self.base.inner.sync(MAX_SYNC_REPEATS);
}
}
// private methods
impl<K, V, S> Cache<K, V, S>
where
K: Hash + Eq + Send + Sync + 'static,
V: Clone + Send + Sync + 'static,
S: BuildHasher + Clone + Send + Sync + 'static,
{
#[inline]
fn schedule_write_op(
ch: &Sender<WriteOp<K, V>>,
op: WriteOp<K, V>,
housekeeper: Option<&HouseKeeperArc<K, V, S>>,
) -> Result<(), TrySendError<WriteOp<K, V>>> {
let mut op = op;
// NOTES:
// - This will block when the channel is full.
// - We are doing a busy-loop here. We were originally calling `ch.send(op)?`,
// but we got a notable performance degradation.
loop {
BaseCache::apply_reads_writes_if_needed(ch, housekeeper);
match ch.try_send(op) {
Ok(()) => break,
Err(TrySendError::Full(op1)) => {
op = op1;
std::thread::sleep(Duration::from_micros(WRITE_RETRY_INTERVAL_MICROS));
}
Err(e @ TrySendError::Disconnected(_)) => return Err(e),
}
}
Ok(())
}
}
// For unit tests.
#[cfg(test)]
impl<K, V, S> Cache<K, V, S>
where
K: Hash + Eq + Send + Sync + 'static,
V: Clone + Send + Sync + 'static,
S: BuildHasher + Clone + Send + Sync + 'static,
{
pub(crate) fn is_table_empty(&self) -> bool {
self.estimated_entry_count() == 0
}
pub(crate) fn invalidation_predicate_count(&self) -> usize {
self.base.invalidation_predicate_count()
}
pub(crate) fn reconfigure_for_testing(&mut self) {
self.base.reconfigure_for_testing();
}
pub(crate) fn set_expiration_clock(&self, clock: Option<crate::common::time::Clock>) {
self.base.set_expiration_clock(clock);
}
}
// To see the debug prints, run test as `cargo test -- --nocapture`
#[cfg(test)]
mod tests {
use super::{Cache, ConcurrentCacheExt};
use crate::{common::time::Clock, sync::CacheBuilder};
use std::{convert::Infallible, sync::Arc, time::Duration};
#[test]
fn basic_single_thread() {
let mut cache = Cache::new(3);
cache.reconfigure_for_testing();
// Make the cache exterior immutable.
let cache = cache;
cache.insert("a", "alice");
cache.insert("b", "bob");
assert_eq!(cache.get(&"a"), Some("alice"));
assert_eq!(cache.get(&"b"), Some("bob"));
cache.sync();
// counts: a -> 1, b -> 1
cache.insert("c", "cindy");
assert_eq!(cache.get(&"c"), Some("cindy"));
// counts: a -> 1, b -> 1, c -> 1
cache.sync();
assert_eq!(cache.get(&"a"), Some("alice"));
assert_eq!(cache.get(&"b"), Some("bob"));
cache.sync();
// counts: a -> 2, b -> 2, c -> 1
// "d" should not be admitted because its frequency is too low.
cache.insert("d", "david"); // count: d -> 0
cache.sync();
assert_eq!(cache.get(&"d"), None); // d -> 1
cache.insert("d", "david");
cache.sync();
assert_eq!(cache.get(&"d"), None); // d -> 2
// "d" should be admitted and "c" should be evicted
// because d's frequency is higher than c's.
cache.insert("d", "dennis");
cache.sync();
assert_eq!(cache.get(&"a"), Some("alice"));
assert_eq!(cache.get(&"b"), Some("bob"));
assert_eq!(cache.get(&"c"), None);
assert_eq!(cache.get(&"d"), Some("dennis"));
cache.invalidate(&"b");
assert_eq!(cache.get(&"b"), None);
}
#[test]
fn size_aware_eviction() {
let weigher = |_k: &&str, v: &(&str, u32)| v.1;
let alice = ("alice", 10);
let bob = ("bob", 15);
let bill = ("bill", 20);
let cindy = ("cindy", 5);
let david = ("david", 15);
let dennis = ("dennis", 15);
let mut cache = Cache::builder().max_capacity(31).weigher(weigher).build();
cache.reconfigure_for_testing();
// Make the cache exterior immutable.
let cache = cache;
cache.insert("a", alice);
cache.insert("b", bob);
assert_eq!(cache.get(&"a"), Some(alice));
assert_eq!(cache.get(&"b"), Some(bob));
cache.sync();
// order (LRU -> MRU) and counts: a -> 1, b -> 1
cache.insert("c", cindy);
assert_eq!(cache.get(&"c"), Some(cindy));
// order and counts: a -> 1, b -> 1, c -> 1
cache.sync();
assert_eq!(cache.get(&"a"), Some(alice));
assert_eq!(cache.get(&"b"), Some(bob));
cache.sync();
// order and counts: c -> 1, a -> 2, b -> 2
// To enter "d" (weight: 15), it needs to evict "c" (w: 5) and "a" (w: 10).
// "d" must have higher count than 3, which is the aggregated count
// of "a" and "c".
cache.insert("d", david); // count: d -> 0
cache.sync();
assert_eq!(cache.get(&"d"), None); // d -> 1
cache.insert("d", david);
cache.sync();
assert_eq!(cache.get(&"d"), None); // d -> 2
cache.insert("d", david);
cache.sync();
assert_eq!(cache.get(&"d"), None); // d -> 3
cache.insert("d", david);
cache.sync();
assert_eq!(cache.get(&"d"), None); // d -> 4
// Finally "d" should be admitted by evicting "c" and "a".
cache.insert("d", dennis);
cache.sync();
assert_eq!(cache.get(&"a"), None);
assert_eq!(cache.get(&"b"), Some(bob));
assert_eq!(cache.get(&"c"), None);
assert_eq!(cache.get(&"d"), Some(dennis));
// Update "b" with "bill" (w: 15 -> 20). This should evict "d" (w: 15).
cache.insert("b", bill);
cache.sync();
assert_eq!(cache.get(&"b"), Some(bill));
assert_eq!(cache.get(&"d"), None);
// Re-add "a" (w: 10) and update "b" with "bob" (w: 20 -> 15).
cache.insert("a", alice);
cache.insert("b", bob);
cache.sync();
assert_eq!(cache.get(&"a"), Some(alice));
assert_eq!(cache.get(&"b"), Some(bob));
assert_eq!(cache.get(&"d"), None);
// Verify the sizes.
assert_eq!(cache.estimated_entry_count(), 2);
assert_eq!(cache.weighted_size(), 25);
}
#[test]
fn basic_multi_threads() {
let num_threads = 4;
let cache = Cache::new(100);
let handles = (0..num_threads)
.map(|id| {
let cache = cache.clone();
std::thread::spawn(move || {
cache.insert(10, format!("{}-100", id));
cache.get(&10);
cache.insert(20, format!("{}-200", id));
cache.invalidate(&10);
})
})
.collect::<Vec<_>>();
handles.into_iter().for_each(|h| h.join().expect("Failed"));
assert!(cache.get(&10).is_none());
assert!(cache.get(&20).is_some());
}
#[test]
fn invalidate_all() {
let mut cache = Cache::new(100);
cache.reconfigure_for_testing();
// Make the cache exterior immutable.
let cache = cache;
cache.insert("a", "alice");
cache.insert("b", "bob");
cache.insert("c", "cindy");
assert_eq!(cache.get(&"a"), Some("alice"));
assert_eq!(cache.get(&"b"), Some("bob"));
assert_eq!(cache.get(&"c"), Some("cindy"));
cache.sync();
cache.invalidate_all();
cache.sync();
cache.insert("d", "david");
cache.sync();
assert!(cache.get(&"a").is_none());
assert!(cache.get(&"b").is_none());
assert!(cache.get(&"c").is_none());
assert_eq!(cache.get(&"d"), Some("david"));
}
#[test]
fn invalidate_entries_if() -> Result<(), Box<dyn std::error::Error>> {
use std::collections::HashSet;
let mut cache = CacheBuilder::new(100)
.support_invalidation_closures()
.build();
cache.reconfigure_for_testing();
let (clock, mock) = Clock::mock();
cache.set_expiration_clock(Some(clock));
// Make the cache exterior immutable.
let cache = cache;
cache.insert(0, "alice");
cache.insert(1, "bob");
cache.insert(2, "alex");
cache.sync();
mock.increment(Duration::from_secs(5)); // 5 secs from the start.
cache.sync();
assert_eq!(cache.get(&0), Some("alice"));
assert_eq!(cache.get(&1), Some("bob"));
assert_eq!(cache.get(&2), Some("alex"));
let names = ["alice", "alex"].iter().cloned().collect::<HashSet<_>>();
cache.invalidate_entries_if(move |_k, &v| names.contains(v))?;
assert_eq!(cache.base.invalidation_predicate_count(), 1);
mock.increment(Duration::from_secs(5)); // 10 secs from the start.
cache.insert(3, "alice");
// Run the invalidation task and wait for it to finish. (TODO: Need a better way than sleeping)
cache.sync(); // To submit the invalidation task.
std::thread::sleep(Duration::from_millis(200));
cache.sync(); // To process the task result.
std::thread::sleep(Duration::from_millis(200));
assert!(cache.get(&0).is_none());
assert!(cache.get(&2).is_none());
assert_eq!(cache.get(&1), Some("bob"));
// This should survive as it was inserted after calling invalidate_entries_if.
assert_eq!(cache.get(&3), Some("alice"));
assert_eq!(cache.estimated_entry_count(), 2);
assert_eq!(cache.invalidation_predicate_count(), 0);
mock.increment(Duration::from_secs(5)); // 15 secs from the start.
cache.invalidate_entries_if(|_k, &v| v == "alice")?;
cache.invalidate_entries_if(|_k, &v| v == "bob")?;
assert_eq!(cache.invalidation_predicate_count(), 2);
// Run the invalidation task and wait for it to finish. (TODO: Need a better way than sleeping)
cache.sync(); // To submit the invalidation task.
std::thread::sleep(Duration::from_millis(200));
cache.sync(); // To process the task result.
std::thread::sleep(Duration::from_millis(200));
assert!(cache.get(&1).is_none());
assert!(cache.get(&3).is_none());
assert_eq!(cache.estimated_entry_count(), 0);
assert_eq!(cache.invalidation_predicate_count(), 0);
Ok(())
}
#[test]
fn time_to_live() {
let mut cache = CacheBuilder::new(100)
.time_to_live(Duration::from_secs(10))
.build();
cache.reconfigure_for_testing();
let (clock, mock) = Clock::mock();
cache.set_expiration_clock(Some(clock));
// Make the cache exterior immutable.
let cache = cache;
cache.insert("a", "alice");
cache.sync();
mock.increment(Duration::from_secs(5)); // 5 secs from the start.
cache.sync();
cache.get(&"a");
mock.increment(Duration::from_secs(5)); // 10 secs.
cache.sync();
assert_eq!(cache.get(&"a"), None);
assert!(cache.is_table_empty());
cache.insert("b", "bob");
cache.sync();
assert_eq!(cache.estimated_entry_count(), 1);
mock.increment(Duration::from_secs(5)); // 15 secs.
cache.sync();
assert_eq!(cache.get(&"b"), Some("bob"));
assert_eq!(cache.estimated_entry_count(), 1);
cache.insert("b", "bill");
cache.sync();
mock.increment(Duration::from_secs(5)); // 20 secs
cache.sync();
assert_eq!(cache.get(&"b"), Some("bill"));
assert_eq!(cache.estimated_entry_count(), 1);
mock.increment(Duration::from_secs(5)); // 25 secs
cache.sync();
assert_eq!(cache.get(&"a"), None);
assert_eq!(cache.get(&"b"), None);
assert!(cache.is_table_empty());
}
#[test]
fn time_to_idle() {
let mut cache = CacheBuilder::new(100)
.time_to_idle(Duration::from_secs(10))
.build();
cache.reconfigure_for_testing();
let (clock, mock) = Clock::mock();
cache.set_expiration_clock(Some(clock));
// Make the cache exterior immutable.
let cache = cache;
cache.insert("a", "alice");
cache.sync();
mock.increment(Duration::from_secs(5)); // 5 secs from the start.
cache.sync();
assert_eq!(cache.get(&"a"), Some("alice"));
mock.increment(Duration::from_secs(5)); // 10 secs.
cache.sync();
cache.insert("b", "bob");
cache.sync();
assert_eq!(cache.estimated_entry_count(), 2);
mock.increment(Duration::from_secs(5)); // 15 secs.
cache.sync();
assert_eq!(cache.get(&"a"), None);
assert_eq!(cache.get(&"b"), Some("bob"));
assert_eq!(cache.estimated_entry_count(), 1);
mock.increment(Duration::from_secs(10)); // 25 secs
cache.sync();
assert_eq!(cache.get(&"a"), None);
assert_eq!(cache.get(&"b"), None);
assert!(cache.is_table_empty());
}
#[test]
fn get_or_insert_with() {
use std::thread::{sleep, spawn};
let cache = Cache::new(100);
const KEY: u32 = 0;
// This test will run five threads:
//
// Thread1 will be the first thread to call `get_or_insert_with` for a key, so
// its async block will be evaluated and then a &str value "thread1" will be
// inserted to the cache.
let thread1 = {
let cache1 = cache.clone();
spawn(move || {
// Call `get_or_insert_with` immediately.
let v = cache1.get_or_insert_with(KEY, || {
// Wait for 300 ms and return a &str value.
sleep(Duration::from_millis(300));
"thread1"
});
assert_eq!(v, "thread1");
})
};
// Thread2 will be the second thread to call `get_or_insert_with` for the same
// key, so its async block will not be evaluated. Once thread1's async block
// finishes, it will get the value inserted by thread1's async block.
let thread2 = {
let cache2 = cache.clone();
spawn(move || {
// Wait for 100 ms before calling `get_or_insert_with`.
sleep(Duration::from_millis(100));
let v = cache2.get_or_insert_with(KEY, || unreachable!());
assert_eq!(v, "thread1");
})
};
// Thread3 will be the third thread to call `get_or_insert_with` for the same
// key. By the time it calls, thread1's async block should have finished
// already and the value should be already inserted to the cache. So its
// async block will not be evaluated and will get the value insert by thread1's
// async block immediately.
let thread3 = {
let cache3 = cache.clone();
spawn(move || {
// Wait for 400 ms before calling `get_or_insert_with`.
sleep(Duration::from_millis(400));
let v = cache3.get_or_insert_with(KEY, || unreachable!());
assert_eq!(v, "thread1");
})
};
// Thread4 will call `get` for the same key. It will call when thread1's async
// block is still running, so it will get none for the key.
let thread4 = {
let cache4 = cache.clone();
spawn(move || {
// Wait for 200 ms before calling `get`.
sleep(Duration::from_millis(200));
let maybe_v = cache4.get(&KEY);
assert!(maybe_v.is_none());
})
};
// Thread5 will call `get` for the same key. It will call after thread1's async
// block finished, so it will get the value insert by thread1's async block.
let thread5 = {
let cache5 = cache.clone();
spawn(move || {
// Wait for 400 ms before calling `get`.
sleep(Duration::from_millis(400));
let maybe_v = cache5.get(&KEY);
assert_eq!(maybe_v, Some("thread1"));
})
};
for t in vec![thread1, thread2, thread3, thread4, thread5] {
t.join().expect("Failed to join");
}
}
#[test]
fn get_or_try_insert_with() {
use std::{
sync::Arc,
thread::{sleep, spawn},
};
// Note that MyError does not implement std::error::Error trait
// like anyhow::Error.
#[derive(Debug)]
pub struct MyError(String);
type MyResult<T> = Result<T, Arc<MyError>>;
let cache = Cache::new(100);
const KEY: u32 = 0;
// This test will run eight async threads:
//
// Thread1 will be the first thread to call `get_or_insert_with` for a key, so
// its async block will be evaluated and then an error will be returned.
// Nothing will be inserted to the cache.
let thread1 = {
let cache1 = cache.clone();
spawn(move || {
// Call `get_or_try_insert_with` immediately.
let v = cache1.get_or_try_insert_with(KEY, || {
// Wait for 300 ms and return an error.
sleep(Duration::from_millis(300));
Err(MyError("thread1 error".into()))
});
assert!(v.is_err());
})
};
// Thread2 will be the second thread to call `get_or_insert_with` for the same
// key, so its async block will not be evaluated. Once thread1's async block
// finishes, it will get the same error value returned by thread1's async
// block.
let thread2 = {
let cache2 = cache.clone();
spawn(move || {
// Wait for 100 ms before calling `get_or_try_insert_with`.
sleep(Duration::from_millis(100));
let v: MyResult<_> = cache2.get_or_try_insert_with(KEY, || unreachable!());
assert!(v.is_err());
})
};
// Thread3 will be the third thread to call `get_or_insert_with` for the same
// key. By the time it calls, thread1's async block should have finished
// already, but the key still does not exist in the cache. So its async block
// will be evaluated and then an okay &str value will be returned. That value
// will be inserted to the cache.
let thread3 = {
let cache3 = cache.clone();
spawn(move || {
// Wait for 400 ms before calling `get_or_try_insert_with`.
sleep(Duration::from_millis(400));
let v: MyResult<_> = cache3.get_or_try_insert_with(KEY, || {
// Wait for 300 ms and return an Ok(&str) value.
sleep(Duration::from_millis(300));
Ok("thread3")
});
assert_eq!(v.unwrap(), "thread3");
})
};
// thread4 will be the fourth thread to call `get_or_insert_with` for the same
// key. So its async block will not be evaluated. Once thread3's async block
// finishes, it will get the same okay &str value.
let thread4 = {
let cache4 = cache.clone();
spawn(move || {
// Wait for 500 ms before calling `get_or_try_insert_with`.
sleep(Duration::from_millis(500));
let v: MyResult<_> = cache4.get_or_try_insert_with(KEY, || unreachable!());
assert_eq!(v.unwrap(), "thread3");
})
};
// Thread5 will be the fifth thread to call `get_or_insert_with` for the same
// key. So its async block will not be evaluated. By the time it calls,
// thread3's async block should have finished already, so its async block will
// not be evaluated and will get the value insert by thread3's async block
// immediately.
let thread5 = {
let cache5 = cache.clone();
spawn(move || {
// Wait for 800 ms before calling `get_or_try_insert_with`.
sleep(Duration::from_millis(800));
let v: MyResult<_> = cache5.get_or_try_insert_with(KEY, || unreachable!());
assert_eq!(v.unwrap(), "thread3");
})
};
// Thread6 will call `get` for the same key. It will call when thread1's async
// block is still running, so it will get none for the key.
let thread6 = {
let cache6 = cache.clone();
spawn(move || {
// Wait for 200 ms before calling `get`.
sleep(Duration::from_millis(200));
let maybe_v = cache6.get(&KEY);
assert!(maybe_v.is_none());
})
};
// Thread7 will call `get` for the same key. It will call after thread1's async
// block finished with an error. So it will get none for the key.
let thread7 = {
let cache7 = cache.clone();
spawn(move || {
// Wait for 400 ms before calling `get`.
sleep(Duration::from_millis(400));
let maybe_v = cache7.get(&KEY);
assert!(maybe_v.is_none());
})
};
// Thread8 will call `get` for the same key. It will call after thread3's async
// block finished, so it will get the value insert by thread3's async block.
let thread8 = {
let cache8 = cache.clone();
spawn(move || {
// Wait for 800 ms before calling `get`.
sleep(Duration::from_millis(800));
let maybe_v = cache8.get(&KEY);
assert_eq!(maybe_v, Some("thread3"));
})
};
for t in vec![
thread1, thread2, thread3, thread4, thread5, thread6, thread7, thread8,
] {
t.join().expect("Failed to join");
}
}
#[test]
// https://github.com/moka-rs/moka/issues/43
fn handle_panic_in_get_or_insert_with() {
use std::{sync::Barrier, thread};
let cache = Cache::new(16);
let barrier = Arc::new(Barrier::new(2));
{
let cache_ref = cache.clone();
let barrier_ref = barrier.clone();
thread::spawn(move || {
let _ = cache_ref.get_or_insert_with(1, || {
barrier_ref.wait();
thread::sleep(Duration::from_millis(50));
panic!("Panic during get_or_try_insert_with");
});
});
}
barrier.wait();
assert_eq!(cache.get_or_insert_with(1, || 5), 5);
}
#[test]
// https://github.com/moka-rs/moka/issues/43
fn handle_panic_in_get_or_try_insert_with() {
use std::{sync::Barrier, thread};
let cache = Cache::new(16);
let barrier = Arc::new(Barrier::new(2));
{
let cache_ref = cache.clone();
let barrier_ref = barrier.clone();
thread::spawn(move || {
let _ = cache_ref.get_or_try_insert_with(1, || {
barrier_ref.wait();
thread::sleep(Duration::from_millis(50));
panic!("Panic during get_or_try_insert_with");
}) as Result<_, Arc<Infallible>>;
});
}
barrier.wait();
assert_eq!(
cache.get_or_try_insert_with(1, || Ok(5)) as Result<_, Arc<Infallible>>,
Ok(5)
);
}
}