Struct concread::arcache::ARCache[−][src]

pub struct ARCache<K, V> where
    K: Hash + Eq + Ord + Clone + Debug + Sync + Send + 'static,
    V: Clone + Debug + Sync + Send + 'static,  { /* fields omitted */ }

Expand description

A concurrently readable adaptive replacement cache. Operations are performed on the cache via read and write operations.

Implementations

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impl<K: Hash + Eq + Ord + Clone + Debug + Sync + Send + 'static, V: Clone + Debug + Sync + Send + 'static> ARCache<K, V>

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pub fn new(
    total: usize,
    threads: usize,
    ex_ro_miss: usize,
    ex_rw_miss: usize,
    read_cache: bool
) -> Self

Create a new ARCache, that derives it’s size based on your expected workload.

The values are total number of items you want to have in memory, the number of read threads you expect concurrently, the expected average number of cache misses per read operation, and the expected average number of writes or write cache misses per operation. The following formula is assumed:

max + (threads * (max/16)) + (threads * avg number of misses per op) + avg number of writes per transaction

The cache may still exceed your provided total, and inaccurate tuning numbers will yield a situation where you may use too-little ram, or too much. This could be to your read misses exceeding your expected amount causing the queues to have more items in them at a time, or your writes are larger than expected.

If you set ex_ro_miss to zero, no read thread local cache will be configured, but space will still be reserved for channel communication.

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pub fn new_size(max: usize, read_max: usize) -> Self

Create a new ARCache, with a capacity of max main cache items and read_max Note that due to the way the cache operates, the number of items can and will exceed max on a regular basis, so you should consider using new and specifying your expected workload parameters to have a better derived cache size.

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pub fn new_size_watermark(max: usize, read_max: usize, watermark: usize) -> Self

See [new_size] for more information. This allows manual configuration of the data tracking watermark. To disable this, set to 0. Watermark must be less than max.

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pub fn read(&self) -> ARCacheReadTxn<'_, K, V>

Begin a read operation on the cache. This reader has a thread-local cache for items that are localled included via insert, and can communicate back to the main cache to safely include items.

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pub fn write(&self) -> ARCacheWriteTxn<'_, K, V>

Begin a write operation on the cache. This writer has a thread-local store for all items that have been included or dirtied in the transactions, items may be removed from this cache (ie deleted, invalidated).

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