This directory contains examples of how to use Moka cache. Each example is a standalone binary that can be run with the following command:

$ cargo run --example <example_name> -F sync,future

Each example has a suffix _async or _sync:

• _async indicates that the example uses the moka::future::Cache, which is a Future-aware, concurrent cache.
• _sync indicates that the example uses the moka::sync::Cache, which is a multi-thread safe, concurrent cache.

• basics_async and basics_sync

  • Shares a cache between async tasks or OS threads.
    • Do not wrap a Cache with Arc<Mutex<_>>! Just clone the Cache and you are all set.
  • Uses insert, get and invalidate methods.

• size_aware_eviction_sync

  • Configures the max capacity of the cache based on the total size of the cached entries.

Atomically inserts, updates and removes an entry from the cache depending on the existence of the entry.

• counter_async and counter_sync
  • Atomically increments a cached u64 by 1. If the entry does not exist, inserts a new entry with the value 1.
  • Uses and_upsert_with method.
• bounded_counter_async and bounded_counter_sync
  • Same as above except removing the entry when the value is 2.
  • and_compute_with method.
• append_value_async and append_value_sync
  • Atomically appends an i32 to a cached Arc<RwLock<Vec<i32>>>. If the entry does not exist, inserts a new entry.
  • Uses and_upsert_with method.
• try_append_value_async and try_append_value_sync
  • Atomically reads an char from a reader and appends it to a cached Arc<RwLock<String>>, but reading may fail by an early EOF.
  • Uses and_try_compute_with method.

• eviction_listener_sync

  • Configures the time_to_live expiration policy.
  • Registers a listener (closure) to be notified when an entry is evicted from the cache.
  • Uses insert, invalidate, invalidate_all and run_pending_tasks methods.
  • Demonstrates when the expired entries will be actually evicted from the cache, and why the run_pending_tasks method could be important in some cases.

• cascading_drop_async

  • Controls the lifetime of the objects in a separate BTreeMap collection from the cache using an eviction listener.
  • Beside the cache APIs, uses BTreeMap, Arc and mpsc channel (multi-producer, single consumer channel).

• reinsert_expired_entries_sync

  • Reinserts the expired entries into the cache using eviction listener and worker threads.
  • Spawns two worker threads; one for reinserting entries, and the other for calling run_pending_tasks.
  • Uses a mpsc channel (multi-producer, single consumer channel) to send commands from the eviction listener to the first worker thread.

The examples are not meant to be exhaustive. Please check the API documentation for more examples and details.