connpool is a high-performance, generic connection pool crate designed for Rust applications. It provides a thread-safe, asynchronous pool for managing and reusing connections (or any other resource) with both global and local (per-key) limits.

• Concurrent access - uses Arc and RwLock for thread-safe operations.
• Global and local limits - enforce both global pool limits and per-key local limits using semaphores.
• Asynchronous - supports async Rust.
• Automatic eviction - automatically evicts items when the pool is full.
• Flexible key/value types - works with any key/value types that implement Eq + Hash.
• Unbounded mode - option to create a pool without a global limit.

use connpool::Pool;

#[tokio::main]
async fn main() {
    // Create a new pool with a global limit of 10 connections
    let pool = Pool::new(10);

    // Pull a connection for a specific key
    let item = pool.pull("my_key").await;

    // Use the connection
    if let Some(value) = item.inner() {
        let value: usize = *value;
        println!("Got value: {:?}", value);
    }

    // The connection is automatically returned to the pool when `item` is dropped
    // Alternatively, drop the connection
    let _ = item.take();
}

• Local limits - set per-key limits to restrict the number of concurrent connections for specific keys.
• Manual management - use pull_with_local_limit for fine-grained control over local limits.

This project is licensed under the MIT License.