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//! A full-featured connection pool, designed for asynchronous connections
//! (using tokio). Originally based on [r2d2](https://github.com/sfackler/r2d2).
//!
//! Opening a new database connection every time one is needed is both
//! inefficient and can lead to resource exhaustion under high traffic
//! conditions. A connection pool maintains a set of open connections to a
//! database, handing them out for repeated use.
//!
//! bb8 is agnostic to the connection type it is managing. Implementors of the
//! `ManageConnection` trait provide the database-specific logic to create and
//! check the health of connections.
//!
//! # Example
//!
//! Using an imaginary "foodb" database.
//!
//! ```ignore
//! #[tokio::main]
//! async fn main() {
//! let manager = bb8_foodb::FooConnectionManager::new("localhost:1234");
//! let pool = bb8::Pool::builder().build(manager).await.unwrap();
//!
//! for _ in 0..20 {
//! let pool = pool.clone();
//! tokio::spawn(async move {
//! let conn = pool.get().await.unwrap();
//! // use the connection
//! // it will be returned to the pool when it falls out of scope.
//! });
//! }
//! }
//! ```
#![allow(clippy::needless_doctest_main)]
#![deny(missing_docs, missing_debug_implementations)]
mod api;
pub use api::{
Builder, CustomizeConnection, ErrorSink, ManageConnection, NopErrorSink, Pool,
PooledConnection, QueueStrategy, RunError, State,
};
mod inner;
mod internals;
mod lock {
#[cfg(feature = "parking_lot")]
use parking_lot::Mutex as MutexImpl;
#[cfg(feature = "parking_lot")]
use parking_lot::MutexGuard;
#[cfg(not(feature = "parking_lot"))]
use std::sync::Mutex as MutexImpl;
#[cfg(not(feature = "parking_lot"))]
use std::sync::MutexGuard;
pub(crate) struct Mutex<T>(MutexImpl<T>);
impl<T> Mutex<T> {
pub(crate) fn new(val: T) -> Self {
Self(MutexImpl::new(val))
}
pub(crate) fn lock(&self) -> MutexGuard<'_, T> {
#[cfg(feature = "parking_lot")]
{
self.0.lock()
}
#[cfg(not(feature = "parking_lot"))]
{
self.0.lock().unwrap()
}
}
}
}