Crate r2d2

A generic connection pool.

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.

r2d2 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.

use std::thread;

extern crate r2d2;
extern crate r2d2_foodb;

fn main() {
    let manager = r2d2_foodb::FooConnectionManager::new("localhost:1234");
    let pool = r2d2::Pool::builder()
        .max_size(15)
        .build(manager)
        .unwrap();

    for _ in 0..20 {
        let pool = pool.clone();
        thread::spawn(move || {
            let conn = pool.get().unwrap();
            // use the connection
            // it will be returned to the pool when it falls out of scope.
        })
    }
}

Re-exports

• pub use crate::event::HandleEvent;
• pub use crate::event::NopEventHandler;

Modules

• event
  Event subscriptions.

Structs

• Builder
  A builder for a connection pool.
• Error
  The error type returned by methods in this crate.
• Extensions
  A “type map” used to associate data with pooled connections.
• LoggingErrorHandler
  A HandleError implementation which logs at the error level.
• NopConnectionCustomizer
  A CustomizeConnection which does nothing.
• NopErrorHandler
  A HandleError implementation which does nothing.
• Pool
  A generic connection pool.
• PooledConnection
  A smart pointer wrapping a connection.
• State
  Information about the state of a Pool.

Traits

• CustomizeConnection
  A trait which allows for customization of connections.
• HandleError
  A trait which handles errors reported by the ManageConnection.
• ManageConnection
  A trait which provides connection-specific functionality.