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r2d2

A generic connection pool for Rust.

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.

A (possibly not exhaustive) list of adaptors for different backends:

Backend	Adaptor Crate
rust-postgres	r2d2-postgres
redis-rs	use `r2d2` feature of redis-rs
rust-memcache	r2d2-memcache
rust-mysql-simple	r2d2-mysql
rusqlite	r2d2-sqlite
rsfbclient	r2d2-firebird
rusted-cypher	r2d2-cypher
diesel	diesel::r2d2 (docs)
couchdb	r2d2-couchdb
mongodb (archived)<br>use official mongodb driver instead	r2d2-mongodb<br>(deprecated: official driver handles pooling internally)
odbc	r2d2-odbc
jfs	r2d2-jfs
oracle	r2d2-oracle
ldap3	r2d2-ldap
duckdb-rs	use `r2d2` feature of duckdb-rs

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.
        })
    }
}

License

Licensed under either of

Apache License, Version 2.0 (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.

Contribution

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in the work by you shall be dual licensed as above, without any additional terms or conditions.