Deadpool is a dead simple async pool for connections and objects of any type.
This crate provides two implementations:
Managed pool (deadpool::managed::Pool)
managed feature in your Cargo.tomlUnmanaged pool (deadpool::unmanaged::Pool)
unmanaged feature in your Cargo.toml| Feature | Description | Extra dependencies | Default |
| ------- | ----------- | ------------------ | ------- |
| managed | Enable managed pool implementation | – | yes |
| unmanaged | Enable unmanaged pool implementation | async-trait | yes |
| config | Enable support for config crate | config, serde/derive | yes |
This is the obvious choice for connection pools of any kind. Deadpool already comes with a couple of database connection pools which work out of the box.
```rust use asynctrait::asynctrait;
enum Error { Fail }
struct Computer {}
struct Manager {}
type Pool = deadpool::managed::Pool
impl Computer { async fn get_answer(&self) -> i32 { 42 } }
impl deadpool::managed::Manager
async fn main() { let mgr = Manager {}; let pool = Pool::new(mgr, 16); let mut conn = pool.get().await.unwrap(); let answer = conn.getanswer().await; asserteq!(answer, 42); } ```
Deadpool supports various database backends by implementing the
deadpool::managed::Manager trait. The following backends are
currently supported:
Backend | Crate ----------------------------------------------------------- | ----- tokio-postgres | deadpool-postgres lapin (AMQP) | deadpool-lapin redis | deadpool-redis
Deadpool is by no means the only pool implementation available. It does things a little different and that is the main reason for it to exist:
Deadpool is compatible with any executor. Objects are returned to the
pool using the Drop trait. The health of those objects is checked upon
next retrieval and not when they are returned. Deadpool never performs any
actions in the background. This is the reason why deadpool does not need
to spawn futures and does not rely on a background thread or task of any
type.
Identical startup and runtime behaviour. When writing long running
application there usually should be no difference between startup and
runtime if a database connection is temporarily not available. Nobody
would expect an application to crash if the database becomes unavailable
at runtime. So it should not crash on startup either. Creating the pool
never fails and errors are only ever returned when calling Pool::get().
If you really want your application to crash on startup if objects can
not be created on startup simply call
pool.get().await.expect("DB connection failed") right after creating
the pool.
Deadpool is fast. The code which returns connections to the pool contains no blocking code and retrival uses only one locking primitive.
Deadpool is simple. Dead simple. There is very little API surface.
The actual code is barely 100 lines of code and lives in the two functions
Pool::get and Object::drop.
r2d2 provides a lot more configuration
options but only provides a synchroneous interface.
bb8 uses a callback based interface (See
pool.run)
and provides the same configuration options as r2d2. At the time of
writing there is no official release which supports async/.await.
mobc provides an async/.await based
interface and provides a lot more configuration options. It requires an
executor though and the code is a lot more complex.
An unmanaged pool is useful when you can't write a manager for the objects
you want to pool or simply don't want to. This pool implementation is slightly
faster than the managed pool because it does not use a Manager trait to
create and recycle objects but leaves it up to the user.
```rust use deadpool::unmanaged::Pool;
struct Computer {}
impl Computer { async fn get_answer(&self) -> i32 { 42 } }
async fn main() { let pool = Pool::from(vec![ Computer {}, Computer {}, ]); let s = pool.get().await; asserteq!(s.getanswer().await, 42); } ```
Licensed under either of
at your option.