Lock Free Object Pool

A thread-safe object pool collection with automatic return.

Some implementations are lockfree :

• LinearObjectPool
• SpinLockObjectPool

Other use std::Mutex :

• MutexObjectPool

And NoneObjectPool basic allocation without pool.

Usage

[dependencies]
lockfree-object-pool = "0.1"

extern crate lockfree_object_pool;

Example

The general pool creation looks like this for

 let pool = LinearObjectPool::<u32>::new(
     ||  Default::default(), 
     |v| {*v = 0; });

And use the object pool

  let mut item = pool.pull();
  *item = 5;
  ...  

At the end of the scope item return in object pool.

Interface

All implementations support same interface :

struct ObjectPool<T> {  
}

impl<T> ObjectPool<T> {
  // for LinearObjectPool, SpinLockObjectPool and MutexObjectPool
  // init closure used to create an element
  // reset closure used to reset element a dropped element
  pub fn new<R, I>(init: I, reset: R) -> Self
    where
        R: Fn(&mut T) + 'static,
        I: Fn() -> T + 'static + Clone,
    {
      ...
    }

  // for NoneObjectPool
  // init closure used to create an element
  pub fn new<I>(init: I) -> Self
    where
        I: Fn() -> T + 'static
    {
      ...
    }

  pub fn pull(&self) -> Reusable<T> {
    ...
  }
}

struct Reusable<T> {  
}

impl<'a, T> DerefMut for Reusable<'a, T> {
    fn deref_mut(&mut self) -> &mut Self::Target {
        ...
    }
}

impl<'a, T> Deref for MutexReusable<'a, T> {
    type Target = T;

    fn deref(&self) -> &Self::Target {
        ...
    }
}

Multithreading

All implementation support allocation/desallocation from on or more thread. You only need to wrap the pool in a [std::sync::Arc] :

 let pool = Arc::new(LinearObjectPool::<u32>::new(
     ||  Default::default(), 
     |v| {*v = 0; }));

Performance

Global report.

Allocation

Report monothreading and multithreading.

Desallocation

Report monothreading and multithreading.

Comparison with Similar Crates

• crate 'sharded-slab': I like pull interface but i dislike

  • Default / Reset trait because not enough flexible
  • Performance

• crate 'object-pool': use a spinlock to sync and the performance are pretty good but i dislike :

  • need to specify fallback at each pull call :

  use object_pool::Pool;
  let pool = Pool::<Vec<u8>>::new(32, || Vec::with_capacity(4096);
  // ...
  let item1 = pool.pull(|| Vec::with_capacity(4096));
  // ...
  let item2 = pool.pull(|| Vec::with_capacity(4096));
  

  • no reset mechanism, need to do manually

TODO

• why the object-pool with spinlock has so bad performance compared to spinlock mutex use by crate 'object-pool'
• have a Poll::create_owned like in crate 'sharded-slab'
• impl a tree object pool (cf toolsbox)

Implementation detail

TODO

Licence

cf Boost Licence

Related Projects

• crate 'object-pool' - A thread-safe object pool in rust with mutex
• crate 'sharded-slab' - A lock-free concurrent slab
• toolsbox - Some object pool implementation en c++