swarm_pool

An object pooling system for Rust, optimized for perfomance.

Change log

version 0.1.7:
- Removed Copy dependencies, PoolObjects do no longer rely on the implementation of the Copy trait.
- Implemented the Clone & Default traits for Spawn. Spawn.clone() behaves in the same way as Spawn.mirror() does. The These where implemented so that PoolObjects can hold Spawn reference objects as field properties. Default on Spawn should not be used and is only there to make the above possible.
version 0.1.4:
- Added iterators find(), for_while(), for_each(), for_all() & enumerate() to SwarmComtrol, these makes it possible to iterate over all spawns inside the update() loop.

Using the swarm pool

The pooling system manages object instances of a cutom type, and provides update loops to iterate over them.

In order to create a new swarm pool, you need to define what your pool object and swarm properties types are going to look like. Your pool object must at leas implement the Default, Copy and Clone traits from the standard library. The swarm properties, on the other hand, does not depend on any traits.

Basic swarm setup example

extern crate swarm_pool;
use swarm_pool::Swarm;

// create an object you want to pool
#[derive(Default, Clone)]     
pub struct MyPoolObject {           
    pub name: &static str,
    pub value: usize,
}

// create properties you want to share with pooled objects
pub struct MySwarmProperties;

fn main() {
    let swarm = Swarm::<MyPoolObject, MySwarmProperties>::new(10, MySwarmProperties);
    assert!(swarm.capacity() == 10);
}

The swarm is now ready to be used. First of all we need to Spawn new pool instances. In reality all objects in the pool are allready created and are waiting to be used. This means that all objects ( from 0 up to, but not including, the maximum capacity) can be accessed through the fetch() methode. The difference between spawned and non-spawned pool objects is that spawned object are included in all of the Swarm pools iterator methodes and non-spawned object are not.

Spawning and looping

let mut swarm = Swarm::<MyPoolObject, _>::new(10, ());
let spawn1 = swarm.spawn().unwrap();
let spawn2 = swarm.spawn().unwrap();
  
assert_eq!(swarm.fetch_ref(&spawn1).value, 0);
assert_eq!(swarm.fetch_ref(&spawn2).value, 0);

swarm.for_each(|obj| {
    obj.value = 42;
});

assert_eq!(swarm.fetch_ref(&spawn1).value, 42);
assert_eq!(swarm.fetch_ref(&spawn2).value, 42);

The real power of this library is not just looping through a few object instances, it is controlling and cross referencing them. There are 2 powerful methodes that can be used to do so: Swarm.for_all() and Swarm.update(). Both have their advantages and disadvantages, for_all loop is fast (equal to a standard vec for loop) but cannot spawn nor kill pool objects, update is easy to use, gives full control, but is slow (less than half the speed).

Cross referencing using for_all & update

// change properties to contain references to our spawned pool objects
pub struct MySwarmProperties { 
    john: Option<Spawn>, 
    cristy: Option<Spawn>,
}

let properties = MySwarmProperties { john: None, cristy: None };

let mut swarm = Swarm::<MyPoolObject, MySwarmProperties>::new(10, properties);
let s_john = swarm.spawn().unwrap();
let s_cristy = swarm.spawn().unwrap();

swarm.properties.john = Some(s_john.mirror());
swarm.properties.cristy = Some(s_cristy.mirror());

swarm.fetch(&s_john).name = "John";
swarm.fetch(&s_cristy).name = "Cristy";

// using the for_all methode
swarm.for_all(|target, list, props| {

    // john tells critsy to have a value of 2
    if list[*target].name == "John" { 
        if let Some(cristy) = &props.cristy {
            list[cristy.pos()].value = 2; 
        }
    }
    // cristy tells john to have a value of 1
    if list[*target].name == "Cristy" { 
        if let Some(john) = &props.john {
            list[john.pos()].value = 1; 
        }
    }
});

assert_eq!(swarm.fetch_ref(&s_john).value, 1);
assert_eq!(swarm.fetch_ref(&s_cristy).value, 2);

// using the update methode
swarm.update(|ctl| {
    let name = ctl.target().name;
    let cristy = ctl.properties.cristy.as_ref().unwrap().mirror();
    let john = ctl.properties.john.as_ref().unwrap().mirror();

    // john tells critsy to have a value of 4
    if name == "John" { 
        ctl.fetch(&cristy).value = 4; 
    }
    // cristy tells john to have a value of 5
    if name == "Cristy" { 
        ctl.fetch(&john).value = 5; 
    }
});

assert_eq!(swarm.fetch_ref(&s_john).value, 5);
assert_eq!(swarm.fetch_ref(&s_cristy).value, 4);