Module pool

Memory and object pools

Target support

This module / API is only available on these compilation targets:

• ARM architectures which instruction set include the LDREX, CLREX and STREX instructions, e.g. thumbv7m-none-eabi but not thumbv6m-none-eabi
• 32-bit x86, e.g. i686-unknown-linux-gnu

Benchmarks

• compilation settings

  • codegen-units = 1
  • lto = 'fat'
  • opt-level = 'z'

• compilation target: thumbv7em-none-eabihf

• CPU: ARM Cortex-M4F

• test program:

use heapless::box_pool;

box_pool!(P: ()); // or `arc_pool!` or `object_pool!`

bkpt();
let res = P.alloc(());
bkpt();

if let Ok(boxed) = res {
    bkpt();
    drop(boxed);
    bkpt();
}

• measurement method: the cycle counter (CYCCNT) register was sampled each time a breakpoint (bkpt) was hit. the difference between the “after” and the “before” value of CYCCNT yields the execution time in clock cycles.

API	clock cycles
BoxPool::alloc	23
pool::boxed::Box::drop	23
ArcPool::alloc	28
pool::arc::Arc::drop	59
ObjectPool::request	23
pool::object::Object::drop	23

Note that the execution time won’t include T’s initialization nor T’s destructor which will be present in the general case for Box and Arc.

Modules

• arc
  std::sync::Arc-like API on top of a lock-free memory pool
• boxed
  std::boxed::Box-like API on top of a lock-free memory pool
• object
  Object pool API