Struct VMPool 

pub struct VMPool { /* private fields */ }

Pool of reusable VM instances.

VM::new does ~3 Vec allocations (stack, frames, globals) at construction. Callers that run many small chunks back-to-back — REPL-style invocation, batch script execution, eval loops — pay that cost on every call. VMPool recycles the allocations: the first acquire allocates, subsequent acquires pop a previously- released VM and reset it via VM::reset.

Example

use fusevm::{ChunkBuilder, Op, VMPool, VMResult, Value};

let mut pool = VMPool::new();

for _ in 0..1000 {
    let mut b = ChunkBuilder::new();
    b.emit(Op::LoadInt(40), 1);
    b.emit(Op::LoadInt(2), 1);
    b.emit(Op::Add, 1);

    let mut vm = pool.acquire(b.build());
    let result = vm.run();
    assert!(matches!(result, VMResult::Ok(Value::Int(42))));
    pool.release(vm);
}

Implementations

impl VMPool

pub fn new() -> Self

Construct an empty pool.

pub fn with_capacity(cap: usize) -> Self

Construct with a pre-allocated capacity.

pub fn acquire(&mut self, chunk: Chunk) -> VM

Acquire a VM ready to run chunk. Pops a recycled VM if available; otherwise constructs a fresh one. The returned VM inherits the pool’s previously-released VMs’ allocations (Vec capacities preserved).

pub fn release(&mut self, vm: VM)

Return a VM to the pool for later reuse. The VM’s allocations are kept; only state is cleared on the next acquire.

pub fn with<F, T>(&mut self, chunk: Chunk, f: F) -> T

where F: FnOnce(&mut VM) -> T,

Run a closure against an acquired VM, returning it to the pool after the closure finishes (RAII-style scope).

pub fn len(&self) -> usize

Number of VMs currently held in the pool (released, ready for reuse). Doesn’t count VMs currently checked out via acquire.

pub fn is_empty(&self) -> bool

Whether the pool is empty.

Trait Implementations

impl Default for VMPool

fn default() -> Self

Returns the “default value” for a type.