Struct MemoryLedger 

pub struct MemoryLedger { /* private fields */ }

Gate 2: a budget and a counter. Never a probe.

Implementations

impl MemoryLedger

pub fn new(budget: u64) -> MemoryLedger

A ledger with budget bytes to give out.

pub fn budget(&self) -> u64

The budget.

pub fn reserved(&self) -> u64

Bytes currently reserved by operations in flight.

pub fn try_reserve(&self, bytes: u64) -> bool

Reserve bytes, or refuse.

A compare-and-swap loop rather than “load, check, add”: between a load and an add, two concurrent admissions both see room and both take it, and a budget that can be exceeded by the number of racing threads is not a budget. Nothing is allocated here and nothing is allocated by the caller before here — the refusal arrives before the cost.

pub fn charge(&self, bytes: u64) -> bool

Charge bytes whether or not they fit, and say which it was.

The reserve path for an operation that is already running: see Growth for why this cannot refuse. The counter is allowed to exceed the budget, and while it does, MemoryLedger::try_reserve refuses every new admission — which is the whole mechanism by which one enormous transfer quiets the box instead of taking it down.

pub fn release(&self, bytes: u64)

Give bytes back.

Saturating, because a ledger that can go negative under a double release would hand out the whole budget twice.

Trait Implementations

impl Debug for MemoryLedger

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.