Struct TaskBudget 

pub struct TaskBudget { /* private fields */ }

Tracks execution time budget for a task.

Created at task start, automatically records metrics on drop. Use for all Ring 0 operations and Ring 1 chunks.

Example

use laminar_core::budget::TaskBudget;

fn process_event(event: &Event) {
    let _budget = TaskBudget::ring0_event();
    // Process event...
    // Metrics recorded automatically when _budget is dropped
}

Performance

The budget tracking overhead is designed to be < 10ns, consisting of:

• Instant::now() on creation (~10-30ns depending on platform)
• Elapsed time calculation on drop (~10-30ns)
• Atomic counter increments for metrics (~10ns)

For Ring 0 hot paths where even this is too much, use TaskBudget::ring0_event_untracked() which skips metrics recording.

Implementations

impl TaskBudget

pub const RING0_EVENT_NS: u64 = 500

Single event processing budget: 500ns

pub const RING0_BATCH_NS: u64 = 5_000

Batch of events budget: 5μs (up to ~10 events)

pub const RING0_LOOKUP_NS: u64 = 200

State lookup budget: 200ns

pub const RING0_WINDOW_NS: u64 = 10_000

Window trigger budget: 10μs

pub const RING0_ITERATION_NS: u64 = 10_000

Iteration budget: 10μs (for one reactor poll cycle)

pub const RING1_CHUNK_NS: u64 = 1_000_000

Background work chunk budget: 1ms

pub const RING1_CHECKPOINT_NS: u64 = 10_000_000

Checkpoint preparation budget: 10ms

pub const RING1_WAL_FLUSH_NS: u64 = 100_000

WAL flush budget: 100μs

pub const RING1_COMPACTION_NS: u64 = 5_000_000

Compaction chunk budget: 5ms

pub fn ring0_event() -> Self

Create budget for Ring 0 single event.

Budget: 500ns

pub fn ring0_event_untracked() -> Self

Create budget for Ring 0 single event without metrics.

Use this in extremely hot paths where even atomic counter updates are too expensive.

pub fn ring0_batch() -> Self

Create budget for Ring 0 batch of events.

Budget: 5μs

pub fn ring0_lookup() -> Self

Create budget for Ring 0 state lookup.

Budget: 200ns

pub fn ring0_window() -> Self

Create budget for Ring 0 window trigger.

Budget: 10μs

pub fn ring0_iteration() -> Self

Create budget for Ring 0 iteration (one poll cycle).

Budget: 10μs

pub fn ring1_chunk() -> Self

Create budget for Ring 1 background chunk.

Budget: 1ms

pub fn ring1_checkpoint() -> Self

Create budget for Ring 1 checkpoint preparation.

Budget: 10ms

pub fn ring1_wal_flush() -> Self

Create budget for Ring 1 WAL flush.

Budget: 100μs

pub fn ring1_compaction() -> Self

Create budget for Ring 1 compaction chunk.

Budget: 5ms

pub fn custom(name: &'static str, ring: u8, budget_ns: u64) -> Self

Create a custom budget.

Arguments

• name - Task name for metrics (must be a static string)
• ring - Ring number (0, 1, or 2)
• budget_ns - Budget in nanoseconds

pub fn custom_untracked(name: &'static str, ring: u8, budget_ns: u64) -> Self

Create a custom budget without metrics recording.

pub fn name(&self) -> &'static str

Get the task name.

pub fn ring(&self) -> u8

Get the ring number.

pub fn budget_ns(&self) -> u64

Get the budget in nanoseconds.

pub fn elapsed_ns(&self) -> u64

Get elapsed time in nanoseconds.

Note: Truncation from u128 to u64 is acceptable here because:

• u64 can hold ~584 years of nanoseconds
• Budget tracking is for sub-second operations

pub fn remaining_ns(&self) -> i64

Get remaining budget in nanoseconds (negative if exceeded).

Returns a signed value where:

• Positive: nanoseconds of budget remaining
• Negative: nanoseconds over budget

pub fn exceeded(&self) -> bool

Check if budget is exceeded.

pub fn almost_exceeded(&self) -> bool

Check if budget is almost exceeded (>80% used).

Useful for early warnings and preemptive yielding.

pub fn half_used(&self) -> bool

Check if budget is half used (>50%).

Useful for chunking decisions.

pub fn percentage_used(&self) -> u64

Get the percentage of budget used (0-100+).

Values over 100 indicate the budget was exceeded.

Trait Implementations

impl Debug for TaskBudget

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

Formats the value using the given formatter.

impl Drop for TaskBudget

fn drop(&mut self)

Executes the destructor for this type.