Enum StopCondition 

pub enum StopCondition {
    MaxRows(u64),
    MaxBytes(u64),
    SchemaStable {
        consecutive_stable_rows: u64,
    },
    ConfidenceThreshold(f64),
    MemoryPressure(f64),
    Any(Vec<StopCondition>),
    All(Vec<StopCondition>),
    Never,
}

A composable condition that can trigger early termination of profiling.

Conditions other than StopCondition::MaxRows are checked per chunk for performance. Their observed boundary can therefore vary with chunk size.

Variants

MaxRows(u64)

Stop after processing this many rows.

MaxBytes(u64)

Stop after consuming this many bytes from the source.

The CSV streaming engines, file and async, size each read to the budget that remains, so they stop at the end of the first record at or past the limit: bytes_consumed counts bytes read by the profiling pass, including the header, and exceeds the value by less than one record. Fraction stops or progress can require a separate CSV row-count scan before this budget takes effect. The async JSON reader still evaluates it after whole chunks.

SchemaStable

Stop when column types have not changed for approximately N rows after the initial schema baseline (accumulated across chunks).

Fields

consecutive_stable_rows: u64

Approximate number of rows with no type changes before stopping. Rows are accumulated per-chunk, so the actual count depends on chunk granularity.

ConfidenceThreshold(f64)

Stop when rows_processed / estimated_total >= threshold.

This is the fraction of the estimated row count read, rather than a statistical confidence level. Only meaningful when an estimate exists. When no estimate exists, this condition is inert.

MemoryPressure(f64)

Stop when memory usage exceeds this fraction of the configured limit.

Value in 0.0..=1.0 (e.g., 0.9 = 90% of memory limit).

Any(Vec<StopCondition>)

Stop when any sub-condition triggers.

All(Vec<StopCondition>)

Stop when all sub-conditions have triggered.

Never

Never stop early — process the entire stream (default).

Implementations

impl StopCondition

pub fn schema_inference() -> Self

Preset for schema-only profiling: stop after 10K rows or when schema stabilizes (no type changes for 1,000 consecutive rows).

pub fn quality_sample() -> Self

Preset for quality sampling: stop after 50K rows, 50 MB, or 95% of the estimated row count.

pub fn max_rows(&self) -> Option<u64>

The row count at which this condition can first trigger on rows alone, if any.

Mirrors the internal evaluate method: Any fires as soon as one child fires, so it takes the minimum of the children that a row count can trigger. All fires only once every child has fired, so it takes the maximum, and yields None if any child cannot be triggered by rows at all (a byte cap, Never, …) — such a condition can never be satisfied by rows alone.

Used two ways: parsers that can only enforce a row cap consult it after checking is_row_limit_only, and the incremental engine uses it as a per-row guardrail alongside the real evaluator.

pub fn max_bytes(&self) -> Option<u64>

The byte count at which this condition can first trigger on bytes alone, if any: the byte counterpart of max_rows, with the same Any/All rules.

The incremental engine sizes its reads to the budget that remains under it, so the scan stops at a record boundary rather than at the end of a large chunk.

pub fn is_row_limit_only(&self) -> bool

Whether this condition is expressible purely as a row limit.

Never never fires; a bare MaxRows is a row cap; a composite qualifies when every leaf is one of those. Anything else (byte caps, schema stability, confidence) needs a real evaluator, so a parser that can only cap rows must not silently accept it.

pub fn needs_row_count(&self) -> bool

Whether any leaf needs a total row count to evaluate its read fraction.

Trait Implementations

impl Clone for StopCondition

fn clone(&self) -> Self

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for StopCondition

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

Formats the value using the given formatter.

impl Default for StopCondition

fn default() -> Self

Returns the “default value” for a type.