Struct FetchPolicy 

pub struct FetchPolicy {
    pub concurrency: usize,
    pub coalesce_gap: u64,
    pub max_span: u64,
    pub retries: u32,
    pub backoff_ms: u64,
    pub trace: bool,
    pub whole_body_cap: u64,
    pub open_read: u64,
    pub whole_max: u64,
}

How HttpRangeReader fetches: fan-out, coalescing, retries, and the whole-body cap. FetchPolicy::from_env reads it once when a reader opens.

Fields

concurrency: usize

Requests in flight at once in read_many (RETE_HTTP_CONCURRENCY, 1–64; 1 fetches a batch sequentially). Also what the reader reports to the planner as its RangeReader::concurrency.

coalesce_gap: u64

Two ranges of one batch at most this many bytes apart are fetched as one request (RETE_HTTP_COALESCE_KB; 0 merges only touching or overlapping ranges).

max_span: u64

Coalescing never grows a request past this many bytes, so one huge span does not serialize what could have gone out in parallel.

retries: u32

Extra attempts for a transiently failing request (RETE_HTTP_RETRIES, at most 10; 0 = no retry).

backoff_ms: u64

The first backoff; it quadruples per retry, capped at 2 s.

trace: bool

RETE_HTTP_TRACE: one stderr line per read and per batch, to see which ranges a query needed and which of them went out together.

whole_body_cap: u64

The largest whole body a host that ignores Range may send and still have it kept (WHOLE_BODY_CAP); a larger one is refused by name.

open_read: u64

Bytes the open reads first, as its length probe (OPEN_READ); 0 probes with HEAD instead and keeps nothing.

whole_max: u64

A file at most this long is fetched whole by the open: the first read gives its length, one more read the rest, and no later read leaves memory (RETE_HTTP_WHOLE_MB, WHOLE_FILE_MAX; 0 never).

Implementations

impl FetchPolicy

pub const DEFAULT: FetchPolicy

16 in flight matches the wasm client’s fetch-worker pool and the Node client’s reteReadMany cap; a CDN or S3 serves that many concurrent range reads happily.

pub fn from_env() -> Self

FetchPolicy::DEFAULT with the RETE_HTTP_* overrides applied.

Trait Implementations

impl Clone for FetchPolicy

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for FetchPolicy

impl Debug for FetchPolicy

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

Formats the value using the given formatter.

impl Default for FetchPolicy

fn default() -> Self

Returns the “default value” for a type.

impl Eq for FetchPolicy

impl PartialEq for FetchPolicy

fn eq(&self, other: &Self) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for FetchPolicy