Enum NackReason 

#[non_exhaustive]
#[repr(u8)]
pub enum NackReason {
    BadMagic = 1,
    VersionMismatch = 2,
    BadHeaderCrc = 3,
    PayloadTooLarge = 4,
    BadPayloadCrc = 5,
    InternalError = 6,
    EmptyPayload = 7,
    UnknownMessage = 8,
    ReservedFlagsSet = 9,
    BadBatchFraming = 11,
}

Re-export of weir_core::NackReason — the payload of ClientError::Nack. Re-exported so consumers can match on the reason (e.g. to distinguish the connection-closing Nacks) without taking a direct dependency on weir-core. Reason byte carried as the first byte of every Nack message payload. Wire values are fixed and must not change without a WIRE_VERSION bump.

VersionMismatch Nack payload format: [NackReason::VersionMismatch (0x02), daemon_wire_version (u8)]. The second byte lets the client produce a specific error: “daemon is on wire protocol v1; this client is built against v2 — upgrade the daemon or downgrade the client.”

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

BadMagic = 1

Frame did not start with the b"WEIR" magic.

VersionMismatch = 2

Frame’s version byte did not equal the daemon’s WIRE_VERSION. The Nack payload’s second byte carries the daemon’s version (see above).

BadHeaderCrc = 3

Header CRC32 did not match the header bytes.

PayloadTooLarge = 4

Declared payload_len exceeded the daemon’s effective cap.

BadPayloadCrc = 5

Payload CRC32 did not match the payload bytes.

InternalError = 6

The daemon hit an internal error (e.g. queue saturation); transient.

EmptyPayload = 7

The push carried a zero-length payload, which the WAB cannot represent: an empty record’s length prefix is four zero bytes, identical to the end-of-records sentinel, so storing one would truncate the segment. Rejected at ingest.

UnknownMessage = 8

The frame’s header was structurally valid (magic, version, and header CRC all passed) but carried a message_type or durability byte this daemon does not recognise — a PERMANENT client protocol error (typically version skew). Distinct from InternalError (a transient daemon-side condition that keeps the connection open): the daemon closes the connection after this Nack. Retrying the identical frame will not succeed (F25).

ReservedFlagsSet = 9

The frame’s header was structurally valid but set one or more bits in the reserved flags byte, which must be zero in wire v1. A daemon rejects such a frame rather than silently ignoring a flag it does not understand (which could mean a producer believed a semantic flag took effect when it did not). Permanent; the daemon closes the connection (F52).

BadBatchFraming = 11

A PushBatch body could not be parsed: bad batch version, zero records, a record length that disagrees with the body, or trailing bytes.

0x0B, not 0x0A. 0x0A is this tree’s worked example of an unassigned reason — a try_from test asserts it errors, a client test asserts it surfaces as UnknownNack(0x0A), four polyglot clients branch on >= 0x0A, and the frozen vector nack_reserved_reason IS 0x0A. Assigning it would break a frozen vector, which the freeze forbids.

Implementations

impl NackReason

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

The canonical snake_case metric-label string for this reason.

These strings match the daemon’s Prometheus reason label values exactly (the nack_total{reason=...} series), so an ops consumer — an autoscaler, an alerting rule, a dashboard — can map a NackReason it receives over the wire to the metric label it must query, without hard-coding the strings. Inverse of NackReason::from_metric_label.

use weir_core::NackReason;
assert_eq!(NackReason::PayloadTooLarge.as_metric_label(), "payload_too_large");

pub fn from_metric_label(s: &str) -> Option<NackReason>

Parses a snake_case metric label back into its NackReason, or None if the string is not a known label. Inverse of NackReason::as_metric_label.

use weir_core::NackReason;
assert_eq!(
    NackReason::from_metric_label("payload_too_large"),
    Some(NackReason::PayloadTooLarge),
);
assert_eq!(NackReason::from_metric_label("nope"), None);

Trait Implementations

impl Clone for NackReason

fn clone(&self) -> NackReason

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for NackReason

impl Debug for NackReason

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

Formats the value using the given formatter.

impl Display for NackReason

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

Formats the value using the given formatter.

impl Eq for NackReason

impl Error for NackReason

fn source(&self) -> Option<&(dyn Error + 'static)>

Returns the lower-level source of this error, if any.

fn description(&self) -> &str

👎Deprecated since 1.42.0:

use the Display impl or to_string()

fn cause(&self) -> Option<&dyn Error>

👎Deprecated since 1.33.0:

replaced by Error::source, which can support downcasting

fn provide<'a>(&'a self, request: &mut Request<'a>)

🔬This is a nightly-only experimental API. (error_generic_member_access)

Provides type-based access to context intended for error reports.

impl PartialEq for NackReason

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for NackReason

impl TryFrom<u8> for NackReason

type Error = UnknownNackReason

The type returned in the event of a conversion error.

fn try_from(value: u8) -> Result<NackReason, <NackReason as TryFrom<u8>>::Error>

Performs the conversion.