Struct Watermark 

#[non_exhaustive]
pub struct Watermark {
    pub cursor: Option<Bytes>,
    pub checkpoint_hi: Option<u64>,
    pub checkpoint_lo: Option<u64>,
}

Available on crate feature unstable only.

Progress markers for a query scan. Carried both on every item and as standalone wire frames between items when the underlying scan advances without producing a matching item.

Exactly one of checkpoint_hi / checkpoint_lo is set per response stream — whichever matches the request ordering. The unscanned side is always unset.

Fields (Non-exhaustive)

Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional Struct { .. } syntax; cannot be matched against without a wildcard ..; and struct update syntax will not work.

cursor: Option<Bytes>

Opaque cursor at this scan position. Use as options.after (ascending) or options.before (descending) on the next request to resume from here. Clients should track the most recently received cursor across both standalone and item-embedded watermarks as the safe resume point.

checkpoint_hi: Option<u64>

Ascending scans only. Every matching item in checkpoints <= checkpoint_hi has been emitted; checkpoints strictly greater may still hold unscanned matches. Non-decreasing across the stream.

Unset only on frames whose scan position is still at the genesis checkpoint (cp 0). Set on every subsequent frame.

checkpoint_lo: Option<u64>

Descending scans only. Every matching item in checkpoints >= checkpoint_lo has been emitted; checkpoints strictly less may still hold unscanned matches. Non-increasing across the stream.

Implementations

impl Watermark

pub const CURSOR_FIELD: &'static MessageField

pub const CHECKPOINT_HI_FIELD: &'static MessageField

pub const CHECKPOINT_LO_FIELD: &'static MessageField

impl Watermark

pub fn path_builder() -> WatermarkFieldPathBuilder

impl Watermark

pub const fn const_default() -> Self

pub fn cursor_opt(&self) -> Option<&[u8]>

If cursor is set, returns Some with the value; otherwise returns None.

pub fn set_cursor<T: Into<Bytes>>(&mut self, field: T)

Sets cursor with the provided value.

pub fn with_cursor<T: Into<Bytes>>(self, field: T) -> Self

Sets cursor with the provided value.

pub fn checkpoint_hi_opt_mut(&mut self) -> Option<&mut u64>

If checkpoint_hi is set, returns Some with a mutable reference to the value; otherwise returns None.

pub fn checkpoint_hi_mut(&mut self) -> &mut u64

Returns a mutable reference to checkpoint_hi. If the field is unset, it is first initialized with the default value.

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

If checkpoint_hi is set, returns Some with the value; otherwise returns None.

pub fn set_checkpoint_hi(&mut self, field: u64)

Sets checkpoint_hi with the provided value.

pub fn with_checkpoint_hi(self, field: u64) -> Self

Sets checkpoint_hi with the provided value.

pub fn checkpoint_lo_opt_mut(&mut self) -> Option<&mut u64>

If checkpoint_lo is set, returns Some with a mutable reference to the value; otherwise returns None.

pub fn checkpoint_lo_mut(&mut self) -> &mut u64

Returns a mutable reference to checkpoint_lo. If the field is unset, it is first initialized with the default value.

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

If checkpoint_lo is set, returns Some with the value; otherwise returns None.

pub fn set_checkpoint_lo(&mut self, field: u64)

Sets checkpoint_lo with the provided value.

pub fn with_checkpoint_lo(self, field: u64) -> Self

Sets checkpoint_lo with the provided value.

impl Watermark

pub fn cursor(&self) -> &[u8]

Returns the value of cursor, or the default value if cursor is unset.

pub fn checkpoint_hi(&self) -> u64

Returns the value of checkpoint_hi, or the default value if checkpoint_hi is unset.

pub fn checkpoint_lo(&self) -> u64

Returns the value of checkpoint_lo, or the default value if checkpoint_lo is unset.

Trait Implementations

impl Clone for Watermark

fn clone(&self) -> Watermark

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for Watermark

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

Formats the value using the given formatter.

impl Default for Watermark

fn default() -> Self

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for Watermark

fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>

where D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Hash for Watermark

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl Message for Watermark

fn encoded_len(&self) -> usize

Returns the encoded length of the message without a length delimiter.

fn clear(&mut self)

Clears the message, resetting all fields to their default.

fn encode(&self, buf: &mut impl BufMut) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message to a buffer.

fn encode_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message to a newly allocated buffer.

fn encode_length_delimited( &self, buf: &mut impl BufMut, ) -> Result<(), EncodeError>

where Self: Sized,

Encodes the message with a length-delimiter to a buffer.

fn encode_length_delimited_to_vec(&self) -> Vec<u8>

where Self: Sized,

Encodes the message with a length-delimiter to a newly allocated buffer.

fn decode(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes an instance of the message from a buffer.

fn decode_length_delimited(buf: impl Buf) -> Result<Self, DecodeError>

where Self: Default,

Decodes a length-delimited instance of the message from the buffer.

fn merge(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes an instance of the message from a buffer, and merges it into self.

fn merge_length_delimited(&mut self, buf: impl Buf) -> Result<(), DecodeError>

where Self: Sized,

Decodes a length-delimited instance of the message from buffer, and merges it into self.

impl MessageFields for Watermark

const FIELDS: &'static [&'static MessageField]

impl PartialEq for Watermark

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Serialize for Watermark

fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>

where S: Serializer,

Serialize this value into the given Serde serializer.

impl Eq for Watermark

impl StructuralPartialEq for Watermark