Enum WsBackpressure 

pub enum WsBackpressure {
    Block,
    DropOldest,
    DropNewest,
    Buffer {
        max_bytes: usize,
    },
    Sample {
        rate: u32,
    },
}

Strategy applied when the bounded channel is full and cannot accept more messages.

WebSocket sources produce data at the rate of the remote sender. When the downstream processing pipeline cannot keep up, one of these strategies governs how the connector handles the overflow.

Implementation status (2026-03-07):

• Block: fully implemented (TCP backpressure propagation)
• DropNewest: implemented in source.rs via try_send
• DropOldest, Buffer, Sample: parsed from SQL WITH, fall back to DropNewest behavior with a debug log.

Variants

Block

Block WS read – TCP backpressure propagates to sender.

This is the safest option: the WebSocket read loop simply stops reading, which causes the TCP window to fill, eventually slowing the remote sender. No data is lost, but latency increases.

DropOldest

Drop oldest messages from bounded channel when full.

Not yet implemented – falls back to DropNewest behavior (incoming message silently discarded via try_send).

DropNewest

Drop incoming message when channel full (don’t enqueue).

The newly arriving message is silently discarded. Useful when freshness of already-buffered data matters more than completeness.

Buffer

Buffer up to max_bytes, then drop oldest.

Not yet implemented – falls back to DropNewest behavior (incoming message silently discarded via try_send). The max_bytes field is parsed from SQL WITH but currently ignored.

Fields

max_bytes: usize

Maximum buffer size in bytes before eviction kicks in.

Sample

Sample: keep every Nth message.

Not yet implemented – falls back to DropNewest behavior (incoming message silently discarded via try_send). The rate field is parsed from SQL WITH but currently ignored.

Fields

rate: u32

Keep every Nth message (e.g., rate = 10 keeps 10% of messages).

Trait Implementations

impl Clone for WsBackpressure

fn clone(&self) -> WsBackpressure

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for WsBackpressure

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

Formats the value using the given formatter.

impl Default for WsBackpressure

fn default() -> WsBackpressure

Returns the “default value” for a type.

impl<'de> Deserialize<'de> for WsBackpressure

fn deserialize<__D>(__deserializer: __D) -> Result<Self, __D::Error>

where __D: Deserializer<'de>,

Deserialize this value from the given Serde deserializer.

impl Serialize for WsBackpressure

fn serialize<__S>(&self, __serializer: __S) -> Result<__S::Ok, __S::Error>

where __S: Serializer,

Serialize this value into the given Serde serializer.