Module filter 

Available on crate feature transport only.

Transport Filter Engine

Provides transport-level message filtering using CEL syntax with SIMD fast-path for simple patterns. Embedded in every transport – filters are configured via the config cascade and applied automatically.

Performance Tiers

• Tier 1 – SIMD field extraction (~50-100ns/msg). Always enabled.
• Tier 2 – Pre-compiled CEL (~500ns-1us/msg). Requires allow_cel_filters_in/out.
• Tier 3 – Complex CEL with regex/iteration (~5-50us/msg). Requires allow_complex_filters_in/out.

Usage

Transports construct TransportFilterEngine from config at creation time. The engine is a no-op when no filters are configured (zero overhead).

kafka:
  filters_in:
    - expression: 'has(_internal)'
      action: drop
    - expression: 'status == "poison"'
      action: dlq

Re-exports

pub use budget::BudgetError;

pub use budget::FilterBudget;

pub use config::FilterAction;

pub use config::FilterDirection;

pub use config::FilterRule;

pub use config::FilterTier;

pub use config::TransportFilterTierConfig;

Modules

budget

Static AST + runtime payload budget for Tier 2/3 CEL filters.

classify

Classify CEL expressions into performance tiers via text pattern matching.

compiled

Compiled filter representations and evaluation logic.

config

Filter configuration types for transport-level message filtering.

metrics

Filter metrics – counters per direction and action.

Structs

FilteredBatch

Result of partitioning a batch of messages through inbound filters.

FilteredDlqEntry

A DLQ entry produced by inbound filtering.

TransportFilterEngine

Transport-level message filter engine.

Enums

FilterDisposition

Result of evaluating a filter against a message payload.