Feature Integrations

Optional Cargo features. Enable them on both [build-dependencies] and [dependencies] — the generator decides what to emit from its own feature set.

[build-dependencies]
ergo-sbe = { version = "0.1", features = ["compact_str", "chrono"] }

[dependencies]
ergo-sbe = { version = "0.1", features = ["compact_str", "chrono"] }

Measure with var_data_types_bench / chrono_converter_bench rather than quoting numbers from this page. DTO materialisation is never the hot path.

CompactString

Primarily for domain DTOs. Replaces String with compact_str::CompactString (≤24 bytes on the stack). The codec also gains into_<field>_as_compact_str() on text var-data stages.

use ergo_sbe::{DomainVarData, GenerationConfig};

let config = GenerationConfig::new("msgs")
    .with_domain_objects(DomainVarData::CompactStrings);

pub struct QuoteDomain {
    pub symbol: ergo_sbe::compact_str::CompactString,
    pub venue: ergo_sbe::compact_str::CompactString,
    pub price: Decimal,
}

let (symbol, _next_stage) = L3BookDecoder::try_decode(wire, 0)?
    .skip_bids()?
    .skip_asks()?
    .into_symbol_as_compact_str()?;

SmolStr

O(1) clone regardless of length. DomainVarData::SmolStrings plus into_<field>_as_smol_str().

let config = GenerationConfig::new("msgs")
    .with_domain_objects(DomainVarData::SmolStrings);

Bytes

Reference-counted buffer. DomainVarData::BytesCrate plus into_<field>_as_bytes().

let config = GenerationConfig::new("relay")
    .with_domain_objects(DomainVarData::BytesCrate);

let original = bytes::Bytes::copy_from_slice(b"payload");
let clone = original.clone();
let sub = original.slice(4..);

let (payload, next) = stage.into_payload_as_bytes()?;

Chrono

Schema fields are typically uint64 with a timestamp semanticType. The converters take i64. Map them with with_domain_type:

use ergo_sbe::{GenerationConfig, ConversionSelector};

let config = GenerationConfig::new("msgs")
    .with_domain_type(
        ConversionSelector::semantic_type("UTCTimestamp"),
        "chrono::DateTime<chrono::Utc>",
    )
    .with_domain_type(
        ConversionSelector::semantic_type("UTCTimestampMicros"),
        "chrono::NaiveDateTime",
    );

let created: chrono::DateTime<chrono::Utc> = dec.created_at()?;
let updated: chrono::NaiveDateTime = dec.updated_at()?;
enc.created_at(chrono::Utc::now())?;
enc.updated_at(chrono::DateTime::from_timestamp(1_720_000_000, 0).unwrap().naive_utc())?;

One semantic_type("UTCTimestamp") covers every field with that attribute. Worked example: Timestamps.

Direct converters (chrono feature):

use ergo_sbe::chrono_converters::*;

let dt = i64_nanos_to_datetime(1_720_000_000_000_000_000);
let ns = datetime_to_i64_nanos(dt);
let naive = i64_micros_to_naive(1_720_000_000_000_000);
assert_eq!(naive_to_i64_micros(naive), 1_720_000_000_000_000);

Combining

[build-dependencies]
ergo-sbe = { version = "0.1", features = ["compact_str", "bytes", "chrono"] }

[dependencies]
ergo-sbe = { version = "0.1", features = ["compact_str", "bytes", "chrono"] }

let config = GenerationConfig::new("msgs")
    .with_domain_objects(DomainVarData::CompactStrings)
    .with_domain_type(
        ConversionSelector::semantic_type("UTCTimestamp"),
        "chrono::DateTime<chrono::Utc>",
    );