greptime-meter

OverView

The greptime-meter provides an abstraction about data read/write computation and collection. It consists of the following crates:

• meter-core: provides some core traits and data structures.
• meter-macros: provides some macros for user convenience, include write_meter! etc.
• meter-example: provides a simple implementation of meter-core and an example.

Documentation

cargo doc --open --no-deps

Write admission migration

• MeterRecord::new(catalog, schema, value, rows, source) now takes an explicit insertion row count. Read records use rows = 0; value keeps its calculated metering meaning (for example, WCU/RCU).
• Implement Collect::on_write with a boxed Send future returning Result<(), meter_core::collect::WriteRejected>. Reject before recording accepted usage. on_read remains synchronous.
• Await write_meter!(catalog, schema, requests, rows, source) and handle its rejection before dispatch. It returns the calculated value on success. Missing calculators still submit the row count with value = 0.
• For bulk writes, await write_meter!(record) with a precomputed MeterRecord. This uses the same Registry::record_write operation without a calculator.
• meter-macros defaults to noop: both write forms return Ok(0) without evaluating arguments, including row-count scans. Set default-features = false to enable collection. Direct registry calls always invoke registered collectors.

Collection happens before write dispatch. Success means admission and recording, not successful persistence. The registry neither implements quota policy nor refunds usage after a downstream failure. No registered collector permits writes.

Downstream integration is a manual checkpoint: update both meter-core and meter-macros to the same intended revision and regenerate the consumer's lockfile. Publishing and downstream dependency changes are separate steps.

Validation

Run enabled and noop configurations separately to avoid feature unification hiding the enabled macro implementation:

cargo check --workspace --all-targets
cargo check -p meter-macros -p meter-example --all-targets --no-default-features
cargo fmt --all -- --check
cargo clippy --workspace --all-targets -- -D warnings
cargo clippy -p meter-macros -p meter-example --all-targets --no-default-features -- -D warnings
cargo nextest run --workspace
cargo nextest run -p meter-macros --no-default-features
cargo nextest run -p meter-macros --features noop
cargo test --doc --workspace
cargo test --doc -p meter-macros --no-default-features