meterstore 0.8.0

//! A real PostgreSQL and a real Iceberg warehouse, in one call.
//!
//! Starting a container, connecting a pool, building a temporary warehouse,
//! loading a SQL catalog, creating both tiers and assembling a store is eighty
//! lines every suite would otherwise repeat — and it is the setup a *deployment*
//! has to get right too, so a copy per suite is a copy per suite to drift.
//!
//! # Why the fixtures are real
//!
//! §17 draws the line at storage fidelity: the things worth testing here are the
//! ones a fake cannot fail at. Catalog compare-and-swap, advisory-lock scope,
//! partition detach visibility, Parquet round-tripping of a `Decimal128` — a
//! mock agrees with whatever the code does. So the harness starts the real
//! thing.
//!
//! What it does **not** do is start a container per harness. Isolation is a
//! *database*, which costs milliseconds; a container costs seconds, and at a
//! couple of hundred integration tests that was the wall clock. See
//! [`postgres`](super::postgres) for the trade and for how to opt out.

use std::sync::Arc;

use sqlx::PgPool;
use time::{Duration, OffsetDateTime};

use crate::cold::{IcebergCold, IcebergSqlCatalog, WarehouseAuth};
use crate::config::{TableConfig, ValidatedTableConfig};
use crate::error::Result;
use crate::hot::PostgresHot;
use crate::session::MeterStore;
use crate::tiering::store::{ColdStore, HotStore};
use crate::watermark::ArchivalWindow;

/// Both tiers, running, with a table already created.
///
/// Holds the container and the warehouse directory, so both live exactly as long
/// as the harness does — a dropped `TempDir` takes the Iceberg data with it, and
/// a test that let it go early would fail somewhere unrelated.
pub struct TestHarness {
    hot: Arc<PostgresHot>,
    cold: Arc<IcebergCold>,
    config: ValidatedTableConfig,
    url: String,
    _warehouse: tempfile::TempDir,
}

impl std::fmt::Debug for TestHarness {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("TestHarness")
            .field("table", &self.config.name())
            .finish_non_exhaustive()
    }
}

impl TestHarness {
    /// The PostgreSQL image every suite runs against.
    ///
    /// See [`postgres::IMAGE_TAG`](super::postgres::IMAGE_TAG), which is where it
    /// is chosen; re-exported here because that is where suites look for it.
    pub const POSTGRES_IMAGE_TAG: &'static str = super::postgres::IMAGE_TAG;

    /// The table name the harness creates.
    ///
    /// Carries the `_versions` suffix, because that is the physical name: the
    /// table holds every version of every reading, and the resolved view is what
    /// queries should use (§13.7.2).
    pub const TABLE: &'static str = "readings_versions";

    /// Start both tiers with the default table configuration.
    pub async fn start() -> Result<Self> {
        Self::with_config(
            TableConfig::new(Self::TABLE)
                .settlement_lag(Duration::DAY)
                .build()?,
        )
        .await
    }

    /// Start both tiers with a specific table configuration.
    pub async fn with_config(config: ValidatedTableConfig) -> Result<Self> {
        // A database of its own on the process-wide container: the same
        // isolation for milliseconds instead of seconds.
        let url = super::postgres::fresh_database().await?;

        let pool = PgPool::connect(&url)
            .await
            .map_err(|e| crate::Error::Storage(e.to_string()))?;
        let hot = Arc::new(PostgresHot::new(pool));

        let warehouse = tempfile::tempdir()
            .map_err(|e| crate::Error::Storage(format!("temp warehouse: {e}")))?;
        // Dogfood the public cold-tier constructor rather than wiring the
        // SqlCatalog by hand — the same builder every deployment uses.
        let warehouse_uri = format!("file://{}", warehouse.path().display());
        let cold = IcebergSqlCatalog {
            database_url: &url,
            warehouse_uri: &warehouse_uri,
            catalog_name: "meterstore",
            namespace: "metering",
            file_target_bytes: 8 * 1024 * 1024,
            metadata_pool_max_connections: 10,
            auth: &WarehouseAuth::default(),
        }
        .build()
        .await?
        .cold();

        let harness = Self {
            hot,
            cold,
            config,
            url,
            _warehouse: warehouse,
        };

        // One entry point, exactly as a deployment should use (§7.3): the hot
        // table's primary key, the cold schema and the resolution `PARTITION BY`
        // all have to agree, and creating them separately is where they drift.
        harness
            .hot
            .create_tables(
                harness.config.name(),
                &harness.config.merge_key(),
                &harness.config.extra_columns(),
                harness.config.time_model(),
            )
            .await?;
        harness
            .cold
            .create_tables(
                harness.config.name(),
                &harness.config.identity_column_names(),
                &harness.config.extra_columns(),
            )
            .await?;

        Ok(harness)
    }

    /// The hot tier.
    pub fn hot(&self) -> &Arc<PostgresHot> {
        &self.hot
    }

    /// The cold tier.
    pub fn cold(&self) -> &Arc<IcebergCold> {
        &self.cold
    }

    /// The table configuration both tiers were created with.
    pub fn config(&self) -> &ValidatedTableConfig {
        &self.config
    }

    /// The PostgreSQL connection URL, for a second pool or a raw statement.
    pub fn url(&self) -> &str {
        &self.url
    }

    /// The warehouse root on disk.
    ///
    /// Exposed so a test can open the written files with something **other than**
    /// this crate — which is the only way to check the claim in P2 that the
    /// output is standard rather than merely self-consistent.
    pub fn warehouse(&self) -> &std::path::Path {
        self._warehouse.path()
    }

    /// Every Parquet data file the cold tier has written, sorted by path.
    ///
    /// Found by walking the warehouse rather than by reading the manifests, on
    /// purpose: reading them through Iceberg would be asking this crate's
    /// dependency whether this crate's dependency can read its own output.
    pub fn parquet_files(&self) -> Vec<std::path::PathBuf> {
        fn walk(dir: &std::path::Path, out: &mut Vec<std::path::PathBuf>) {
            let Ok(entries) = std::fs::read_dir(dir) else {
                return;
            };
            for entry in entries.flatten() {
                let path = entry.path();
                if path.is_dir() {
                    walk(&path, out);
                } else if path.extension().is_some_and(|e| e == "parquet") {
                    out.push(path);
                }
            }
        }

        let mut out = Vec::new();
        walk(self._warehouse.path(), &mut out);
        out.sort();
        out
    }

    /// A store over both tiers.
    pub async fn store(&self) -> Result<MeterStore> {
        self.builder_for(self.config.clone()).await?.build().await
    }

    /// A builder for **another** table over the same two tiers.
    ///
    /// A deployment that holds a second stream — non-authoritative ESA values
    /// beside billing readings, say — needs two tables against one PostgreSQL
    /// and one Iceberg catalog. Feed the builders to
    /// [`MeterCatalog`](crate::MeterCatalog) to get them in one session.
    ///
    /// The table's storage is not created here; call
    /// [`MeterStore::create_tables`] or the catalog's equivalent.
    pub async fn builder_for(
        &self,
        config: ValidatedTableConfig,
    ) -> Result<crate::MeterStoreBuilder> {
        // Created first because the provider needs a table to load a schema from.
        self.cold
            .create_table_with(
                config.name(),
                &config.extra_columns(),
                &config.identity_column_names(),
            )
            .await?;

        Ok(MeterStore::builder()
            .hot(Arc::clone(&self.hot) as Arc<dyn HotStore>)
            .cold(
                Arc::clone(&self.cold) as Arc<dyn ColdStore>,
                self.cold.table_provider(config.name()).await?,
            )
            .table(config))
    }

    /// Make sure the hot tier can hold `[from, to)`.
    pub async fn ensure_partitions(&self, from: OffsetDateTime, to: OffsetDateTime) -> Result<()> {
        self.hot
            .ensure_partitions(self.config.name(), from, to, self.config.archival_step())
            .await
            .map(|_| ())
    }

    /// Place the tier boundary at `at` without archiving anything.
    ///
    /// A test convenience, not a workaround: the archiver bootstraps its own
    /// boundary on a table that has never archived, crossing the empty stretch
    /// below the first partition in a single commit. What this adds is *exactly
    /// where* the boundary sits, so a test can state "everything before this is
    /// settled" rather than inferring it from where the fixture happens to start.
    pub async fn seed_watermark(&self, at: OffsetDateTime) -> Result<()> {
        self.seed_watermark_for(self.config.name(), at, self.config.archival_step())
            .await
    }

    /// Place another table's boundary, for a harness hosting more than one.
    pub async fn seed_watermark_for(
        &self,
        table: &str,
        at: OffsetDateTime,
        step: time::Duration,
    ) -> Result<()> {
        self.cold
            .append_and_commit(
                table,
                crate::tiering::store::stream_of(Vec::new()),
                crate::tiering::store::WriteHints::default(),
                ArchivalWindow::new(at - step, at)?,
            )
            .await
            .map(|_| ())
    }

    /// Write a workload's series through the store, tier-routed.
    ///
    /// Goes through [`MeterStore::append`] rather than raw SQL so the routing
    /// rule — a correction below the watermark goes to Iceberg, not PostgreSQL —
    /// is exercised rather than bypassed.
    pub async fn ingest(
        &self,
        store: &MeterStore,
        series: &[crate::encode::StoredSeries],
    ) -> Result<()> {
        for delivery in series {
            store.append(std::slice::from_ref(delivery)).await?;
        }
        Ok(())
    }

    /// [`ingest`](Self::ingest) for a **Zählerstandsgang** workload.
    ///
    /// Through [`MeterStore::append_readings`], for the same reason: the routing
    /// rule and the reconciliation a late correction goes through are the things
    /// under test, and raw SQL would step past both.
    pub async fn ingest_readings(
        &self,
        store: &MeterStore,
        deliveries: &[crate::encode::StoredReadings],
    ) -> Result<()> {
        for delivery in deliveries {
            store
                .append_readings(std::slice::from_ref(delivery))
                .await?;
        }
        Ok(())
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn the_pinned_image_meets_the_documented_minimum() {
        // The documented floor is **12**, where `ATTACH PARTITION` stopped taking
        // `ACCESS EXCLUSIVE` on the parent — which is what keeps partition
        // creation off the ingest path's critical lock. The container library's
        // own default is 11-alpine, below that, so the tag has to be set rather
        // than inherited.
        //
        // The suite pins a much newer one on purpose: the floor is what the
        // design *needs*, and what the tests run against should be what a
        // deployment plausibly runs.
        let major: u32 = TestHarness::POSTGRES_IMAGE_TAG
            .split('-')
            .next()
            .and_then(|m| m.parse().ok())
            .expect("the tag must start with a major version");
        assert!(major >= 12, "the documented floor is PostgreSQL 12");
    }

    #[test]
    fn the_table_name_announces_that_it_holds_versions() {
        // The name is load-bearing (§13.7.2): the relation that looks like the
        // obvious thing to query must not be the one that double-counts.
        assert!(TestHarness::TABLE.ends_with("_versions"));
    }
}