webhooker/internal/database/event_tier_indexes_test.go

package database_test

import (
	"context"
	"fmt"
	"testing"
	"time"

	"github.com/google/uuid"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"gorm.io/gorm"
	"sneak.berlin/go/webhooker/internal/database"
)

// TestWebhookDBManager_OpenAddsEventTierIndexes verifies that a new
// per-webhook database has these indexes.
func TestWebhookDBManager_OpenAddsEventTierIndexes(t *testing.T) {
	t.Parallel()

	indexes := []struct {
		model any
		name  string
	}{
		{&database.Delivery{}, "idx_deliveries_status"},
		{&database.Delivery{}, "idx_deliveries_event_id"},
		{&database.DeliveryResult{}, "idx_delivery_results_delivery_id"},
		{&database.Event{}, "idx_events_deleted_at_created_at"},
		{&database.Event{}, "idx_events_created_at"},
	}

	mgr, lc := setupTestWebhookDBManager(t)
	ctx := context.Background()
	require.NoError(t, lc.Start(ctx))

	defer func() { require.NoError(t, lc.Stop(ctx)) }()

	webhookID := uuid.New().String()

	db, err := mgr.GetDB(webhookID)
	require.NoError(t, err)

	for _, ix := range indexes {
		assert.True(t, db.Migrator().HasIndex(ix.model, ix.name),
			"a new database should have %s", ix.name)
	}
}

// TestEventTierQueriesUseTheirIndexes verifies that the statements the
// indexes are for use them. GORM builds each statement in a dry run as
// the code named above it does, soft-delete condition included, and
// SQLite, which keeps no statistics on these tables, must plan to seek
// on each index listed by the columns in parentheses.
func TestEventTierQueriesUseTheirIndexes(t *testing.T) {
	t.Parallel()

	mgr, lc := setupTestWebhookDBManager(t)
	ctx := context.Background()
	require.NoError(t, lc.Start(ctx))

	defer func() { require.NoError(t, lc.Stop(ctx)) }()

	db, err := mgr.GetDB(uuid.New().String())
	require.NoError(t, err)

	dry := db.Session(&gorm.Session{DryRun: true})
	ids := []string{
		uuid.New().String(), uuid.New().String(), uuid.New().String(),
	}
	cutoff := time.Now()

	var (
		deliveries []database.Delivery
		results    []database.DeliveryResult
		depths     []struct{ Depth int }
		removed    []database.TargetTotals
	)

	byStatus := "idx_deliveries_status (status=? AND deleted_at=?)"
	byEvent := "idx_deliveries_event_id (event_id=? AND deleted_at=?)"

	// The delivery engine: recovery and the retry sweep, the sweep for
	// stranded pending deliveries, and the queue depth count.
	assertPlanUses(t, db, dry.Where(
		"status = ?", database.DeliveryStatusRetrying,
	).Find(&deliveries), byStatus)
	assertPlanUses(t, db, dry.Where(
		"status = ? AND updated_at < ?",
		database.DeliveryStatusPending, cutoff,
	).Limit(500).Find(&deliveries), byStatus)
	assertPlanUses(t, db, dry.Model(&database.Delivery{}).
		Select("target_id", "status", "count(*) as depth").
		Where("status IN ?", []database.DeliveryStatus{
			database.DeliveryStatusPending,
			database.DeliveryStatusRetrying,
		}).Group("target_id, status").Find(&depths), byStatus)

	// The event log: each event's deliveries, then their attempts
	// (loadEventsWithDeliveries, loadDeliveryResults).
	assertPlanUses(t, db, dry.Where("event_id = ?", ids[0]).
		Find(&deliveries), byEvent)
	assertPlanUses(t, db, dry.Where("delivery_id IN ?", ids).
		Order("attempt_num ASC").Find(&results),
		"idx_delivery_results_delivery_id (delivery_id=? AND deleted_at=?)")

	// Retention (reapExpired, deleteEvents): one batch of expired
	// events, then their attempts, deliveries and the events.
	var expired []string

	assertPlanUses(t, db, dry.Unscoped().Model(&database.Event{}).
		Where("created_at < ?", cutoff).
		Limit(database.ExportReapBatchSize).Pluck("id", &expired),
		"idx_events_created_at (created_at<?)")
	assertPlanUses(t, db, dry.Unscoped().Where(
		"delivery_id IN (?)", dry.Unscoped().Model(&database.Delivery{}).
			Select("id").Where("event_id IN ?", ids),
	).Delete(&database.DeliveryResult{}),
		"idx_delivery_results_delivery_id (delivery_id=?)",
		"idx_deliveries_event_id (event_id=?)")
	assertPlanUses(t, db, dry.Unscoped().Model(&database.Delivery{}).
		Select("target_id, count(*) AS deliveries_removed, "+
			"count(CASE WHEN status = ? THEN 1 END) AS failed_removed",
			database.DeliveryStatusFailed).
		Where("event_id IN ?", ids).Group("target_id").Find(&removed),
		"idx_deliveries_event_id (event_id=?)")
	assertPlanUses(t, db, dry.Unscoped().Where("event_id IN ?", ids).
		Delete(&database.Delivery{}), "idx_deliveries_event_id (event_id=?)")
	assertPlanUses(t, db, dry.Unscoped().Where("id IN ?", ids).
		Delete(&database.Event{}), "sqlite_autoindex_events_1 (id=?)")
}

// TestEventLogFiltersUseTheStatusIndex does the same for the event log's
// Failed and Pending lists, of the newest events with a delivery in
// given statuses, and for their counts (eventsWithStatus and
// countEventsWithStatus in the handlers). The lists must also reach
// the events table only by ID: from the matching deliveries, then from
// the newest of those events.
func TestEventLogFiltersUseTheStatusIndex(t *testing.T) {
	t.Parallel()

	mgr, lc := setupTestWebhookDBManager(t)
	ctx := context.Background()
	require.NoError(t, lc.Start(ctx))

	defer func() { require.NoError(t, lc.Stop(ctx)) }()

	webhookID := uuid.New().String()

	db, err := mgr.GetDB(webhookID)
	require.NoError(t, err)

	dry := db.Session(&gorm.Session{DryRun: true})
	byStatus := "idx_deliveries_status (status=? AND deleted_at=?)"
	pending := []database.DeliveryStatus{
		database.DeliveryStatusPending,
		database.DeliveryStatusRetrying,
	}

	var (
		rows  []struct{ ID string }
		count int64
	)

	matching := dry.Model(&database.Delivery{}).
		Distinct("event_id").Where("status IN ?", pending)
	newest := dry.Table("(?) AS matching", matching).
		Joins("CROSS JOIN events ON events.id = matching.event_id").
		Where(
			"events.webhook_id = ? AND events.deleted_at IS NULL",
			webhookID,
		).
		Order("events.created_at DESC").Limit(50).
		Select("events.id AS event_id")

	// Each step of the plan is printed in braces, so these name the
	// lookup that follows each scan.
	byID := "{SEARCH events USING INDEX sqlite_autoindex_events_1 (id=?)}"

	assertPlanUses(t, db, dry.Table("(?) AS newest", newest).
		Joins("CROSS JOIN events ON events.id = newest.event_id").
		Select("id").Order("created_at DESC").Limit(50).Find(&rows),
		byStatus, "{SCAN matching} "+byID, "{SCAN newest} "+byID)
	assertPlanUses(t, db, dry.Model(&database.Delivery{}).
		Distinct("event_id").Where("status IN ?", pending).Count(&count),
		byStatus)
}

// TestStatisticsQueriesUseTheirIndexes does the same for the webhook
// page's statistics (readEventStats in the handlers): deliveries in
// progress, each target's deliveries finished since a time, which must
// come from the index alone, and events received since a time.
func TestStatisticsQueriesUseTheirIndexes(t *testing.T) {
	t.Parallel()

	mgr, lc := setupTestWebhookDBManager(t)
	ctx := context.Background()
	require.NoError(t, lc.Start(ctx))

	defer func() { require.NoError(t, lc.Stop(ctx)) }()

	db, err := mgr.GetDB(uuid.New().String())
	require.NoError(t, err)

	dry := db.Session(&gorm.Session{DryRun: true})
	since := time.Now()

	var (
		count    int64
		byTarget []struct{ TargetID string }
	)

	assertPlanUses(t, db, dry.Model(&database.Delivery{}).
		Where("status IN ?", []database.DeliveryStatus{
			database.DeliveryStatusPending,
			database.DeliveryStatusRetrying,
		}).Count(&count),
		"idx_deliveries_status (status=? AND deleted_at=?)")
	assertPlanUses(t, db, dry.Model(&database.Delivery{}).
		Select("target_id, "+
			"count(CASE WHEN status = ? THEN 1 END) AS delivered, "+
			"count(CASE WHEN status = ? THEN 1 END) AS failed",
			database.DeliveryStatusDelivered,
			database.DeliveryStatusFailed).
		Where("status IN ? AND finished_at >= ?",
			[]database.DeliveryStatus{
				database.DeliveryStatusDelivered,
				database.DeliveryStatusFailed,
			}, since).
		Group("target_id").Find(&byTarget),
		"COVERING INDEX idx_deliveries_status "+
			"(status=? AND deleted_at=? AND finished_at>?)")
	assertPlanUses(t, db, dry.Model(&database.Event{}).
		Where("created_at >= ?", since).Count(&count),
		"idx_events_deleted_at_created_at "+
			"(deleted_at=? AND created_at>?)")
}

// TestResubmitCountUsesItsIndex does the same for the event log's count
// of the events resubmitted from each of a page's events (resubmitCounts
// in the handlers). It passes a full page of 25 ids: with an index on
// resubmitted_from_id alone, SQLite uses it for three ids and turns to
// the deleted_at index from five.
func TestResubmitCountUsesItsIndex(t *testing.T) {
	t.Parallel()

	mgr, lc := setupTestWebhookDBManager(t)
	ctx := context.Background()
	require.NoError(t, lc.Start(ctx))

	defer func() { require.NoError(t, lc.Stop(ctx)) }()

	db, err := mgr.GetDB(uuid.New().String())
	require.NoError(t, err)

	dry := db.Session(&gorm.Session{DryRun: true})

	page := make([]string, 25)
	for i := range page {
		page[i] = uuid.New().String()
	}

	var counts []struct{ Total int }

	assertPlanUses(t, db, dry.Model(&database.Event{}).
		Select("resubmitted_from_id, count(*) AS total").
		Where("resubmitted_from_id IN ?", page).
		Group("resubmitted_from_id").Find(&counts),
		"idx_events_resubmitted_from_id "+
			"(resubmitted_from_id=? AND deleted_at=?)")
}

// TestEntrypointEventsUseTheirIndex does the same for the webhook
// page's count, for each entrypoint, of the events that arrived on its
// URL since the retention cutoff (addEntrypointEvents in the
// handlers), which must come from the index alone. It passes 25
// entrypoints, as TestResubmitCountUsesItsIndex passes 25 events.
func TestEntrypointEventsUseTheirIndex(t *testing.T) {
	t.Parallel()

	mgr, lc := setupTestWebhookDBManager(t)
	ctx := context.Background()
	require.NoError(t, lc.Start(ctx))

	defer func() { require.NoError(t, lc.Stop(ctx)) }()

	db, err := mgr.GetDB(uuid.New().String())
	require.NoError(t, err)

	dry := db.Session(&gorm.Session{DryRun: true})

	entrypoints := make([]string, 25)
	for i := range entrypoints {
		entrypoints[i] = uuid.New().String()
	}

	var rows []struct{ Events int }

	assertPlanUses(t, db, dry.Model(&database.Event{}).
		Select("entrypoint_id, count(*) AS events").
		Where("entrypoint_id IN ? AND resubmitted_from_id IS NULL",
			entrypoints).
		Where("created_at >= ?", time.Now()).
		Group("entrypoint_id").Find(&rows),
		"COVERING INDEX idx_events_entrypoint_id "+
			"(entrypoint_id=? AND deleted_at=? AND "+
			"resubmitted_from_id=? AND created_at>?)")
}

// assertPlanUses asserts that SQLite's plan for a statement GORM built
// in a dry run, run with the same SQL and arguments GORM would send,
// names each of the given indexes.
func assertPlanUses(
	t *testing.T, db, built *gorm.DB, indexes ...string,
) {
	t.Helper()

	var plan []struct{ Detail string }

	require.NoError(t, db.Raw(
		"EXPLAIN QUERY PLAN "+built.Statement.SQL.String(),
		built.Statement.Vars...,
	).Scan(&plan).Error)

	for _, index := range indexes {
		assert.Contains(t, fmt.Sprint(plan), index,
			built.Statement.SQL.String())
	}
}