bvandeusen
8784e938bd
Extracts the in-flight check + scan-start logic from handleTriggerScan into a shared library.TryStartScan helper used by both manual and (future) scheduled paths. Folds in the lazy 1-hour stuck-scan reaper: in-flight rows older than StuckScanThreshold get FinishScanRun-ed with error_message="reaped (stale)" and the new scan proceeds. handleTriggerScan becomes a thin wrapper preserving the same external HTTP behavior (202/409/500). Operators no longer need to manually clear stuck rows after a server crash — the next manual trigger reaps it. Tests gated on MINSTREL_TEST_DATABASE_URL: no-in-flight starts; fresh-in-flight skips with row pointer; stale-in-flight reaps (verified via finished_at + error_message); DB error propagates.
67 lines
2.3 KiB
Go
67 lines
2.3 KiB
Go
package library
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import (
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"context"
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"errors"
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"fmt"
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"log/slog"
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"time"
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"github.com/jackc/pgx/v5"
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"github.com/jackc/pgx/v5/pgxpool"
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"git.fabledsword.com/bvandeusen/minstrel/internal/coverart"
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"git.fabledsword.com/bvandeusen/minstrel/internal/db/dbq"
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)
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// StuckScanThreshold is the age past which an in-flight scan_runs row is
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// reaped on the next TryStartScan attempt. Real scans on realistic libraries
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// finish well within this; the threshold is set far above legitimate scan
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// duration so a normally-running scan is never reaped accidentally.
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const StuckScanThreshold = 1 * time.Hour
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// TryStartScan attempts to start a new scan, with built-in handling for
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// stuck/stale in-flight rows.
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//
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// Behavior:
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// - No in-flight row → starts RunScan in a detached goroutine; returns (true, nil, nil).
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// - In-flight row, started_at > StuckScanThreshold ago → reaps via FinishScanRun
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// with error_message="reaped (stale)", then starts new scan; returns (true, nil, nil).
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// - In-flight row, started_at within threshold → returns (false, &row, nil); caller
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// decides what to do (HTTP handler returns 409; scheduler logs skip).
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// - DB error during the in-flight check or reap → returns (false, nil, err).
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func TryStartScan(ctx context.Context, pool *pgxpool.Pool,
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scanner *Scanner, enricher *coverart.Enricher,
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logger *slog.Logger, cfg RunScanConfig,
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) (started bool, existing *dbq.GetInFlightScanRunRow, err error) {
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q := dbq.New(pool)
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row, qerr := q.GetInFlightScanRun(ctx)
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if qerr == nil {
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// Found an in-flight row. Reap if stale, else skip.
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age := time.Since(row.StartedAt.Time)
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if age > StuckScanThreshold {
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logger.Warn("reaping stale in-flight scan",
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"id", row.ID, "started_at", row.StartedAt.Time, "age", age)
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if rerr := q.FinishScanRun(ctx, dbq.FinishScanRunParams{
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ID: row.ID,
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Column2: "reaped (stale)",
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}); rerr != nil {
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return false, nil, fmt.Errorf("reap stale scan: %w", rerr)
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}
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// Fall through to start a new scan.
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} else {
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return false, &row, nil
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}
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} else if !errors.Is(qerr, pgx.ErrNoRows) {
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return false, nil, fmt.Errorf("in-flight check: %w", qerr)
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}
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// No in-flight (or just reaped). Start RunScan detached.
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go func() {
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if _, runErr := RunScan(ctx, pool, scanner, enricher, logger, cfg); runErr != nil {
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logger.Warn("scan run failed", "err", runErr)
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}
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}()
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return true, nil, nil
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}
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