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feat: TUI skeleton and a synthetic workload generator #2
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0d1a450
feat(tui): add the TUI skeleton wired to the CLI
mickamy 75cac73
feat(workload): add a synthetic load generator with compose wiring
mickamy 42e49c9
fix(tui): truncate query text on rune boundaries
mickamy 3902de0
fix(tui): prevent duplicate poll loops on pause/unpause
mickamy 7025c8d
test: raise coverage and ignore the dev workload tool
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,227 @@ | ||
| package main | ||
|
|
||
| import ( | ||
| "context" | ||
| "fmt" | ||
| "log" | ||
| "math/rand/v2" | ||
| "os" | ||
| "os/signal" | ||
| "sync" | ||
| "syscall" | ||
| "time" | ||
|
|
||
| "github.com/jackc/pgx/v5/pgxpool" | ||
| ) | ||
|
|
||
| const ( | ||
| // defaultDSN points at the local compose database; password is the dev one. | ||
| defaultDSN = "postgres://postgres:pass@postgres:5432/dev" //nolint:gosec // dev-only default DSN | ||
| poolSize = 20 | ||
| seedRows = 1000 | ||
| normalWorkers = 8 | ||
| extraWorkers = 4 // nPlusOne, longQueries, blocker, contender | ||
| hotRowID = 1 // the single row the blocker and contenders fight over | ||
| ) | ||
|
|
||
| func main() { | ||
| if err := run(); err != nil { | ||
| log.Fatalf("workload: %v", err) | ||
| } | ||
| } | ||
|
|
||
| func run() error { | ||
| ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM) | ||
| defer stop() | ||
|
|
||
| dsn := os.Getenv("WORKLOAD_DSN") | ||
| if dsn == "" { | ||
| dsn = defaultDSN | ||
| } | ||
|
|
||
| pool, err := connect(ctx, dsn) | ||
| if err != nil { | ||
| return err | ||
| } | ||
| defer pool.Close() | ||
|
|
||
| if err := setup(ctx, pool); err != nil { | ||
| return err | ||
| } | ||
|
|
||
| log.Println("workload: generating traffic (ctrl-c to stop)") | ||
|
|
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| workers := make([]func(context.Context, *pgxpool.Pool), 0, normalWorkers+extraWorkers) | ||
| for range normalWorkers { | ||
| workers = append(workers, normalLoad) | ||
| } | ||
|
|
||
| workers = append(workers, nPlusOne, longQueries, blocker, contender) | ||
|
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| var wg sync.WaitGroup | ||
|
|
||
| for _, w := range workers { | ||
| wg.Go(func() { | ||
| w(ctx, pool) | ||
| }) | ||
| } | ||
|
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|
||
|
|
||
| <-ctx.Done() | ||
| wg.Wait() | ||
| log.Println("workload: stopped") | ||
|
|
||
| return nil | ||
| } | ||
|
|
||
| func connect(ctx context.Context, dsn string) (*pgxpool.Pool, error) { | ||
| cfg, err := pgxpool.ParseConfig(dsn) | ||
| if err != nil { | ||
| return nil, fmt.Errorf("parse dsn: %w", err) | ||
| } | ||
|
|
||
| cfg.MaxConns = poolSize | ||
|
|
||
| for { | ||
| pool, err := pgxpool.NewWithConfig(ctx, cfg) | ||
| if err == nil { | ||
| if pingErr := pool.Ping(ctx); pingErr == nil { | ||
| return pool, nil | ||
| } else { | ||
| pool.Close() | ||
| err = pingErr | ||
| } | ||
| } | ||
|
|
||
| log.Printf("workload: waiting for db: %v", err) | ||
|
|
||
| if !wait(ctx, time.Second) { | ||
| return nil, fmt.Errorf("canceled while connecting: %w", ctx.Err()) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| func setup(ctx context.Context, pool *pgxpool.Pool) error { | ||
| // pg_stat_statements needs shared_preload_libraries; tolerate its absence. | ||
| if _, err := pool.Exec(ctx, `CREATE EXTENSION IF NOT EXISTS pg_stat_statements`); err != nil { | ||
| log.Printf("workload: pg_stat_statements unavailable: %v", err) | ||
| } | ||
|
|
||
| schema := []string{ | ||
| `CREATE TABLE IF NOT EXISTS items ( | ||
| id int PRIMARY KEY, | ||
| name text NOT NULL, | ||
| value int NOT NULL | ||
| )`, | ||
| fmt.Sprintf(`INSERT INTO items | ||
| SELECT g, 'item-' || g, g | ||
| FROM generate_series(1, %d) g | ||
| ON CONFLICT (id) DO NOTHING`, seedRows), | ||
| } | ||
|
|
||
| for _, stmt := range schema { | ||
| if _, err := pool.Exec(ctx, stmt); err != nil { | ||
| return fmt.Errorf("setup: %w", err) | ||
| } | ||
| } | ||
|
|
||
| return nil | ||
| } | ||
|
|
||
| // normalLoad does steady point reads and writes across random rows. | ||
| func normalLoad(ctx context.Context, pool *pgxpool.Pool) { | ||
| for wait(ctx, jitter(5*time.Millisecond, 45*time.Millisecond)) { | ||
| id := rand.IntN(seedRows) + 1 //nolint:gosec // weak RNG is fine for a load generator | ||
|
|
||
| var ( | ||
| name string | ||
| value int | ||
| ) | ||
|
|
||
| _ = pool.QueryRow(ctx, `SELECT name, value FROM items WHERE id = $1`, id).Scan(&name, &value) | ||
| _, _ = pool.Exec(ctx, `UPDATE items SET value = value + 1 WHERE id = $1`, id) | ||
| } | ||
| } | ||
|
|
||
| // nPlusOne fetches a batch of ids then queries each one separately, the classic | ||
| // pattern that is cheap per call but dominates pg_stat_statements by count. | ||
| func nPlusOne(ctx context.Context, pool *pgxpool.Pool) { | ||
| for wait(ctx, 500*time.Millisecond) { | ||
| rows, err := pool.Query(ctx, `SELECT id FROM items ORDER BY random() LIMIT 50`) | ||
| if err != nil { | ||
| continue | ||
| } | ||
|
|
||
| var ids []int | ||
|
|
||
| for rows.Next() { | ||
| var id int | ||
| if err := rows.Scan(&id); err == nil { | ||
| ids = append(ids, id) | ||
| } | ||
| } | ||
|
|
||
| rows.Close() | ||
|
|
||
| for _, id := range ids { | ||
| var name string | ||
|
|
||
| _ = pool.QueryRow(ctx, `SELECT name FROM items WHERE id = $1`, id).Scan(&name) | ||
| } | ||
| } | ||
| } | ||
|
|
||
| // longQueries runs an occasional multi-second query so the Activity screen has | ||
| // a long DURATION to surface. | ||
| func longQueries(ctx context.Context, pool *pgxpool.Pool) { | ||
| for wait(ctx, 2*time.Second) { | ||
| seconds := rand.IntN(8) + 3 //nolint:gosec // weak RNG is fine for a load generator | ||
|
|
||
| _, _ = pool.Exec(ctx, `SELECT pg_sleep($1)`, seconds) | ||
| } | ||
| } | ||
|
|
||
| // blocker holds a row lock inside an open transaction, then sits idle, creating | ||
| // an idle-in-transaction backend that blocks the contender. | ||
| func blocker(ctx context.Context, pool *pgxpool.Pool) { | ||
| for wait(ctx, 3*time.Second) { | ||
| holdLock(ctx, pool) | ||
| } | ||
| } | ||
|
|
||
| func holdLock(ctx context.Context, pool *pgxpool.Pool) { | ||
| tx, err := pool.Begin(ctx) | ||
| if err != nil { | ||
| return | ||
| } | ||
| defer func() { _ = tx.Rollback(ctx) }() | ||
|
|
||
| if _, err := tx.Exec(ctx, `UPDATE items SET value = value WHERE id = $1`, hotRowID); err != nil { | ||
| return | ||
| } | ||
|
|
||
| wait(ctx, 5*time.Second) | ||
|
|
||
| _ = tx.Commit(ctx) | ||
| } | ||
|
|
||
| // contender repeatedly updates the hot row, so it blocks whenever the blocker | ||
| // is holding the lock. | ||
| func contender(ctx context.Context, pool *pgxpool.Pool) { | ||
| for wait(ctx, time.Second) { | ||
| _, _ = pool.Exec(ctx, `UPDATE items SET value = value + 1 WHERE id = $1`, hotRowID) | ||
| } | ||
| } | ||
|
|
||
| // wait sleeps for d, returning false if the context is canceled first. | ||
| func wait(ctx context.Context, d time.Duration) bool { | ||
| select { | ||
| case <-ctx.Done(): | ||
| return false | ||
| case <-time.After(d): | ||
| return true | ||
| } | ||
| } | ||
|
|
||
| func jitter(minimum, maximum time.Duration) time.Duration { | ||
| return minimum + rand.N(maximum-minimum) //nolint:gosec // weak RNG is fine for a load generator | ||
| } | ||
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,4 @@ | ||
| -- Runs once on a fresh data directory (after postgres starts with | ||
| -- shared_preload_libraries=pg_stat_statements), so the Statements screen works | ||
| -- out of the box in local and CI databases. | ||
| CREATE EXTENSION IF NOT EXISTS pg_stat_statements; |
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