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package db
import (
"context"
"fmt"
"strconv"
"time"
"github.com/jackc/pgx/v5/pgxpool"
)
// PoolOptions tunes pgxpool for API/worker processes.
//
// Sizing guidance (multi-instance): MaxConns ≈ (Postgres max_connections reserved) / instance_count.
// Typical per-process MaxConns is 2050; MinConns ≈ 1030% of MaxConns (warm floor).
// Always set MaxConnLifetimeJitter (~1020% of MaxConnLifetime) to avoid thundering-herd reconnects.
// Defaults match historical NewPool hardcodes, plus idle recycle + statement timeout for multi-tenant churn.
type PoolOptions struct {
MaxConns int32
MinConns int32
MaxConnLifetime time.Duration
// MaxConnLifetimeJitter adds random extra lifetime per connection (pgxpool); 0 disables.
MaxConnLifetimeJitter time.Duration
MaxConnIdleTime time.Duration
HealthCheckPeriod time.Duration
// StatementTimeout sets Postgres statement_timeout on each connection (0 disables).
StatementTimeout time.Duration
}
// DefaultPoolOptions returns safe production-oriented defaults used when config omits overrides.
func DefaultPoolOptions() PoolOptions {
return PoolOptions{
MaxConns: 20,
MinConns: 2,
MaxConnLifetime: time.Hour,
MaxConnLifetimeJitter: 6 * time.Minute, // ~10% of lifetime
MaxConnIdleTime: 5 * time.Minute,
HealthCheckPeriod: time.Minute,
StatementTimeout: 30 * time.Second,
}
}
// NewPool opens a pgx pool with sizing/timeouts from opts (see DefaultPoolOptions).
func NewPool(ctx context.Context, databaseURL string, opts PoolOptions) (*pgxpool.Pool, error) {
cfg, err := ParsePoolConfig(databaseURL, opts)
if err != nil {
return nil, err
}
pool, err := pgxpool.NewWithConfig(ctx, cfg)
if err != nil {
return nil, fmt.Errorf("connect database: %w", err)
}
if err := pool.Ping(ctx); err != nil {
pool.Close()
return nil, fmt.Errorf("ping database: %w", err)
}
return pool, nil
}
// ParsePoolConfig builds a pgxpool.Config without connecting (unit-testable).
func ParsePoolConfig(databaseURL string, opts PoolOptions) (*pgxpool.Config, error) {
cfg, err := pgxpool.ParseConfig(databaseURL)
if err != nil {
return nil, fmt.Errorf("parse database url: %w", err)
}
applyPoolOptions(cfg, opts)
return cfg, nil
}
func applyPoolOptions(cfg *pgxpool.Config, opts PoolOptions) {
cfg.MaxConns = opts.MaxConns
cfg.MinConns = opts.MinConns
cfg.MaxConnLifetime = opts.MaxConnLifetime
cfg.MaxConnLifetimeJitter = opts.MaxConnLifetimeJitter
cfg.MaxConnIdleTime = opts.MaxConnIdleTime
cfg.HealthCheckPeriod = opts.HealthCheckPeriod
if opts.StatementTimeout > 0 {
if cfg.ConnConfig.RuntimeParams == nil {
cfg.ConnConfig.RuntimeParams = map[string]string{}
}
// Postgres accepts integer milliseconds for statement_timeout.
cfg.ConnConfig.RuntimeParams["statement_timeout"] = strconv.FormatInt(opts.StatementTimeout.Milliseconds(), 10)
}
}