feat: support database connectors and HTTP server configuration

database/connector.go

@@ -0,0 +1,82 @@
+package database
+
+import (
+	"context"
+	"database/sql"
+	"database/sql/driver"
+	"errors"
+	"reflect"
+	"time"
+)
+
+// PoolConfig contains only driver-independent settings. Connection credentials,
+// TLS, logging and dial behavior belong to the application's Connector.
+// Start from DefaultPoolConfig; zero PingTimeout is invalid.
+type PoolConfig struct {
+	MaxOpenConns    int           `json:"maxOpenConns"`
+	MaxIdleConns    int           `json:"maxIdleConns"`
+	ConnMaxLifetime time.Duration `json:"connMaxLifetime"`
+	ConnMaxIdleTime time.Duration `json:"connMaxIdleTime"`
+	PingTimeout     time.Duration `json:"pingTimeout"`
+}
+
+func DefaultPoolConfig() PoolConfig {
+	return PoolConfig{MaxOpenConns: 10, MaxIdleConns: 5, ConnMaxLifetime: 30 * time.Minute, ConnMaxIdleTime: 5 * time.Minute, PingTimeout: 5 * time.Second}
+}
+
+func (c PoolConfig) Validate() error {
+	if c.MaxOpenConns < 0 || c.MaxIdleConns < 0 {
+		return errors.New("database pool limits cannot be negative")
+	}
+	if c.MaxOpenConns > 0 && c.MaxIdleConns > c.MaxOpenConns {
+		return errors.New("max idle connections cannot exceed max open connections")
+	}
+	if c.ConnMaxLifetime < 0 || c.ConnMaxIdleTime < 0 || c.PingTimeout <= 0 {
+		return errors.New("database timeouts are invalid")
+	}
+	return nil
+}
+
+func (c PoolConfig) config() Config {
+	return Config{MaxOpenConns: c.MaxOpenConns, MaxIdleConns: c.MaxIdleConns, ConnMaxLifetime: c.ConnMaxLifetime, ConnMaxIdleTime: c.ConnMaxIdleTime, PingTimeout: c.PingTimeout}
+}
+
+// OpenConnector opens an independent pool using the supplied standard Connector.
+// No registered driver name or DSN is required. It applies cfg and completes a
+// startup Ping bounded by ctx and PingTimeout before returning.
+//
+// Validation failures and an already-canceled ctx leave the Connector untouched.
+// Once sql.OpenDB is called, the pool owns its lifecycle: a failed startup closes
+// the pool; on success the caller must Close the returned DB. As in database/sql,
+// this also closes a Connector that implements io.Closer. Use a separate Connector
+// for each pool if it owns resources. Nil ctx means context.Background.
+func OpenConnector(ctx context.Context, connector driver.Connector, cfg PoolConfig) (*DB, error) {
+	if nilConnector(connector) {
+		return nil, errors.New("database connector is required")
+	}
+	if err := cfg.Validate(); err != nil {
+		return nil, err
+	}
+	if ctx == nil {
+		ctx = context.Background()
+	}
+	if err := ctx.Err(); err != nil {
+		return nil, err
+	}
+	return initializePool(ctx, sql.OpenDB(connector), cfg.config())
+}
+
+func nilConnector(connector driver.Connector) bool {
+	if connector == nil {
+		return true
+	}
+	v := reflect.ValueOf(connector)
+	switch v.Kind() {
+	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Pointer, reflect.Slice:
+		return v.IsNil()
+	}
+	return false
+}
+
+// PoolConfig returns a copy of the settings used to create this pool.
+func (db *DB) PoolConfig() PoolConfig { return db.config.PoolConfig() }