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sqlconn.go
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sqlconn.go
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// Package sqlconn provides a simple way to manage a SQL-based database connection.
package sqlconn
import (
"context"
"database/sql"
"fmt"
"strings"
"sync"
"github.com/Vonage/gosrvlib/pkg/logging"
"go.uber.org/zap"
)
// ConnectFunc is the type of function called to perform the actual DB connection.
type ConnectFunc func(ctx context.Context, cfg *config) (*sql.DB, error)
// CheckConnectionFunc is the type of function called to perform a DB connection check.
type CheckConnectionFunc func(ctx context.Context, db *sql.DB) error
// SQLOpenFunc is the type of function called to open the DB. (Only for monkey patch testing).
type SQLOpenFunc func(driverName, dataSourceName string) (*sql.DB, error)
// SQLConn is the structure that helps to manage a SQL DB connection.
type SQLConn struct {
cfg *config
db *sql.DB
dbLock sync.RWMutex
logger *zap.Logger
}
// Connect attempts to connect to a SQL database.
func Connect(ctx context.Context, url string, opts ...Option) (*SQLConn, error) {
driver, dsn, err := parseConnectionURL(url)
if err != nil {
return nil, err
}
cfg := defaultConfig(driver, dsn)
for _, applyOpt := range opts {
applyOpt(cfg)
}
if err := cfg.validate(); err != nil {
return nil, err
}
db, err := cfg.connectFunc(ctx, cfg)
if err != nil {
return nil, err
}
db.SetConnMaxIdleTime(cfg.connMaxIdleTime)
db.SetConnMaxLifetime(cfg.connMaxLifetime)
db.SetMaxIdleConns(cfg.connMaxIdleCount)
db.SetMaxOpenConns(cfg.connMaxOpenCount)
l := logging.WithComponent(ctx, "sqlconn")
c := SQLConn{
cfg: cfg,
db: db,
logger: l,
}
// wait for shutdown signal or context cancelation
go func() {
select {
case <-cfg.shutdownSignalChan:
l.Debug("sqlconn shutdown signal received")
case <-ctx.Done():
l.Warn("sqlconn context canceled")
}
_ = c.Shutdown(ctx)
}()
cfg.shutdownWaitGroup.Add(1)
return &c, nil
}
// DB returns a database connection from the pool.
func (c *SQLConn) DB() *sql.DB {
c.dbLock.RLock()
defer c.dbLock.RUnlock()
return c.db
}
// HealthCheck performs a health check of the database connection.
func (c *SQLConn) HealthCheck(ctx context.Context) error {
c.dbLock.RLock()
defer c.dbLock.RUnlock()
if c.db == nil {
return fmt.Errorf("database not unavailable")
}
ctx, cancel := context.WithTimeout(ctx, c.cfg.pingTimeout)
defer cancel()
return c.cfg.checkConnectionFunc(ctx, c.db)
}
// Shutdown closes the database and prevents new queries from starting.
// It waits for all queries that have started processing on the server to finish.
func (c *SQLConn) Shutdown(_ context.Context) error {
c.logger.Debug("shutting down sql connection")
c.dbLock.Lock()
defer c.dbLock.Unlock()
err := c.db.Close()
c.db = nil
c.cfg.shutdownWaitGroup.Add(-1)
c.logger.Debug("sql connection shutdown complete", zap.Error(err))
return err //nolint:wrapcheck
}
func checkConnection(ctx context.Context, db *sql.DB) error {
if err := db.PingContext(ctx); err != nil {
return fmt.Errorf("failed ping on database: %w", err)
}
//nolint:rowserrcheck
rows, err := db.QueryContext(ctx, "SELECT 1")
if err != nil {
return fmt.Errorf("failed running check query on database: %w", err)
}
defer logging.Close(ctx, rows, "failed closing SQL rows")
return nil
}
func connectWithBackoff(ctx context.Context, cfg *config) (*sql.DB, error) {
db, err := cfg.sqlOpenFunc(cfg.driver, cfg.dsn)
if err != nil {
return nil, fmt.Errorf("failed opening database connection: %w", err)
}
ctx, cancel := context.WithTimeout(ctx, cfg.pingTimeout)
defer cancel()
if err = cfg.checkConnectionFunc(ctx, db); err != nil {
return nil, fmt.Errorf("failed checking database connection: %w", err)
}
return db, nil
}
// parseConnectionURL attempts to extract the driver/dsn pair from a string in the format <DRIVER>://<DSN>
// if only the DSN part is set, the driver will need to be specified via a configuration option.
func parseConnectionURL(url string) (string, string, error) {
if url == "" {
return "", "", nil
}
parts := strings.Split(url, "://")
switch len(parts) {
case 1:
return "", parts[0], nil
case 2:
return parts[0], parts[1], nil
}
return "", "", fmt.Errorf("invalid connection string: %q", url)
}