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package sql
import (
"database/sql"
"fmt"
"runtime"
"sync"
"github.com/GoogleCloudPlatform/cloudsql-proxy/proxy/dialers/mysql"
"github.com/pkg/errors"
"repodiff/constants"
)
var mux sync.Mutex
var db *sql.DB
type handleRowFn func(*sql.Rows)
func newDBConnectionPool() (*sql.DB, error) {
cfg := mysql.Cfg(
constants.GetConfigVar("GCP_DB_INSTANCE_CONNECTION_NAME"),
constants.GetConfigVar("GCP_DB_USER"),
constants.GetConfigVar("GCP_DB_PASSWORD"),
)
cfg.DBName = constants.GetConfigVar("GCP_DB_NAME")
return mysql.DialCfg(cfg)
}
func maxParallelism() int {
maxProcs := runtime.GOMAXPROCS(0)
numCPU := runtime.NumCPU()
if maxProcs < numCPU {
return maxProcs
}
return numCPU
}
func GetDBConnectionPool() (*sql.DB, error) {
if db != nil {
return db, nil
}
mux.Lock()
defer mux.Unlock()
// check, lock, check; redundant check for thread safety
if db != nil {
return db, nil
}
var err error
db, err = newDBConnectionPool()
if err != nil {
return nil, err
}
connections := maxParallelism()
// unless explicitly specified, the default connection pool size is unlimited
db.SetMaxOpenConns(connections)
// unless explicitly specified, the default is 0 where idle connections are immediately closed
db.SetMaxIdleConns(connections)
return db, nil
}
func SingleTransactionInsert(db *sql.DB, insertQuery string, rowsOfCols [][]interface{}) error {
tx, err := db.Begin()
if err != nil {
return errors.Wrap(err, "Error starting transaction")
}
stmt, err := tx.Prepare(insertQuery)
if err != nil {
return errors.Wrap(err, "Error preparing statement")
}
defer stmt.Close()
for _, cols := range rowsOfCols {
_, err = stmt.Exec(
cols...,
)
if err != nil {
tx.Rollback()
return errors.Wrap(err, "Error inserting values")
}
}
err = tx.Commit()
if err != nil {
tx.Rollback()
return errors.Wrap(
err,
"Error committing transaction",
)
}
return nil
}
func Select(db *sql.DB, rowHandler handleRowFn, query string, args ...interface{}) error {
rows, err := db.Query(
query,
args...,
)
if err != nil {
return err
}
defer rows.Close()
for rows.Next() {
rowHandler(rows)
}
if err = rows.Err(); err != nil {
return err
}
return nil
}
func TruncateTable(db *sql.DB, tableName string) error {
_, err := db.Exec(
fmt.Sprintf("TRUNCATE TABLE %s", tableName),
)
return err
}
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