127 lines
3.1 KiB
Go
127 lines
3.1 KiB
Go
// Copyright 2019 Drone IO, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package db
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import (
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"database/sql"
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"github.com/jmoiron/sqlx"
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)
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// Driver defines the database driver.
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type Driver int
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// Database driver enums.
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const (
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Sqlite = iota + 1
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Mysql
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Postgres
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)
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type (
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// A Scanner represents an object that can be scanned
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// for values.
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Scanner interface {
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Scan(dest ...interface{}) error
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}
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// A Locker represents an object that can be locked and unlocked.
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Locker interface {
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Lock()
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Unlock()
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RLock()
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RUnlock()
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}
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// Binder interface defines database field bindings.
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Binder interface {
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BindNamed(query string, arg interface{}) (string, []interface{}, error)
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}
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// Queryer interface defines a set of methods for
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// querying the database.
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Queryer interface {
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Query(query string, args ...interface{}) (*sql.Rows, error)
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QueryRow(query string, args ...interface{}) *sql.Row
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}
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// Execer interface defines a set of methods for executing
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// read and write commands against the database.
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Execer interface {
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Queryer
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Exec(query string, args ...interface{}) (sql.Result, error)
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}
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// DB is a pool of zero or more underlying connections to
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// the drone database.
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DB struct {
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conn *sqlx.DB
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lock Locker
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driver Driver
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}
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)
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// View executes a function within the context of a managed read-only
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// transaction. Any error that is returned from the function is returned
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// from the View() method.
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func (db *DB) View(fn func(Queryer, Binder) error) error {
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db.lock.RLock()
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err := fn(db.conn, db.conn)
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db.lock.RUnlock()
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return err
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}
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// Lock obtains a write lock to the database (sqlite only) and executes
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// a function. Any error that is returned from the function is returned
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// from the Lock() method.
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func (db *DB) Lock(fn func(Execer, Binder) error) error {
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db.lock.Lock()
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err := fn(db.conn, db.conn)
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db.lock.Unlock()
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return err
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}
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// Update executes a function within the context of a read-write managed
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// transaction. If no error is returned from the function then the
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// transaction is committed. If an error is returned then the entire
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// transaction is rolled back. Any error that is returned from the function
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// or returned from the commit is returned from the Update() method.
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func (db *DB) Update(fn func(Execer, Binder) error) error {
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db.lock.Lock()
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defer db.lock.Unlock()
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tx, err := db.conn.Begin()
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if err != nil {
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return err
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}
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err = fn(tx, db.conn)
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if err != nil {
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tx.Rollback()
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return err
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}
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return tx.Commit()
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}
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// Driver returns the name of the SQL driver.
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func (db *DB) Driver() Driver {
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return db.driver
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}
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// Close closes the database connection.
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func (db *DB) Close() error {
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return db.conn.Close()
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}
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