1469 lines
36 KiB
Go
1469 lines
36 KiB
Go
// Copyright 2011 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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// Package sql provides a generic interface around SQL (or SQL-like)
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// databases.
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//
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// The sql package must be used in conjunction with a database driver.
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// See http://golang.org/s/sqldrivers for a list of drivers.
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package sql
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import (
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"database/sql/driver"
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"errors"
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"fmt"
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"io"
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"runtime"
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"sync"
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)
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var drivers = make(map[string]driver.Driver)
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// Register makes a database driver available by the provided name.
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// If Register is called twice with the same name or if driver is nil,
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// it panics.
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func Register(name string, driver driver.Driver) {
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if driver == nil {
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panic("sql: Register driver is nil")
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}
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if _, dup := drivers[name]; dup {
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panic("sql: Register called twice for driver " + name)
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}
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drivers[name] = driver
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}
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// RawBytes is a byte slice that holds a reference to memory owned by
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// the database itself. After a Scan into a RawBytes, the slice is only
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// valid until the next call to Next, Scan, or Close.
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type RawBytes []byte
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// NullString represents a string that may be null.
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// NullString implements the Scanner interface so
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// it can be used as a scan destination:
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//
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// var s NullString
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// err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&s)
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// ...
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// if s.Valid {
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// // use s.String
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// } else {
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// // NULL value
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// }
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//
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type NullString struct {
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String string
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Valid bool // Valid is true if String is not NULL
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}
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// Scan implements the Scanner interface.
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func (ns *NullString) Scan(value interface{}) error {
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if value == nil {
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ns.String, ns.Valid = "", false
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return nil
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}
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ns.Valid = true
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return convertAssign(&ns.String, value)
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}
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// Value implements the driver Valuer interface.
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func (ns NullString) Value() (driver.Value, error) {
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if !ns.Valid {
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return nil, nil
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}
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return ns.String, nil
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}
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// NullInt64 represents an int64 that may be null.
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// NullInt64 implements the Scanner interface so
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// it can be used as a scan destination, similar to NullString.
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type NullInt64 struct {
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Int64 int64
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Valid bool // Valid is true if Int64 is not NULL
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}
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// Scan implements the Scanner interface.
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func (n *NullInt64) Scan(value interface{}) error {
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if value == nil {
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n.Int64, n.Valid = 0, false
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return nil
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}
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n.Valid = true
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return convertAssign(&n.Int64, value)
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}
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// Value implements the driver Valuer interface.
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func (n NullInt64) Value() (driver.Value, error) {
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if !n.Valid {
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return nil, nil
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}
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return n.Int64, nil
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}
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// NullFloat64 represents a float64 that may be null.
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// NullFloat64 implements the Scanner interface so
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// it can be used as a scan destination, similar to NullString.
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type NullFloat64 struct {
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Float64 float64
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Valid bool // Valid is true if Float64 is not NULL
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}
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// Scan implements the Scanner interface.
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func (n *NullFloat64) Scan(value interface{}) error {
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if value == nil {
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n.Float64, n.Valid = 0, false
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return nil
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}
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n.Valid = true
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return convertAssign(&n.Float64, value)
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}
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// Value implements the driver Valuer interface.
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func (n NullFloat64) Value() (driver.Value, error) {
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if !n.Valid {
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return nil, nil
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}
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return n.Float64, nil
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}
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// NullBool represents a bool that may be null.
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// NullBool implements the Scanner interface so
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// it can be used as a scan destination, similar to NullString.
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type NullBool struct {
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Bool bool
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Valid bool // Valid is true if Bool is not NULL
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}
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// Scan implements the Scanner interface.
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func (n *NullBool) Scan(value interface{}) error {
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if value == nil {
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n.Bool, n.Valid = false, false
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return nil
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}
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n.Valid = true
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return convertAssign(&n.Bool, value)
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}
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// Value implements the driver Valuer interface.
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func (n NullBool) Value() (driver.Value, error) {
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if !n.Valid {
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return nil, nil
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}
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return n.Bool, nil
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}
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// Scanner is an interface used by Scan.
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type Scanner interface {
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// Scan assigns a value from a database driver.
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//
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// The src value will be of one of the following restricted
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// set of types:
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//
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// int64
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// float64
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// bool
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// []byte
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// string
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// time.Time
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// nil - for NULL values
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//
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// An error should be returned if the value can not be stored
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// without loss of information.
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Scan(src interface{}) error
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}
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// ErrNoRows is returned by Scan when QueryRow doesn't return a
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// row. In such a case, QueryRow returns a placeholder *Row value that
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// defers this error until a Scan.
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var ErrNoRows = errors.New("sql: no rows in result set")
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// DB is a database handle. It's safe for concurrent use by multiple
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// goroutines.
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//
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// The sql package creates and frees connections automatically; it
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// also maintains a free pool of idle connections. If the database has
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// a concept of per-connection state, such state can only be reliably
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// observed within a transaction. Once DB.Begin is called, the
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// returned Tx is bound to a single connection. Once Commit or
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// Rollback is called on the transaction, that transaction's
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// connection is returned to DB's idle connection pool. The pool size
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// can be controlled with SetMaxIdleConns.
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type DB struct {
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driver driver.Driver
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dsn string
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mu sync.Mutex // protects following fields
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freeConn []*driverConn
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closed bool
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dep map[finalCloser]depSet
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lastPut map[*driverConn]string // stacktrace of last conn's put; debug only
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maxIdle int // zero means defaultMaxIdleConns; negative means 0
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}
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// driverConn wraps a driver.Conn with a mutex, to
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// be held during all calls into the Conn. (including any calls onto
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// interfaces returned via that Conn, such as calls on Tx, Stmt,
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// Result, Rows)
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type driverConn struct {
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db *DB
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sync.Mutex // guards following
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ci driver.Conn
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closed bool
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finalClosed bool // ci.Close has been called
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openStmt map[driver.Stmt]bool
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// guarded by db.mu
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inUse bool
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onPut []func() // code (with db.mu held) run when conn is next returned
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dbmuClosed bool // same as closed, but guarded by db.mu, for connIfFree
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}
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func (dc *driverConn) removeOpenStmt(si driver.Stmt) {
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dc.Lock()
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defer dc.Unlock()
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delete(dc.openStmt, si)
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}
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func (dc *driverConn) prepareLocked(query string) (driver.Stmt, error) {
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si, err := dc.ci.Prepare(query)
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if err == nil {
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// Track each driverConn's open statements, so we can close them
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// before closing the conn.
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//
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// TODO(bradfitz): let drivers opt out of caring about
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// stmt closes if the conn is about to close anyway? For now
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// do the safe thing, in case stmts need to be closed.
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//
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// TODO(bradfitz): after Go 1.1, closing driver.Stmts
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// should be moved to driverStmt, using unique
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// *driverStmts everywhere (including from
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// *Stmt.connStmt, instead of returning a
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// driver.Stmt), using driverStmt as a pointer
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// everywhere, and making it a finalCloser.
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if dc.openStmt == nil {
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dc.openStmt = make(map[driver.Stmt]bool)
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}
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dc.openStmt[si] = true
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}
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return si, err
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}
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// the dc.db's Mutex is held.
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func (dc *driverConn) closeDBLocked() error {
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dc.Lock()
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if dc.closed {
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dc.Unlock()
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return errors.New("sql: duplicate driverConn close")
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}
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dc.closed = true
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dc.Unlock() // not defer; removeDep finalClose calls may need to lock
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return dc.db.removeDepLocked(dc, dc)()
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}
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func (dc *driverConn) Close() error {
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dc.Lock()
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if dc.closed {
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dc.Unlock()
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return errors.New("sql: duplicate driverConn close")
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}
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dc.closed = true
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dc.Unlock() // not defer; removeDep finalClose calls may need to lock
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// And now updates that require holding dc.mu.Lock.
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dc.db.mu.Lock()
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dc.dbmuClosed = true
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fn := dc.db.removeDepLocked(dc, dc)
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dc.db.mu.Unlock()
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return fn()
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}
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func (dc *driverConn) finalClose() error {
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dc.Lock()
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for si := range dc.openStmt {
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si.Close()
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}
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dc.openStmt = nil
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err := dc.ci.Close()
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dc.ci = nil
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dc.finalClosed = true
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dc.Unlock()
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return err
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}
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// driverStmt associates a driver.Stmt with the
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// *driverConn from which it came, so the driverConn's lock can be
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// held during calls.
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type driverStmt struct {
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sync.Locker // the *driverConn
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si driver.Stmt
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}
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func (ds *driverStmt) Close() error {
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ds.Lock()
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defer ds.Unlock()
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return ds.si.Close()
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}
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// depSet is a finalCloser's outstanding dependencies
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type depSet map[interface{}]bool // set of true bools
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// The finalCloser interface is used by (*DB).addDep and related
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// dependency reference counting.
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type finalCloser interface {
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// finalClose is called when the reference count of an object
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// goes to zero. (*DB).mu is not held while calling it.
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finalClose() error
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}
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// addDep notes that x now depends on dep, and x's finalClose won't be
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// called until all of x's dependencies are removed with removeDep.
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func (db *DB) addDep(x finalCloser, dep interface{}) {
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//println(fmt.Sprintf("addDep(%T %p, %T %p)", x, x, dep, dep))
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db.mu.Lock()
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defer db.mu.Unlock()
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db.addDepLocked(x, dep)
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}
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func (db *DB) addDepLocked(x finalCloser, dep interface{}) {
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if db.dep == nil {
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db.dep = make(map[finalCloser]depSet)
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}
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xdep := db.dep[x]
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if xdep == nil {
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xdep = make(depSet)
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db.dep[x] = xdep
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}
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xdep[dep] = true
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}
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// removeDep notes that x no longer depends on dep.
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// If x still has dependencies, nil is returned.
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// If x no longer has any dependencies, its finalClose method will be
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// called and its error value will be returned.
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func (db *DB) removeDep(x finalCloser, dep interface{}) error {
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db.mu.Lock()
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fn := db.removeDepLocked(x, dep)
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db.mu.Unlock()
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return fn()
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}
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func (db *DB) removeDepLocked(x finalCloser, dep interface{}) func() error {
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//println(fmt.Sprintf("removeDep(%T %p, %T %p)", x, x, dep, dep))
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done := false
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xdep := db.dep[x]
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if xdep != nil {
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delete(xdep, dep)
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if len(xdep) == 0 {
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delete(db.dep, x)
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done = true
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}
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}
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if !done {
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return func() error { return nil }
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}
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return func() error {
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//println(fmt.Sprintf("calling final close on %T %v (%#v)", x, x, x))
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return x.finalClose()
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}
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}
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// Open opens a database specified by its database driver name and a
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// driver-specific data source name, usually consisting of at least a
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// database name and connection information.
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//
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// Most users will open a database via a driver-specific connection
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// helper function that returns a *DB. No database drivers are included
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// in the Go standard library. See http://golang.org/s/sqldrivers for
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// a list of third-party drivers.
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//
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// Open may just validate its arguments without creating a connection
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// to the database. To verify that the data source name is valid, call
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// Ping.
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func Open(driverName, dataSourceName string) (*DB, error) {
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driveri, ok := drivers[driverName]
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if !ok {
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return nil, fmt.Errorf("sql: unknown driver %q (forgotten import?)", driverName)
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}
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db := &DB{
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driver: driveri,
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dsn: dataSourceName,
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lastPut: make(map[*driverConn]string),
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}
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return db, nil
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}
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// Ping verifies a connection to the database is still alive,
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// establishing a connection if necessary.
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func (db *DB) Ping() error {
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// TODO(bradfitz): give drivers an optional hook to implement
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// this in a more efficient or more reliable way, if they
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// have one.
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dc, err := db.conn()
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if err != nil {
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return err
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}
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db.putConn(dc, nil)
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return nil
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}
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// Close closes the database, releasing any open resources.
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func (db *DB) Close() error {
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db.mu.Lock()
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defer db.mu.Unlock()
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var err error
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for _, dc := range db.freeConn {
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err1 := dc.closeDBLocked()
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if err1 != nil {
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err = err1
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}
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}
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db.freeConn = nil
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db.closed = true
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return err
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}
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const defaultMaxIdleConns = 2
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func (db *DB) maxIdleConnsLocked() int {
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n := db.maxIdle
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switch {
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case n == 0:
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// TODO(bradfitz): ask driver, if supported, for its default preference
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return defaultMaxIdleConns
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case n < 0:
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return 0
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default:
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return n
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}
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}
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// SetMaxIdleConns sets the maximum number of connections in the idle
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// connection pool.
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//
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// If n <= 0, no idle connections are retained.
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func (db *DB) SetMaxIdleConns(n int) {
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db.mu.Lock()
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defer db.mu.Unlock()
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if n > 0 {
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db.maxIdle = n
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} else {
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// No idle connections.
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db.maxIdle = -1
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}
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for len(db.freeConn) > 0 && len(db.freeConn) > n {
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nfree := len(db.freeConn)
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dc := db.freeConn[nfree-1]
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db.freeConn[nfree-1] = nil
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db.freeConn = db.freeConn[:nfree-1]
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go dc.Close()
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}
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}
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// conn returns a newly-opened or cached *driverConn
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func (db *DB) conn() (*driverConn, error) {
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db.mu.Lock()
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if db.closed {
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db.mu.Unlock()
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return nil, errors.New("sql: database is closed")
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}
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if n := len(db.freeConn); n > 0 {
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conn := db.freeConn[n-1]
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db.freeConn = db.freeConn[:n-1]
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conn.inUse = true
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db.mu.Unlock()
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return conn, nil
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}
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db.mu.Unlock()
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ci, err := db.driver.Open(db.dsn)
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if err != nil {
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return nil, err
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}
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dc := &driverConn{
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db: db,
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ci: ci,
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}
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db.mu.Lock()
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db.addDepLocked(dc, dc)
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dc.inUse = true
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db.mu.Unlock()
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return dc, nil
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}
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var (
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errConnClosed = errors.New("database/sql: internal sentinel error: conn is closed")
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errConnBusy = errors.New("database/sql: internal sentinel error: conn is busy")
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)
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// connIfFree returns (wanted, nil) if wanted is still a valid conn and
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// isn't in use.
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//
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// The error is errConnClosed if the connection if the requested connection
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// is invalid because it's been closed.
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//
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// The error is errConnBusy if the connection is in use.
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func (db *DB) connIfFree(wanted *driverConn) (*driverConn, error) {
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db.mu.Lock()
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defer db.mu.Unlock()
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if wanted.inUse {
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return nil, errConnBusy
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}
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if wanted.dbmuClosed {
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return nil, errConnClosed
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}
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for i, conn := range db.freeConn {
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if conn != wanted {
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continue
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}
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db.freeConn[i] = db.freeConn[len(db.freeConn)-1]
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db.freeConn = db.freeConn[:len(db.freeConn)-1]
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wanted.inUse = true
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return wanted, nil
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}
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// TODO(bradfitz): shouldn't get here. After Go 1.1, change this to:
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// panic("connIfFree call requested a non-closed, non-busy, non-free conn")
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// Which passes all the tests, but I'm too paranoid to include this
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// late in Go 1.1.
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// Instead, treat it like a busy connection:
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return nil, errConnBusy
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}
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|
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// putConnHook is a hook for testing.
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var putConnHook func(*DB, *driverConn)
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|
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// noteUnusedDriverStatement notes that si is no longer used and should
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// be closed whenever possible (when c is next not in use), unless c is
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// already closed.
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func (db *DB) noteUnusedDriverStatement(c *driverConn, si driver.Stmt) {
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db.mu.Lock()
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defer db.mu.Unlock()
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if c.inUse {
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c.onPut = append(c.onPut, func() {
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si.Close()
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})
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} else {
|
|
c.Lock()
|
|
defer c.Unlock()
|
|
if !c.finalClosed {
|
|
si.Close()
|
|
}
|
|
}
|
|
}
|
|
|
|
// debugGetPut determines whether getConn & putConn calls' stack traces
|
|
// are returned for more verbose crashes.
|
|
const debugGetPut = false
|
|
|
|
// putConn adds a connection to the db's free pool.
|
|
// err is optionally the last error that occurred on this connection.
|
|
func (db *DB) putConn(dc *driverConn, err error) {
|
|
db.mu.Lock()
|
|
if !dc.inUse {
|
|
if debugGetPut {
|
|
fmt.Printf("putConn(%v) DUPLICATE was: %s\n\nPREVIOUS was: %s", dc, stack(), db.lastPut[dc])
|
|
}
|
|
panic("sql: connection returned that was never out")
|
|
}
|
|
if debugGetPut {
|
|
db.lastPut[dc] = stack()
|
|
}
|
|
dc.inUse = false
|
|
|
|
for _, fn := range dc.onPut {
|
|
fn()
|
|
}
|
|
dc.onPut = nil
|
|
|
|
if err == driver.ErrBadConn {
|
|
// Don't reuse bad connections.
|
|
db.mu.Unlock()
|
|
return
|
|
}
|
|
if putConnHook != nil {
|
|
putConnHook(db, dc)
|
|
}
|
|
if n := len(db.freeConn); !db.closed && n < db.maxIdleConnsLocked() {
|
|
db.freeConn = append(db.freeConn, dc)
|
|
db.mu.Unlock()
|
|
return
|
|
}
|
|
db.mu.Unlock()
|
|
|
|
dc.Close()
|
|
}
|
|
|
|
// Prepare creates a prepared statement for later queries or executions.
|
|
// Multiple queries or executions may be run concurrently from the
|
|
// returned statement.
|
|
func (db *DB) Prepare(query string) (*Stmt, error) {
|
|
var stmt *Stmt
|
|
var err error
|
|
for i := 0; i < 10; i++ {
|
|
stmt, err = db.prepare(query)
|
|
if err != driver.ErrBadConn {
|
|
break
|
|
}
|
|
}
|
|
return stmt, err
|
|
}
|
|
|
|
func (db *DB) prepare(query string) (*Stmt, error) {
|
|
// TODO: check if db.driver supports an optional
|
|
// driver.Preparer interface and call that instead, if so,
|
|
// otherwise we make a prepared statement that's bound
|
|
// to a connection, and to execute this prepared statement
|
|
// we either need to use this connection (if it's free), else
|
|
// get a new connection + re-prepare + execute on that one.
|
|
dc, err := db.conn()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
dc.Lock()
|
|
si, err := dc.prepareLocked(query)
|
|
dc.Unlock()
|
|
if err != nil {
|
|
db.putConn(dc, err)
|
|
return nil, err
|
|
}
|
|
stmt := &Stmt{
|
|
db: db,
|
|
query: query,
|
|
css: []connStmt{{dc, si}},
|
|
}
|
|
db.addDep(stmt, stmt)
|
|
db.putConn(dc, nil)
|
|
return stmt, nil
|
|
}
|
|
|
|
// Exec executes a query without returning any rows.
|
|
// The args are for any placeholder parameters in the query.
|
|
func (db *DB) Exec(query string, args ...interface{}) (Result, error) {
|
|
var res Result
|
|
var err error
|
|
for i := 0; i < 10; i++ {
|
|
res, err = db.exec(query, args)
|
|
if err != driver.ErrBadConn {
|
|
break
|
|
}
|
|
}
|
|
return res, err
|
|
}
|
|
|
|
func (db *DB) exec(query string, args []interface{}) (res Result, err error) {
|
|
dc, err := db.conn()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer func() {
|
|
db.putConn(dc, err)
|
|
}()
|
|
|
|
if execer, ok := dc.ci.(driver.Execer); ok {
|
|
dargs, err := driverArgs(nil, args)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
dc.Lock()
|
|
resi, err := execer.Exec(query, dargs)
|
|
dc.Unlock()
|
|
if err != driver.ErrSkip {
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return driverResult{dc, resi}, nil
|
|
}
|
|
}
|
|
|
|
dc.Lock()
|
|
si, err := dc.ci.Prepare(query)
|
|
dc.Unlock()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer withLock(dc, func() { si.Close() })
|
|
return resultFromStatement(driverStmt{dc, si}, args...)
|
|
}
|
|
|
|
// Query executes a query that returns rows, typically a SELECT.
|
|
// The args are for any placeholder parameters in the query.
|
|
func (db *DB) Query(query string, args ...interface{}) (*Rows, error) {
|
|
var rows *Rows
|
|
var err error
|
|
for i := 0; i < 10; i++ {
|
|
rows, err = db.query(query, args)
|
|
if err != driver.ErrBadConn {
|
|
break
|
|
}
|
|
}
|
|
return rows, err
|
|
}
|
|
|
|
func (db *DB) query(query string, args []interface{}) (*Rows, error) {
|
|
ci, err := db.conn()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
releaseConn := func(err error) { db.putConn(ci, err) }
|
|
|
|
return db.queryConn(ci, releaseConn, query, args)
|
|
}
|
|
|
|
// queryConn executes a query on the given connection.
|
|
// The connection gets released by the releaseConn function.
|
|
func (db *DB) queryConn(dc *driverConn, releaseConn func(error), query string, args []interface{}) (*Rows, error) {
|
|
if queryer, ok := dc.ci.(driver.Queryer); ok {
|
|
dargs, err := driverArgs(nil, args)
|
|
if err != nil {
|
|
releaseConn(err)
|
|
return nil, err
|
|
}
|
|
dc.Lock()
|
|
rowsi, err := queryer.Query(query, dargs)
|
|
dc.Unlock()
|
|
if err != driver.ErrSkip {
|
|
if err != nil {
|
|
releaseConn(err)
|
|
return nil, err
|
|
}
|
|
// Note: ownership of dc passes to the *Rows, to be freed
|
|
// with releaseConn.
|
|
rows := &Rows{
|
|
dc: dc,
|
|
releaseConn: releaseConn,
|
|
rowsi: rowsi,
|
|
}
|
|
return rows, nil
|
|
}
|
|
}
|
|
|
|
dc.Lock()
|
|
si, err := dc.ci.Prepare(query)
|
|
dc.Unlock()
|
|
if err != nil {
|
|
releaseConn(err)
|
|
return nil, err
|
|
}
|
|
|
|
ds := driverStmt{dc, si}
|
|
rowsi, err := rowsiFromStatement(ds, args...)
|
|
if err != nil {
|
|
releaseConn(err)
|
|
dc.Lock()
|
|
si.Close()
|
|
dc.Unlock()
|
|
return nil, err
|
|
}
|
|
|
|
// Note: ownership of ci passes to the *Rows, to be freed
|
|
// with releaseConn.
|
|
rows := &Rows{
|
|
dc: dc,
|
|
releaseConn: releaseConn,
|
|
rowsi: rowsi,
|
|
closeStmt: si,
|
|
}
|
|
return rows, nil
|
|
}
|
|
|
|
// QueryRow executes a query that is expected to return at most one row.
|
|
// QueryRow always return a non-nil value. Errors are deferred until
|
|
// Row's Scan method is called.
|
|
func (db *DB) QueryRow(query string, args ...interface{}) *Row {
|
|
rows, err := db.Query(query, args...)
|
|
return &Row{rows: rows, err: err}
|
|
}
|
|
|
|
// Begin starts a transaction. The isolation level is dependent on
|
|
// the driver.
|
|
func (db *DB) Begin() (*Tx, error) {
|
|
var tx *Tx
|
|
var err error
|
|
for i := 0; i < 10; i++ {
|
|
tx, err = db.begin()
|
|
if err != driver.ErrBadConn {
|
|
break
|
|
}
|
|
}
|
|
return tx, err
|
|
}
|
|
|
|
func (db *DB) begin() (tx *Tx, err error) {
|
|
dc, err := db.conn()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
dc.Lock()
|
|
txi, err := dc.ci.Begin()
|
|
dc.Unlock()
|
|
if err != nil {
|
|
db.putConn(dc, err)
|
|
return nil, err
|
|
}
|
|
return &Tx{
|
|
db: db,
|
|
dc: dc,
|
|
txi: txi,
|
|
}, nil
|
|
}
|
|
|
|
// Driver returns the database's underlying driver.
|
|
func (db *DB) Driver() driver.Driver {
|
|
return db.driver
|
|
}
|
|
|
|
// Tx is an in-progress database transaction.
|
|
//
|
|
// A transaction must end with a call to Commit or Rollback.
|
|
//
|
|
// After a call to Commit or Rollback, all operations on the
|
|
// transaction fail with ErrTxDone.
|
|
type Tx struct {
|
|
db *DB
|
|
|
|
// dc is owned exclusively until Commit or Rollback, at which point
|
|
// it's returned with putConn.
|
|
dc *driverConn
|
|
txi driver.Tx
|
|
|
|
// done transitions from false to true exactly once, on Commit
|
|
// or Rollback. once done, all operations fail with
|
|
// ErrTxDone.
|
|
done bool
|
|
}
|
|
|
|
var ErrTxDone = errors.New("sql: Transaction has already been committed or rolled back")
|
|
|
|
func (tx *Tx) close() {
|
|
if tx.done {
|
|
panic("double close") // internal error
|
|
}
|
|
tx.done = true
|
|
tx.db.putConn(tx.dc, nil)
|
|
tx.dc = nil
|
|
tx.txi = nil
|
|
}
|
|
|
|
func (tx *Tx) grabConn() (*driverConn, error) {
|
|
if tx.done {
|
|
return nil, ErrTxDone
|
|
}
|
|
return tx.dc, nil
|
|
}
|
|
|
|
// Commit commits the transaction.
|
|
func (tx *Tx) Commit() error {
|
|
if tx.done {
|
|
return ErrTxDone
|
|
}
|
|
defer tx.close()
|
|
tx.dc.Lock()
|
|
defer tx.dc.Unlock()
|
|
return tx.txi.Commit()
|
|
}
|
|
|
|
// Rollback aborts the transaction.
|
|
func (tx *Tx) Rollback() error {
|
|
if tx.done {
|
|
return ErrTxDone
|
|
}
|
|
defer tx.close()
|
|
tx.dc.Lock()
|
|
defer tx.dc.Unlock()
|
|
return tx.txi.Rollback()
|
|
}
|
|
|
|
// Prepare creates a prepared statement for use within a transaction.
|
|
//
|
|
// The returned statement operates within the transaction and can no longer
|
|
// be used once the transaction has been committed or rolled back.
|
|
//
|
|
// To use an existing prepared statement on this transaction, see Tx.Stmt.
|
|
func (tx *Tx) Prepare(query string) (*Stmt, error) {
|
|
// TODO(bradfitz): We could be more efficient here and either
|
|
// provide a method to take an existing Stmt (created on
|
|
// perhaps a different Conn), and re-create it on this Conn if
|
|
// necessary. Or, better: keep a map in DB of query string to
|
|
// Stmts, and have Stmt.Execute do the right thing and
|
|
// re-prepare if the Conn in use doesn't have that prepared
|
|
// statement. But we'll want to avoid caching the statement
|
|
// in the case where we only call conn.Prepare implicitly
|
|
// (such as in db.Exec or tx.Exec), but the caller package
|
|
// can't be holding a reference to the returned statement.
|
|
// Perhaps just looking at the reference count (by noting
|
|
// Stmt.Close) would be enough. We might also want a finalizer
|
|
// on Stmt to drop the reference count.
|
|
dc, err := tx.grabConn()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
dc.Lock()
|
|
si, err := dc.ci.Prepare(query)
|
|
dc.Unlock()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
stmt := &Stmt{
|
|
db: tx.db,
|
|
tx: tx,
|
|
txsi: &driverStmt{
|
|
Locker: dc,
|
|
si: si,
|
|
},
|
|
query: query,
|
|
}
|
|
return stmt, nil
|
|
}
|
|
|
|
// Stmt returns a transaction-specific prepared statement from
|
|
// an existing statement.
|
|
//
|
|
// Example:
|
|
// updateMoney, err := db.Prepare("UPDATE balance SET money=money+? WHERE id=?")
|
|
// ...
|
|
// tx, err := db.Begin()
|
|
// ...
|
|
// res, err := tx.Stmt(updateMoney).Exec(123.45, 98293203)
|
|
func (tx *Tx) Stmt(stmt *Stmt) *Stmt {
|
|
// TODO(bradfitz): optimize this. Currently this re-prepares
|
|
// each time. This is fine for now to illustrate the API but
|
|
// we should really cache already-prepared statements
|
|
// per-Conn. See also the big comment in Tx.Prepare.
|
|
|
|
if tx.db != stmt.db {
|
|
return &Stmt{stickyErr: errors.New("sql: Tx.Stmt: statement from different database used")}
|
|
}
|
|
dc, err := tx.grabConn()
|
|
if err != nil {
|
|
return &Stmt{stickyErr: err}
|
|
}
|
|
dc.Lock()
|
|
si, err := dc.ci.Prepare(stmt.query)
|
|
dc.Unlock()
|
|
return &Stmt{
|
|
db: tx.db,
|
|
tx: tx,
|
|
txsi: &driverStmt{
|
|
Locker: dc,
|
|
si: si,
|
|
},
|
|
query: stmt.query,
|
|
stickyErr: err,
|
|
}
|
|
}
|
|
|
|
// Exec executes a query that doesn't return rows.
|
|
// For example: an INSERT and UPDATE.
|
|
func (tx *Tx) Exec(query string, args ...interface{}) (Result, error) {
|
|
dc, err := tx.grabConn()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
if execer, ok := dc.ci.(driver.Execer); ok {
|
|
dargs, err := driverArgs(nil, args)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
dc.Lock()
|
|
resi, err := execer.Exec(query, dargs)
|
|
dc.Unlock()
|
|
if err == nil {
|
|
return driverResult{dc, resi}, nil
|
|
}
|
|
if err != driver.ErrSkip {
|
|
return nil, err
|
|
}
|
|
}
|
|
|
|
dc.Lock()
|
|
si, err := dc.ci.Prepare(query)
|
|
dc.Unlock()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer withLock(dc, func() { si.Close() })
|
|
|
|
return resultFromStatement(driverStmt{dc, si}, args...)
|
|
}
|
|
|
|
// Query executes a query that returns rows, typically a SELECT.
|
|
func (tx *Tx) Query(query string, args ...interface{}) (*Rows, error) {
|
|
dc, err := tx.grabConn()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
releaseConn := func(error) {}
|
|
return tx.db.queryConn(dc, releaseConn, query, args)
|
|
}
|
|
|
|
// QueryRow executes a query that is expected to return at most one row.
|
|
// QueryRow always return a non-nil value. Errors are deferred until
|
|
// Row's Scan method is called.
|
|
func (tx *Tx) QueryRow(query string, args ...interface{}) *Row {
|
|
rows, err := tx.Query(query, args...)
|
|
return &Row{rows: rows, err: err}
|
|
}
|
|
|
|
// connStmt is a prepared statement on a particular connection.
|
|
type connStmt struct {
|
|
dc *driverConn
|
|
si driver.Stmt
|
|
}
|
|
|
|
// Stmt is a prepared statement. Stmt is safe for concurrent use by multiple goroutines.
|
|
type Stmt struct {
|
|
// Immutable:
|
|
db *DB // where we came from
|
|
query string // that created the Stmt
|
|
stickyErr error // if non-nil, this error is returned for all operations
|
|
|
|
closemu sync.RWMutex // held exclusively during close, for read otherwise.
|
|
|
|
// If in a transaction, else both nil:
|
|
tx *Tx
|
|
txsi *driverStmt
|
|
|
|
mu sync.Mutex // protects the rest of the fields
|
|
closed bool
|
|
|
|
// css is a list of underlying driver statement interfaces
|
|
// that are valid on particular connections. This is only
|
|
// used if tx == nil and one is found that has idle
|
|
// connections. If tx != nil, txsi is always used.
|
|
css []connStmt
|
|
}
|
|
|
|
// Exec executes a prepared statement with the given arguments and
|
|
// returns a Result summarizing the effect of the statement.
|
|
func (s *Stmt) Exec(args ...interface{}) (Result, error) {
|
|
s.closemu.RLock()
|
|
defer s.closemu.RUnlock()
|
|
dc, releaseConn, si, err := s.connStmt()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
defer releaseConn(nil)
|
|
|
|
return resultFromStatement(driverStmt{dc, si}, args...)
|
|
}
|
|
|
|
func resultFromStatement(ds driverStmt, args ...interface{}) (Result, error) {
|
|
ds.Lock()
|
|
want := ds.si.NumInput()
|
|
ds.Unlock()
|
|
|
|
// -1 means the driver doesn't know how to count the number of
|
|
// placeholders, so we won't sanity check input here and instead let the
|
|
// driver deal with errors.
|
|
if want != -1 && len(args) != want {
|
|
return nil, fmt.Errorf("sql: expected %d arguments, got %d", want, len(args))
|
|
}
|
|
|
|
dargs, err := driverArgs(&ds, args)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
ds.Lock()
|
|
resi, err := ds.si.Exec(dargs)
|
|
ds.Unlock()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return driverResult{ds.Locker, resi}, nil
|
|
}
|
|
|
|
// connStmt returns a free driver connection on which to execute the
|
|
// statement, a function to call to release the connection, and a
|
|
// statement bound to that connection.
|
|
func (s *Stmt) connStmt() (ci *driverConn, releaseConn func(error), si driver.Stmt, err error) {
|
|
if err = s.stickyErr; err != nil {
|
|
return
|
|
}
|
|
s.mu.Lock()
|
|
if s.closed {
|
|
s.mu.Unlock()
|
|
err = errors.New("sql: statement is closed")
|
|
return
|
|
}
|
|
|
|
// In a transaction, we always use the connection that the
|
|
// transaction was created on.
|
|
if s.tx != nil {
|
|
s.mu.Unlock()
|
|
ci, err = s.tx.grabConn() // blocks, waiting for the connection.
|
|
if err != nil {
|
|
return
|
|
}
|
|
releaseConn = func(error) {}
|
|
return ci, releaseConn, s.txsi.si, nil
|
|
}
|
|
|
|
var cs connStmt
|
|
match := false
|
|
for i := 0; i < len(s.css); i++ {
|
|
v := s.css[i]
|
|
_, err := s.db.connIfFree(v.dc)
|
|
if err == nil {
|
|
match = true
|
|
cs = v
|
|
break
|
|
}
|
|
if err == errConnClosed {
|
|
// Lazily remove dead conn from our freelist.
|
|
s.css[i] = s.css[len(s.css)-1]
|
|
s.css = s.css[:len(s.css)-1]
|
|
i--
|
|
}
|
|
|
|
}
|
|
s.mu.Unlock()
|
|
|
|
// Make a new conn if all are busy.
|
|
// TODO(bradfitz): or wait for one? make configurable later?
|
|
if !match {
|
|
for i := 0; ; i++ {
|
|
dc, err := s.db.conn()
|
|
if err != nil {
|
|
return nil, nil, nil, err
|
|
}
|
|
dc.Lock()
|
|
si, err := dc.prepareLocked(s.query)
|
|
dc.Unlock()
|
|
if err == driver.ErrBadConn && i < 10 {
|
|
continue
|
|
}
|
|
if err != nil {
|
|
return nil, nil, nil, err
|
|
}
|
|
s.mu.Lock()
|
|
cs = connStmt{dc, si}
|
|
s.css = append(s.css, cs)
|
|
s.mu.Unlock()
|
|
break
|
|
}
|
|
}
|
|
|
|
conn := cs.dc
|
|
releaseConn = func(err error) { s.db.putConn(conn, err) }
|
|
return conn, releaseConn, cs.si, nil
|
|
}
|
|
|
|
// Query executes a prepared query statement with the given arguments
|
|
// and returns the query results as a *Rows.
|
|
func (s *Stmt) Query(args ...interface{}) (*Rows, error) {
|
|
s.closemu.RLock()
|
|
defer s.closemu.RUnlock()
|
|
|
|
dc, releaseConn, si, err := s.connStmt()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
ds := driverStmt{dc, si}
|
|
rowsi, err := rowsiFromStatement(ds, args...)
|
|
if err != nil {
|
|
releaseConn(err)
|
|
return nil, err
|
|
}
|
|
|
|
// Note: ownership of ci passes to the *Rows, to be freed
|
|
// with releaseConn.
|
|
rows := &Rows{
|
|
dc: dc,
|
|
rowsi: rowsi,
|
|
// releaseConn set below
|
|
}
|
|
s.db.addDep(s, rows)
|
|
rows.releaseConn = func(err error) {
|
|
releaseConn(err)
|
|
s.db.removeDep(s, rows)
|
|
}
|
|
return rows, nil
|
|
}
|
|
|
|
func rowsiFromStatement(ds driverStmt, args ...interface{}) (driver.Rows, error) {
|
|
ds.Lock()
|
|
want := ds.si.NumInput()
|
|
ds.Unlock()
|
|
|
|
// -1 means the driver doesn't know how to count the number of
|
|
// placeholders, so we won't sanity check input here and instead let the
|
|
// driver deal with errors.
|
|
if want != -1 && len(args) != want {
|
|
return nil, fmt.Errorf("sql: statement expects %d inputs; got %d", want, len(args))
|
|
}
|
|
|
|
dargs, err := driverArgs(&ds, args)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
ds.Lock()
|
|
rowsi, err := ds.si.Query(dargs)
|
|
ds.Unlock()
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
return rowsi, nil
|
|
}
|
|
|
|
// QueryRow executes a prepared query statement with the given arguments.
|
|
// If an error occurs during the execution of the statement, that error will
|
|
// be returned by a call to Scan on the returned *Row, which is always non-nil.
|
|
// If the query selects no rows, the *Row's Scan will return ErrNoRows.
|
|
// Otherwise, the *Row's Scan scans the first selected row and discards
|
|
// the rest.
|
|
//
|
|
// Example usage:
|
|
//
|
|
// var name string
|
|
// err := nameByUseridStmt.QueryRow(id).Scan(&name)
|
|
func (s *Stmt) QueryRow(args ...interface{}) *Row {
|
|
rows, err := s.Query(args...)
|
|
if err != nil {
|
|
return &Row{err: err}
|
|
}
|
|
return &Row{rows: rows}
|
|
}
|
|
|
|
// Close closes the statement.
|
|
func (s *Stmt) Close() error {
|
|
s.closemu.Lock()
|
|
defer s.closemu.Unlock()
|
|
|
|
if s.stickyErr != nil {
|
|
return s.stickyErr
|
|
}
|
|
s.mu.Lock()
|
|
defer s.mu.Unlock()
|
|
if s.closed {
|
|
return nil
|
|
}
|
|
s.closed = true
|
|
|
|
if s.tx != nil {
|
|
s.txsi.Close()
|
|
return nil
|
|
}
|
|
|
|
return s.db.removeDep(s, s)
|
|
}
|
|
|
|
func (s *Stmt) finalClose() error {
|
|
for _, v := range s.css {
|
|
s.db.noteUnusedDriverStatement(v.dc, v.si)
|
|
v.dc.removeOpenStmt(v.si)
|
|
s.db.removeDep(v.dc, s)
|
|
}
|
|
s.css = nil
|
|
return nil
|
|
}
|
|
|
|
// Rows is the result of a query. Its cursor starts before the first row
|
|
// of the result set. Use Next to advance through the rows:
|
|
//
|
|
// rows, err := db.Query("SELECT ...")
|
|
// ...
|
|
// for rows.Next() {
|
|
// var id int
|
|
// var name string
|
|
// err = rows.Scan(&id, &name)
|
|
// ...
|
|
// }
|
|
// err = rows.Err() // get any error encountered during iteration
|
|
// ...
|
|
type Rows struct {
|
|
dc *driverConn // owned; must call releaseConn when closed to release
|
|
releaseConn func(error)
|
|
rowsi driver.Rows
|
|
|
|
closed bool
|
|
lastcols []driver.Value
|
|
lasterr error
|
|
closeStmt driver.Stmt // if non-nil, statement to Close on close
|
|
}
|
|
|
|
// Next prepares the next result row for reading with the Scan method.
|
|
// It returns true on success, false if there is no next result row.
|
|
// Every call to Scan, even the first one, must be preceded by a call
|
|
// to Next.
|
|
func (rs *Rows) Next() bool {
|
|
if rs.closed {
|
|
return false
|
|
}
|
|
if rs.lasterr != nil {
|
|
return false
|
|
}
|
|
if rs.lastcols == nil {
|
|
rs.lastcols = make([]driver.Value, len(rs.rowsi.Columns()))
|
|
}
|
|
rs.lasterr = rs.rowsi.Next(rs.lastcols)
|
|
if rs.lasterr == io.EOF {
|
|
rs.Close()
|
|
}
|
|
return rs.lasterr == nil
|
|
}
|
|
|
|
// Err returns the error, if any, that was encountered during iteration.
|
|
func (rs *Rows) Err() error {
|
|
if rs.lasterr == io.EOF {
|
|
return nil
|
|
}
|
|
return rs.lasterr
|
|
}
|
|
|
|
// Columns returns the column names.
|
|
// Columns returns an error if the rows are closed, or if the rows
|
|
// are from QueryRow and there was a deferred error.
|
|
func (rs *Rows) Columns() ([]string, error) {
|
|
if rs.closed {
|
|
return nil, errors.New("sql: Rows are closed")
|
|
}
|
|
if rs.rowsi == nil {
|
|
return nil, errors.New("sql: no Rows available")
|
|
}
|
|
return rs.rowsi.Columns(), nil
|
|
}
|
|
|
|
// Scan copies the columns in the current row into the values pointed
|
|
// at by dest.
|
|
//
|
|
// If an argument has type *[]byte, Scan saves in that argument a copy
|
|
// of the corresponding data. The copy is owned by the caller and can
|
|
// be modified and held indefinitely. The copy can be avoided by using
|
|
// an argument of type *RawBytes instead; see the documentation for
|
|
// RawBytes for restrictions on its use.
|
|
//
|
|
// If an argument has type *interface{}, Scan copies the value
|
|
// provided by the underlying driver without conversion. If the value
|
|
// is of type []byte, a copy is made and the caller owns the result.
|
|
func (rs *Rows) Scan(dest ...interface{}) error {
|
|
if rs.closed {
|
|
return errors.New("sql: Rows closed")
|
|
}
|
|
if rs.lasterr != nil {
|
|
return rs.lasterr
|
|
}
|
|
if rs.lastcols == nil {
|
|
return errors.New("sql: Scan called without calling Next")
|
|
}
|
|
if len(dest) != len(rs.lastcols) {
|
|
return fmt.Errorf("sql: expected %d destination arguments in Scan, not %d", len(rs.lastcols), len(dest))
|
|
}
|
|
for i, sv := range rs.lastcols {
|
|
err := convertAssign(dest[i], sv)
|
|
if err != nil {
|
|
return fmt.Errorf("sql: Scan error on column index %d: %v", i, err)
|
|
}
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// Close closes the Rows, preventing further enumeration. If the
|
|
// end is encountered, the Rows are closed automatically. Close
|
|
// is idempotent.
|
|
func (rs *Rows) Close() error {
|
|
if rs.closed {
|
|
return nil
|
|
}
|
|
rs.closed = true
|
|
err := rs.rowsi.Close()
|
|
if rs.closeStmt != nil {
|
|
rs.closeStmt.Close()
|
|
}
|
|
rs.releaseConn(err)
|
|
return err
|
|
}
|
|
|
|
// Row is the result of calling QueryRow to select a single row.
|
|
type Row struct {
|
|
// One of these two will be non-nil:
|
|
err error // deferred error for easy chaining
|
|
rows *Rows
|
|
}
|
|
|
|
// Scan copies the columns from the matched row into the values
|
|
// pointed at by dest. If more than one row matches the query,
|
|
// Scan uses the first row and discards the rest. If no row matches
|
|
// the query, Scan returns ErrNoRows.
|
|
func (r *Row) Scan(dest ...interface{}) error {
|
|
if r.err != nil {
|
|
return r.err
|
|
}
|
|
|
|
// TODO(bradfitz): for now we need to defensively clone all
|
|
// []byte that the driver returned (not permitting
|
|
// *RawBytes in Rows.Scan), since we're about to close
|
|
// the Rows in our defer, when we return from this function.
|
|
// the contract with the driver.Next(...) interface is that it
|
|
// can return slices into read-only temporary memory that's
|
|
// only valid until the next Scan/Close. But the TODO is that
|
|
// for a lot of drivers, this copy will be unnecessary. We
|
|
// should provide an optional interface for drivers to
|
|
// implement to say, "don't worry, the []bytes that I return
|
|
// from Next will not be modified again." (for instance, if
|
|
// they were obtained from the network anyway) But for now we
|
|
// don't care.
|
|
for _, dp := range dest {
|
|
if _, ok := dp.(*RawBytes); ok {
|
|
return errors.New("sql: RawBytes isn't allowed on Row.Scan")
|
|
}
|
|
}
|
|
|
|
defer r.rows.Close()
|
|
if !r.rows.Next() {
|
|
return ErrNoRows
|
|
}
|
|
err := r.rows.Scan(dest...)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// A Result summarizes an executed SQL command.
|
|
type Result interface {
|
|
LastInsertId() (int64, error)
|
|
RowsAffected() (int64, error)
|
|
}
|
|
|
|
type driverResult struct {
|
|
sync.Locker // the *driverConn
|
|
resi driver.Result
|
|
}
|
|
|
|
func (dr driverResult) LastInsertId() (int64, error) {
|
|
dr.Lock()
|
|
defer dr.Unlock()
|
|
return dr.resi.LastInsertId()
|
|
}
|
|
|
|
func (dr driverResult) RowsAffected() (int64, error) {
|
|
dr.Lock()
|
|
defer dr.Unlock()
|
|
return dr.resi.RowsAffected()
|
|
}
|
|
|
|
func stack() string {
|
|
var buf [2 << 10]byte
|
|
return string(buf[:runtime.Stack(buf[:], false)])
|
|
}
|
|
|
|
// withLock runs while holding lk.
|
|
func withLock(lk sync.Locker, fn func()) {
|
|
lk.Lock()
|
|
fn()
|
|
lk.Unlock()
|
|
}
|