gitea/models/db/context.go
Jason Song c6c4d66004
Fix misuse of TxContext (#30061)
Help #29999, or its tests cannot pass.

Also, add some comments to clarify the usage of `TxContext`.

I don't check all usages of `TxContext` because there are too many
(almost 140+). It's a better idea to replace them with `WithTx` instead
of checking them one by one. However, that may be another refactoring
PR.
2024-03-25 15:00:16 +08:00

332 lines
9.5 KiB
Go

// Copyright 2019 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package db
import (
"context"
"database/sql"
"xorm.io/builder"
"xorm.io/xorm"
)
// DefaultContext is the default context to run xorm queries in
// will be overwritten by Init with HammerContext
var DefaultContext context.Context
// contextKey is a value for use with context.WithValue.
type contextKey struct {
name string
}
// enginedContextKey is a context key. It is used with context.Value() to get the current Engined for the context
var (
enginedContextKey = &contextKey{"engined"}
_ Engined = &Context{}
)
// Context represents a db context
type Context struct {
context.Context
e Engine
transaction bool
}
func newContext(ctx context.Context, e Engine, transaction bool) *Context {
return &Context{
Context: ctx,
e: e,
transaction: transaction,
}
}
// InTransaction if context is in a transaction
func (ctx *Context) InTransaction() bool {
return ctx.transaction
}
// Engine returns db engine
func (ctx *Context) Engine() Engine {
return ctx.e
}
// Value shadows Value for context.Context but allows us to get ourselves and an Engined object
func (ctx *Context) Value(key any) any {
if key == enginedContextKey {
return ctx
}
return ctx.Context.Value(key)
}
// WithContext returns this engine tied to this context
func (ctx *Context) WithContext(other context.Context) *Context {
return newContext(ctx, ctx.e.Context(other), ctx.transaction)
}
// Engined structs provide an Engine
type Engined interface {
Engine() Engine
}
// GetEngine will get a db Engine from this context or return an Engine restricted to this context
func GetEngine(ctx context.Context) Engine {
if e := getEngine(ctx); e != nil {
return e
}
return x.Context(ctx)
}
// getEngine will get a db Engine from this context or return nil
func getEngine(ctx context.Context) Engine {
if engined, ok := ctx.(Engined); ok {
return engined.Engine()
}
enginedInterface := ctx.Value(enginedContextKey)
if enginedInterface != nil {
return enginedInterface.(Engined).Engine()
}
return nil
}
// Committer represents an interface to Commit or Close the Context
type Committer interface {
Commit() error
Close() error
}
// halfCommitter is a wrapper of Committer.
// It can be closed early, but can't be committed early, it is useful for reusing a transaction.
type halfCommitter struct {
committer Committer
committed bool
}
func (c *halfCommitter) Commit() error {
c.committed = true
// should do nothing, and the parent committer will commit later
return nil
}
func (c *halfCommitter) Close() error {
if c.committed {
// it's "commit and close", should do nothing, and the parent committer will commit later
return nil
}
// it's "rollback and close", let the parent committer rollback right now
return c.committer.Close()
}
// TxContext represents a transaction Context,
// it will reuse the existing transaction in the parent context or create a new one.
// Some tips to use:
//
// 1 It's always recommended to use `WithTx` in new code instead of `TxContext`, since `WithTx` will handle the transaction automatically.
// 2. To maintain the old code which uses `TxContext`:
// a. Always call `Close()` before returning regardless of whether `Commit()` has been called.
// b. Always call `Commit()` before returning if there are no errors, even if the code did not change any data.
// c. Remember the `Committer` will be a halfCommitter when a transaction is being reused.
// So calling `Commit()` will do nothing, but calling `Close()` without calling `Commit()` will rollback the transaction.
// And all operations submitted by the caller stack will be rollbacked as well, not only the operations in the current function.
// d. It doesn't mean rollback is forbidden, but always do it only when there is an error, and you do want to rollback.
func TxContext(parentCtx context.Context) (*Context, Committer, error) {
if sess, ok := inTransaction(parentCtx); ok {
return newContext(parentCtx, sess, true), &halfCommitter{committer: sess}, nil
}
sess := x.NewSession()
if err := sess.Begin(); err != nil {
sess.Close()
return nil, nil, err
}
return newContext(DefaultContext, sess, true), sess, nil
}
// WithTx represents executing database operations on a transaction, if the transaction exist,
// this function will reuse it otherwise will create a new one and close it when finished.
func WithTx(parentCtx context.Context, f func(ctx context.Context) error) error {
if sess, ok := inTransaction(parentCtx); ok {
err := f(newContext(parentCtx, sess, true))
if err != nil {
// rollback immediately, in case the caller ignores returned error and tries to commit the transaction.
_ = sess.Close()
}
return err
}
return txWithNoCheck(parentCtx, f)
}
func txWithNoCheck(parentCtx context.Context, f func(ctx context.Context) error) error {
sess := x.NewSession()
defer sess.Close()
if err := sess.Begin(); err != nil {
return err
}
if err := f(newContext(parentCtx, sess, true)); err != nil {
return err
}
return sess.Commit()
}
// Insert inserts records into database
func Insert(ctx context.Context, beans ...any) error {
_, err := GetEngine(ctx).Insert(beans...)
return err
}
// Exec executes a sql with args
func Exec(ctx context.Context, sqlAndArgs ...any) (sql.Result, error) {
return GetEngine(ctx).Exec(sqlAndArgs...)
}
func Get[T any](ctx context.Context, cond builder.Cond) (object *T, exist bool, err error) {
if !cond.IsValid() {
panic("cond is invalid in db.Get(ctx, cond). This should not be possible.")
}
var bean T
has, err := GetEngine(ctx).Where(cond).NoAutoCondition().Get(&bean)
if err != nil {
return nil, false, err
} else if !has {
return nil, false, nil
}
return &bean, true, nil
}
func GetByID[T any](ctx context.Context, id int64) (object *T, exist bool, err error) {
var bean T
has, err := GetEngine(ctx).ID(id).NoAutoCondition().Get(&bean)
if err != nil {
return nil, false, err
} else if !has {
return nil, false, nil
}
return &bean, true, nil
}
func Exist[T any](ctx context.Context, cond builder.Cond) (bool, error) {
if !cond.IsValid() {
panic("cond is invalid in db.Exist(ctx, cond). This should not be possible.")
}
var bean T
return GetEngine(ctx).Where(cond).NoAutoCondition().Exist(&bean)
}
func ExistByID[T any](ctx context.Context, id int64) (bool, error) {
var bean T
return GetEngine(ctx).ID(id).NoAutoCondition().Exist(&bean)
}
// DeleteByID deletes the given bean with the given ID
func DeleteByID[T any](ctx context.Context, id int64) (int64, error) {
var bean T
return GetEngine(ctx).ID(id).NoAutoCondition().NoAutoTime().Delete(&bean)
}
func DeleteByIDs[T any](ctx context.Context, ids ...int64) error {
if len(ids) == 0 {
return nil
}
var bean T
_, err := GetEngine(ctx).In("id", ids).NoAutoCondition().NoAutoTime().Delete(&bean)
return err
}
func Delete[T any](ctx context.Context, opts FindOptions) (int64, error) {
if opts == nil || !opts.ToConds().IsValid() {
panic("opts are empty or invalid in db.Delete(ctx, opts). This should not be possible.")
}
var bean T
return GetEngine(ctx).Where(opts.ToConds()).NoAutoCondition().NoAutoTime().Delete(&bean)
}
// DeleteByBean deletes all records according non-empty fields of the bean as conditions.
func DeleteByBean(ctx context.Context, bean any) (int64, error) {
return GetEngine(ctx).Delete(bean)
}
// FindIDs finds the IDs for the given table name satisfying the given condition
// By passing a different value than "id" for "idCol", you can query for foreign IDs, i.e. the repo IDs which satisfy the condition
func FindIDs(ctx context.Context, tableName, idCol string, cond builder.Cond) ([]int64, error) {
ids := make([]int64, 0, 10)
if err := GetEngine(ctx).Table(tableName).
Cols(idCol).
Where(cond).
Find(&ids); err != nil {
return nil, err
}
return ids, nil
}
// DecrByIDs decreases the given column for entities of the "bean" type with one of the given ids by one
// Timestamps of the entities won't be updated
func DecrByIDs(ctx context.Context, ids []int64, decrCol string, bean any) error {
_, err := GetEngine(ctx).Decr(decrCol).In("id", ids).NoAutoCondition().NoAutoTime().Update(bean)
return err
}
// DeleteBeans deletes all given beans, beans must contain delete conditions.
func DeleteBeans(ctx context.Context, beans ...any) (err error) {
e := GetEngine(ctx)
for i := range beans {
if _, err = e.Delete(beans[i]); err != nil {
return err
}
}
return nil
}
// TruncateBeans deletes all given beans, beans may contain delete conditions.
func TruncateBeans(ctx context.Context, beans ...any) (err error) {
e := GetEngine(ctx)
for i := range beans {
if _, err = e.Truncate(beans[i]); err != nil {
return err
}
}
return nil
}
// CountByBean counts the number of database records according non-empty fields of the bean as conditions.
func CountByBean(ctx context.Context, bean any) (int64, error) {
return GetEngine(ctx).Count(bean)
}
// TableName returns the table name according a bean object
func TableName(bean any) string {
return x.TableName(bean)
}
// InTransaction returns true if the engine is in a transaction otherwise return false
func InTransaction(ctx context.Context) bool {
_, ok := inTransaction(ctx)
return ok
}
func inTransaction(ctx context.Context) (*xorm.Session, bool) {
e := getEngine(ctx)
if e == nil {
return nil, false
}
switch t := e.(type) {
case *xorm.Engine:
return nil, false
case *xorm.Session:
if t.IsInTx() {
return t, true
}
return nil, false
default:
return nil, false
}
}