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gitea/models/db/context.go
Jason Song a35714372d
Fix halfCommitter and WithTx (#22366)
Related to #22362.

I overlooked that there's always `committer.Close()`, like:

```go
		ctx, committer, err := db.TxContext(db.DefaultContext)
		if err != nil {
			return nil
		}
		defer committer.Close()

		// ...

		if err != nil {
			return nil
		}

		// ...

		return committer.Commit()
```

So the `Close` of `halfCommitter` should ignore `commit and close`, it's
not a rollback.

See: [Why `halfCommitter` and `WithTx` should rollback IMMEDIATELY or
commit
LATER](https://github.com/go-gitea/gitea/pull/22366#issuecomment-1374778612).

Co-authored-by: techknowlogick <techknowlogick@gitea.io>
2023-01-09 12:19:19 -05:00

255 lines
6.9 KiB
Go

// Copyright 2019 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package db
import (
"context"
"database/sql"
"xorm.io/xorm"
"xorm.io/xorm/schemas"
)
// 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 interface{}) interface{} {
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.
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 ...interface{}) error {
_, err := GetEngine(ctx).Insert(beans...)
return err
}
// Exec executes a sql with args
func Exec(ctx context.Context, sqlAndArgs ...interface{}) (sql.Result, error) {
return GetEngine(ctx).Exec(sqlAndArgs...)
}
// GetByBean filled empty fields of the bean according non-empty fields to query in database.
func GetByBean(ctx context.Context, bean interface{}) (bool, error) {
return GetEngine(ctx).Get(bean)
}
// DeleteByBean deletes all records according non-empty fields of the bean as conditions.
func DeleteByBean(ctx context.Context, bean interface{}) (int64, error) {
return GetEngine(ctx).Delete(bean)
}
// DeleteBeans deletes all given beans, beans should contain delete conditions.
func DeleteBeans(ctx context.Context, beans ...interface{}) (err error) {
e := GetEngine(ctx)
for i := range beans {
if _, err = e.Delete(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 interface{}) (int64, error) {
return GetEngine(ctx).Count(bean)
}
// TableName returns the table name according a bean object
func TableName(bean interface{}) string {
return x.TableName(bean)
}
// EstimateCount returns an estimate of total number of rows in table
func EstimateCount(ctx context.Context, bean interface{}) (int64, error) {
e := GetEngine(ctx)
e.Context(ctx)
var rows int64
var err error
tablename := TableName(bean)
switch x.Dialect().URI().DBType {
case schemas.MYSQL:
_, err = e.Context(ctx).SQL("SELECT table_rows FROM information_schema.tables WHERE tables.table_name = ? AND tables.table_schema = ?;", tablename, x.Dialect().URI().DBName).Get(&rows)
case schemas.POSTGRES:
// the table can live in multiple schemas of a postgres database
// See https://wiki.postgresql.org/wiki/Count_estimate
tablename = x.TableName(bean, true)
_, err = e.Context(ctx).SQL("SELECT reltuples::bigint AS estimate FROM pg_class WHERE oid = ?::regclass;", tablename).Get(&rows)
case schemas.MSSQL:
_, err = e.Context(ctx).SQL("sp_spaceused ?;", tablename).Get(&rows)
default:
return e.Context(ctx).Count(tablename)
}
return rows, err
}
// 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
}
}