mirror of
https://github.com/cwinfo/matterbridge.git
synced 2024-11-25 11:01:35 +00:00
116 lines
3.6 KiB
Go
116 lines
3.6 KiB
Go
// Copyright 2014 Google Inc. All rights reserved.
|
|
// Use of this source code is governed by the Apache 2.0
|
|
// license that can be found in the LICENSE file.
|
|
|
|
package internal
|
|
|
|
// This file implements hooks for applying datastore transactions.
|
|
|
|
import (
|
|
"errors"
|
|
"reflect"
|
|
|
|
"github.com/golang/protobuf/proto"
|
|
netcontext "golang.org/x/net/context"
|
|
|
|
basepb "google.golang.org/appengine/internal/base"
|
|
pb "google.golang.org/appengine/internal/datastore"
|
|
)
|
|
|
|
var transactionSetters = make(map[reflect.Type]reflect.Value)
|
|
|
|
// RegisterTransactionSetter registers a function that sets transaction information
|
|
// in a protocol buffer message. f should be a function with two arguments,
|
|
// the first being a protocol buffer type, and the second being *datastore.Transaction.
|
|
func RegisterTransactionSetter(f interface{}) {
|
|
v := reflect.ValueOf(f)
|
|
transactionSetters[v.Type().In(0)] = v
|
|
}
|
|
|
|
// applyTransaction applies the transaction t to message pb
|
|
// by using the relevant setter passed to RegisterTransactionSetter.
|
|
func applyTransaction(pb proto.Message, t *pb.Transaction) {
|
|
v := reflect.ValueOf(pb)
|
|
if f, ok := transactionSetters[v.Type()]; ok {
|
|
f.Call([]reflect.Value{v, reflect.ValueOf(t)})
|
|
}
|
|
}
|
|
|
|
var transactionKey = "used for *Transaction"
|
|
|
|
func transactionFromContext(ctx netcontext.Context) *transaction {
|
|
t, _ := ctx.Value(&transactionKey).(*transaction)
|
|
return t
|
|
}
|
|
|
|
func withTransaction(ctx netcontext.Context, t *transaction) netcontext.Context {
|
|
return netcontext.WithValue(ctx, &transactionKey, t)
|
|
}
|
|
|
|
type transaction struct {
|
|
transaction pb.Transaction
|
|
finished bool
|
|
}
|
|
|
|
var ErrConcurrentTransaction = errors.New("internal: concurrent transaction")
|
|
|
|
func RunTransactionOnce(c netcontext.Context, f func(netcontext.Context) error, xg bool, readOnly bool, previousTransaction *pb.Transaction) (*pb.Transaction, error) {
|
|
if transactionFromContext(c) != nil {
|
|
return nil, errors.New("nested transactions are not supported")
|
|
}
|
|
|
|
// Begin the transaction.
|
|
t := &transaction{}
|
|
req := &pb.BeginTransactionRequest{
|
|
App: proto.String(FullyQualifiedAppID(c)),
|
|
}
|
|
if xg {
|
|
req.AllowMultipleEg = proto.Bool(true)
|
|
}
|
|
if previousTransaction != nil {
|
|
req.PreviousTransaction = previousTransaction
|
|
}
|
|
if readOnly {
|
|
req.Mode = pb.BeginTransactionRequest_READ_ONLY.Enum()
|
|
} else {
|
|
req.Mode = pb.BeginTransactionRequest_READ_WRITE.Enum()
|
|
}
|
|
if err := Call(c, "datastore_v3", "BeginTransaction", req, &t.transaction); err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Call f, rolling back the transaction if f returns a non-nil error, or panics.
|
|
// The panic is not recovered.
|
|
defer func() {
|
|
if t.finished {
|
|
return
|
|
}
|
|
t.finished = true
|
|
// Ignore the error return value, since we are already returning a non-nil
|
|
// error (or we're panicking).
|
|
Call(c, "datastore_v3", "Rollback", &t.transaction, &basepb.VoidProto{})
|
|
}()
|
|
if err := f(withTransaction(c, t)); err != nil {
|
|
return &t.transaction, err
|
|
}
|
|
t.finished = true
|
|
|
|
// Commit the transaction.
|
|
res := &pb.CommitResponse{}
|
|
err := Call(c, "datastore_v3", "Commit", &t.transaction, res)
|
|
if ae, ok := err.(*APIError); ok {
|
|
/* TODO: restore this conditional
|
|
if appengine.IsDevAppServer() {
|
|
*/
|
|
// The Python Dev AppServer raises an ApplicationError with error code 2 (which is
|
|
// Error.CONCURRENT_TRANSACTION) and message "Concurrency exception.".
|
|
if ae.Code == int32(pb.Error_BAD_REQUEST) && ae.Detail == "ApplicationError: 2 Concurrency exception." {
|
|
return &t.transaction, ErrConcurrentTransaction
|
|
}
|
|
if ae.Code == int32(pb.Error_CONCURRENT_TRANSACTION) {
|
|
return &t.transaction, ErrConcurrentTransaction
|
|
}
|
|
}
|
|
return &t.transaction, err
|
|
}
|