mirror of
https://github.com/ceph/ceph-csi.git
synced 2024-12-21 04:20:23 +00:00
97 lines
3.5 KiB
Go
97 lines
3.5 KiB
Go
// Copyright 2011 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 datastore
|
|
|
|
import (
|
|
"errors"
|
|
|
|
"golang.org/x/net/context"
|
|
|
|
"google.golang.org/appengine/internal"
|
|
pb "google.golang.org/appengine/internal/datastore"
|
|
)
|
|
|
|
func init() {
|
|
internal.RegisterTransactionSetter(func(x *pb.Query, t *pb.Transaction) {
|
|
x.Transaction = t
|
|
})
|
|
internal.RegisterTransactionSetter(func(x *pb.GetRequest, t *pb.Transaction) {
|
|
x.Transaction = t
|
|
})
|
|
internal.RegisterTransactionSetter(func(x *pb.PutRequest, t *pb.Transaction) {
|
|
x.Transaction = t
|
|
})
|
|
internal.RegisterTransactionSetter(func(x *pb.DeleteRequest, t *pb.Transaction) {
|
|
x.Transaction = t
|
|
})
|
|
}
|
|
|
|
// ErrConcurrentTransaction is returned when a transaction is rolled back due
|
|
// to a conflict with a concurrent transaction.
|
|
var ErrConcurrentTransaction = errors.New("datastore: concurrent transaction")
|
|
|
|
// RunInTransaction runs f in a transaction. It calls f with a transaction
|
|
// context tc that f should use for all App Engine operations.
|
|
//
|
|
// If f returns nil, RunInTransaction attempts to commit the transaction,
|
|
// returning nil if it succeeds. If the commit fails due to a conflicting
|
|
// transaction, RunInTransaction retries f, each time with a new transaction
|
|
// context. It gives up and returns ErrConcurrentTransaction after three
|
|
// failed attempts. The number of attempts can be configured by specifying
|
|
// TransactionOptions.Attempts.
|
|
//
|
|
// If f returns non-nil, then any datastore changes will not be applied and
|
|
// RunInTransaction returns that same error. The function f is not retried.
|
|
//
|
|
// Note that when f returns, the transaction is not yet committed. Calling code
|
|
// must be careful not to assume that any of f's changes have been committed
|
|
// until RunInTransaction returns nil.
|
|
//
|
|
// Since f may be called multiple times, f should usually be idempotent.
|
|
// datastore.Get is not idempotent when unmarshaling slice fields.
|
|
//
|
|
// Nested transactions are not supported; c may not be a transaction context.
|
|
func RunInTransaction(c context.Context, f func(tc context.Context) error, opts *TransactionOptions) error {
|
|
xg := false
|
|
if opts != nil {
|
|
xg = opts.XG
|
|
}
|
|
readOnly := false
|
|
if opts != nil {
|
|
readOnly = opts.ReadOnly
|
|
}
|
|
attempts := 3
|
|
if opts != nil && opts.Attempts > 0 {
|
|
attempts = opts.Attempts
|
|
}
|
|
var t *pb.Transaction
|
|
var err error
|
|
for i := 0; i < attempts; i++ {
|
|
if t, err = internal.RunTransactionOnce(c, f, xg, readOnly, t); err != internal.ErrConcurrentTransaction {
|
|
return err
|
|
}
|
|
}
|
|
return ErrConcurrentTransaction
|
|
}
|
|
|
|
// TransactionOptions are the options for running a transaction.
|
|
type TransactionOptions struct {
|
|
// XG is whether the transaction can cross multiple entity groups. In
|
|
// comparison, a single group transaction is one where all datastore keys
|
|
// used have the same root key. Note that cross group transactions do not
|
|
// have the same behavior as single group transactions. In particular, it
|
|
// is much more likely to see partially applied transactions in different
|
|
// entity groups, in global queries.
|
|
// It is valid to set XG to true even if the transaction is within a
|
|
// single entity group.
|
|
XG bool
|
|
// Attempts controls the number of retries to perform when commits fail
|
|
// due to a conflicting transaction. If omitted, it defaults to 3.
|
|
Attempts int
|
|
// ReadOnly controls whether the transaction is a read only transaction.
|
|
// Read only transactions are potentially more efficient.
|
|
ReadOnly bool
|
|
}
|