62 lines
1.9 KiB
Go
62 lines
1.9 KiB
Go
/*
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Copyright The containerd Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package metadata
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import (
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"context"
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"github.com/pkg/errors"
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bolt "go.etcd.io/bbolt"
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)
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type transactionKey struct{}
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// WithTransactionContext returns a new context holding the provided
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// bolt transaction. Functions which require a bolt transaction will
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// first check to see if a transaction is already created on the
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// context before creating their own.
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func WithTransactionContext(ctx context.Context, tx *bolt.Tx) context.Context {
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return context.WithValue(ctx, transactionKey{}, tx)
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}
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type transactor interface {
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View(fn func(*bolt.Tx) error) error
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Update(fn func(*bolt.Tx) error) error
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}
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// view gets a bolt db transaction either from the context
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// or starts a new one with the provided bolt database.
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func view(ctx context.Context, db transactor, fn func(*bolt.Tx) error) error {
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tx, ok := ctx.Value(transactionKey{}).(*bolt.Tx)
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if !ok {
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return db.View(fn)
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}
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return fn(tx)
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}
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// update gets a writable bolt db transaction either from the context
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// or starts a new one with the provided bolt database.
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func update(ctx context.Context, db transactor, fn func(*bolt.Tx) error) error {
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tx, ok := ctx.Value(transactionKey{}).(*bolt.Tx)
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if !ok {
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return db.Update(fn)
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} else if !tx.Writable() {
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return errors.Wrap(bolt.ErrTxNotWritable, "unable to use transaction from context")
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}
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return fn(tx)
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}
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