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bolt.go
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bolt.go
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package metadata
import (
"context"
"github.com/boltdb/bolt"
"github.com/pkg/errors"
)
type transactionKey struct{}
// WithTransactionContext returns a new context holding the provided
// bolt transaction. Functions which require a bolt transaction will
// first check to see if a transaction is already created on the
// context before creating their own.
func WithTransactionContext(ctx context.Context, tx *bolt.Tx) context.Context {
return context.WithValue(ctx, transactionKey{}, tx)
}
// view gets a bolt db transaction either from the context
// or starts a new one with the provided bolt database.
func view(ctx context.Context, db *bolt.DB, fn func(*bolt.Tx) error) error {
tx, ok := ctx.Value(transactionKey{}).(*bolt.Tx)
if !ok {
return db.View(fn)
}
return fn(tx)
}
// update gets a writable bolt db transaction either from the context
// or starts a new one with the provided bolt database.
func update(ctx context.Context, db *bolt.DB, fn func(*bolt.Tx) error) error {
tx, ok := ctx.Value(transactionKey{}).(*bolt.Tx)
if !ok {
return db.Update(fn)
} else if !tx.Writable() {
return errors.Wrap(bolt.ErrTxNotWritable, "unable to use transaction from context")
}
return fn(tx)
}