132 lines
3.7 KiB
Go
132 lines
3.7 KiB
Go
// +build kvdb_etcd
|
|
|
|
package etcd
|
|
|
|
import (
|
|
"sync"
|
|
|
|
"github.com/btcsuite/btcwallet/walletdb"
|
|
)
|
|
|
|
// readWriteTx holds a reference to the STM transaction.
|
|
type readWriteTx struct {
|
|
// stm is the reference to the parent STM.
|
|
stm STM
|
|
|
|
// rootBucketID holds the sha256 hash of the root bucket id, which is used
|
|
// for key space spearation.
|
|
rootBucketID [bucketIDLength]byte
|
|
|
|
// active is true if the transaction hasn't been committed yet.
|
|
active bool
|
|
|
|
// lock is passed on for manual txns when the backend is instantiated
|
|
// such that we read/write lock transactions to ensure a single writer.
|
|
lock sync.Locker
|
|
}
|
|
|
|
// newReadWriteTx creates an rw transaction with the passed STM.
|
|
func newReadWriteTx(stm STM, prefix string, lock sync.Locker) *readWriteTx {
|
|
return &readWriteTx{
|
|
stm: stm,
|
|
active: true,
|
|
lock: lock,
|
|
rootBucketID: makeBucketID([]byte(prefix)),
|
|
}
|
|
}
|
|
|
|
// rooBucket is a helper function to return the always present
|
|
// pseudo root bucket.
|
|
func rootBucket(tx *readWriteTx) *readWriteBucket {
|
|
return newReadWriteBucket(tx, tx.rootBucketID[:], tx.rootBucketID[:])
|
|
}
|
|
|
|
// ReadBucket opens the root bucket for read only access. If the bucket
|
|
// described by the key does not exist, nil is returned.
|
|
func (tx *readWriteTx) ReadBucket(key []byte) walletdb.ReadBucket {
|
|
return rootBucket(tx).NestedReadWriteBucket(key)
|
|
}
|
|
|
|
// ForEachBucket iterates through all top level buckets.
|
|
func (tx *readWriteTx) ForEachBucket(fn func(key []byte) error) error {
|
|
root := rootBucket(tx)
|
|
// We can safely use ForEach here since on the top level there are
|
|
// no values, only buckets.
|
|
return root.ForEach(func(key []byte, val []byte) error {
|
|
if val != nil {
|
|
// A non-nil value would mean that we have a non
|
|
// walletdb/kvdb compatibel database containing
|
|
// arbitrary key/values.
|
|
return walletdb.ErrInvalid
|
|
}
|
|
|
|
return fn(key)
|
|
})
|
|
}
|
|
|
|
// Rollback closes the transaction, discarding changes (if any) if the
|
|
// database was modified by a write transaction.
|
|
func (tx *readWriteTx) Rollback() error {
|
|
// If the transaction has been closed roolback will fail.
|
|
if !tx.active {
|
|
return walletdb.ErrTxClosed
|
|
}
|
|
|
|
if tx.lock != nil {
|
|
defer tx.lock.Unlock()
|
|
}
|
|
|
|
// Rollback the STM and set the tx to inactive.
|
|
tx.stm.Rollback()
|
|
tx.active = false
|
|
|
|
return nil
|
|
}
|
|
|
|
// ReadWriteBucket opens the root bucket for read/write access. If the
|
|
// bucket described by the key does not exist, nil is returned.
|
|
func (tx *readWriteTx) ReadWriteBucket(key []byte) walletdb.ReadWriteBucket {
|
|
return rootBucket(tx).NestedReadWriteBucket(key)
|
|
}
|
|
|
|
// CreateTopLevelBucket creates the top level bucket for a key if it
|
|
// does not exist. The newly-created bucket it returned.
|
|
func (tx *readWriteTx) CreateTopLevelBucket(key []byte) (walletdb.ReadWriteBucket, error) {
|
|
return rootBucket(tx).CreateBucketIfNotExists(key)
|
|
}
|
|
|
|
// DeleteTopLevelBucket deletes the top level bucket for a key. This
|
|
// errors if the bucket can not be found or the key keys a single value
|
|
// instead of a bucket.
|
|
func (tx *readWriteTx) DeleteTopLevelBucket(key []byte) error {
|
|
return rootBucket(tx).DeleteNestedBucket(key)
|
|
}
|
|
|
|
// Commit commits the transaction if not already committed. Will return
|
|
// error if the underlying STM fails.
|
|
func (tx *readWriteTx) Commit() error {
|
|
// Commit will fail if the transaction is already committed.
|
|
if !tx.active {
|
|
return walletdb.ErrTxClosed
|
|
}
|
|
|
|
if tx.lock != nil {
|
|
defer tx.lock.Unlock()
|
|
}
|
|
|
|
// Try committing the transaction.
|
|
if err := tx.stm.Commit(); err != nil {
|
|
return err
|
|
}
|
|
|
|
// Mark the transaction as not active after commit.
|
|
tx.active = false
|
|
|
|
return nil
|
|
}
|
|
|
|
// OnCommit sets the commit callback (overriding if already set).
|
|
func (tx *readWriteTx) OnCommit(cb func()) {
|
|
tx.stm.OnCommit(cb)
|
|
}
|