lbcwallet/walletdb/bdb/db.go

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// Copyright (c) 2014 The btcsuite developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package bdb
import (
"io"
"os"
"github.com/btcsuite/btcwallet/walletdb"
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"github.com/coreos/bbolt"
)
// convertErr converts some bolt errors to the equivalent walletdb error.
func convertErr(err error) error {
switch err {
// Database open/create errors.
case bbolt.ErrDatabaseNotOpen:
return walletdb.ErrDbNotOpen
case bbolt.ErrInvalid:
return walletdb.ErrInvalid
// Transaction errors.
case bbolt.ErrTxNotWritable:
return walletdb.ErrTxNotWritable
case bbolt.ErrTxClosed:
return walletdb.ErrTxClosed
// Value/bucket errors.
case bbolt.ErrBucketNotFound:
return walletdb.ErrBucketNotFound
case bbolt.ErrBucketExists:
return walletdb.ErrBucketExists
case bbolt.ErrBucketNameRequired:
return walletdb.ErrBucketNameRequired
case bbolt.ErrKeyRequired:
return walletdb.ErrKeyRequired
case bbolt.ErrKeyTooLarge:
return walletdb.ErrKeyTooLarge
case bbolt.ErrValueTooLarge:
return walletdb.ErrValueTooLarge
case bbolt.ErrIncompatibleValue:
return walletdb.ErrIncompatibleValue
}
// Return the original error if none of the above applies.
return err
}
// transaction represents a database transaction. It can either by read-only or
// read-write and implements the walletdb Tx interfaces. The transaction
// provides a root bucket against which all read and writes occur.
type transaction struct {
boltTx *bbolt.Tx
}
func (tx *transaction) ReadBucket(key []byte) walletdb.ReadBucket {
return tx.ReadWriteBucket(key)
}
func (tx *transaction) ReadWriteBucket(key []byte) walletdb.ReadWriteBucket {
boltBucket := tx.boltTx.Bucket(key)
if boltBucket == nil {
return nil
}
return (*bucket)(boltBucket)
}
func (tx *transaction) CreateTopLevelBucket(key []byte) (walletdb.ReadWriteBucket, error) {
boltBucket, err := tx.boltTx.CreateBucket(key)
if err != nil {
return nil, convertErr(err)
}
return (*bucket)(boltBucket), nil
}
func (tx *transaction) DeleteTopLevelBucket(key []byte) error {
err := tx.boltTx.DeleteBucket(key)
if err != nil {
return convertErr(err)
}
return nil
}
// Commit commits all changes that have been made through the root bucket and
// all of its sub-buckets to persistent storage.
//
// This function is part of the walletdb.ReadWriteTx interface implementation.
func (tx *transaction) Commit() error {
return convertErr(tx.boltTx.Commit())
}
// Rollback undoes all changes that have been made to the root bucket and all of
// its sub-buckets.
//
// This function is part of the walletdb.ReadTx interface implementation.
func (tx *transaction) Rollback() error {
return convertErr(tx.boltTx.Rollback())
}
// OnCommit takes a function closure that will be executed when the transaction
// successfully gets committed.
//
// This function is part of the walletdb.ReadWriteTx interface implementation.
func (tx *transaction) OnCommit(f func()) {
tx.boltTx.OnCommit(f)
}
// bucket is an internal type used to represent a collection of key/value pairs
// and implements the walletdb Bucket interfaces.
type bucket bbolt.Bucket
// Enforce bucket implements the walletdb Bucket interfaces.
var _ walletdb.ReadWriteBucket = (*bucket)(nil)
// NestedReadWriteBucket retrieves a nested bucket with the given key. Returns
// nil if the bucket does not exist.
//
// This function is part of the walletdb.ReadWriteBucket interface implementation.
func (b *bucket) NestedReadWriteBucket(key []byte) walletdb.ReadWriteBucket {
boltBucket := (*bbolt.Bucket)(b).Bucket(key)
// Don't return a non-nil interface to a nil pointer.
if boltBucket == nil {
return nil
}
return (*bucket)(boltBucket)
}
func (b *bucket) NestedReadBucket(key []byte) walletdb.ReadBucket {
return b.NestedReadWriteBucket(key)
}
// CreateBucket creates and returns a new nested bucket with the given key.
// Returns ErrBucketExists if the bucket already exists, ErrBucketNameRequired
// if the key is empty, or ErrIncompatibleValue if the key value is otherwise
// invalid.
//
// This function is part of the walletdb.ReadWriteBucket interface implementation.
func (b *bucket) CreateBucket(key []byte) (walletdb.ReadWriteBucket, error) {
boltBucket, err := (*bbolt.Bucket)(b).CreateBucket(key)
if err != nil {
return nil, convertErr(err)
}
return (*bucket)(boltBucket), nil
}
// CreateBucketIfNotExists creates and returns a new nested bucket with the
// given key if it does not already exist. Returns ErrBucketNameRequired if the
// key is empty or ErrIncompatibleValue if the key value is otherwise invalid.
//
// This function is part of the walletdb.ReadWriteBucket interface implementation.
func (b *bucket) CreateBucketIfNotExists(key []byte) (walletdb.ReadWriteBucket, error) {
boltBucket, err := (*bbolt.Bucket)(b).CreateBucketIfNotExists(key)
if err != nil {
return nil, convertErr(err)
}
return (*bucket)(boltBucket), nil
}
// DeleteNestedBucket removes a nested bucket with the given key. Returns
// ErrTxNotWritable if attempted against a read-only transaction and
// ErrBucketNotFound if the specified bucket does not exist.
//
// This function is part of the walletdb.ReadWriteBucket interface implementation.
func (b *bucket) DeleteNestedBucket(key []byte) error {
return convertErr((*bbolt.Bucket)(b).DeleteBucket(key))
}
// ForEach invokes the passed function with every key/value pair in the bucket.
// This includes nested buckets, in which case the value is nil, but it does not
// include the key/value pairs within those nested buckets.
//
// NOTE: The values returned by this function are only valid during a
// transaction. Attempting to access them after a transaction has ended will
// likely result in an access violation.
//
// This function is part of the walletdb.ReadBucket interface implementation.
func (b *bucket) ForEach(fn func(k, v []byte) error) error {
return convertErr((*bbolt.Bucket)(b).ForEach(fn))
}
// Put saves the specified key/value pair to the bucket. Keys that do not
// already exist are added and keys that already exist are overwritten. Returns
// ErrTxNotWritable if attempted against a read-only transaction.
//
// This function is part of the walletdb.ReadWriteBucket interface implementation.
func (b *bucket) Put(key, value []byte) error {
return convertErr((*bbolt.Bucket)(b).Put(key, value))
}
// Get returns the value for the given key. Returns nil if the key does
// not exist in this bucket (or nested buckets).
//
// NOTE: The value returned by this function is only valid during a
// transaction. Attempting to access it after a transaction has ended
// will likely result in an access violation.
//
// This function is part of the walletdb.ReadBucket interface implementation.
func (b *bucket) Get(key []byte) []byte {
return (*bbolt.Bucket)(b).Get(key)
}
// Delete removes the specified key from the bucket. Deleting a key that does
// not exist does not return an error. Returns ErrTxNotWritable if attempted
// against a read-only transaction.
//
// This function is part of the walletdb.ReadWriteBucket interface implementation.
func (b *bucket) Delete(key []byte) error {
return convertErr((*bbolt.Bucket)(b).Delete(key))
}
func (b *bucket) ReadCursor() walletdb.ReadCursor {
return b.ReadWriteCursor()
}
// ReadWriteCursor returns a new cursor, allowing for iteration over the bucket's
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// key/value pairs and nested buckets in forward or backward order.
//
// This function is part of the walletdb.ReadWriteBucket interface implementation.
func (b *bucket) ReadWriteCursor() walletdb.ReadWriteCursor {
return (*cursor)((*bbolt.Bucket)(b).Cursor())
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}
// Tx returns the bucket's transaction.
//
// This function is part of the walletdb.ReadWriteBucket interface implementation.
func (b *bucket) Tx() walletdb.ReadWriteTx {
return &transaction{
(*bbolt.Bucket)(b).Tx(),
}
}
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// cursor represents a cursor over key/value pairs and nested buckets of a
// bucket.
//
// Note that open cursors are not tracked on bucket changes and any
// modifications to the bucket, with the exception of cursor.Delete, invalidate
// the cursor. After invalidation, the cursor must be repositioned, or the keys
// and values returned may be unpredictable.
type cursor bbolt.Cursor
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// Delete removes the current key/value pair the cursor is at without
// invalidating the cursor. Returns ErrTxNotWritable if attempted on a read-only
// transaction, or ErrIncompatibleValue if attempted when the cursor points to a
// nested bucket.
//
// This function is part of the walletdb.ReadWriteCursor interface implementation.
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func (c *cursor) Delete() error {
return convertErr((*bbolt.Cursor)(c).Delete())
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}
// First positions the cursor at the first key/value pair and returns the pair.
//
// This function is part of the walletdb.ReadCursor interface implementation.
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func (c *cursor) First() (key, value []byte) {
return (*bbolt.Cursor)(c).First()
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}
// Last positions the cursor at the last key/value pair and returns the pair.
//
// This function is part of the walletdb.ReadCursor interface implementation.
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func (c *cursor) Last() (key, value []byte) {
return (*bbolt.Cursor)(c).Last()
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}
// Next moves the cursor one key/value pair forward and returns the new pair.
//
// This function is part of the walletdb.ReadCursor interface implementation.
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func (c *cursor) Next() (key, value []byte) {
return (*bbolt.Cursor)(c).Next()
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}
// Prev moves the cursor one key/value pair backward and returns the new pair.
//
// This function is part of the walletdb.ReadCursor interface implementation.
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func (c *cursor) Prev() (key, value []byte) {
return (*bbolt.Cursor)(c).Prev()
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}
// Seek positions the cursor at the passed seek key. If the key does not exist,
// the cursor is moved to the next key after seek. Returns the new pair.
//
// This function is part of the walletdb.ReadCursor interface implementation.
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func (c *cursor) Seek(seek []byte) (key, value []byte) {
return (*bbolt.Cursor)(c).Seek(seek)
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}
// db represents a collection of namespaces which are persisted and implements
// the walletdb.Db interface. All database access is performed through
// transactions which are obtained through the specific Namespace.
type db bbolt.DB
// Enforce db implements the walletdb.Db interface.
var _ walletdb.DB = (*db)(nil)
func (db *db) beginTx(writable bool) (*transaction, error) {
boltTx, err := (*bbolt.DB)(db).Begin(writable)
if err != nil {
return nil, convertErr(err)
}
return &transaction{boltTx: boltTx}, nil
}
func (db *db) BeginReadTx() (walletdb.ReadTx, error) {
return db.beginTx(false)
}
func (db *db) BeginReadWriteTx() (walletdb.ReadWriteTx, error) {
return db.beginTx(true)
}
// Copy writes a copy of the database to the provided writer. This call will
// start a read-only transaction to perform all operations.
//
// This function is part of the walletdb.Db interface implementation.
func (db *db) Copy(w io.Writer) error {
return convertErr((*bbolt.DB)(db).View(func(tx *bbolt.Tx) error {
return tx.Copy(w)
}))
}
// Close cleanly shuts down the database and syncs all data.
//
// This function is part of the walletdb.Db interface implementation.
func (db *db) Close() error {
return convertErr((*bbolt.DB)(db).Close())
}
// filesExists reports whether the named file or directory exists.
func fileExists(name string) bool {
if _, err := os.Stat(name); err != nil {
if os.IsNotExist(err) {
return false
}
}
return true
}
// openDB opens the database at the provided path. walletdb.ErrDbDoesNotExist
// is returned if the database doesn't exist and the create flag is not set.
func openDB(dbPath string, create bool) (walletdb.DB, error) {
if !create && !fileExists(dbPath) {
return nil, walletdb.ErrDbDoesNotExist
}
boltDB, err := bbolt.Open(dbPath, 0600, nil)
return (*db)(boltDB), convertErr(err)
}