Method MoveBucket

bucket.go:336–403

MoveBucket moves a sub-bucket from the source bucket to the destination bucket. Returns an error if 1. the sub-bucket cannot be found in the source bucket; 2. or the key already exists in the destination bucket; 3. or the key represents a non-bucket value; 4. the source and destination buckets are t

(key []byte, dstBucket *Bucket)

//  3. or the key represents a non-bucket value;
//  4. the source and destination buckets are the same.
func (b *Bucket) MoveBucket(key []byte, dstBucket *Bucket) (err error) {
	lg := b.tx.db.Logger()
	if lg != discardLogger {
		lg.Debugf("Moving bucket %q", key)
		defer func() {
			if err != nil {
				lg.Errorf("Moving bucket %q failed: %v", key, err)
			} else {
				lg.Debugf("Moving bucket %q successfully", key)
			}
		}()
	}

	if b.tx.db == nil || dstBucket.tx.db == nil {
		return errors.ErrTxClosed
	} else if !b.Writable() || !dstBucket.Writable() {
		return errors.ErrTxNotWritable
	}

	if b.tx.db.Path() != dstBucket.tx.db.Path() || b.tx != dstBucket.tx {
		lg.Errorf("The source and target buckets are not in the same db file, source bucket in %s and target bucket in %s", b.tx.db.Path(), dstBucket.tx.db.Path())
		return errors.ErrDifferentDB
	}

	newKey := cloneBytes(key)

	// Move cursor to correct position.
	c := b.Cursor()
	k, v, flags := c.seek(newKey)

	// Return an error if bucket doesn't exist or is not a bucket.
	if !bytes.Equal(newKey, k) {
		return errors.ErrBucketNotFound
	} else if (flags & common.BucketLeafFlag) == 0 {
		lg.Errorf("An incompatible key %s exists in the source bucket", newKey)
		return errors.ErrIncompatibleValue
	}

	// Do nothing (return true directly) if the source bucket and the
	// destination bucket are actually the same bucket.
	if b == dstBucket || (b.RootPage() == dstBucket.RootPage() && b.RootPage() != 0) {
		lg.Errorf("The source bucket (%s) and the target bucket (%s) are the same bucket", b, dstBucket)
		return errors.ErrSameBuckets
	}

	// check whether the key already exists in the destination bucket
	curDst := dstBucket.Cursor()
	k, _, flags = curDst.seek(newKey)

	// Return an error if there is an existing key in the destination bucket.
	if bytes.Equal(newKey, k) {
		if (flags & common.BucketLeafFlag) != 0 {
			return errors.ErrBucketExists
		}
		lg.Errorf("An incompatible key %s exists in the target bucket", newKey)
		return errors.ErrIncompatibleValue
	}