Method openBucket

bucket.go:115–143

Helper method that re-interprets a sub-bucket value from a parent into a Bucket

(value []byte)

// Helper method that re-interprets a sub-bucket value
// from a parent into a Bucket
func (b *Bucket) openBucket(value []byte) *Bucket {
	var child = newBucket(b.tx)

	// Unaligned access requires a copy to be made.
	const unalignedMask = unsafe.Alignof(struct {
		common.InBucket
		common.Page
	}{}) - 1
	unaligned := uintptr(unsafe.Pointer(&value[0]))&unalignedMask != 0
	if unaligned {
		value = cloneBytes(value)
	}

	// If this is a writable transaction then we need to copy the bucket entry.
	// Read-only transactions can point directly at the mmap entry.
	if b.tx.writable && !unaligned {
		child.InBucket = &common.InBucket{}
		*child.InBucket = *(*common.InBucket)(unsafe.Pointer(&value[0]))
	} else {
		child.InBucket = (*common.InBucket)(unsafe.Pointer(&value[0]))
	}

	// Save a reference to the inline page if the bucket is inline.
	if child.RootPage() == 0 {
		child.page = (*common.Page)(unsafe.Pointer(&value[common.BucketHeaderSize]))
	}

	return &child
}

// CreateBucket creates a new bucket at the given key and returns the new bucket.
// Returns an error if the key already exists, if the bucket name is blank, or if the bucket name is too long.