rss-tools/vendor/go.etcd.io/bbolt/internal/common/inode.go (view raw)
| 1 | package common |
| 2 | |
| 3 | import "unsafe" |
| 4 | |
| 5 | // Inode represents an internal node inside of a node. |
| 6 | // It can be used to point to elements in a page or point |
| 7 | // to an element which hasn't been added to a page yet. |
| 8 | type Inode struct { |
| 9 | flags uint32 |
| 10 | pgid Pgid |
| 11 | key []byte |
| 12 | value []byte |
| 13 | } |
| 14 | |
| 15 | type Inodes []Inode |
| 16 | |
| 17 | func (in *Inode) Flags() uint32 { |
| 18 | return in.flags |
| 19 | } |
| 20 | |
| 21 | func (in *Inode) SetFlags(flags uint32) { |
| 22 | in.flags = flags |
| 23 | } |
| 24 | |
| 25 | func (in *Inode) Pgid() Pgid { |
| 26 | return in.pgid |
| 27 | } |
| 28 | |
| 29 | func (in *Inode) SetPgid(id Pgid) { |
| 30 | in.pgid = id |
| 31 | } |
| 32 | |
| 33 | func (in *Inode) Key() []byte { |
| 34 | return in.key |
| 35 | } |
| 36 | |
| 37 | func (in *Inode) SetKey(key []byte) { |
| 38 | in.key = key |
| 39 | } |
| 40 | |
| 41 | func (in *Inode) Value() []byte { |
| 42 | return in.value |
| 43 | } |
| 44 | |
| 45 | func (in *Inode) SetValue(value []byte) { |
| 46 | in.value = value |
| 47 | } |
| 48 | |
| 49 | func ReadInodeFromPage(p *Page) Inodes { |
| 50 | inodes := make(Inodes, int(p.Count())) |
| 51 | isLeaf := p.IsLeafPage() |
| 52 | for i := 0; i < int(p.Count()); i++ { |
| 53 | inode := &inodes[i] |
| 54 | if isLeaf { |
| 55 | elem := p.LeafPageElement(uint16(i)) |
| 56 | inode.SetFlags(elem.Flags()) |
| 57 | inode.SetKey(elem.Key()) |
| 58 | inode.SetValue(elem.Value()) |
| 59 | } else { |
| 60 | elem := p.BranchPageElement(uint16(i)) |
| 61 | inode.SetPgid(elem.Pgid()) |
| 62 | inode.SetKey(elem.Key()) |
| 63 | } |
| 64 | Assert(len(inode.Key()) > 0, "read: zero-length inode key") |
| 65 | } |
| 66 | |
| 67 | return inodes |
| 68 | } |
| 69 | |
| 70 | func WriteInodeToPage(inodes Inodes, p *Page) uint32 { |
| 71 | // Loop over each item and write it to the page. |
| 72 | // off tracks the offset into p of the start of the next data. |
| 73 | off := unsafe.Sizeof(*p) + p.PageElementSize()*uintptr(len(inodes)) |
| 74 | isLeaf := p.IsLeafPage() |
| 75 | for i, item := range inodes { |
| 76 | Assert(len(item.Key()) > 0, "write: zero-length inode key") |
| 77 | |
| 78 | // Create a slice to write into of needed size and advance |
| 79 | // byte pointer for next iteration. |
| 80 | sz := len(item.Key()) + len(item.Value()) |
| 81 | b := UnsafeByteSlice(unsafe.Pointer(p), off, 0, sz) |
| 82 | off += uintptr(sz) |
| 83 | |
| 84 | // Write the page element. |
| 85 | if isLeaf { |
| 86 | elem := p.LeafPageElement(uint16(i)) |
| 87 | elem.SetPos(uint32(uintptr(unsafe.Pointer(&b[0])) - uintptr(unsafe.Pointer(elem)))) |
| 88 | elem.SetFlags(item.Flags()) |
| 89 | elem.SetKsize(uint32(len(item.Key()))) |
| 90 | elem.SetVsize(uint32(len(item.Value()))) |
| 91 | } else { |
| 92 | elem := p.BranchPageElement(uint16(i)) |
| 93 | elem.SetPos(uint32(uintptr(unsafe.Pointer(&b[0])) - uintptr(unsafe.Pointer(elem)))) |
| 94 | elem.SetKsize(uint32(len(item.Key()))) |
| 95 | elem.SetPgid(item.Pgid()) |
| 96 | Assert(elem.Pgid() != p.Id(), "write: circular dependency occurred") |
| 97 | } |
| 98 | |
| 99 | // Write data for the element to the end of the page. |
| 100 | l := copy(b, item.Key()) |
| 101 | copy(b[l:], item.Value()) |
| 102 | } |
| 103 | |
| 104 | return uint32(off) |
| 105 | } |
| 106 | |
| 107 | func UsedSpaceInPage(inodes Inodes, p *Page) uint32 { |
| 108 | off := unsafe.Sizeof(*p) + p.PageElementSize()*uintptr(len(inodes)) |
| 109 | for _, item := range inodes { |
| 110 | sz := len(item.Key()) + len(item.Value()) |
| 111 | off += uintptr(sz) |
| 112 | } |
| 113 | |
| 114 | return uint32(off) |
| 115 | } |