| package bolt |
| |
| import ( |
| "fmt" |
| "os" |
| "unsafe" |
| ) |
| |
| const pageHeaderSize = int(unsafe.Offsetof(((*page)(nil)).ptr)) |
| |
| const maxAllocSize = 0xFFFFFFF |
| const minKeysPerPage = 2 |
| |
| const branchPageElementSize = int(unsafe.Sizeof(branchPageElement{})) |
| const leafPageElementSize = int(unsafe.Sizeof(leafPageElement{})) |
| |
| const ( |
| branchPageFlag = 0x01 |
| leafPageFlag = 0x02 |
| metaPageFlag = 0x04 |
| freelistPageFlag = 0x10 |
| ) |
| |
| const ( |
| bucketLeafFlag = 0x01 |
| ) |
| |
| type pgid uint64 |
| |
| type page struct { |
| id pgid |
| flags uint16 |
| count uint16 |
| overflow uint32 |
| ptr uintptr |
| } |
| |
| // typ returns a human readable page type string used for debugging. |
| func (p *page) typ() string { |
| if (p.flags & branchPageFlag) != 0 { |
| return "branch" |
| } else if (p.flags & leafPageFlag) != 0 { |
| return "leaf" |
| } else if (p.flags & metaPageFlag) != 0 { |
| return "meta" |
| } else if (p.flags & freelistPageFlag) != 0 { |
| return "freelist" |
| } |
| return fmt.Sprintf("unknown<%02x>", p.flags) |
| } |
| |
| // meta returns a pointer to the metadata section of the page. |
| func (p *page) meta() *meta { |
| return (*meta)(unsafe.Pointer(&p.ptr)) |
| } |
| |
| // leafPageElement retrieves the leaf node by index |
| func (p *page) leafPageElement(index uint16) *leafPageElement { |
| n := &((*[0x7FFFFFF]leafPageElement)(unsafe.Pointer(&p.ptr)))[index] |
| return n |
| } |
| |
| // leafPageElements retrieves a list of leaf nodes. |
| func (p *page) leafPageElements() []leafPageElement { |
| return ((*[0x7FFFFFF]leafPageElement)(unsafe.Pointer(&p.ptr)))[:] |
| } |
| |
| // branchPageElement retrieves the branch node by index |
| func (p *page) branchPageElement(index uint16) *branchPageElement { |
| return &((*[0x7FFFFFF]branchPageElement)(unsafe.Pointer(&p.ptr)))[index] |
| } |
| |
| // branchPageElements retrieves a list of branch nodes. |
| func (p *page) branchPageElements() []branchPageElement { |
| return ((*[0x7FFFFFF]branchPageElement)(unsafe.Pointer(&p.ptr)))[:] |
| } |
| |
| // dump writes n bytes of the page to STDERR as hex output. |
| func (p *page) hexdump(n int) { |
| buf := (*[maxAllocSize]byte)(unsafe.Pointer(p))[:n] |
| fmt.Fprintf(os.Stderr, "%x\n", buf) |
| } |
| |
| type pages []*page |
| |
| func (s pages) Len() int { return len(s) } |
| func (s pages) Swap(i, j int) { s[i], s[j] = s[j], s[i] } |
| func (s pages) Less(i, j int) bool { return s[i].id < s[j].id } |
| |
| // branchPageElement represents a node on a branch page. |
| type branchPageElement struct { |
| pos uint32 |
| ksize uint32 |
| pgid pgid |
| } |
| |
| // key returns a byte slice of the node key. |
| func (n *branchPageElement) key() []byte { |
| buf := (*[maxAllocSize]byte)(unsafe.Pointer(n)) |
| return buf[n.pos : n.pos+n.ksize] |
| } |
| |
| // leafPageElement represents a node on a leaf page. |
| type leafPageElement struct { |
| flags uint32 |
| pos uint32 |
| ksize uint32 |
| vsize uint32 |
| } |
| |
| // key returns a byte slice of the node key. |
| func (n *leafPageElement) key() []byte { |
| buf := (*[maxAllocSize]byte)(unsafe.Pointer(n)) |
| return buf[n.pos : n.pos+n.ksize] |
| } |
| |
| // value returns a byte slice of the node value. |
| func (n *leafPageElement) value() []byte { |
| buf := (*[maxAllocSize]byte)(unsafe.Pointer(n)) |
| return buf[n.pos+n.ksize : n.pos+n.ksize+n.vsize] |
| } |
| |
| // PageInfo represents human readable information about a page. |
| type PageInfo struct { |
| ID int |
| Type string |
| Count int |
| OverflowCount int |
| } |
| |
| type pgids []pgid |
| |
| func (s pgids) Len() int { return len(s) } |
| func (s pgids) Swap(i, j int) { s[i], s[j] = s[j], s[i] } |
| func (s pgids) Less(i, j int) bool { return s[i] < s[j] } |