mirror of
https://github.com/go-gitea/gitea.git
synced 2024-12-04 14:46:57 -05:00
173 lines
4.3 KiB
Go
173 lines
4.3 KiB
Go
|
package bolt
|
||
|
|
||
|
import (
|
||
|
"fmt"
|
||
|
"os"
|
||
|
"sort"
|
||
|
"unsafe"
|
||
|
)
|
||
|
|
||
|
const pageHeaderSize = int(unsafe.Offsetof(((*page)(nil)).ptr))
|
||
|
|
||
|
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 (*[maxAllocSize]byte)(unsafe.Pointer(&buf[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 (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos]))[:n.ksize:n.ksize]
|
||
|
}
|
||
|
|
||
|
// value returns a byte slice of the node value.
|
||
|
func (n *leafPageElement) value() []byte {
|
||
|
buf := (*[maxAllocSize]byte)(unsafe.Pointer(n))
|
||
|
return (*[maxAllocSize]byte)(unsafe.Pointer(&buf[n.pos+n.ksize]))[:n.vsize: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] }
|
||
|
|
||
|
// merge returns the sorted union of a and b.
|
||
|
func (a pgids) merge(b pgids) pgids {
|
||
|
// Return the opposite slice if one is nil.
|
||
|
if len(a) == 0 {
|
||
|
return b
|
||
|
} else if len(b) == 0 {
|
||
|
return a
|
||
|
}
|
||
|
|
||
|
// Create a list to hold all elements from both lists.
|
||
|
merged := make(pgids, 0, len(a)+len(b))
|
||
|
|
||
|
// Assign lead to the slice with a lower starting value, follow to the higher value.
|
||
|
lead, follow := a, b
|
||
|
if b[0] < a[0] {
|
||
|
lead, follow = b, a
|
||
|
}
|
||
|
|
||
|
// Continue while there are elements in the lead.
|
||
|
for len(lead) > 0 {
|
||
|
// Merge largest prefix of lead that is ahead of follow[0].
|
||
|
n := sort.Search(len(lead), func(i int) bool { return lead[i] > follow[0] })
|
||
|
merged = append(merged, lead[:n]...)
|
||
|
if n >= len(lead) {
|
||
|
break
|
||
|
}
|
||
|
|
||
|
// Swap lead and follow.
|
||
|
lead, follow = follow, lead[n:]
|
||
|
}
|
||
|
|
||
|
// Append what's left in follow.
|
||
|
merged = append(merged, follow...)
|
||
|
|
||
|
return merged
|
||
|
}
|