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package common
import (
"fmt"
"hash/fnv"
"io"
"unsafe"
"go.etcd.io/bbolt/errors"
)
type Meta struct {
magic uint32
version uint32
pageSize uint32
flags uint32
root InBucket
freelist Pgid
pgid Pgid
txid Txid
checksum uint64
}
// Validate checks the marker bytes and version of the meta page to ensure it matches this binary.
func (m *Meta) Validate() error {
if m.magic != Magic {
return errors.ErrInvalid
} else if m.version != Version {
return errors.ErrVersionMismatch
} else if m.checksum != m.Sum64() {
return errors.ErrChecksum
}
return nil
}
// Copy copies one meta object to another.
func (m *Meta) Copy(dest *Meta) {
*dest = *m
}
// Write writes the meta onto a page.
func (m *Meta) Write(p *Page) {
if m.root.root >= m.pgid {
panic(fmt.Sprintf("root bucket pgid (%d) above high water mark (%d)", m.root.root, m.pgid))
} else if m.freelist >= m.pgid && m.freelist != PgidNoFreelist {
// TODO: reject pgidNoFreeList if !NoFreelistSync
panic(fmt.Sprintf("freelist pgid (%d) above high water mark (%d)", m.freelist, m.pgid))
}
// Page id is either going to be 0 or 1 which we can determine by the transaction ID.
p.id = Pgid(m.txid % 2)
p.SetFlags(MetaPageFlag)
// Calculate the checksum.
m.checksum = m.Sum64()
m.Copy(p.Meta())
}
// Sum64 generates the checksum for the meta.
func (m *Meta) Sum64() uint64 {
var h = fnv.New64a()
_, _ = h.Write((*[unsafe.Offsetof(Meta{}.checksum)]byte)(unsafe.Pointer(m))[:])
return h.Sum64()
}
func (m *Meta) Magic() uint32 {
return m.magic
}
func (m *Meta) SetMagic(v uint32) {
m.magic = v
}
func (m *Meta) Version() uint32 {
return m.version
}
func (m *Meta) SetVersion(v uint32) {
m.version = v
}
func (m *Meta) PageSize() uint32 {
return m.pageSize
}
func (m *Meta) SetPageSize(v uint32) {
m.pageSize = v
}
func (m *Meta) Flags() uint32 {
return m.flags
}
func (m *Meta) SetFlags(v uint32) {
m.flags = v
}
func (m *Meta) SetRootBucket(b InBucket) {
m.root = b
}
func (m *Meta) RootBucket() *InBucket {
return &m.root
}
func (m *Meta) Freelist() Pgid {
return m.freelist
}
func (m *Meta) SetFreelist(v Pgid) {
m.freelist = v
}
func (m *Meta) IsFreelistPersisted() bool {
return m.freelist != PgidNoFreelist
}
func (m *Meta) Pgid() Pgid {
return m.pgid
}
func (m *Meta) SetPgid(id Pgid) {
m.pgid = id
}
func (m *Meta) Txid() Txid {
return m.txid
}
func (m *Meta) SetTxid(id Txid) {
m.txid = id
}
func (m *Meta) IncTxid() {
m.txid += 1
}
func (m *Meta) DecTxid() {
m.txid -= 1
}
func (m *Meta) Checksum() uint64 {
return m.checksum
}
func (m *Meta) SetChecksum(v uint64) {
m.checksum = v
}
func (m *Meta) Print(w io.Writer) {
fmt.Fprintf(w, "Version: %d\n", m.version)
fmt.Fprintf(w, "Page Size: %d bytes\n", m.pageSize)
fmt.Fprintf(w, "Flags: %08x\n", m.flags)
fmt.Fprintf(w, "Root: <pgid=%d>\n", m.root.root)
fmt.Fprintf(w, "Freelist: <pgid=%d>\n", m.freelist)
fmt.Fprintf(w, "HWM: <pgid=%d>\n", m.pgid)
fmt.Fprintf(w, "Txn ID: %d\n", m.txid)
fmt.Fprintf(w, "Checksum: %016x\n", m.checksum)
fmt.Fprintf(w, "\n")
}
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