func (f *bitFiler) WriteAt(b []byte, off int64) (n int, err error) {
off0 := off
pgI := off >> bfBits
pgO := int(off & bfMask)
n = len(b)
rem := n
var nc int
for rem != 0 {
pg := f.m[pgI]
if pg == nil {
pg = &bitPage{}
if f.parent != nil {
_, err = f.parent.ReadAt(pg.data[:], off&^bfMask)
if err != nil && !fileutil.IsEOF(err) {
return
}
err = nil
}
f.m[pgI] = pg
}
nc = copy(pg.data[pgO:], b)
pgI++
pg.dirty = true
for i := pgO; i < pgO+nc; i++ {
pg.flags[i>>3] |= bitmask[i&7]
}
pgO = 0
rem -= nc
b = b[nc:]
off += int64(nc)
}
f.size = mathutil.MaxInt64(f.size, off0+int64(n))
return
}
// WriteAt implements Filer.
func (f *MemFiler) WriteAt(b []byte, off int64) (n int, err error) {
pgI := off >> pgBits
pgO := int(off & pgMask)
n = len(b)
rem := n
var nc int
for rem != 0 {
if pgO == 0 && rem >= pgSize && bytes.Equal(b[:pgSize], zeroPage[:]) {
delete(f.m, pgI)
nc = pgSize
} else {
pg := f.m[pgI]
if pg == nil {
pg = new([pgSize]byte)
f.m[pgI] = pg
}
nc = copy((*pg)[pgO:], b)
}
pgI++
pgO = 0
rem -= nc
b = b[nc:]
}
f.size = mathutil.MaxInt64(f.size, off+int64(n))
return
}
// Size implements Filer.
func (f *InnerFiler) Size() (int64, error) {
sz, err := f.outer.Size()
if err != nil {
return 0, err
}
return mathutil.MaxInt64(sz-f.off, 0), nil
}
// WriteAt implements Filer.
func (f *SimpleFileFiler) WriteAt(b []byte, off int64) (n int, err error) {
if f.size < 0 { // boot
fi, err := os.Stat(f.file.Name())
if err != nil {
return 0, err
}
f.size = fi.Size()
}
f.size = mathutil.MaxInt64(f.size, int64(len(b))+off)
return f.file.WriteAt(b, off)
}
// NewACIDFiler0 returns a newly created ACIDFiler0 with WAL in wal.
//
// If the WAL is zero sized then a previous clean shutdown of db is taken for
// granted and no recovery procedure is taken.
//
// If the WAL is of non zero size then it is checked for having a
// commited/fully finished transaction not yet been reflected in db. If such
// transaction exists it's committed to db. If the recovery process finishes
// successfully, the WAL is truncated to zero size and fsync'ed prior to return
// from NewACIDFiler0.
func NewACIDFiler(db Filer, wal *os.File) (r *ACIDFiler0, err error) {
fi, err := wal.Stat()
if err != nil {
return
}
r = &ACIDFiler0{wal: wal}
if fi.Size() != 0 {
if err = r.recoverDb(db); err != nil {
return
}
}
acidWriter := (*acidWriter0)(r)
if r.RollbackFiler, err = NewRollbackFiler(
db,
func(sz int64) (err error) {
// Checkpoint
if err = acidWriter.writePacket([]interface{}{wpt00Checkpoint, sz}); err != nil {
return
}
if err = r.bwal.Flush(); err != nil {
return
}
r.bwal = nil
if err = r.wal.Sync(); err != nil {
return
}
wfi, err := r.wal.Stat()
switch err != nil {
case true:
// unexpected, but ignored
case false:
r.peakWal = mathutil.MaxInt64(wfi.Size(), r.peakWal)
}
// Phase 1 commit complete
for _, v := range r.data {
if _, err := db.WriteAt(v.b, v.off); err != nil {
return err
}
}
if err = db.Truncate(sz); err != nil {
return
}
if err = db.Sync(); err != nil {
return
}
// Phase 2 commit complete
if !r.testHook {
if err = r.wal.Truncate(0); err != nil {
return
}
if _, err = r.wal.Seek(0, 0); err != nil {
return
}
}
r.testHook = false
return r.wal.Sync()
},
acidWriter,
); err != nil {
return
}
return r, nil
}