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package packfile
import (
"io"
"gopkg.in/src-d/go-git.v4/core"
)
// Format specifies if the packfile uses ref-deltas or ofs-deltas.
type Format int
// Possible values of the Format type.
const (
UnknownFormat Format = iota
OFSDeltaFormat
REFDeltaFormat
)
var (
// ErrMaxObjectsLimitReached is returned by Decode when the number
// of objects in the packfile is higher than
// Decoder.MaxObjectsLimit.
ErrMaxObjectsLimitReached = NewError("max. objects limit reached")
// ErrInvalidObject is returned by Decode when an invalid object is
// found in the packfile.
ErrInvalidObject = NewError("invalid git object")
// ErrPackEntryNotFound is returned by Decode when a reference in
// the packfile references and unknown object.
ErrPackEntryNotFound = NewError("can't find a pack entry")
// ErrZLib is returned by Decode when there was an error unzipping
// the packfile contents.
ErrZLib = NewError("zlib reading error")
)
const (
// DefaultMaxObjectsLimit is the maximum amount of objects the
// decoder will decode before returning ErrMaxObjectsLimitReached.
DefaultMaxObjectsLimit = 1 << 20
)
// Decoder reads and decodes packfiles from an input stream.
type Decoder struct {
// MaxObjectsLimit is the limit of objects to be load in the packfile, if
// a packfile excess this number an error is throw, the default value
// is defined by DefaultMaxObjectsLimit, usually the default limit is more
// than enough to work with any repository, with higher values and huge
// repositories you can run out of memory.
MaxObjectsLimit uint32
p *Parser
s core.ObjectStorage
}
// NewDecoder returns a new Decoder that reads from r.
func NewDecoder(r ReadRecaller) *Decoder {
return &Decoder{
MaxObjectsLimit: DefaultMaxObjectsLimit,
p: NewParser(r),
}
}
// Decode reads a packfile and stores it in the value pointed to by s.
func (d *Decoder) Decode(s core.ObjectStorage) error {
d.s = s
count, err := d.p.ReadHeader()
if err != nil {
return err
}
if count > d.MaxObjectsLimit {
return ErrMaxObjectsLimitReached.AddDetails("%d", count)
}
err = d.readObjects(count)
return err
}
func (d *Decoder) readObjects(count uint32) error {
// This code has 50-80 µs of overhead per object not counting zlib inflation.
// Together with zlib inflation, it's 400-410 µs for small objects.
// That's 1 sec for ~2450 objects, ~4.20 MB, or ~250 ms per MB,
// of which 12-20 % is _not_ zlib inflation (ie. is our code).
for i := 0; i < int(count); i++ {
start, err := d.p.Offset()
if err != nil {
return err
}
obj, err := d.p.ReadObject()
if err != nil {
if err == io.EOF {
break
}
return err
}
err = d.p.Remember(start, obj)
if err != nil {
return err
}
_, err = d.s.Set(obj)
if err == io.EOF {
break
}
}
return nil
}
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