Fix versioning. Remove objMap.

Tested with test/versioning.py Objects in versioned buckets are not appendable.

Versioning is handled as follows.

In PUT (new) object, version in db table is set as follows in meta/types/object.go.

func (o *Object) GetCreateSql() (string, []interface{}, uint64) {
version := math.MaxUint64 - uint64(o.LastModifiedTime.UnixNano())

And responsed to client with converted versionId in meta/client/tidbclient/object.go

func (t *TidbClient) PutObject(object *Object, tx DB) (err error) {
if tx == nil {
    tx, err = t.Client.Begin()
    if err != nil {
        return err
    }
    defer func() {
        if err == nil {
            err = tx.(*sql.Tx).Commit()
        }
        if err != nil {
            tx.(*sql.Tx).Rollback()
        }
    }()
}
sql, args, iversion := object.GetCreateSql()
object.VersionId = ConvertRawVersionToS3Version(iversion)

In ListObjectVersions, object versions will be returned in meta/client/tidbclient/bucket.go and meta/client/tidbclient/object.go.


func (t *TidbClient) GetObject(bucketName, objectName, version string) (object *Object, err error) {
var ibucketname, iname, customattributes, acl, lastModifiedTime string
var iversion uint64

var row *sql.Row
sqltext := "select bucketname,name,version,location,pool,ownerid,size,objectid,lastmodifiedtime,etag,contenttype," +
    "customattributes,acl,nullversion,deletemarker,ssetype,encryptionkey,initializationvector,type,storageclass from objects where bucketname=? and name=? "
if version == "" {
    sqltext += "order by bucketname,name,version limit 1;"
    row = t.Client.QueryRow(sqltext, bucketName, objectName)
} else if version == ObjectNullVersion {
    sqltext += "and nullversion=1 limit 1;" // There should be only one NullVersion object.
    row = t.Client.QueryRow(sqltext, bucketName, objectName)
} else {
    sqltext += "and version=?;"
    internalVersion, err := ConvertS3VersionToRawVersion(version)
    if err != nil {
        return nil, ErrInternalError
    }
    row = t.Client.QueryRow(sqltext, bucketName, objectName, internalVersion)
}
...
object.VersionId = ConvertRawVersionToS3Version(iversion)

return
}


3. In GET object, objectid for ceph will be get with client specified version Id.
4. In PUT objects in versioned buckets in storage/object.go, old objects will be handled in storage/object.go.

func (yig *YigStorage) checkOldObject(bucketName, objectName, versioning string) (err error) { switch versioning { case meta.VersionDisabled: // Delete all the bucketName + objectName. return yig.removeAllObjectsEntryByName(bucketName, objectName) // TODO: not deleted.

case meta.VersionEnabled:
    // Do nothing.

case meta.VersionSuspended:
    // Delete null version object.
    var object *meta.Object
    if object, err = yig.MetaStorage.GetObjectVersion(bucketName, objectName, meta.ObjectNullVersion, false); err != nil {
        if err == ErrNoSuchKey {
            return nil
        }
        return err
    }

    return yig.MetaStorage.DeleteObject(object, object.DeleteMarker)

default:
    return errors.New("No Such versioning status!")
}

return nil

}


TODO work
1. Lifecycle and versioning adaption. 
https://docs.aws.amazon.com/AmazonS3/latest/dev/intro-lifecycle-rules.html#intro-lifecycle-rules-actions

journeymidnight / yig

Fix versioning. Remove objMap. #243