frostfs-node/pkg/local_object_storage/engine/head.go
Leonard Lyubich 318639e5bf [] *: Clarify docs about returned errors from apistatus package
`apistatus` package provides types which implement build-in `error`
interface. Add `error of type` pattern when documenting these errors in
order to clarify how these errors should be handled (e.g. `errors.Is` is
not good).

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
2022-03-17 16:34:00 +03:00

163 lines
3.7 KiB
Go

package engine
import (
"errors"
"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/shard"
"github.com/nspcc-dev/neofs-node/pkg/local_object_storage/util"
apistatus "github.com/nspcc-dev/neofs-sdk-go/client/status"
objectSDK "github.com/nspcc-dev/neofs-sdk-go/object"
addressSDK "github.com/nspcc-dev/neofs-sdk-go/object/address"
)
// HeadPrm groups the parameters of Head operation.
type HeadPrm struct {
addr *addressSDK.Address
raw bool
}
// HeadRes groups resulting values of Head operation.
type HeadRes struct {
head *objectSDK.Object
}
// WithAddress is a Head option to set the address of the requested object.
//
// Option is required.
func (p *HeadPrm) WithAddress(addr *addressSDK.Address) *HeadPrm {
if p != nil {
p.addr = addr
}
return p
}
// WithRaw is a Head option to set raw flag value. If flag is unset, then Head
// returns header of virtual object, otherwise it returns SplitInfo of virtual
// object.
func (p *HeadPrm) WithRaw(raw bool) *HeadPrm {
if p != nil {
p.raw = raw
}
return p
}
// Header returns the requested object header.
//
// Instance has empty payload.
func (r *HeadRes) Header() *objectSDK.Object {
return r.head
}
// Head reads object header from local storage.
//
// Returns any error encountered that
// did not allow to completely read the object header.
//
// Returns an error of type apistatus.ObjectNotFound if requested object is missing in local storage.
// Returns an error of type apistatus.ObjectAlreadyRemoved if requested object was inhumed.
//
// Returns an error if executions are blocked (see BlockExecution).
func (e *StorageEngine) Head(prm *HeadPrm) (res *HeadRes, err error) {
err = e.execIfNotBlocked(func() error {
res, err = e.head(prm)
return err
})
return
}
func (e *StorageEngine) head(prm *HeadPrm) (*HeadRes, error) {
if e.metrics != nil {
defer elapsed(e.metrics.AddHeadDuration)()
}
var (
head *objectSDK.Object
siErr *objectSDK.SplitInfoError
errNotFound apistatus.ObjectNotFound
outSI *objectSDK.SplitInfo
outError error = errNotFound
)
shPrm := new(shard.HeadPrm).
WithAddress(prm.addr).
WithRaw(prm.raw)
e.iterateOverSortedShards(prm.addr, func(_ int, sh hashedShard) (stop bool) {
res, err := sh.Head(shPrm)
if err != nil {
switch {
case shard.IsErrNotFound(err):
return false // ignore, go to next shard
case errors.As(err, &siErr):
siErr = err.(*objectSDK.SplitInfoError)
if outSI == nil {
outSI = objectSDK.NewSplitInfo()
}
util.MergeSplitInfo(siErr.SplitInfo(), outSI)
// stop iterating over shards if SplitInfo structure is complete
if outSI.Link() != nil && outSI.LastPart() != nil {
return true
}
return false
case shard.IsErrRemoved(err):
outError = err
return true // stop, return it back
default:
e.reportShardError(sh, "could not head object from shard", err)
return false
}
}
head = res.Object()
return true
})
if outSI != nil {
return nil, objectSDK.NewSplitInfoError(outSI)
}
if head == nil {
return nil, outError
}
return &HeadRes{
head: head,
}, nil
}
// Head reads object header from local storage by provided address.
func Head(storage *StorageEngine, addr *addressSDK.Address) (*objectSDK.Object, error) {
res, err := storage.Head(new(HeadPrm).
WithAddress(addr),
)
if err != nil {
return nil, err
}
return res.Header(), nil
}
// HeadRaw reads object header from local storage by provided address and raw
// flag.
func HeadRaw(storage *StorageEngine, addr *addressSDK.Address, raw bool) (*objectSDK.Object, error) {
res, err := storage.Head(new(HeadPrm).
WithAddress(addr).
WithRaw(raw),
)
if err != nil {
return nil, err
}
return res.Header(), nil
}