frostfs-node/pkg/services/object/range/chain.go
Leonard Lyubich 759605410a [#53] object/range: Do not add chain element without the need
In previous implementation one excess element could be added to the chain.
Add previous sibling presence check to prevent this.

Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
2020-10-02 11:25:36 +03:00

114 lines
2 KiB
Go

package rangesvc
import (
"fmt"
objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
"github.com/nspcc-dev/neofs-node/pkg/core/object"
)
type rangeTraverser struct {
chain *rangeChain
seekBounds *rangeBounds
}
type rangeBounds struct {
left, right uint64
}
type objectRange struct {
rng *objectSDK.Range
id *objectSDK.ID
}
type rangeChain struct {
next, prev *rangeChain
bounds *rangeBounds
id *objectSDK.ID
}
func newRangeTraverser(originSize uint64, rightElement *object.Object, rngSeek *objectSDK.Range) *rangeTraverser {
right := &rangeChain{
bounds: &rangeBounds{
left: originSize - rightElement.GetPayloadSize(),
right: originSize,
},
id: rightElement.GetID(),
}
left := &rangeChain{
id: rightElement.GetPreviousID(),
}
left.next, right.prev = right, left
return &rangeTraverser{
chain: right,
seekBounds: &rangeBounds{
left: rngSeek.GetOffset(),
right: rngSeek.GetOffset() + rngSeek.GetLength(),
},
}
}
func (c *rangeTraverser) next() *objectRange {
left := c.chain.bounds.left
seekLeft := c.seekBounds.left
res := new(objectRange)
if left > seekLeft {
res.id = c.chain.prev.id
} else {
res.id = c.chain.id
res.rng = objectSDK.NewRange()
res.rng.SetOffset(seekLeft - left)
res.rng.SetLength(min(c.chain.bounds.right, c.seekBounds.right) - seekLeft)
}
return res
}
func min(a, b uint64) uint64 {
if a < b {
return a
}
return b
}
func (c *rangeTraverser) pushHeader(obj *object.Object) {
id := obj.GetID()
if !id.Equal(c.chain.prev.id) {
panic(fmt.Sprintf("(%T) unexpected identifier in header", c))
}
sz := obj.GetPayloadSize()
c.chain.prev.bounds = &rangeBounds{
left: c.chain.bounds.left - sz,
right: c.chain.bounds.left,
}
c.chain = c.chain.prev
if prev := obj.GetPreviousID(); prev != nil {
c.chain.prev = &rangeChain{
next: c.chain,
id: prev,
}
}
}
func (c *rangeTraverser) pushSuccessSize(sz uint64) {
c.seekBounds.left += sz
if c.seekBounds.left >= c.chain.bounds.right && c.chain.next != nil {
c.chain = c.chain.next
}
}