forked from TrueCloudLab/frostfs-node
136 lines
2.5 KiB
Go
136 lines
2.5 KiB
Go
package util
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import (
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"fmt"
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objectSDK "github.com/nspcc-dev/neofs-api-go/pkg/object"
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"github.com/nspcc-dev/neofs-node/pkg/core/object"
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)
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type RangeTraverser struct {
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chain *rangeChain
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seekBounds *rangeBounds
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}
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type rangeBounds struct {
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left, right uint64
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}
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type rangeChain struct {
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next, prev *rangeChain
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bounds *rangeBounds
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id *objectSDK.ID
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}
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func NewRangeTraverser(originSize uint64, rightElement *object.Object, rngSeek *objectSDK.Range) *RangeTraverser {
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right := &rangeChain{
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bounds: &rangeBounds{
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left: originSize - rightElement.PayloadSize(),
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right: originSize,
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},
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id: rightElement.ID(),
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}
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left := &rangeChain{
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id: rightElement.PreviousID(),
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}
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left.next, right.prev = right, left
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return &RangeTraverser{
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chain: right,
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seekBounds: &rangeBounds{
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left: rngSeek.GetOffset(),
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right: rngSeek.GetOffset() + rngSeek.GetLength(),
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},
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}
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}
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func (c *RangeTraverser) Next() (id *objectSDK.ID, rng *objectSDK.Range) {
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left := c.chain.bounds.left
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seekLeft := c.seekBounds.left
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if left > seekLeft {
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id = c.chain.prev.id
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} else {
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id = c.chain.id
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rng = objectSDK.NewRange()
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rng.SetOffset(seekLeft - left)
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rng.SetLength(min(c.chain.bounds.right, c.seekBounds.right) - seekLeft)
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}
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return
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}
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func min(a, b uint64) uint64 {
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if a < b {
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return a
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}
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return b
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}
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func (c *RangeTraverser) PushHeader(obj *object.Object) {
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id := obj.ID()
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if !id.Equal(c.chain.prev.id) {
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panic(fmt.Sprintf("(%T) unexpected identifier in header", c))
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}
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sz := obj.PayloadSize()
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c.chain.prev.bounds = &rangeBounds{
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left: c.chain.bounds.left - sz,
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right: c.chain.bounds.left,
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}
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c.chain = c.chain.prev
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if prev := obj.PreviousID(); prev != nil {
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c.chain.prev = &rangeChain{
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next: c.chain,
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id: prev,
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}
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}
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}
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func (c *RangeTraverser) PushSuccessSize(sz uint64) {
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c.seekBounds.left += sz
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if c.seekBounds.left >= c.chain.bounds.right && c.chain.next != nil {
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c.chain = c.chain.next
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}
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}
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// SetSeekRange moves the chain to the specified range.
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// The range is expected to be within the filled chain.
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func (c *RangeTraverser) SetSeekRange(r *objectSDK.Range) {
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ln, off := r.GetLength(), r.GetOffset()
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for {
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if off < c.chain.bounds.left {
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if c.chain.prev == nil {
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break
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}
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c.chain = c.chain.prev
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} else if off >= c.chain.bounds.left && off < c.chain.bounds.right {
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break
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} else if off >= c.chain.bounds.right {
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if c.chain.next == nil {
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break
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}
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c.chain = c.chain.next
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}
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}
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if c.seekBounds == nil {
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c.seekBounds = new(rangeBounds)
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}
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c.seekBounds.left, c.seekBounds.right = off, off+ln
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}
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