111 lines
2.5 KiB
Go
111 lines
2.5 KiB
Go
package pfile
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import (
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"git.crumpington.com/public/jldb/lib/errs"
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"git.crumpington.com/public/jldb/mdb/change"
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)
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type Index struct {
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fList *freeList
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aList allocList
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seen map[[2]uint64]struct{}
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mask []bool
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}
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func NewIndex(f *File) (*Index, error) {
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maxPage, err := f.maxPage()
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if err != nil {
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return nil, err
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}
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idx := &Index{
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fList: newFreeList(maxPage),
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aList: *newAllocList(),
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seen: map[[2]uint64]struct{}{},
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mask: []bool{},
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}
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err = f.iterate(func(pageID uint64, page dataPage) error {
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header := page.Header()
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switch header.PageType {
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case pageTypeHead:
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idx.aList.Create(header.CollectionID, header.ItemID, pageID)
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case pageTypeData:
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if !idx.aList.Push(header.CollectionID, header.ItemID, pageID) {
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return errs.Corrupt.WithMsg("encountered data page with no corresponding head page")
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}
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case pageTypeFree:
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idx.fList.Push(pageID)
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}
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return nil
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})
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return idx, err
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}
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func (idx *Index) StageChanges(changes []change.Change) {
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clear(idx.seen)
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if cap(idx.mask) < len(changes) {
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idx.mask = make([]bool, len(changes))
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}
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idx.mask = idx.mask[:len(changes)]
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for i := len(changes) - 1; i >= 0; i-- {
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key := [2]uint64{changes[i].CollectionID, changes[i].ItemID}
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if _, ok := idx.seen[key]; ok {
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idx.mask[i] = false
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continue
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}
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idx.seen[key] = struct{}{}
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idx.mask[i] = true
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}
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for i, active := range idx.mask {
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if !active {
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continue
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}
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if changes[i].Store {
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count := idx.getPageCountForData(len(changes[i].Data))
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changes[i].WritePageIDs = idx.fList.Pop(count, changes[i].WritePageIDs)
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}
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if pages := idx.aList.Remove(changes[i].CollectionID, changes[i].ItemID); pages != nil {
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changes[i].ClearPageIDs = pages
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}
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}
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}
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func (idx *Index) UnstageChanges(changes []change.Change) {
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for i := range changes {
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if len(changes[i].WritePageIDs) > 0 {
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idx.fList.Push(changes[i].WritePageIDs...)
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changes[i].WritePageIDs = changes[i].WritePageIDs[:0]
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}
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if len(changes[i].ClearPageIDs) > 0 {
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idx.aList.Store(changes[i].CollectionID, changes[i].ItemID, changes[i].ClearPageIDs)
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changes[i].ClearPageIDs = changes[i].ClearPageIDs[:0]
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}
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}
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}
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func (idx *Index) ApplyChanges(changes []change.Change) {
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for i := range changes {
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if len(changes[i].WritePageIDs) > 0 {
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idx.aList.Store(changes[i].CollectionID, changes[i].ItemID, changes[i].WritePageIDs)
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}
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if len(changes[i].ClearPageIDs) > 0 {
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idx.fList.Push(changes[i].ClearPageIDs...)
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}
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}
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}
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func (idx *Index) getPageCountForData(dataSize int) int {
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count := dataSize / pageDataSize
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if dataSize%pageDataSize != 0 {
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count++
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}
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return count
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}
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