mirror of
https://github.com/osmarks/mycorrhiza.git
synced 2024-10-30 03:36:16 +00:00
159 lines
4.1 KiB
Go
159 lines
4.1 KiB
Go
// Package backlinks maintains the index of backlinks and lets you update it and query it.
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package backlinks
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import (
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"log"
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"os"
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"github.com/bouncepaw/mycorrhiza/hyphae"
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"github.com/bouncepaw/mycorrhiza/util"
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)
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// yieldHyphaBacklinks gets backlinks for the desired hypha, sorts and yields them one by one.
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func yieldHyphaBacklinks(hyphaName string) <-chan string {
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hyphaName = util.CanonicalName(hyphaName)
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out := make(chan string)
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sorted := hyphae.PathographicSort(out)
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go func() {
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backlinks, exists := backlinkIndex[hyphaName]
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if exists {
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for link := range backlinks {
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out <- link
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}
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}
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close(out)
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}()
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return sorted
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}
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var backlinkConveyor = make(chan backlinkIndexOperation) // No need to buffer because these operations are rare.
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// RunBacklinksConveyor runs an index operation processing loop. Call it somewhere in main.
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func RunBacklinksConveyor() {
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// It is supposed to run as a goroutine for all the time. So, don't blame the infinite loop.
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defer close(backlinkConveyor)
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for {
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(<-backlinkConveyor).apply()
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}
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}
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var backlinkIndex = make(map[string]linkSet)
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// IndexBacklinks traverses all text hyphae, extracts links from them and forms an initial index. Call it when indexing and reindexing hyphae.
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func IndexBacklinks() {
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// It is safe to ignore the mutex, because there is only one worker.
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for h := range hyphae.FilterHyphaeWithText(hyphae.YieldExistingHyphae()) {
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foundLinks := extractHyphaLinksFromContent(h.CanonicalName(), fetchText(h))
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for _, link := range foundLinks {
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if _, exists := backlinkIndex[link]; !exists {
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backlinkIndex[link] = make(linkSet)
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}
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backlinkIndex[link][h.CanonicalName()] = struct{}{}
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}
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}
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}
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// BacklinksCount returns the amount of backlinks to the hypha.
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func BacklinksCount(h hyphae.Hypha) int {
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if links, exists := backlinkIndex[h.CanonicalName()]; exists {
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return len(links)
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}
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return 0
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}
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// Using set here seems like the most appropriate solution
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type linkSet map[string]struct{}
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func toLinkSet(xs []string) linkSet {
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result := make(linkSet)
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for _, x := range xs {
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result[x] = struct{}{}
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}
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return result
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}
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func fetchText(h hyphae.Hypha) string {
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var path string
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switch h := h.(type) {
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case *hyphae.EmptyHypha:
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return ""
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case *hyphae.TextualHypha:
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path = h.TextFilePath()
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case *hyphae.MediaHypha:
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if !h.HasTextFile() {
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return ""
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}
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path = h.TextFilePath()
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}
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text, err := os.ReadFile(path)
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if err != nil {
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log.Println(err)
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return ""
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}
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return string(text)
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}
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// backlinkIndexOperation is an operation for the backlink index. This operation is executed async-safe.
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type backlinkIndexOperation interface {
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apply()
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}
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// backlinkIndexEdit contains data for backlink index update after a hypha edit
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type backlinkIndexEdit struct {
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name string
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oldLinks []string
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newLinks []string
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}
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// apply changes backlink index respective to the operation data
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func (op backlinkIndexEdit) apply() {
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oldLinks := toLinkSet(op.oldLinks)
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newLinks := toLinkSet(op.newLinks)
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for link := range oldLinks {
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if _, exists := newLinks[link]; !exists {
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delete(backlinkIndex[link], op.name)
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}
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}
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for link := range newLinks {
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if _, exists := oldLinks[link]; !exists {
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if _, exists := backlinkIndex[link]; !exists {
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backlinkIndex[link] = make(linkSet)
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}
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backlinkIndex[link][op.name] = struct{}{}
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}
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}
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}
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// backlinkIndexDeletion contains data for backlink index update after a hypha deletion
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type backlinkIndexDeletion struct {
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name string
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links []string
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}
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// apply changes backlink index respective to the operation data
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func (op backlinkIndexDeletion) apply() {
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for _, link := range op.links {
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if lSet, exists := backlinkIndex[link]; exists {
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delete(lSet, op.name)
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}
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}
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}
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// backlinkIndexRenaming contains data for backlink index update after a hypha renaming
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type backlinkIndexRenaming struct {
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oldName string
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newName string
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links []string
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}
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// apply changes backlink index respective to the operation data
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func (op backlinkIndexRenaming) apply() {
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for _, link := range op.links {
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if lSet, exists := backlinkIndex[link]; exists {
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delete(lSet, op.oldName)
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backlinkIndex[link][op.newName] = struct{}{}
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}
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}
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}
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