Separate the two types of crawling

1) crawling the documents in the index to update these documents;
2) crawling the whole github.

api/internal/crawl/cmd/crawler/crawler.go

@@ -67,19 +67,18 @@ func main() {
 			github.Filename("kustomization.yml")),
 	)
 
-	crawler.CrawlFromSeed(ctx, docs, []crawler.Crawler{ghCrawler},
-		// Converter takes in a plain document and processes it for the
-		// index.
-		func(d *doc.Document) (crawler.CrawledDocument, error) {
+	// docConverter takes in a plain document and processes it for the index.
+	docConverter := func(d *doc.Document) (crawler.CrawledDocument, error) {
 		kdoc := doc.KustomizationDocument{
 			Document: *d,
 		}
 
 		err := kdoc.ParseYAML()
 		return &kdoc, err
-		},
-		// IndexFunc updates the value in the index.
-		func(cdoc crawler.CrawledDocument, crwlr crawler.Crawler) error {
+	}
+
+	// Index updates the value in the index.
+	index := func(cdoc crawler.CrawledDocument, crwlr crawler.Crawler) error {
 		switch d := cdoc.(type) {
 		case *doc.KustomizationDocument:
 			fmt.Println("Inserting: ", d.ID(), d)
@@ -88,6 +87,15 @@ func main() {
 		default:
 			return fmt.Errorf("type %T not supported", d)
 		}
-		},
-	)
+	}
+
+	// seen tracks the IDs of all the documents in the index.
+	// This helps avoid indexing a given document multiple times.
+	seen := make(map[string]struct{})
+
+	crawlers := []crawler.Crawler{ghCrawler}
+
+	crawler.CrawlFromSeed(ctx, docs, crawlers, docConverter, index, seen)
+
+	crawler.CrawlGithub(ctx, crawlers, docConverter, index, seen)
 }

api/internal/crawl/crawler/crawler.go

@@ -40,6 +40,7 @@ type Crawler interface {
 type CrawledDocument interface {
 	ID() string
 	GetDocument() *doc.Document
+	// Get all the Documents directly referred in a Document.
 	GetResources() ([]*doc.Document, error)
 	WasCached() bool
 }
@@ -49,33 +50,24 @@ type CrawlSeed []*doc.Document
 type IndexFunc func(CrawledDocument, Crawler) error
 type Converter func(*doc.Document) (CrawledDocument, error)
 
-// Cleaner, more efficient, and more extensible crawler implementation.
-// The seed must include the ids of each document in the index.
-func CrawlFromSeed(ctx context.Context, seed CrawlSeed,
-	crawlers []Crawler, conv Converter, indx IndexFunc) {
-
-	seen := make(map[string]struct{})
-
-	logIfErr := func(err error) {
+func logIfErr(err error) {
 	if err == nil {
 		return
 	}
 	logger.Println("error: ", err)
 }
 
-	stack := make(CrawlSeed, 0)
-
-	findMatch := func(d *doc.Document) Crawler {
+func findMatch(d *doc.Document, crawlers []Crawler) Crawler {
 	for _, crawl := range crawlers {
 		if crawl.Match(d) {
 			return crawl
 		}
 	}
-
 	return nil
 }
 
-	addBranches := func(cdoc CrawledDocument, match Crawler) {
+func addBranches(cdoc CrawledDocument, match Crawler, indx IndexFunc,
+	seen map[string]struct{}, stack *CrawlSeed) {
 	if _, ok := seen[cdoc.ID()]; ok {
 		return
 	}
@@ -97,87 +89,74 @@ func CrawlFromSeed(ctx context.Context, seed CrawlSeed,
 		if _, ok := seen[dep.ID()]; ok {
 			continue
 		}
-			stack = append(stack, dep)
+		*stack = append(*stack, dep)
 	}
 }
 
-	doCrawl := func(docsPtr *CrawlSeed) {
-		n := len(*docsPtr)
-		for i := 0; i < n; i++ {
-			next := (*docsPtr)[i]
-			match := findMatch(next)
+func doCrawl(ctx context.Context, docsPtr *CrawlSeed, crawlers []Crawler, conv Converter, indx IndexFunc,
+	seen map[string]struct{}, stack *CrawlSeed) {
+	docCount := 0
+	// During the execution of the for loop, more Documents may be added into (*docsPtr).
+	for len(*docsPtr) > 0 {
+		docCount++
+		// get the last Document in (*docPtr), which will be crawled in this iteration.
+		tail := (*docsPtr)[len(*docsPtr)-1]
+
+		// remove the last Document in (*docPtr)
+		*docsPtr = (*docsPtr)[:(len(*docsPtr)-1)]
+
+		match := findMatch(tail, crawlers)
 		if match == nil {
 			logIfErr(fmt.Errorf(
-					"%v could not match any crawler", next))
+				"%v could not match any crawler", tail))
 			continue
 		}
 
-			logger.Println("Crawling ", next.RepositoryURL, next.FilePath)
-			err := match.FetchDocument(ctx, next)
+		logger.Println("Crawling ", tail.RepositoryURL, tail.FilePath)
+		err := match.FetchDocument(ctx, tail)
 		logIfErr(err)
 		// If there was no change or there is an error, we don't have
 		// to branch out, since the dependencies are already in the
 		// index, or we cannot find the document.
-			if err != nil || next.WasCached() {
-				if next.WasCached() {
-					logger.Println(next.RepositoryURL, next.FilePath, "is cached already")
+		if err != nil || tail.WasCached() {
+			if tail.WasCached() {
+				logger.Println(tail.RepositoryURL, tail.FilePath, "is cached already")
 			}
 			continue
 		}
 
-			logIfErr(match.SetCreated(ctx, next))
+		logIfErr(match.SetCreated(ctx, tail))
 
-			cdoc, err := conv(next)
+		cdoc, err := conv(tail)
 		logIfErr(err)
 
-			addBranches(cdoc, match)
+		addBranches(cdoc, match, indx, seen, stack)
 	}
+	logger.Printf("%d documents were crawled by doCrawl\n", docCount)
 }
 
+// CrawlFromSeed updates all the documents in seed, and crawls all the new
+// documents referred in the seed.
+func CrawlFromSeed(ctx context.Context, seed CrawlSeed, crawlers []Crawler,
+	conv Converter, indx IndexFunc,	seen map[string]struct{}) {
+
+	// stack tracks the documents directly referred in other documents.
+	stack := make(CrawlSeed, 0)
+
 	// Exploit seed to update bulk of corpus.
 	logger.Printf("updating %d documents from seed\n", len(seed))
-	doCrawl(&seed)
-	// Traverse any new links added while updating corpus.
+	// each unique document in seed will be crawled once.
+	doCrawl(ctx, &seed, crawlers, conv, indx, seen, &stack)
+
+	// Traverse any new documents added while updating corpus.
 	logger.Printf("crawling %d new documents found in the seed\n", len(stack))
-	doCrawl(&stack)
-
-	ch := make(chan CrawledDocument, 1<<10)
-	wg := sync.WaitGroup{}
-
-	wg.Add(1)
-	go func() {
-		defer wg.Done()
-		for cdoc := range ch {
-			if _, ok := seen[cdoc.ID()]; ok {
-				continue
-			}
-			match := findMatch(cdoc.GetDocument())
-			if match == nil {
-				logIfErr(fmt.Errorf(
-					"%v could not match any crawler", cdoc))
-				continue
-			}
-			addBranches(cdoc, match)
-		}
-	}()
-
-	// Exploration through APIs.
-	errs := CRunner(ctx, ch, crawlers)
-	if errs != nil {
-		for _, err := range errs {
-			logIfErr(err)
-		}
-	}
-	close(ch)
-	logger.Println("Processing the new documents from the crawlers' exploration.")
-	wg.Wait()
-	// Handle deps of newly discovered documents.
-	logger.Printf("crawling the %d new documents from the crawlers' exploration.",
-		len(stack))
-	doCrawl(&stack)
+	// While crawling each document in stack, the documents directly referred in the document
+	// will be added into stack.
+	// After this statement is done, stack will become empty.
+	doCrawl(ctx, &stack, crawlers, conv, indx, seen, &stack)
 }
 
-// CRunner is a blocking function and only returns once all of the
+// CrawlGithubRunner is a blocking function and only returns once all of the
 // crawlers are finished with execution.
 //
 // This function uses the output channel to forward kustomization documents
@@ -188,14 +167,14 @@ func CrawlFromSeed(ctx context.Context, seed CrawlSeed,
 // index of the crawler that emitted the error. Although the errors themselves
 // can be nil, the array will always be exactly the size of the crawlers array.
 //
-// CRunner takes in a seed, which represents the documents stored in an
+// CrawlGithubRunner takes in a seed, which represents the documents stored in an
 // index somewhere. The document data is not required to be populated. If there
 // are many documents, this is preferable. The order of iteration over the seed
-// is not guaranteed, but the CRunner does guarantee that every element
+// is not guaranteed, but the CrawlGithub does guarantee that every element
 // from the seed will be processed before any other documents from the
 // crawlers.
-func CRunner(ctx context.Context,
-	output chan<- CrawledDocument, crawlers []Crawler) []error {
+func CrawlGithubRunner(ctx context.Context, output chan<- CrawledDocument,
+	crawlers []Crawler) []error {
 
 	errs := make([]error, len(crawlers))
 	wg := sync.WaitGroup{}
@@ -236,3 +215,45 @@ func CRunner(ctx context.Context,
 	wg.Wait()
 	return errs
 }
+
+// CrawlGithub crawls all the kustomization files on Github.
+func CrawlGithub(ctx context.Context, crawlers []Crawler, conv Converter,
+	indx IndexFunc,	seen map[string]struct{}) {
+	// stack tracks the documents directly referred in other documents.
+	stack := make(CrawlSeed, 0)
+
+	// ch is channel where all the crawlers sends the crawled documents to.
+	ch := make(chan CrawledDocument, 1<<10)
+
+	wg := sync.WaitGroup{}
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+		for cdoc := range ch {
+			if _, ok := seen[cdoc.ID()]; ok {
+				continue
+			}
+			match := findMatch(cdoc.GetDocument(), crawlers)
+			if match == nil {
+				logIfErr(fmt.Errorf(
+					"%v could not match any crawler", cdoc))
+				continue
+			}
+			addBranches(cdoc, match, indx, seen, &stack)
+		}
+	}()
+
+	if errs := CrawlGithubRunner(ctx, ch, crawlers); errs != nil {
+		for _, err := range errs {
+			logIfErr(err)
+		}
+	}
+	close(ch)
+	logger.Println("Processing the documents found from crawling github")
+	wg.Wait()
+	// Handle deps of newly discovered documents.
+	logger.Printf("crawling the %d new documents referred by other documents",
+		len(stack))
+	doCrawl(ctx, &stack, crawlers, conv, indx, seen, &stack)
+}

api/internal/crawl/crawler/crawler_test.go

@@ -38,12 +38,13 @@ func (c testCrawler) FetchDocument(_ context.Context, d *doc.Document) error {
 		return nil
 	}
 	for _, suffix := range konfig.RecognizedKustomizationFileNames() {
-		fmt.Println(d.ID(), "/", suffix)
-		i, ok := c.lukp[d.ID()+"/"+suffix]
+		savedFilePath := d.FilePath
+		d.FilePath += "/" + suffix
+		i, ok := c.lukp[d.ID()]
 		if !ok {
+			d.FilePath = savedFilePath
 			continue
 		}
-		d.FilePath += "/" + suffix
 		d.DocumentData = c.docs[i].DocumentData
 		return nil
 	}
@@ -106,8 +107,8 @@ func (s sortableDocs) Len() int {
 	return len(s)
 }
 
-func TestCrawlerRunner(t *testing.T) {
-	fmt.Println("testing CRunner")
+func TestCrawlGithubRunner(t *testing.T) {
+	fmt.Println("testing CrawlGithubRunner")
 	tests := []struct {
 		tc   []Crawler
 		errs []error
@@ -178,7 +179,7 @@ func TestCrawlerRunner(t *testing.T) {
 			defer close(output)
 			defer wg.Done()
 
-			errs := CRunner(context.Background(),
+			errs := CrawlGithubRunner(context.Background(),
 				output, test.tc)
 
 			// Check that errors are returned as they should be.
@@ -302,29 +303,6 @@ resources:
 					RepositoryURL: kustomizeRepo,
 					FilePath:      "examples/seedcrawl2/job.yaml",
 				}},
-				// Visited from the crawler runner.
-				{Document: doc.Document{
-					RepositoryURL: kustomizeRepo,
-					FilePath:      "examples/other/base/kustomization.yaml",
-					DocumentData: `
-resources:
-- ../app
-`,
-				}},
-				// Visited from the crawler runner.
-				{Document: doc.Document{
-					RepositoryURL: kustomizeRepo,
-					FilePath:      "examples/other/app/kustomization.yaml",
-					DocumentData: `
-resources:
-- resource.yaml
-`,
-				}},
-				// Visited from crawling runner imported as resource.
-				{Document: doc.Document{
-					RepositoryURL: kustomizeRepo,
-					FilePath:      "examples/other/app/resource.yaml",
-				}},
 			},
 		},
 	}
@@ -342,6 +320,7 @@ resources:
 				visited[d.ID()]++
 				return nil
 			},
+			make(map[string]struct{}),
 		)
 		if lv, lc := len(visited), len(tc.corpus); lv != lc {
 			t.Errorf("error: %d of %d documents visited.", lv, lc)