func handleSearch()

in bigtable/search/search.go [191:277]
73 lines of code
15 McCabe index (conditional complexity)

func handleSearch(w http.ResponseWriter, r *http.Request, table *bigtable.Table) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	query := r.FormValue("q")
	// Split the query into words.
	words := tokenize(query)
	if len(words) == 0 {
		http.Error(w, "Empty query.", http.StatusBadRequest)
		return
	}

	// readRows reads from many rows concurrently.
	readRows := func(rows []string) ([]bigtable.Row, error) {
		results := make([]bigtable.Row, len(rows))
		errors := make([]error, len(rows))
		var wg sync.WaitGroup
		for i, row := range rows {
			wg.Add(1)
			go func(i int, row string) {
				defer wg.Done()
				results[i], errors[i] = table.ReadRow(ctx, row, bigtable.RowFilter(bigtable.LatestNFilter(1)))
			}(i, row)
		}
		wg.Wait()
		for _, err := range errors {
			if err != nil {
				return nil, err
			}
		}
		return results, nil
	}

	// For each query word, get the list of documents containing it.
	results, err := readRows(words)
	if err != nil {
		http.Error(w, "Error reading index: "+err.Error(), http.StatusInternalServerError)
		return
	}

	// Count how many of the query words each result contained.
	hits := make(map[string]int)
	for _, r := range results {
		for _, r := range r[indexColumnFamily] {
			hits[r.Column]++
		}
	}

	// Build a slice of all the documents that matched every query word.
	var matches []string
	for doc, count := range hits {
		if count == len(words) {
			matches = append(matches, doc[len(indexColumnFamily+":"):])
		}
	}

	// Fetch the content of those documents from the Bigtable.
	content, err := readRows(matches)
	if err != nil {
		http.Error(w, "Error reading results: "+err.Error(), http.StatusInternalServerError)
		return
	}

	type result struct{ Title, Snippet string }
	data := struct {
		Query   string
		Results []result
	}{query, nil}

	// Output links and snippets.
	for i, doc := range matches {
		var text string
		c := content[i][contentColumnFamily]
		if len(c) > 0 {
			text = string(c[0].Value)
		}
		if len(text) > 100 {
			text = text[:100] + "..."
		}
		data.Results = append(data.Results, result{doc, text})
	}
	var buf bytes.Buffer
	if err := searchTemplate.ExecuteTemplate(&buf, "", data); err != nil {
		http.Error(w, "Error executing HTML template: "+err.Error(), http.StatusInternalServerError)
		return
	}
	io.Copy(w, &buf)
}