r/w map locks; concurrent safety

6 files changed, 67 insertions, 16 deletions

diff --git a/crane.go b/crane.go
index 32e9a5f..bd5bb8a 100644
--- a/crane.go
+++ b/crane.go
@@ -17,6 +17,7 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+	"sync"
 
 	"golang.org/x/net/publicsuffix"
 )
@@ -64,12 +65,13 @@ type Paper struct {
 }
 
 type Papers struct {
+	sync.RWMutex
 	List map[string]map[string]*Paper
 	Path string
 }
 
 type Resp struct {
-	Papers           map[string]map[string]*Paper
+	Papers           Papers
 	Status           string
 	LastPaperDL      string
 	LastUsedCategory string
@@ -121,6 +123,7 @@ func getPaperFileNameFromResp(resp *http.Response) string {
 func (papers *Papers) getUniqueName(category string, name string) string {
 	newName := name
 	ext := 2
+	papers.RLock()
 	for {
 		key := filepath.Join(category, newName+".pdf")
 		if _, exists := papers.List[category][key]; exists != true {
@@ -130,6 +133,7 @@ func (papers *Papers) getUniqueName(category string, name string) string {
 			ext++
 		}
 	}
+	papers.RUnlock()
 	return newName
 }
 
@@ -142,6 +146,9 @@ func (papers *Papers) findPapersWalk(path string, info os.FileInfo,
 		return nil
 	}
 
+	papers.Lock()
+	defer papers.Unlock()
+
 	// derive category name (e.g. Mathematics) from directory name; used as key
 	var category string
 	if i, _ := os.Stat(path); i.IsDir() {
@@ -246,10 +253,12 @@ func (papers *Papers) NewPaperFromDOI(doi []byte, category string) (*Paper,
 	// if not matching, check if DOIs match (genuine duplicate)
 	if name != uniqueName {
 		key := filepath.Join(category, name+".pdf")
+		papers.RLock()
 		if meta.DOI == papers.List[category][key].Meta.DOI {
 			return nil, fmt.Errorf("paper %q with DOI %q already downloaded",
 				name, string(doi))
 		}
+		papers.RUnlock()
 	}
 
 	paper.PaperName = uniqueName
@@ -276,8 +285,11 @@ func (papers *Papers) NewPaperFromDOI(doi []byte, category string) (*Paper,
 		return nil, err
 	}
 	paper.Meta = *meta
+
+	papers.Lock()
 	papers.List[category][filepath.Join(category,
 		paper.PaperName+".pdf")] = &paper
+	papers.Unlock()
 	return &paper, nil
 }
 
@@ -315,8 +327,10 @@ func (papers *Papers) NewPaperFromDirectLink(resp *http.Response, meta *Meta,
 	if err := renameFile(tmpPDF.Name(), paper.PaperPath); err != nil {
 		return nil, err
 	}
+	papers.Lock()
 	papers.List[category][filepath.Join(category,
 		paper.PaperName+".pdf")] = &paper
+	papers.Unlock()
 	return &paper, nil
 }
 
@@ -325,6 +339,7 @@ func (papers *Papers) NewPaperFromDirectLink(resp *http.Response, meta *Meta,
 func (papers *Papers) DeletePaper(paper string) error {
 	// check if the category in which the paper is said to belong
 	// exists
+	papers.RLock()
 	category := filepath.Dir(paper)
 	if _, exists := papers.List[category]; exists != true {
 		return fmt.Errorf("category %q does not exist\n",
@@ -336,9 +351,11 @@ func (papers *Papers) DeletePaper(paper string) error {
 		return fmt.Errorf("paper %q does not exist in category %q\n", paper,
 			category)
 	}
+	papers.RUnlock()
 
 	// paper and category exists and the paper belongs to the provided
 	// category; remove it and its XML metadata
+	papers.Lock()
 	if err := os.Remove(papers.List[category][paper].PaperPath); err != nil {
 		return err
 	}
@@ -353,31 +370,40 @@ func (papers *Papers) DeletePaper(paper string) error {
 		}
 	}
 	delete(papers.List[category], paper)
+	papers.Unlock()
 	return nil
 }
 
 // DeleteCategory deletes a category and its contents from the filesystem and
 // the papers.List set
 func (papers *Papers) DeleteCategory(category string) error {
+	papers.RLock()
 	if _, exists := papers.List[category]; exists != true {
 		return fmt.Errorf("category %q does not exist in the set\n", category)
 	}
+	papers.RUnlock()
+
+	papers.Lock()
 	if err := os.RemoveAll(filepath.Join(papers.Path, category)); err != nil {
 		return err
 	}
+
 	// remove subcategories (nested directories) which exist under the primary
 	for key, _ := range papers.List {
 		if strings.HasPrefix(key, category+"/") {
 			delete(papers.List, key)
 		}
 	}
+
 	delete(papers.List, category)
+	papers.Unlock()
 	return nil
 }
 
 // MovePaper moves a paper to the destination category on the filesystem and
 // the papers.List set
 func (papers *Papers) MovePaper(paper string, category string) error {
+	papers.RLock()
 	prevCategory := filepath.Dir(paper)
 	if _, exists := papers.List[prevCategory]; exists != true {
 		return fmt.Errorf("category %q does not exist\n", prevCategory)
@@ -393,6 +419,9 @@ func (papers *Papers) MovePaper(paper string, category string) error {
 		return fmt.Errorf("paper %q exists in destination category %q\n",
 			paper, category)
 	}
+	papers.RUnlock()
+
+	papers.Lock()
 	paperDest := filepath.Join(filepath.Join(papers.Path, category),
 		papers.List[prevCategory][paper].PaperName+".pdf")
 	if err := os.Rename(papers.List[prevCategory][paper].PaperPath, paperDest);
@@ -422,12 +451,15 @@ func (papers *Papers) MovePaper(paper string, category string) error {
 		}
 	}
 	delete(papers.List[prevCategory], paper)
+
+	papers.Unlock()
 	return nil
 }
 
 // RenameCategory renames a category on the filesystem and the paper.List set
 func (papers *Papers) RenameCategory(oldCategory string,
 	newCategory string) error {
+	papers.RLock()
 	if _, exists := papers.List[oldCategory]; exists != true {
 		return fmt.Errorf("category %q does not exist in the set\n", oldCategory)
 	}
@@ -438,6 +470,9 @@ func (papers *Papers) RenameCategory(oldCategory string,
 		filepath.Join(papers.Path, newCategory)); err != nil {
 		return err
 	}
+	papers.RUnlock()
+
+	papers.Lock()
 	papers.List[newCategory] = make(map[string]*Paper)
 	for k, v := range papers.List[oldCategory] {
 		pPaperPath := filepath.Join(papers.Path, filepath.Join(newCategory,
@@ -453,6 +488,8 @@ func (papers *Papers) RenameCategory(oldCategory string,
 		}
 	}
 	delete(papers.List, oldCategory)
+
+	papers.Unlock()
 	return nil
 }
 
diff --git a/http.go b/http.go
index fcfd38f..ad42c2b 100644
--- a/http.go
+++ b/http.go
@@ -20,9 +20,12 @@ func (papers *Papers) IndexHandler(w http.ResponseWriter, r *http.Request) {
 		filepath.Join(templateDir, "index.html"),
 		filepath.Join(templateDir, "list.html"),
 	)
+	papers.RLock()
 	res := Resp{
-		Papers: papers.List,
+		Papers: *papers,
 	}
+	papers.RUnlock()
+
 	t.Execute(w, &res)
 }
 
@@ -33,9 +36,12 @@ func (papers *Papers) AdminHandler(w http.ResponseWriter, r *http.Request) {
 		filepath.Join(templateDir, "layout.html"),
 		filepath.Join(templateDir, "list.html"),
 	)
+	papers.RLock()
 	res := Resp{
-		Papers: papers.List,
+		Papers: *papers,
 	}
+	papers.RUnlock()
+
 	if user != "" && pass != "" {
 		username, password, ok := r.BasicAuth()
 		if ok && user == username && pass == password {
@@ -58,9 +64,12 @@ func (papers *Papers) EditHandler(w http.ResponseWriter, r *http.Request) {
 		filepath.Join(templateDir, "layout.html"),
 		filepath.Join(templateDir, "list.html"),
 	)
+	papers.RLock()
 	res := Resp{
-		Papers: papers.List,
+		Papers: *papers,
 	}
+	papers.RUnlock()
+
 	if user != "" && pass != "" {
 		username, password, ok := r.BasicAuth()
 		if !ok || user != username || pass != password {
@@ -152,7 +161,8 @@ func (papers *Papers) AddHandler(w http.ResponseWriter, r *http.Request) {
 	// sanitize input; we use the category to build the path used to save
 	// papers
 	nc = strings.Trim(strings.Replace(nc, "..", "", -1), "/.")
-	res := Resp{Papers: papers.List}
+
+	res := Resp{}
 
 	// paper download, both required fields populated
 	if len(strings.TrimSpace(p)) > 0 && len(strings.TrimSpace(c)) > 0 {
@@ -194,6 +204,10 @@ func (papers *Papers) AddHandler(w http.ResponseWriter, r *http.Request) {
 			res.Status = fmt.Sprintf("category %q added successfully", nc)
 		}
 	}
+	papers.RLock()
+	res.Papers = *papers
+	papers.RUnlock()
+
 	t.Execute(w, &res)
 }
 
diff --git a/templates/admin-edit.html b/templates/admin-edit.html
index 57a9aaa..7b30294 100644
--- a/templates/admin-edit.html
+++ b/templates/admin-edit.html
@@ -3,13 +3,13 @@
 <p>{{ .Status }}</p>
 <table id='header'>
   <tr>
-  {{ $categoryCount := len .Papers }}
+  {{ $categoryCount := len .Papers.List }}
   {{ if gt $categoryCount 0 }}
     <td class='inpt'>
       <form method='post' action='/admin/edit/'>
         <input type="text" id="rename-category" name="rename-to" placeholder="Mathematics">
         <select class="sel" name="rename-category" id="category">
-        {{ range $category, $papers := .Papers }}
+        {{ range $category, $papers := .Papers.List }}
         <option value="{{ $category }}">{{ $category }}</option>
         {{ end }}
         </select>
@@ -20,7 +20,7 @@
   </tr>
 </table>
 <div class="cat">
-  <span>{{ range $category, $paper := .Papers }}[<a href="#{{ $category }}">{{ $category }}</a>] {{ end }}</span>
+  <span>{{ range $category, $paper := .Papers.List }}[<a href="#{{ $category }}">{{ $category }}</a>] {{ end }}</span>
 </div>
 <table class='tabs'>
   <tr>
@@ -36,7 +36,7 @@
       <option value="delete">Delete</option>
     </optgroup>
     <optgroup label="Move To">
-      {{ range $category, $papers := .Papers }}
+      {{ range $category, $papers := .Papers.List }}
       <option value="move-{{ $category }}">{{ $category }}</option>
       {{ end }}
     </optgroup>
@@ -44,7 +44,7 @@
   <input class="btn" type="submit" value="Save" />
   </div>
 <div class='papers nowrap list'>
-{{ range $category, $papers := .Papers }}
+{{ range $category, $papers := .Papers.List }}
   {{ $paperCount := len $papers }}
   <div class="papersection">
   <input type="checkbox" id="{{ $category }}" name="category" value="{{ $category }}">
diff --git a/templates/admin.html b/templates/admin.html
index 22b0e0a..05cf04f 100644
--- a/templates/admin.html
+++ b/templates/admin.html
@@ -14,7 +14,7 @@
     </form>
 		</td>
 	</tr>
-  {{ $categoryCount := len .Papers }}
+  {{ $categoryCount := len .Papers.List }}
   {{ if gt $categoryCount 0 }}
 	<tr>
     <td class='inpt'>
@@ -25,7 +25,7 @@
           {{ if $lastUsedCategory }}
           <option value="{{ .LastUsedCategory }}">{{ $lastUsedCategory }}</option>
           {{ end }}
-          {{ range $category, $papers := .Papers }}
+          {{ range $category, $papers := .Papers.List }}
           {{ if ne $category $lastUsedCategory }}
           <option value="{{ $category }}">{{ $category }}</option>
           {{ end }}
@@ -39,7 +39,7 @@
 </table>
 {{ if gt $categoryCount 0 }}
 <div class="cat">
-  <span>{{ range $category, $paper := .Papers }}[<a href="#{{ $category }}">{{ $category }}</a>] {{ end }}</span>
+  <span>{{ range $category, $paper := .Papers.List }}[<a href="#{{ $category }}">{{ $category }}</a>] {{ end }}</span>
 </div>
 <table class='tabs'>
   <tr>
diff --git a/templates/index.html b/templates/index.html
index 30023cd..6397671 100644
--- a/templates/index.html
+++ b/templates/index.html
@@ -2,10 +2,10 @@
 {{ define "content" }}
 <table id='header'>
 </table>
-{{ $categoryCount := len .Papers }}
+{{ $categoryCount := len .Papers.List }}
 {{ if gt $categoryCount 0 }}
 <div class="cat">
-  <span>{{ range $category, $paper := .Papers }}[<a href="#{{ $category }}">{{ $category }}</a>] {{ end }}</span>
+  <span>{{ range $category, $paper := .Papers.List }}[<a href="#{{ $category }}">{{ $category }}</a>] {{ end }}</span>
 </div>
 <table class='tabs'>
   <td><a class='active' href='/admin/'>Manage</a></td>
diff --git a/templates/list.html b/templates/list.html
index 9e139b9..a08efd6 100644
--- a/templates/list.html
+++ b/templates/list.html
@@ -1,6 +1,6 @@
 {{ define "list" }}
 <div class='papers nowrap list'>
-{{ range $category, $papers := .Papers }}
+{{ range $category, $papers := .Papers.List }}
   {{ $paperCount := len $papers }}
   {{ if ge $paperCount 1 }}
   <div class="papersection">