guard gitlab cache Map with RWMutex to prevent concurrent read/write

fixes #11

fstree/group.go

@@ -18,7 +18,7 @@ type groupNode struct {
 
 type GroupSource interface {
 	GetGroupID() uint64
-	InvalidateCache()
+	InvalidateContentCache()
 }
 
 // Ensure we are implementing the NodeReaddirer interface

fstree/refresh.go

@@ -41,6 +41,6 @@ func (n *refreshNode) Setattr(ctx context.Context, fh fs.FileHandle, in *fuse.Se
 }
 
 func (n *refreshNode) Open(ctx context.Context, flags uint32) (fh fs.FileHandle, fuseFlags uint32, errno syscall.Errno) {
-	n.source.InvalidateCache()
+	n.source.InvalidateContentCache()
 	return nil, 0, 0
 }

platforms/gitlab/client.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"log/slog"
 	"slices"
+	"sync"
 
 	"github.com/badjware/gitlabfs/fstree"
 	"github.com/xanzy/go-gitlab"
@@ -34,8 +35,10 @@ type gitlabClient struct {
 	currentUserCache *User
 
 	// API response cache
-	groupCache map[int]*Group
+	groupCacheMux sync.RWMutex
-	userCache  map[int]*User
+	groupCache    map[int]*Group
+	userCacheMux  sync.RWMutex
+	userCache     map[int]*User
 }
 
 func NewClient(logger *slog.Logger, gitlabUrl string, gitlabToken string, p GitlabClientConfig) (*gitlabClient, error) {

platforms/gitlab/group.go

@@ -16,7 +16,7 @@ type Group struct {
 
 	mux sync.Mutex
 
-	// group content
+	// hold group content
 	childGroups   map[string]fstree.GroupSource
 	childProjects map[string]fstree.RepositorySource
 }
@@ -25,15 +25,17 @@ func (g *Group) GetGroupID() uint64 {
 	return uint64(g.ID)
 }
 
-func (g *Group) InvalidateCache() {
+func (g *Group) InvalidateContentCache() {
 	g.mux.Lock()
 	defer g.mux.Unlock()
 
 	// clear child group from cache
+	g.gitlabClient.groupCacheMux.Lock()
 	for _, childGroup := range g.childGroups {
 		gid := int(childGroup.GetGroupID())
 		delete(g.gitlabClient.groupCache, gid)
 	}
+	g.gitlabClient.groupCacheMux.Unlock()
 	g.childGroups = nil
 
 	// clear child repositories from cache
@@ -43,7 +45,9 @@ func (g *Group) InvalidateCache() {
 func (c *gitlabClient) fetchGroup(gid int) (*Group, error) {
 	// start by searching the cache
 	// TODO: cache invalidation?
+	c.groupCacheMux.RLock()
 	group, found := c.groupCache[gid]
+	c.groupCacheMux.RUnlock()
 	if found {
 		c.logger.Debug("Group cache hit", "gid", gid)
 		return group, nil
@@ -68,7 +72,9 @@ func (c *gitlabClient) fetchGroup(gid int) (*Group, error) {
 	}
 
 	// save in cache
+	c.groupCacheMux.Lock()
 	c.groupCache[gid] = &newGroup
+	c.groupCacheMux.Unlock()
 
 	return &newGroup, nil
 }
@@ -77,15 +83,18 @@ func (c *gitlabClient) newGroupFromGitlabGroup(gitlabGroup *gitlab.Group) (*Grou
 	gid := gitlabGroup.ID
 
 	// start by searching the cache
+	c.groupCacheMux.RLock()
 	group, found := c.groupCache[gid]
+	c.groupCacheMux.RUnlock()
 	if found {
+		// if found in cache, return the cached reference
 		c.logger.Debug("Group cache hit", "gid", gid)
 		return group, nil
 	} else {
 		c.logger.Debug("Group cache miss; registering group", "gid", gid)
 	}
 
-	// if not in cache, convert and save to cache now
+	// if not found in cache, convert and save to cache now
 	newGroup := Group{
 		ID:   gitlabGroup.ID,
 		Name: gitlabGroup.Path,
@@ -97,12 +106,17 @@ func (c *gitlabClient) newGroupFromGitlabGroup(gitlabGroup *gitlab.Group) (*Grou
 	}
 
 	// save in cache
+	c.groupCacheMux.Lock()
 	c.groupCache[gid] = &newGroup
+	c.groupCacheMux.Unlock()
 
 	return &newGroup, nil
 }
 
 func (c *gitlabClient) fetchGroupContent(group *Group) (map[string]fstree.GroupSource, map[string]fstree.RepositorySource, error) {
+	// Only a single routine can fetch the group content at the time.
+	// We lock for the whole duration of the function to avoid fetching the same data from the API
+	// multiple times if concurrent calls where to occur.
 	group.mux.Lock()
 	defer group.mux.Unlock()
 

platforms/gitlab/user.go

@@ -14,7 +14,7 @@ type User struct {
 
 	mux sync.Mutex
 
-	// user content
+	// hold user content
 	childProjects map[string]fstree.RepositorySource
 }
 
@@ -22,7 +22,7 @@ func (u *User) GetGroupID() uint64 {
 	return uint64(u.ID)
 }
 
-func (u *User) InvalidateCache() {
+func (u *User) InvalidateContentCache() {
 	u.mux.Lock()
 	defer u.mux.Unlock()
 
@@ -33,15 +33,18 @@ func (u *User) InvalidateCache() {
 func (c *gitlabClient) fetchUser(uid int) (*User, error) {
 	// start by searching the cache
 	// TODO: cache invalidation?
+	c.userCacheMux.RLock()
 	user, found := c.userCache[uid]
+	c.userCacheMux.RUnlock()
 	if found {
+		// if found in cache, return the cached reference
 		c.logger.Debug("User cache hit", "uid", uid)
 		return user, nil
 	} else {
 		c.logger.Debug("User cache miss", "uid", uid)
 	}
 
-	// If not in cache, fetch group infos from API
+	// If not found in cache, fetch group infos from API
 	gitlabUser, _, err := c.client.Users.GetUser(uid)
 	if err != nil {
 		return nil, fmt.Errorf("failed to fetch user with id %v: %v", uid, err)
@@ -55,6 +58,7 @@ func (c *gitlabClient) fetchUser(uid int) (*User, error) {
 
 	// save in cache
 	c.userCache[uid] = &newUser
+	c.userCacheMux.Unlock()
 
 	return &newUser, nil
 }
@@ -77,6 +81,9 @@ func (c *gitlabClient) fetchCurrentUser() (*User, error) {
 }
 
 func (c *gitlabClient) fetchUserContent(user *User) (map[string]fstree.GroupSource, map[string]fstree.RepositorySource, error) {
+	// Only a single routine can fetch the user content at the time.
+	// We lock for the whole duration of the function to avoid fetching the same data from the API
+	// multiple times if concurrent calls where to occur.
 	user.mux.Lock()
 	defer user.mux.Unlock()