WebDAV: try to preserve the lock fs as much as possible

dataprovider/cacheduser.go

@@ -0,0 +1,142 @@
+package dataprovider
+
+import (
+	"sync"
+	"time"
+
+	"golang.org/x/net/webdav"
+
+	"github.com/drakkan/sftpgo/utils"
+)
+
+var (
+	webDAVUsersCache *usersCache
+)
+
+func init() {
+	webDAVUsersCache = &usersCache{
+		users: map[string]CachedUser{},
+	}
+}
+
+// InitializeWebDAVUserCache initializes the cache for webdav users
+func InitializeWebDAVUserCache(maxSize int) {
+	webDAVUsersCache = &usersCache{
+		users:   map[string]CachedUser{},
+		maxSize: maxSize,
+	}
+}
+
+// CachedUser adds fields useful for caching to a SFTPGo user
+type CachedUser struct {
+	User       User
+	Expiration time.Time
+	Password   string
+	LockSystem webdav.LockSystem
+}
+
+// IsExpired returns true if the cached user is expired
+func (c *CachedUser) IsExpired() bool {
+	if c.Expiration.IsZero() {
+		return false
+	}
+	return c.Expiration.Before(time.Now())
+}
+
+type usersCache struct {
+	sync.RWMutex
+	users   map[string]CachedUser
+	maxSize int
+}
+
+func (cache *usersCache) updateLastLogin(username string) {
+	cache.Lock()
+	defer cache.Unlock()
+
+	if cachedUser, ok := cache.users[username]; ok {
+		cachedUser.User.LastLogin = utils.GetTimeAsMsSinceEpoch(time.Now())
+		cache.users[username] = cachedUser
+	}
+}
+
+// swapWebDAVUser updates an existing cached user with the specified one
+// preserving the lock fs if possible
+func (cache *usersCache) swap(user *User) {
+	cache.Lock()
+	defer cache.Unlock()
+
+	if cachedUser, ok := cache.users[user.Username]; ok {
+		if cachedUser.User.Password != user.Password {
+			// the password changed, the cached user is no longer valid
+			delete(cache.users, user.Username)
+			return
+		}
+		if cachedUser.User.isFsEqual(user) {
+			// the updated user has the same fs as the cached one, we can preserve the lock filesystem
+			cachedUser.User = *user
+			cache.users[user.Username] = cachedUser
+		} else {
+			// filesystem changed, the cached user is no longer valid
+			delete(cache.users, user.Username)
+		}
+	}
+}
+
+func (cache *usersCache) add(cachedUser *CachedUser) {
+	cache.Lock()
+	defer cache.Unlock()
+
+	if cache.maxSize > 0 && len(cache.users) >= cache.maxSize {
+		var userToRemove string
+		var expirationTime time.Time
+
+		for k, v := range cache.users {
+			if userToRemove == "" {
+				userToRemove = k
+				expirationTime = v.Expiration
+				continue
+			}
+			expireTime := v.Expiration
+			if !expireTime.IsZero() && expireTime.Before(expirationTime) {
+				userToRemove = k
+				expirationTime = expireTime
+			}
+		}
+
+		delete(cache.users, userToRemove)
+	}
+
+	if cachedUser.User.Username != "" {
+		cache.users[cachedUser.User.Username] = *cachedUser
+	}
+}
+
+func (cache *usersCache) remove(username string) {
+	cache.Lock()
+	defer cache.Unlock()
+
+	delete(cache.users, username)
+}
+
+func (cache *usersCache) get(username string) (*CachedUser, bool) {
+	cache.RLock()
+	defer cache.RUnlock()
+
+	cachedUser, ok := cache.users[username]
+	return &cachedUser, ok
+}
+
+// CacheWebDAVUser add a user to the WebDAV cache
+func CacheWebDAVUser(cachedUser *CachedUser) {
+	webDAVUsersCache.add(cachedUser)
+}
+
+// GetCachedWebDAVUser returns a previously cached WebDAV user
+func GetCachedWebDAVUser(username string) (*CachedUser, bool) {
+	return webDAVUsersCache.get(username)
+}
+
+// RemoveCachedWebDAVUser removes a cached WebDAV user
+func RemoveCachedWebDAVUser(username string) {
+	webDAVUsersCache.remove(username)
+}