"errors"
"net/http"
"sync"
- "sync/atomic"
"time"
"git.arvados.org/arvados.git/sdk/go/arvados"
metrics cacheMetrics
sessions *lru.TwoQueueCache
setupOnce sync.Once
+ mtx sync.Mutex
chPruneSessions chan struct{}
}
}
type cachedSession struct {
+ cache *cache
expire time.Time
- fs atomic.Value
client *arvados.Client
arvadosclient *arvadosclient.ArvadosClient
keepclient *keepclient.KeepClient
- user atomic.Value
+
+ // mtx is RLocked while session is not safe to evict from cache
+ mtx sync.RWMutex
+ // refresh is locked while reading or writing the following fields
+ refresh sync.Mutex
+ fs arvados.CustomFileSystem
+ user arvados.User
+ userLoaded bool
+ // inuse is RLocked while session is in use by a caller
+ inuse sync.RWMutex
+}
+
+func (sess *cachedSession) Release() {
+ sess.inuse.RUnlock()
+ sess.mtx.RUnlock()
+ select {
+ case sess.cache.chPruneSessions <- struct{}{}:
+ default:
+ }
}
func (c *cache) setup() {
"select": []string{"portable_data_hash"},
}
-// ResetSession unloads any potentially stale state. Should be called
-// after write operations, so subsequent reads don't return stale
-// data.
-func (c *cache) ResetSession(token string) {
- c.setupOnce.Do(c.setup)
- c.sessions.Remove(token)
-}
-
-// Get a long-lived CustomFileSystem suitable for doing a read operation
-// with the given token.
-func (c *cache) GetSession(token string) (arvados.CustomFileSystem, *cachedSession, *arvados.User, error) {
+func (c *cache) checkout(token string) (*cachedSession, error) {
c.setupOnce.Do(c.setup)
- now := time.Now()
+ c.mtx.Lock()
+ defer c.mtx.Unlock()
ent, _ := c.sessions.Get(token)
sess, _ := ent.(*cachedSession)
- expired := false
if sess == nil {
- c.metrics.sessionMisses.Inc()
- sess = &cachedSession{
- expire: now.Add(c.cluster.Collections.WebDAVCache.TTL.Duration()),
- }
- var err error
- sess.client, err = arvados.NewClientFromConfig(c.cluster)
+ client, err := arvados.NewClientFromConfig(c.cluster)
if err != nil {
- return nil, nil, nil, err
+ return nil, err
}
- sess.client.AuthToken = token
- sess.client.Timeout = time.Minute
+ client.AuthToken = token
+ client.Timeout = time.Minute
// A non-empty origin header tells controller to
// prioritize our traffic as interactive, which is
// true most of the time.
origin := c.cluster.Services.WebDAVDownload.ExternalURL
- sess.client.SendHeader = http.Header{"Origin": {origin.Scheme + "://" + origin.Host}}
- sess.arvadosclient, err = arvadosclient.New(sess.client)
+ client.SendHeader = http.Header{"Origin": {origin.Scheme + "://" + origin.Host}}
+ arvadosclient, err := arvadosclient.New(client)
if err != nil {
- return nil, nil, nil, err
+ return nil, err
+ }
+ sess = &cachedSession{
+ cache: c,
+ client: client,
+ arvadosclient: arvadosclient,
+ keepclient: keepclient.New(arvadosclient),
}
- sess.keepclient = keepclient.New(sess.arvadosclient)
c.sessions.Add(token, sess)
- } else if sess.expire.Before(now) {
- c.metrics.sessionMisses.Inc()
- expired = true
- } else {
- c.metrics.sessionHits.Inc()
- }
- select {
- case c.chPruneSessions <- struct{}{}:
- default:
}
+ sess.mtx.RLock()
+ return sess, nil
+}
- fs, _ := sess.fs.Load().(arvados.CustomFileSystem)
- if fs == nil || expired {
- fs = sess.client.SiteFileSystem(sess.keepclient)
- fs.ForwardSlashNameSubstitution(c.cluster.Collections.ForwardSlashNameSubstitution)
- sess.fs.Store(fs)
+// Get a long-lived CustomFileSystem suitable for doing a read or
+// write operation with the given token.
+//
+// If the returned error is nil, the caller must call Release() on the
+// returned session when finished using it.
+func (c *cache) GetSession(token string) (arvados.CustomFileSystem, *cachedSession, *arvados.User, error) {
+ sess, err := c.checkout(token)
+ if err != nil {
+ return nil, nil, nil, err
}
+ sess.refresh.Lock()
+ defer sess.refresh.Unlock()
+ now := time.Now()
+ refresh := sess.expire.Before(now)
+ if sess.fs == nil || !sess.userLoaded || refresh {
+ // Wait for all active users to finish (otherwise they
+ // might make changes to an old fs after we start
+ // using the new fs).
+ sess.inuse.Lock()
+ if !sess.userLoaded || refresh {
+ err := sess.client.RequestAndDecode(&sess.user, "GET", "/arvados/v1/users/current", nil, nil)
+ if he := errorWithHTTPStatus(nil); errors.As(err, &he) && he.HTTPStatus() == http.StatusForbidden {
+ // token is OK, but "get user id" api is out
+ // of scope -- use existing/expired info if
+ // any, or leave empty for unknown user
+ } else if err != nil {
+ sess.inuse.Unlock()
+ sess.mtx.RUnlock()
+ return nil, nil, nil, err
+ }
+ sess.userLoaded = true
+ }
- user, _ := sess.user.Load().(*arvados.User)
- if user == nil || expired {
- user = new(arvados.User)
- err := sess.client.RequestAndDecode(user, "GET", "/arvados/v1/users/current", nil, nil)
- if he := errorWithHTTPStatus(nil); errors.As(err, &he) && he.HTTPStatus() == http.StatusForbidden {
- // token is OK, but "get user id" api is out
- // of scope -- return nil, signifying unknown
- // user
- } else if err != nil {
- return nil, nil, nil, err
+ if sess.fs == nil || refresh {
+ sess.fs = sess.client.SiteFileSystem(sess.keepclient)
+ sess.fs.ForwardSlashNameSubstitution(c.cluster.Collections.ForwardSlashNameSubstitution)
+ sess.expire = now.Add(c.cluster.Collections.WebDAVCache.TTL.Duration())
+ c.metrics.sessionMisses.Inc()
+ } else {
+ c.metrics.sessionHits.Inc()
}
- sess.user.Store(user)
+ sess.inuse.Unlock()
+ } else {
+ c.metrics.sessionHits.Inc()
}
-
- return fs, sess, user, nil
+ sess.inuse.RLock()
+ return sess.fs, sess, &sess.user, nil
}
-// Remove all expired session cache entries, then remove more entries
-// until approximate remaining size <= maxsize/2
+// Remove all expired idle session cache entries, and remove in-memory
+// filesystems until approximate remaining size <= maxsize/2
func (c *cache) pruneSessions() {
now := time.Now()
keys := c.sessions.Keys()
sizes := make([]int64, len(keys))
+ prune := []string(nil)
var size int64
for i, token := range keys {
+ token := token.(string)
ent, ok := c.sessions.Peek(token)
if !ok {
continue
}
- s := ent.(*cachedSession)
- if s.expire.Before(now) {
- c.sessions.Remove(token)
- continue
+ sess := ent.(*cachedSession)
+ sess.refresh.Lock()
+ expired := sess.expire.Before(now)
+ fs := sess.fs
+ sess.refresh.Unlock()
+ if expired {
+ prune = append(prune, token)
}
- if fs, ok := s.fs.Load().(arvados.CustomFileSystem); ok {
+ if fs != nil {
sizes[i] = fs.MemorySize()
size += sizes[i]
}
// least frequently used entries (which Keys() returns last).
for i := len(keys) - 1; i >= 0 && size > c.cluster.Collections.WebDAVCache.MaxCollectionBytes; i-- {
if sizes[i] > 0 {
- c.sessions.Remove(keys[i])
+ prune = append(prune, keys[i].(string))
size -= sizes[i]
}
}
+
+ c.mtx.Lock()
+ defer c.mtx.Unlock()
+ for _, token := range prune {
+ ent, ok := c.sessions.Peek(token)
+ if !ok {
+ continue
+ }
+ sess := ent.(*cachedSession)
+ if sess.mtx.TryLock() {
+ c.sessions.Remove(token)
+ continue
+ }
+ // We can't remove a session that's been checked out
+ // -- that would allow another session to be created
+ // for the same token using a different in-memory
+ // filesystem. Instead, we wait for active requests to
+ // finish and then "unload" it. After this, either the
+ // next GetSession will reload fs/user, or a
+ // subsequent pruneSessions will remove the session.
+ go func() {
+ // Ensure nobody is in GetSession
+ sess.refresh.Lock()
+ // Wait for current usage to finish
+ sess.inuse.Lock()
+ // Release memory
+ sess.fs = nil
+ if sess.expire.Before(now) {
+ // Mark user data as stale
+ sess.userLoaded = false
+ }
+ sess.inuse.Unlock()
+ sess.refresh.Unlock()
+ // Next GetSession will make a new fs
+ }()
+ }
}
// collectionBytes returns the approximate combined memory size of the
if !ok {
continue
}
- if fs, ok := ent.(*cachedSession).fs.Load().(arvados.CustomFileSystem); ok {
+ sess := ent.(*cachedSession)
+ sess.refresh.Lock()
+ fs := sess.fs
+ sess.refresh.Unlock()
+ if fs != nil {
size += uint64(fs.MemorySize())
}
}
projects / arvados.git / commitdiff