services/keep-web/cache.go

   1 // Copyright (C) The Arvados Authors. All rights reserved.
   2 //
   3 // SPDX-License-Identifier: AGPL-3.0
   4
   5 package main
   6
   7 import (
   8         "sync"
   9         "sync/atomic"
  10         "time"
  11
  12         "git.arvados.org/arvados.git/sdk/go/arvados"
  13         "git.arvados.org/arvados.git/sdk/go/arvadosclient"
  14         "git.arvados.org/arvados.git/sdk/go/keepclient"
  15         lru "github.com/hashicorp/golang-lru"
  16         "github.com/prometheus/client_golang/prometheus"
  17 )
  18
  19 const metricsUpdateInterval = time.Second / 10
  20
  21 type cache struct {
  22         cluster     *arvados.Cluster
  23         config      *arvados.WebDAVCacheConfig // TODO: use cluster.Collections.WebDAV instead
  24         registry    *prometheus.Registry
  25         metrics     cacheMetrics
  26         pdhs        *lru.TwoQueueCache
  27         collections *lru.TwoQueueCache
  28         permissions *lru.TwoQueueCache
  29         sessions    *lru.TwoQueueCache
  30         setupOnce   sync.Once
  31 }
  32
  33 type cacheMetrics struct {
  34         requests          prometheus.Counter
  35         collectionBytes   prometheus.Gauge
  36         collectionEntries prometheus.Gauge
  37         sessionEntries    prometheus.Gauge
  38         collectionHits    prometheus.Counter
  39         pdhHits           prometheus.Counter
  40         permissionHits    prometheus.Counter
  41         sessionHits       prometheus.Counter
  42         sessionMisses     prometheus.Counter
  43         apiCalls          prometheus.Counter
  44 }
  45
  46 func (m *cacheMetrics) setup(reg *prometheus.Registry) {
  47         m.requests = prometheus.NewCounter(prometheus.CounterOpts{
  48                 Namespace: "arvados",
  49                 Subsystem: "keepweb_collectioncache",
  50                 Name:      "requests",
  51                 Help:      "Number of targetID-to-manifest lookups handled.",
  52         })
  53         reg.MustRegister(m.requests)
  54         m.collectionHits = prometheus.NewCounter(prometheus.CounterOpts{
  55                 Namespace: "arvados",
  56                 Subsystem: "keepweb_collectioncache",
  57                 Name:      "hits",
  58                 Help:      "Number of pdh-to-manifest cache hits.",
  59         })
  60         reg.MustRegister(m.collectionHits)
  61         m.pdhHits = prometheus.NewCounter(prometheus.CounterOpts{
  62                 Namespace: "arvados",
  63                 Subsystem: "keepweb_collectioncache",
  64                 Name:      "pdh_hits",
  65                 Help:      "Number of uuid-to-pdh cache hits.",
  66         })
  67         reg.MustRegister(m.pdhHits)
  68         m.permissionHits = prometheus.NewCounter(prometheus.CounterOpts{
  69                 Namespace: "arvados",
  70                 Subsystem: "keepweb_collectioncache",
  71                 Name:      "permission_hits",
  72                 Help:      "Number of targetID-to-permission cache hits.",
  73         })
  74         reg.MustRegister(m.permissionHits)
  75         m.apiCalls = prometheus.NewCounter(prometheus.CounterOpts{
  76                 Namespace: "arvados",
  77                 Subsystem: "keepweb_collectioncache",
  78                 Name:      "api_calls",
  79                 Help:      "Number of outgoing API calls made by cache.",
  80         })
  81         reg.MustRegister(m.apiCalls)
  82         m.collectionBytes = prometheus.NewGauge(prometheus.GaugeOpts{
  83                 Namespace: "arvados",
  84                 Subsystem: "keepweb_sessions",
  85                 Name:      "cached_collection_bytes",
  86                 Help:      "Total size of all cached manifests and sessions.",
  87         })
  88         reg.MustRegister(m.collectionBytes)
  89         m.collectionEntries = prometheus.NewGauge(prometheus.GaugeOpts{
  90                 Namespace: "arvados",
  91                 Subsystem: "keepweb_collectioncache",
  92                 Name:      "cached_manifests",
  93                 Help:      "Number of manifests in cache.",
  94         })
  95         reg.MustRegister(m.collectionEntries)
  96         m.sessionEntries = prometheus.NewGauge(prometheus.GaugeOpts{
  97                 Namespace: "arvados",
  98                 Subsystem: "keepweb_sessions",
  99                 Name:      "active",
 100                 Help:      "Number of active token sessions.",
 101         })
 102         reg.MustRegister(m.sessionEntries)
 103         m.sessionHits = prometheus.NewCounter(prometheus.CounterOpts{
 104                 Namespace: "arvados",
 105                 Subsystem: "keepweb_sessions",
 106                 Name:      "hits",
 107                 Help:      "Number of token session cache hits.",
 108         })
 109         reg.MustRegister(m.sessionHits)
 110         m.sessionMisses = prometheus.NewCounter(prometheus.CounterOpts{
 111                 Namespace: "arvados",
 112                 Subsystem: "keepweb_sessions",
 113                 Name:      "misses",
 114                 Help:      "Number of token session cache misses.",
 115         })
 116         reg.MustRegister(m.sessionMisses)
 117 }
 118
 119 type cachedPDH struct {
 120         expire time.Time
 121         pdh    string
 122 }
 123
 124 type cachedCollection struct {
 125         expire     time.Time
 126         collection *arvados.Collection
 127 }
 128
 129 type cachedPermission struct {
 130         expire time.Time
 131 }
 132
 133 type cachedSession struct {
 134         expire time.Time
 135         fs     atomic.Value
 136 }
 137
 138 func (c *cache) setup() {
 139         var err error
 140         c.pdhs, err = lru.New2Q(c.config.MaxUUIDEntries)
 141         if err != nil {
 142                 panic(err)
 143         }
 144         c.collections, err = lru.New2Q(c.config.MaxCollectionEntries)
 145         if err != nil {
 146                 panic(err)
 147         }
 148         c.permissions, err = lru.New2Q(c.config.MaxPermissionEntries)
 149         if err != nil {
 150                 panic(err)
 151         }
 152         c.sessions, err = lru.New2Q(c.config.MaxSessions)
 153         if err != nil {
 154                 panic(err)
 155         }
 156
 157         reg := c.registry
 158         if reg == nil {
 159                 reg = prometheus.NewRegistry()
 160         }
 161         c.metrics.setup(reg)
 162         go func() {
 163                 for range time.Tick(metricsUpdateInterval) {
 164                         c.updateGauges()
 165                 }
 166         }()
 167 }
 168
 169 func (c *cache) updateGauges() {
 170         c.metrics.collectionBytes.Set(float64(c.collectionBytes()))
 171         c.metrics.collectionEntries.Set(float64(c.collections.Len()))
 172         c.metrics.sessionEntries.Set(float64(c.sessions.Len()))
 173 }
 174
 175 var selectPDH = map[string]interface{}{
 176         "select": []string{"portable_data_hash"},
 177 }
 178
 179 // Update saves a modified version (fs) to an existing collection
 180 // (coll) and, if successful, updates the relevant cache entries so
 181 // subsequent calls to Get() reflect the modifications.
 182 func (c *cache) Update(client *arvados.Client, coll arvados.Collection, fs arvados.CollectionFileSystem) error {
 183         c.setupOnce.Do(c.setup)
 184
 185         m, err := fs.MarshalManifest(".")
 186         if err != nil || m == coll.ManifestText {
 187                 return err
 188         }
 189         coll.ManifestText = m
 190         var updated arvados.Collection
 191         defer c.pdhs.Remove(coll.UUID)
 192         err = client.RequestAndDecode(&updated, "PATCH", "arvados/v1/collections/"+coll.UUID, nil, map[string]interface{}{
 193                 "collection": map[string]string{
 194                         "manifest_text": coll.ManifestText,
 195                 },
 196         })
 197         if err == nil {
 198                 c.collections.Add(client.AuthToken+"\000"+coll.PortableDataHash, &cachedCollection{
 199                         expire:     time.Now().Add(time.Duration(c.config.TTL)),
 200                         collection: &updated,
 201                 })
 202         }
 203         return err
 204 }
 205
 206 // ResetSession unloads any potentially stale state. Should be called
 207 // after write operations, so subsequent reads don't return stale
 208 // data.
 209 func (c *cache) ResetSession(token string) {
 210         c.setupOnce.Do(c.setup)
 211         c.sessions.Remove(token)
 212 }
 213
 214 // Get a long-lived CustomFileSystem suitable for doing a read operation
 215 // with the given token.
 216 func (c *cache) GetSession(token string) (arvados.CustomFileSystem, error) {
 217         c.setupOnce.Do(c.setup)
 218         now := time.Now()
 219         ent, _ := c.sessions.Get(token)
 220         sess, _ := ent.(*cachedSession)
 221         expired := false
 222         if sess == nil {
 223                 c.metrics.sessionMisses.Inc()
 224                 sess = &cachedSession{
 225                         expire: now.Add(c.config.TTL.Duration()),
 226                 }
 227                 c.sessions.Add(token, sess)
 228         } else if sess.expire.Before(now) {
 229                 c.metrics.sessionMisses.Inc()
 230                 expired = true
 231         } else {
 232                 c.metrics.sessionHits.Inc()
 233         }
 234         go c.pruneSessions()
 235         fs, _ := sess.fs.Load().(arvados.CustomFileSystem)
 236         if fs != nil && !expired {
 237                 return fs, nil
 238         }
 239         ac, err := arvados.NewClientFromConfig(c.cluster)
 240         if err != nil {
 241                 return nil, err
 242         }
 243         ac.AuthToken = token
 244         arv, err := arvadosclient.New(ac)
 245         if err != nil {
 246                 return nil, err
 247         }
 248         kc := keepclient.New(arv)
 249         fs = ac.SiteFileSystem(kc)
 250         fs.ForwardSlashNameSubstitution(c.cluster.Collections.ForwardSlashNameSubstitution)
 251         sess.fs.Store(fs)
 252         return fs, nil
 253 }
 254
 255 // Remove all expired session cache entries, then remove more entries
 256 // until approximate remaining size <= maxsize/2
 257 func (c *cache) pruneSessions() {
 258         now := time.Now()
 259         var size int64
 260         keys := c.sessions.Keys()
 261         for _, token := range keys {
 262                 ent, ok := c.sessions.Peek(token)
 263                 if !ok {
 264                         continue
 265                 }
 266                 s := ent.(*cachedSession)
 267                 if s.expire.Before(now) {
 268                         c.sessions.Remove(token)
 269                         continue
 270                 }
 271                 if fs, ok := s.fs.Load().(arvados.CustomFileSystem); ok {
 272                         size += fs.MemorySize()
 273                 }
 274         }
 275         // Remove tokens until reaching size limit, starting with the
 276         // least frequently used entries (which Keys() returns last).
 277         for i := len(keys) - 1; i >= 0; i-- {
 278                 token := keys[i]
 279                 if size <= c.cluster.Collections.WebDAVCache.MaxCollectionBytes/2 {
 280                         break
 281                 }
 282                 ent, ok := c.sessions.Peek(token)
 283                 if !ok {
 284                         continue
 285                 }
 286                 s := ent.(*cachedSession)
 287                 fs, _ := s.fs.Load().(arvados.CustomFileSystem)
 288                 if fs == nil {
 289                         continue
 290                 }
 291                 c.sessions.Remove(token)
 292                 size -= fs.MemorySize()
 293         }
 294 }
 295
 296 func (c *cache) Get(arv *arvadosclient.ArvadosClient, targetID string, forceReload bool) (*arvados.Collection, error) {
 297         c.setupOnce.Do(c.setup)
 298         c.metrics.requests.Inc()
 299
 300         permOK := false
 301         permKey := arv.ApiToken + "\000" + targetID
 302         if forceReload {
 303         } else if ent, cached := c.permissions.Get(permKey); cached {
 304                 ent := ent.(*cachedPermission)
 305                 if ent.expire.Before(time.Now()) {
 306                         c.permissions.Remove(permKey)
 307                 } else {
 308                         permOK = true
 309                         c.metrics.permissionHits.Inc()
 310                 }
 311         }
 312
 313         var pdh string
 314         if arvadosclient.PDHMatch(targetID) {
 315                 pdh = targetID
 316         } else if ent, cached := c.pdhs.Get(targetID); cached {
 317                 ent := ent.(*cachedPDH)
 318                 if ent.expire.Before(time.Now()) {
 319                         c.pdhs.Remove(targetID)
 320                 } else {
 321                         pdh = ent.pdh
 322                         c.metrics.pdhHits.Inc()
 323                 }
 324         }
 325
 326         var collection *arvados.Collection
 327         if pdh != "" {
 328                 collection = c.lookupCollection(arv.ApiToken + "\000" + pdh)
 329         }
 330
 331         if collection != nil && permOK {
 332                 return collection, nil
 333         } else if collection != nil {
 334                 // Ask API for current PDH for this targetID. Most
 335                 // likely, the cached PDH is still correct; if so,
 336                 // _and_ the current token has permission, we can
 337                 // use our cached manifest.
 338                 c.metrics.apiCalls.Inc()
 339                 var current arvados.Collection
 340                 err := arv.Get("collections", targetID, selectPDH, &current)
 341                 if err != nil {
 342                         return nil, err
 343                 }
 344                 if current.PortableDataHash == pdh {
 345                         c.permissions.Add(permKey, &cachedPermission{
 346                                 expire: time.Now().Add(time.Duration(c.config.TTL)),
 347                         })
 348                         if pdh != targetID {
 349                                 c.pdhs.Add(targetID, &cachedPDH{
 350                                         expire: time.Now().Add(time.Duration(c.config.UUIDTTL)),
 351                                         pdh:    pdh,
 352                                 })
 353                         }
 354                         return collection, err
 355                 }
 356                 // PDH changed, but now we know we have
 357                 // permission -- and maybe we already have the
 358                 // new PDH in the cache.
 359                 if coll := c.lookupCollection(arv.ApiToken + "\000" + current.PortableDataHash); coll != nil {
 360                         return coll, nil
 361                 }
 362         }
 363
 364         // Collection manifest is not cached.
 365         c.metrics.apiCalls.Inc()
 366         err := arv.Get("collections", targetID, nil, &collection)
 367         if err != nil {
 368                 return nil, err
 369         }
 370         exp := time.Now().Add(time.Duration(c.config.TTL))
 371         c.permissions.Add(permKey, &cachedPermission{
 372                 expire: exp,
 373         })
 374         c.pdhs.Add(targetID, &cachedPDH{
 375                 expire: time.Now().Add(time.Duration(c.config.UUIDTTL)),
 376                 pdh:    collection.PortableDataHash,
 377         })
 378         c.collections.Add(arv.ApiToken+"\000"+collection.PortableDataHash, &cachedCollection{
 379                 expire:     exp,
 380                 collection: collection,
 381         })
 382         if int64(len(collection.ManifestText)) > c.config.MaxCollectionBytes/int64(c.config.MaxCollectionEntries) {
 383                 go c.pruneCollections()
 384         }
 385         return collection, nil
 386 }
 387
 388 // pruneCollections checks the total bytes occupied by manifest_text
 389 // in the collection cache and removes old entries as needed to bring
 390 // the total size down to CollectionBytes. It also deletes all expired
 391 // entries.
 392 //
 393 // pruneCollections does not aim to be perfectly correct when there is
 394 // concurrent cache activity.
 395 func (c *cache) pruneCollections() {
 396         var size int64
 397         now := time.Now()
 398         keys := c.collections.Keys()
 399         entsize := make([]int, len(keys))
 400         expired := make([]bool, len(keys))
 401         for i, k := range keys {
 402                 v, ok := c.collections.Peek(k)
 403                 if !ok {
 404                         continue
 405                 }
 406                 ent := v.(*cachedCollection)
 407                 n := len(ent.collection.ManifestText)
 408                 size += int64(n)
 409                 entsize[i] = n
 410                 expired[i] = ent.expire.Before(now)
 411         }
 412         for i, k := range keys {
 413                 if expired[i] {
 414                         c.collections.Remove(k)
 415                         size -= int64(entsize[i])
 416                 }
 417         }
 418         for i, k := range keys {
 419                 if size <= c.config.MaxCollectionBytes/2 {
 420                         break
 421                 }
 422                 if expired[i] {
 423                         // already removed this entry in the previous loop
 424                         continue
 425                 }
 426                 c.collections.Remove(k)
 427                 size -= int64(entsize[i])
 428         }
 429 }
 430
 431 // collectionBytes returns the approximate combined memory size of the
 432 // collection cache and session filesystem cache.
 433 func (c *cache) collectionBytes() uint64 {
 434         var size uint64
 435         for _, k := range c.collections.Keys() {
 436                 v, ok := c.collections.Peek(k)
 437                 if !ok {
 438                         continue
 439                 }
 440                 size += uint64(len(v.(*cachedCollection).collection.ManifestText))
 441         }
 442         for _, token := range c.sessions.Keys() {
 443                 ent, ok := c.sessions.Peek(token)
 444                 if !ok {
 445                         continue
 446                 }
 447                 if fs, ok := ent.(*cachedSession).fs.Load().(arvados.CustomFileSystem); ok {
 448                         size += uint64(fs.MemorySize())
 449                 }
 450         }
 451         return size
 452 }
 453
 454 func (c *cache) lookupCollection(key string) *arvados.Collection {
 455         e, cached := c.collections.Get(key)
 456         if !cached {
 457                 return nil
 458         }
 459         ent := e.(*cachedCollection)
 460         if ent.expire.Before(time.Now()) {
 461                 c.collections.Remove(key)
 462                 return nil
 463         }
 464         c.metrics.collectionHits.Inc()
 465         return ent.collection
 466 }