ceph/src/mds/Server.h

   1 // -*- mode:C++; tab-width:8; c-basic-offset:2; indent-tabs-mode:t -*-
   2 // vim: ts=8 sw=2 smarttab
   3 /*
   4  * Ceph - scalable distributed file system
   5  *
   6  * Copyright (C) 2004-2006 Sage Weil <sage@newdream.net>
   7  *
   8  * This is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License version 2.1, as published by the Free Software
  11  * Foundation.  See file COPYING.
  12  *
  13  */
  14
  15 #ifndef CEPH_MDS_SERVER_H
  16 #define CEPH_MDS_SERVER_H
  17
  18 #include <string_view>
  19
  20 #include <common/DecayCounter.h>
  21
  22 #include "include/common_fwd.h"
  23
  24 #include "messages/MClientReconnect.h"
  25 #include "messages/MClientReply.h"
  26 #include "messages/MClientRequest.h"
  27 #include "messages/MClientSession.h"
  28 #include "messages/MClientSnap.h"
  29 #include "messages/MClientReclaim.h"
  30 #include "messages/MClientReclaimReply.h"
  31 #include "messages/MLock.h"
  32
  33 #include "CInode.h"
  34 #include "MDSRank.h"
  35 #include "Mutation.h"
  36 #include "MDSContext.h"
  37
  38 class OSDMap;
  39 class LogEvent;
  40 class EMetaBlob;
  41 class EUpdate;
  42 class MDLog;
  43 struct SnapInfo;
  44 class MetricsHandler;
  45
  46 enum {
  47   l_mdss_first = 1000,
  48   l_mdss_dispatch_client_request,
  49   l_mdss_dispatch_peer_request,
  50   l_mdss_handle_client_request,
  51   l_mdss_handle_client_session,
  52   l_mdss_handle_peer_request,
  53   l_mdss_req_create_latency,
  54   l_mdss_req_getattr_latency,
  55   l_mdss_req_getfilelock_latency,
  56   l_mdss_req_link_latency,
  57   l_mdss_req_lookup_latency,
  58   l_mdss_req_lookuphash_latency,
  59   l_mdss_req_lookupino_latency,
  60   l_mdss_req_lookupname_latency,
  61   l_mdss_req_lookupparent_latency,
  62   l_mdss_req_lookupsnap_latency,
  63   l_mdss_req_lssnap_latency,
  64   l_mdss_req_mkdir_latency,
  65   l_mdss_req_mknod_latency,
  66   l_mdss_req_mksnap_latency,
  67   l_mdss_req_open_latency,
  68   l_mdss_req_readdir_latency,
  69   l_mdss_req_rename_latency,
  70   l_mdss_req_renamesnap_latency,
  71   l_mdss_req_rmdir_latency,
  72   l_mdss_req_rmsnap_latency,
  73   l_mdss_req_rmxattr_latency,
  74   l_mdss_req_setattr_latency,
  75   l_mdss_req_setdirlayout_latency,
  76   l_mdss_req_setfilelock_latency,
  77   l_mdss_req_setlayout_latency,
  78   l_mdss_req_setxattr_latency,
  79   l_mdss_req_symlink_latency,
  80   l_mdss_req_unlink_latency,
  81   l_mdss_cap_revoke_eviction,
  82   l_mdss_cap_acquisition_throttle,
  83   l_mdss_last,
  84 };
  85
  86 class Server {
  87 public:
  88   using clock = ceph::coarse_mono_clock;
  89   using time = ceph::coarse_mono_time;
  90
  91   enum class RecallFlags : uint64_t {
  92     NONE = 0,
  93     STEADY = (1<<0),
  94     ENFORCE_MAX = (1<<1),
  95     TRIM = (1<<2),
  96     ENFORCE_LIVENESS = (1<<3),
  97   };
  98   explicit Server(MDSRank *m, MetricsHandler *metrics_handler);
  99   ~Server() {
 100     g_ceph_context->get_perfcounters_collection()->remove(logger);
 101     delete logger;
 102     delete reconnect_done;
 103   }
 104
 105   void create_logger();
 106
 107   // message handler
 108   void dispatch(const cref_t<Message> &m);
 109
 110   void handle_osd_map();
 111
 112   // -- sessions and recovery --
 113   bool waiting_for_reconnect(client_t c) const;
 114   void dump_reconnect_status(Formatter *f) const;
 115
 116   time last_recalled() const {
 117     return last_recall_state;
 118   }
 119
 120   void handle_client_session(const cref_t<MClientSession> &m);
 121   void _session_logged(Session *session, uint64_t state_seq, bool open, version_t pv,
 122                        const interval_set<inodeno_t>& inos_to_free, version_t piv,
 123                        const interval_set<inodeno_t>& inos_to_purge, LogSegment *ls);
 124   version_t prepare_force_open_sessions(map<client_t,entity_inst_t> &cm,
 125                                         map<client_t,client_metadata_t>& cmm,
 126                                         map<client_t,pair<Session*,uint64_t> >& smap);
 127   void finish_force_open_sessions(const map<client_t,pair<Session*,uint64_t> >& smap,
 128                                   bool dec_import=true);
 129   void flush_client_sessions(set<client_t>& client_set, MDSGatherBuilder& gather);
 130   void finish_flush_session(Session *session, version_t seq);
 131   void terminate_sessions();
 132   void find_idle_sessions();
 133
 134   void kill_session(Session *session, Context *on_safe);
 135   size_t apply_blocklist(const std::set<entity_addr_t> &blocklist);
 136   void journal_close_session(Session *session, int state, Context *on_safe);
 137
 138   size_t get_num_pending_reclaim() const { return client_reclaim_gather.size(); }
 139   Session *find_session_by_uuid(std::string_view uuid);
 140   void reclaim_session(Session *session, const cref_t<MClientReclaim> &m);
 141   void finish_reclaim_session(Session *session, const ref_t<MClientReclaimReply> &reply=nullptr);
 142   void handle_client_reclaim(const cref_t<MClientReclaim> &m);
 143
 144   void reconnect_clients(MDSContext *reconnect_done_);
 145   void handle_client_reconnect(const cref_t<MClientReconnect> &m);
 146   void infer_supported_features(Session *session, client_metadata_t& client_metadata);
 147   void update_required_client_features();
 148
 149   //void process_reconnect_cap(CInode *in, int from, ceph_mds_cap_reconnect& capinfo);
 150   void reconnect_gather_finish();
 151   void reconnect_tick();
 152   void recover_filelocks(CInode *in, bufferlist locks, int64_t client);
 153
 154   std::pair<bool, uint64_t> recall_client_state(MDSGatherBuilder* gather, RecallFlags=RecallFlags::NONE);
 155   void force_clients_readonly();
 156
 157   // -- requests --
 158   void handle_client_request(const cref_t<MClientRequest> &m);
 159
 160   void journal_and_reply(MDRequestRef& mdr, CInode *tracei, CDentry *tracedn,
 161                          LogEvent *le, MDSLogContextBase *fin);
 162   void submit_mdlog_entry(LogEvent *le, MDSLogContextBase *fin,
 163                           MDRequestRef& mdr, std::string_view event);
 164   void dispatch_client_request(MDRequestRef& mdr);
 165   void perf_gather_op_latency(const cref_t<MClientRequest> &req, utime_t lat);
 166   void early_reply(MDRequestRef& mdr, CInode *tracei, CDentry *tracedn);
 167   void respond_to_request(MDRequestRef& mdr, int r = 0);
 168   void set_trace_dist(const ref_t<MClientReply> &reply, CInode *in, CDentry *dn,
 169                       MDRequestRef& mdr);
 170
 171   void handle_peer_request(const cref_t<MMDSPeerRequest> &m);
 172   void handle_peer_request_reply(const cref_t<MMDSPeerRequest> &m);
 173   void dispatch_peer_request(MDRequestRef& mdr);
 174   void handle_peer_auth_pin(MDRequestRef& mdr);
 175   void handle_peer_auth_pin_ack(MDRequestRef& mdr, const cref_t<MMDSPeerRequest> &ack);
 176
 177   // some helpers
 178   bool check_fragment_space(MDRequestRef& mdr, CDir *in);
 179   bool check_access(MDRequestRef& mdr, CInode *in, unsigned mask);
 180   bool _check_access(Session *session, CInode *in, unsigned mask, int caller_uid, int caller_gid, int setattr_uid, int setattr_gid);
 181   CDentry *prepare_stray_dentry(MDRequestRef& mdr, CInode *in);
 182   CInode* prepare_new_inode(MDRequestRef& mdr, CDir *dir, inodeno_t useino, unsigned mode,
 183                             const file_layout_t *layout=nullptr);
 184   void journal_allocated_inos(MDRequestRef& mdr, EMetaBlob *blob);
 185   void apply_allocated_inos(MDRequestRef& mdr, Session *session);
 186
 187   CInode* rdlock_path_pin_ref(MDRequestRef& mdr, bool want_auth,
 188                               bool no_want_auth=false);
 189   CDentry* rdlock_path_xlock_dentry(MDRequestRef& mdr, bool create,
 190                                     bool okexist=false, bool want_layout=false);
 191   std::pair<CDentry*, CDentry*>
 192             rdlock_two_paths_xlock_destdn(MDRequestRef& mdr, bool xlock_srcdn);
 193
 194   CDir* try_open_auth_dirfrag(CInode *diri, frag_t fg, MDRequestRef& mdr);
 195
 196   // requests on existing inodes.
 197   void handle_client_getattr(MDRequestRef& mdr, bool is_lookup);
 198   void handle_client_lookup_ino(MDRequestRef& mdr,
 199                                 bool want_parent, bool want_dentry);
 200   void _lookup_snap_ino(MDRequestRef& mdr);
 201   void _lookup_ino_2(MDRequestRef& mdr, int r);
 202   void handle_client_readdir(MDRequestRef& mdr);
 203   void handle_client_file_setlock(MDRequestRef& mdr);
 204   void handle_client_file_readlock(MDRequestRef& mdr);
 205
 206   bool xlock_policylock(MDRequestRef& mdr, CInode *in,
 207                         bool want_layout=false, bool xlock_snaplock=false);
 208   CInode* try_get_auth_inode(MDRequestRef& mdr, inodeno_t ino);
 209   void handle_client_setattr(MDRequestRef& mdr);
 210   void handle_client_setlayout(MDRequestRef& mdr);
 211   void handle_client_setdirlayout(MDRequestRef& mdr);
 212
 213   int parse_quota_vxattr(string name, string value, quota_info_t *quota);
 214   void create_quota_realm(CInode *in);
 215   int parse_layout_vxattr(string name, string value, const OSDMap& osdmap,
 216                           file_layout_t *layout, bool validate=true);
 217   int check_layout_vxattr(MDRequestRef& mdr,
 218                           string name,
 219                           string value,
 220                           file_layout_t *layout);
 221   void handle_set_vxattr(MDRequestRef& mdr, CInode *cur);
 222   void handle_remove_vxattr(MDRequestRef& mdr, CInode *cur);
 223   void handle_client_setxattr(MDRequestRef& mdr);
 224   void handle_client_removexattr(MDRequestRef& mdr);
 225
 226   void handle_client_fsync(MDRequestRef& mdr);
 227
 228   // open
 229   void handle_client_open(MDRequestRef& mdr);
 230   void handle_client_openc(MDRequestRef& mdr);  // O_CREAT variant.
 231   void do_open_truncate(MDRequestRef& mdr, int cmode);  // O_TRUNC variant.
 232
 233   // namespace changes
 234   void handle_client_mknod(MDRequestRef& mdr);
 235   void handle_client_mkdir(MDRequestRef& mdr);
 236   void handle_client_symlink(MDRequestRef& mdr);
 237
 238   // link
 239   void handle_client_link(MDRequestRef& mdr);
 240   void _link_local(MDRequestRef& mdr, CDentry *dn, CInode *targeti, SnapRealm *target_realm);
 241   void _link_local_finish(MDRequestRef& mdr, CDentry *dn, CInode *targeti,
 242                           version_t, version_t, bool);
 243
 244   void _link_remote(MDRequestRef& mdr, bool inc, CDentry *dn, CInode *targeti);
 245   void _link_remote_finish(MDRequestRef& mdr, bool inc, CDentry *dn, CInode *targeti,
 246                            version_t);
 247
 248   void handle_peer_link_prep(MDRequestRef& mdr);
 249   void _logged_peer_link(MDRequestRef& mdr, CInode *targeti, bool adjust_realm);
 250   void _commit_peer_link(MDRequestRef& mdr, int r, CInode *targeti);
 251   void _committed_peer(MDRequestRef& mdr);  // use for rename, too
 252   void handle_peer_link_prep_ack(MDRequestRef& mdr, const cref_t<MMDSPeerRequest> &m);
 253   void do_link_rollback(bufferlist &rbl, mds_rank_t leader, MDRequestRef& mdr);
 254   void _link_rollback_finish(MutationRef& mut, MDRequestRef& mdr,
 255                              map<client_t,ref_t<MClientSnap>>& split);
 256
 257   // unlink
 258   void handle_client_unlink(MDRequestRef& mdr);
 259   bool _dir_is_nonempty_unlocked(MDRequestRef& mdr, CInode *rmdiri);
 260   bool _dir_is_nonempty(MDRequestRef& mdr, CInode *rmdiri);
 261   void _unlink_local(MDRequestRef& mdr, CDentry *dn, CDentry *straydn);
 262   void _unlink_local_finish(MDRequestRef& mdr,
 263                             CDentry *dn, CDentry *straydn,
 264                             version_t);
 265   bool _rmdir_prepare_witness(MDRequestRef& mdr, mds_rank_t who, vector<CDentry*>& trace, CDentry *straydn);
 266   void handle_peer_rmdir_prep(MDRequestRef& mdr);
 267   void _logged_peer_rmdir(MDRequestRef& mdr, CDentry *srcdn, CDentry *straydn);
 268   void _commit_peer_rmdir(MDRequestRef& mdr, int r, CDentry *straydn);
 269   void handle_peer_rmdir_prep_ack(MDRequestRef& mdr, const cref_t<MMDSPeerRequest> &ack);
 270   void do_rmdir_rollback(bufferlist &rbl, mds_rank_t leader, MDRequestRef& mdr);
 271   void _rmdir_rollback_finish(MDRequestRef& mdr, metareqid_t reqid, CDentry *dn, CDentry *straydn);
 272
 273   // rename
 274   void handle_client_rename(MDRequestRef& mdr);
 275   void _rename_finish(MDRequestRef& mdr,
 276                       CDentry *srcdn, CDentry *destdn, CDentry *straydn);
 277
 278   void handle_client_lssnap(MDRequestRef& mdr);
 279   void handle_client_mksnap(MDRequestRef& mdr);
 280   void _mksnap_finish(MDRequestRef& mdr, CInode *diri, SnapInfo &info);
 281   void handle_client_rmsnap(MDRequestRef& mdr);
 282   void _rmsnap_finish(MDRequestRef& mdr, CInode *diri, snapid_t snapid);
 283   void handle_client_renamesnap(MDRequestRef& mdr);
 284   void _renamesnap_finish(MDRequestRef& mdr, CInode *diri, snapid_t snapid);
 285
 286   // helpers
 287   bool _rename_prepare_witness(MDRequestRef& mdr, mds_rank_t who, set<mds_rank_t> &witnesse,
 288                                vector<CDentry*>& srctrace, vector<CDentry*>& dsttrace, CDentry *straydn);
 289   version_t _rename_prepare_import(MDRequestRef& mdr, CDentry *srcdn, bufferlist *client_map_bl);
 290   bool _need_force_journal(CInode *diri, bool empty);
 291   void _rename_prepare(MDRequestRef& mdr,
 292                        EMetaBlob *metablob, bufferlist *client_map_bl,
 293                        CDentry *srcdn, CDentry *destdn, std::string_view alternate_name,
 294                        CDentry *straydn);
 295   /* set not_journaling=true if you're going to discard the results --
 296    * this bypasses the asserts to make sure we're journaling the right
 297    * things on the right nodes */
 298   void _rename_apply(MDRequestRef& mdr, CDentry *srcdn, CDentry *destdn, CDentry *straydn);
 299
 300   // slaving
 301   void handle_peer_rename_prep(MDRequestRef& mdr);
 302   void handle_peer_rename_prep_ack(MDRequestRef& mdr, const cref_t<MMDSPeerRequest> &m);
 303   void handle_peer_rename_notify_ack(MDRequestRef& mdr, const cref_t<MMDSPeerRequest> &m);
 304   void _peer_rename_sessions_flushed(MDRequestRef& mdr);
 305   void _logged_peer_rename(MDRequestRef& mdr, CDentry *srcdn, CDentry *destdn, CDentry *straydn);
 306   void _commit_peer_rename(MDRequestRef& mdr, int r, CDentry *srcdn, CDentry *destdn, CDentry *straydn);
 307   void do_rename_rollback(bufferlist &rbl, mds_rank_t leader, MDRequestRef& mdr, bool finish_mdr=false);
 308   void _rename_rollback_finish(MutationRef& mut, MDRequestRef& mdr, CDentry *srcdn, version_t srcdnpv,
 309                                CDentry *destdn, CDentry *staydn, map<client_t,ref_t<MClientSnap>> splits[2],
 310                                bool finish_mdr);
 311
 312   void evict_cap_revoke_non_responders();
 313   void handle_conf_change(const std::set<std::string>& changed);
 314
 315   bool terminating_sessions = false;
 316
 317   set<client_t> client_reclaim_gather;
 318
 319 private:
 320   friend class MDSContinuation;
 321   friend class ServerContext;
 322   friend class ServerLogContext;
 323   friend class Batch_Getattr_Lookup;
 324
 325   // placeholder for validation handler to store xattr specific
 326   // data
 327   struct XattrInfo {
 328     virtual ~XattrInfo() {
 329     }
 330   };
 331
 332   struct MirrorXattrInfo : XattrInfo {
 333     std::string cluster_id;
 334     std::string fs_id;
 335
 336     static const std::string MIRROR_INFO_REGEX;
 337     static const std::string CLUSTER_ID;
 338     static const std::string FS_ID;
 339
 340     MirrorXattrInfo(std::string_view cluster_id,
 341                     std::string_view fs_id)
 342       : cluster_id(cluster_id),
 343         fs_id(fs_id) {
 344     }
 345   };
 346
 347   struct XattrOp {
 348     int op;
 349     std::string xattr_name;
 350     const bufferlist &xattr_value;
 351     int flags = 0;
 352
 353     std::unique_ptr<XattrInfo> xinfo;
 354
 355     XattrOp(int op, std::string_view xattr_name, const bufferlist &xattr_value, int flags)
 356       : op(op),
 357         xattr_name(xattr_name),
 358         xattr_value(xattr_value),
 359         flags (flags) {
 360     }
 361   };
 362
 363   struct XattrHandler {
 364     const std::string xattr_name;
 365     const std::string description;
 366
 367     // basic checks are to be done in this handler. return -errno to
 368     // reject xattr request (set or remove), zero to proceed. handlers
 369     // may parse xattr value for verification if needed and have an
 370     // option to store custom data in XattrOp::xinfo.
 371     int (Server::*validate)(CInode *cur, const InodeStoreBase::xattr_map_const_ptr xattrs,
 372                             XattrOp *xattr_op);
 373
 374     // set xattr for an inode in xattr_map
 375     void (Server::*setxattr)(CInode *cur, InodeStoreBase::xattr_map_ptr xattrs,
 376                              const XattrOp &xattr_op);
 377
 378     // remove xattr for an inode from xattr_map
 379     void (Server::*removexattr)(CInode *cur, InodeStoreBase::xattr_map_ptr xattrs,
 380                                 const XattrOp &xattr_op);
 381   };
 382
 383   inline static const std::string DEFAULT_HANDLER = "<default>";
 384   static const XattrHandler xattr_handlers[];
 385
 386   const XattrHandler* get_xattr_or_default_handler(std::string_view xattr_name);
 387
 388   // generic variant to set/remove xattr in/from xattr_map
 389   int xattr_validate(CInode *cur, const InodeStoreBase::xattr_map_const_ptr xattrs,
 390                      const std::string &xattr_name, int op, int flags);
 391   void xattr_set(InodeStoreBase::xattr_map_ptr xattrs, const std::string &xattr_name,
 392                  const bufferlist &xattr_value);
 393   void xattr_rm(InodeStoreBase::xattr_map_ptr xattrs, const std::string &xattr_name);
 394
 395   // default xattr handlers
 396   int default_xattr_validate(CInode *cur, const InodeStoreBase::xattr_map_const_ptr xattrs,
 397                              XattrOp *xattr_op);
 398   void default_setxattr_handler(CInode *cur, InodeStoreBase::xattr_map_ptr xattrs,
 399                                 const XattrOp &xattr_op);
 400   void default_removexattr_handler(CInode *cur, InodeStoreBase::xattr_map_ptr xattrs,
 401                                    const XattrOp &xattr_op);
 402
 403   // mirror info xattr handler
 404   int parse_mirror_info_xattr(const std::string &name, const std::string &value,
 405                               std::string &cluster_id, std::string &fs_id);
 406   int mirror_info_xattr_validate(CInode *cur, const InodeStoreBase::xattr_map_const_ptr xattrs,
 407                                  XattrOp *xattr_op);
 408   void mirror_info_setxattr_handler(CInode *cur, InodeStoreBase::xattr_map_ptr xattrs,
 409                                     const XattrOp &xattr_op);
 410   void mirror_info_removexattr_handler(CInode *cur, InodeStoreBase::xattr_map_ptr xattrs,
 411                                        const XattrOp &xattr_op);
 412
 413   static bool is_ceph_vxattr(std::string_view xattr_name) {
 414     return xattr_name.rfind("ceph.dir.layout", 0) == 0 ||
 415            xattr_name.rfind("ceph.file.layout", 0) == 0 ||
 416            xattr_name.rfind("ceph.quota", 0) == 0 ||
 417            xattr_name == "ceph.dir.subvolume"sv ||
 418            xattr_name == "ceph.dir.pin"sv ||
 419            xattr_name == "ceph.dir.pin.random"sv ||
 420            xattr_name == "ceph.dir.pin.distributed"sv;
 421   }
 422
 423   static bool is_allowed_ceph_xattr(std::string_view xattr_name) {
 424     // not a ceph xattr -- allow!
 425     if (xattr_name.rfind("ceph.", 0) != 0) {
 426       return true;
 427     }
 428
 429     return xattr_name == "ceph.mirror.info";
 430   }
 431
 432   void reply_client_request(MDRequestRef& mdr, const ref_t<MClientReply> &reply);
 433   void flush_session(Session *session, MDSGatherBuilder& gather);
 434
 435   MDSRank *mds;
 436   MDCache *mdcache;
 437   MDLog *mdlog;
 438   PerfCounters *logger = nullptr;
 439
 440   // OSDMap full status, used to generate CEPHFS_ENOSPC on some operations
 441   bool is_full = false;
 442
 443   // State for while in reconnect
 444   MDSContext *reconnect_done = nullptr;
 445   int failed_reconnects = 0;
 446   bool reconnect_evicting = false;  // true if I am waiting for evictions to complete
 447                             // before proceeding to reconnect_gather_finish
 448   time reconnect_start = clock::zero();
 449   time reconnect_last_seen = clock::zero();
 450   set<client_t> client_reconnect_gather;  // clients i need a reconnect msg from.
 451   set<client_t> client_reconnect_denied;  // clients whose reconnect msg have been denied .
 452
 453   feature_bitset_t supported_features;
 454   feature_bitset_t required_client_features;
 455
 456   bool forward_all_requests_to_auth = false;
 457   bool replay_unsafe_with_closed_session = false;
 458   double cap_revoke_eviction_timeout = 0;
 459   uint64_t max_snaps_per_dir = 100;
 460   unsigned delegate_inos_pct = 0;
 461
 462   DecayCounter recall_throttle;
 463   time last_recall_state;
 464
 465   MetricsHandler *metrics_handler;
 466
 467   // Cache cap acquisition throttle configs
 468   uint64_t max_caps_per_client;
 469   uint64_t cap_acquisition_throttle;
 470   double max_caps_throttle_ratio;
 471   double caps_throttle_retry_request_timeout;
 472
 473   size_t alternate_name_max = g_conf().get_val<Option::size_t>("mds_alternate_name_max");
 474 };
 475
 476 static inline constexpr auto operator|(Server::RecallFlags a, Server::RecallFlags b) {
 477   using T = std::underlying_type<Server::RecallFlags>::type;
 478   return static_cast<Server::RecallFlags>(static_cast<T>(a) | static_cast<T>(b));
 479 }
 480 static inline constexpr auto operator&(Server::RecallFlags a, Server::RecallFlags b) {
 481   using T = std::underlying_type<Server::RecallFlags>::type;
 482   return static_cast<Server::RecallFlags>(static_cast<T>(a) & static_cast<T>(b));
 483 }
 484 static inline std::ostream& operator<<(std::ostream& os, const Server::RecallFlags& f) {
 485   using T = std::underlying_type<Server::RecallFlags>::type;
 486   return os << "0x" << std::hex << static_cast<T>(f) << std::dec;
 487 }
 488 static inline constexpr bool operator!(const Server::RecallFlags& f) {
 489   using T = std::underlying_type<Server::RecallFlags>::type;
 490   return static_cast<T>(f) == static_cast<T>(0);
 491 }
 492 #endif