refactor channel registration

irc/accounts.go

@@ -59,18 +59,15 @@ type AccountManager struct {
 	accountToMethod   map[string]NickReservationMethod
 }
 
-func NewAccountManager(server *Server) *AccountManager {
-	am := AccountManager{
-		accountToClients:  make(map[string][]*Client),
-		nickToAccount:     make(map[string]string),
-		skeletonToAccount: make(map[string]string),
-		accountToMethod:   make(map[string]NickReservationMethod),
-		server:            server,
-	}
+func (am *AccountManager) Initialize(server *Server) {
+	am.accountToClients = make(map[string][]*Client)
+	am.nickToAccount = make(map[string]string)
+	am.skeletonToAccount = make(map[string]string)
+	am.accountToMethod = make(map[string]NickReservationMethod)
+	am.server = server
 
 	am.buildNickToAccountIndex()
 	am.initVHostRequestQueue()
-	return &am
 }
 
 func (am *AccountManager) buildNickToAccountIndex() {
@@ -855,6 +852,7 @@ func (am *AccountManager) Unregister(account string) error {
 	verificationCodeKey := fmt.Sprintf(keyAccountVerificationCode, casefoldedAccount)
 	verifiedKey := fmt.Sprintf(keyAccountVerified, casefoldedAccount)
 	nicksKey := fmt.Sprintf(keyAccountAdditionalNicks, casefoldedAccount)
+	enforcementKey := fmt.Sprintf(keyAccountEnforcement, casefoldedAccount)
 	vhostKey := fmt.Sprintf(keyAccountVHost, casefoldedAccount)
 	vhostQueueKey := fmt.Sprintf(keyVHostQueueAcctToId, casefoldedAccount)
 	channelsKey := fmt.Sprintf(keyAccountChannels, casefoldedAccount)
@@ -865,14 +863,7 @@ func (am *AccountManager) Unregister(account string) error {
 	// on our way out, unregister all the account's channels and delete them from the db
 	defer func() {
 		for _, channelName := range registeredChannels {
-			info := am.server.channelRegistry.LoadChannel(channelName)
-			if info != nil && info.Founder == casefoldedAccount {
-				am.server.channelRegistry.Delete(channelName, *info)
-			}
-			channel := am.server.channels.Get(channelName)
-			if channel != nil {
-				channel.SetUnregistered(casefoldedAccount)
-			}
+			am.server.channels.SetUnregistered(channelName, casefoldedAccount)
 		}
 	}()
 
@@ -892,6 +883,7 @@ func (am *AccountManager) Unregister(account string) error {
 		tx.Delete(registeredTimeKey)
 		tx.Delete(callbackKey)
 		tx.Delete(verificationCodeKey)
+		tx.Delete(enforcementKey)
 		rawNicks, _ = tx.Get(nicksKey)
 		tx.Delete(nicksKey)
 		credText, err = tx.Get(credentialsKey)

irc/caps/set.go

@@ -16,7 +16,6 @@ type Set [bitsetLen]uint64
 // NewSet returns a new Set, with the given capabilities enabled.
 func NewSet(capabs ...Capability) *Set {
 	var newSet Set
-	utils.BitsetInitialize(newSet[:])
 	newSet.Enable(capabs...)
 	return &newSet
 }

irc/channel.go

@@ -22,7 +22,7 @@ import (
 
 // Channel represents a channel that clients can join.
 type Channel struct {
-	flags             *modes.ModeSet
+	flags             modes.ModeSet
 	lists             map[modes.Mode]*UserMaskSet
 	key               string
 	members           MemberSet
@@ -33,19 +33,22 @@ type Channel struct {
 	createdTime       time.Time
 	registeredFounder string
 	registeredTime    time.Time
-	stateMutex        sync.RWMutex // tier 1
-	joinPartMutex     sync.Mutex   // tier 3
 	topic             string
 	topicSetBy        string
 	topicSetTime      time.Time
 	userLimit         int
 	accountToUMode    map[string]modes.Mode
 	history           history.Buffer
+	stateMutex        sync.RWMutex // tier 1
+	writerSemaphore   Semaphore    // tier 1.5
+	joinPartMutex     sync.Mutex   // tier 3
+	ensureLoaded      utils.Once   // manages loading stored registration info from the database
+	dirtyBits         uint
 }
 
 // NewChannel creates a new channel from a `Server` and a `name`
 // string, which must be unique on the server.
-func NewChannel(s *Server, name string, regInfo *RegisteredChannel) *Channel {
+func NewChannel(s *Server, name string, registered bool) *Channel {
 	casefoldedName, err := CasefoldChannel(name)
 	if err != nil {
 		s.logger.Error("internal", "Bad channel name", name, err.Error())
@@ -54,7 +57,6 @@ func NewChannel(s *Server, name string, regInfo *RegisteredChannel) *Channel {
 
 	channel := &Channel{
 		createdTime: time.Now(), // may be overwritten by applyRegInfo
-		flags:       modes.NewModeSet(),
 		lists: map[modes.Mode]*UserMaskSet{
 			modes.BanMask:    NewUserMaskSet(),
 			modes.ExceptMask: NewUserMaskSet(),
@@ -69,21 +71,43 @@ func NewChannel(s *Server, name string, regInfo *RegisteredChannel) *Channel {
 
 	config := s.Config()
 
-	if regInfo != nil {
-		channel.applyRegInfo(regInfo)
-	} else {
+	channel.writerSemaphore.Initialize(1)
+	channel.history.Initialize(config.History.ChannelLength)
+
+	if !registered {
 		for _, mode := range config.Channels.defaultModes {
 			channel.flags.SetMode(mode, true)
 		}
-	}
-
-	channel.history.Initialize(config.History.ChannelLength)
+		// no loading to do, so "mark" the load operation as "done":
+		channel.ensureLoaded.Do(func() {})
+	} // else: modes will be loaded before first join
 
 	return channel
 }
 
+// EnsureLoaded blocks until the channel's registration info has been loaded
+// from the database.
+func (channel *Channel) EnsureLoaded() {
+	channel.ensureLoaded.Do(func() {
+		nmc := channel.NameCasefolded()
+		info, err := channel.server.channelRegistry.LoadChannel(nmc)
+		if err == nil {
+			channel.applyRegInfo(info)
+		} else {
+			channel.server.logger.Error("internal", "couldn't load channel", nmc, err.Error())
+		}
+	})
+}
+
+func (channel *Channel) IsLoaded() bool {
+	return channel.ensureLoaded.Done()
+}
+
 // read in channel state that was persisted in the DB
-func (channel *Channel) applyRegInfo(chanReg *RegisteredChannel) {
+func (channel *Channel) applyRegInfo(chanReg RegisteredChannel) {
+	channel.stateMutex.Lock()
+	defer channel.stateMutex.Unlock()
+
 	channel.registeredFounder = chanReg.Founder
 	channel.registeredTime = chanReg.RegisteredAt
 	channel.topic = chanReg.Topic
@@ -116,6 +140,7 @@ func (channel *Channel) ExportRegistration(includeFlags uint) (info RegisteredCh
 	defer channel.stateMutex.RUnlock()
 
 	info.Name = channel.name
+	info.NameCasefolded = channel.nameCasefolded
 	info.Founder = channel.registeredFounder
 	info.RegisteredAt = channel.registeredTime
 
@@ -149,6 +174,115 @@ func (channel *Channel) ExportRegistration(includeFlags uint) (info RegisteredCh
 	return
 }
 
+// begin: asynchronous database writeback implementation, modeled on irc/socket.go
+
+// MarkDirty marks part (or all) of a channel's data as needing to be written back
+// to the database, then starts a writer goroutine if necessary.
+// This is the equivalent of Socket.Write().
+func (channel *Channel) MarkDirty(dirtyBits uint) {
+	channel.stateMutex.Lock()
+	isRegistered := channel.registeredFounder != ""
+	channel.dirtyBits = channel.dirtyBits | dirtyBits
+	channel.stateMutex.Unlock()
+	if !isRegistered {
+		return
+	}
+
+	channel.wakeWriter()
+}
+
+// IsClean returns whether a channel can be safely removed from the server.
+// To avoid the obvious TOCTOU race condition, it must be called while holding
+// ChannelManager's lock (that way, no one can join and make the channel dirty again
+// between this method exiting and the actual deletion).
+func (channel *Channel) IsClean() bool {
+	if !channel.writerSemaphore.TryAcquire() {
+		// a database write (which may fail) is in progress, the channel cannot be cleaned up
+		return false
+	}
+	defer channel.writerSemaphore.Release()
+
+	channel.stateMutex.RLock()
+	defer channel.stateMutex.RUnlock()
+	// the channel must be empty, and either be unregistered or fully written to the DB
+	return len(channel.members) == 0 && (channel.registeredFounder == "" || channel.dirtyBits == 0)
+}
+
+func (channel *Channel) wakeWriter() {
+	if channel.writerSemaphore.TryAcquire() {
+		go channel.writeLoop()
+	}
+}
+
+// equivalent of Socket.send()
+func (channel *Channel) writeLoop() {
+	for {
+		// TODO(#357) check the error value of this and implement timed backoff
+		channel.performWrite(0)
+		channel.writerSemaphore.Release()
+
+		channel.stateMutex.RLock()
+		isDirty := channel.dirtyBits != 0
+		isEmpty := len(channel.members) == 0
+		channel.stateMutex.RUnlock()
+
+		if !isDirty {
+			if isEmpty {
+				channel.server.channels.Cleanup(channel)
+			}
+			return // nothing to do
+		} // else: isDirty, so we need to write again
+
+		if !channel.writerSemaphore.TryAcquire() {
+			return
+		}
+	}
+}
+
+// Store writes part (or all) of the channel's data back to the database,
+// blocking until the write is complete. This is the equivalent of
+// Socket.BlockingWrite.
+func (channel *Channel) Store(dirtyBits uint) (err error) {
+	defer func() {
+		channel.stateMutex.Lock()
+		isDirty := channel.dirtyBits != 0
+		isEmpty := len(channel.members) == 0
+		channel.stateMutex.Unlock()
+
+		if isDirty {
+			channel.wakeWriter()
+		} else if isEmpty {
+			channel.server.channels.Cleanup(channel)
+		}
+	}()
+
+	channel.writerSemaphore.Acquire()
+	defer channel.writerSemaphore.Release()
+	return channel.performWrite(dirtyBits)
+}
+
+// do an individual write; equivalent of Socket.send()
+func (channel *Channel) performWrite(additionalDirtyBits uint) (err error) {
+	channel.stateMutex.Lock()
+	dirtyBits := channel.dirtyBits | additionalDirtyBits
+	channel.dirtyBits = 0
+	isRegistered := channel.registeredFounder != ""
+	channel.stateMutex.Unlock()
+
+	if !isRegistered || dirtyBits == 0 {
+		return
+	}
+
+	info := channel.ExportRegistration(dirtyBits)
+	err = channel.server.channelRegistry.StoreChannel(info, dirtyBits)
+	if err != nil {
+		channel.stateMutex.Lock()
+		channel.dirtyBits = channel.dirtyBits | dirtyBits
+		channel.stateMutex.Unlock()
+	}
+	return
+}
+
 // SetRegistered registers the channel, returning an error if it was already registered.
 func (channel *Channel) SetRegistered(founder string) error {
 	channel.stateMutex.Lock()
@@ -698,7 +832,7 @@ func (channel *Channel) SetTopic(client *Client, topic string, rb *ResponseBuffe
 		}
 	}
 
-	go channel.server.channelRegistry.StoreChannel(channel, IncludeTopic)
+	channel.MarkDirty(IncludeTopic)
 }
 
 // CanSpeak returns true if the client can speak on this channel.

irc/channelmanager.go

@@ -19,25 +19,38 @@ type channelManagerEntry struct {
 // providing synchronization for creation of new channels on first join,
 // cleanup of empty channels on last part, and renames.
 type ChannelManager struct {
-	sync.RWMutex // tier 2
-	chans        map[string]*channelManagerEntry
+	sync.RWMutex       // tier 2
+	chans              map[string]*channelManagerEntry
+	registeredChannels map[string]bool
+	server             *Server
 }
 
 // NewChannelManager returns a new ChannelManager.
-func NewChannelManager() *ChannelManager {
-	return &ChannelManager{
-		chans: make(map[string]*channelManagerEntry),
+func (cm *ChannelManager) Initialize(server *Server) {
+	cm.chans = make(map[string]*channelManagerEntry)
+	cm.server = server
+
+	if server.Config().Channels.Registration.Enabled {
+		cm.loadRegisteredChannels()
 	}
 }
 
+func (cm *ChannelManager) loadRegisteredChannels() {
+	registeredChannels := cm.server.channelRegistry.AllChannels()
+	cm.Lock()
+	defer cm.Unlock()
+	cm.registeredChannels = registeredChannels
+}
+
 // Get returns an existing channel with name equivalent to `name`, or nil
-func (cm *ChannelManager) Get(name string) *Channel {
+func (cm *ChannelManager) Get(name string) (channel *Channel) {
 	name, err := CasefoldChannel(name)
 	if err == nil {
 		cm.RLock()
 		defer cm.RUnlock()
 		entry := cm.chans[name]
-		if entry != nil {
+		// if the channel is still loading, pretend we don't have it
+		if entry != nil && entry.channel.IsLoaded() {
 			return entry.channel
 		}
 	}
@@ -55,28 +68,21 @@ func (cm *ChannelManager) Join(client *Client, name string, key string, isSajoin
 	cm.Lock()
 	entry := cm.chans[casefoldedName]
 	if entry == nil {
-		// XXX give up the lock to check for a registration, then check again
-		// to see if we need to create the channel. we could solve this by doing LoadChannel
-		// outside the lock initially on every join, so this is best thought of as an
-		// optimization to avoid that.
-		cm.Unlock()
-		info := client.server.channelRegistry.LoadChannel(casefoldedName)
-		cm.Lock()
-		entry = cm.chans[casefoldedName]
-		if entry == nil {
-			entry = &channelManagerEntry{
-				channel:      NewChannel(server, name, info),
-				pendingJoins: 0,
-			}
-			cm.chans[casefoldedName] = entry
+		registered := cm.registeredChannels[casefoldedName]
+		entry = &channelManagerEntry{
+			channel:      NewChannel(server, name, registered),
+			pendingJoins: 0,
 		}
+		cm.chans[casefoldedName] = entry
 	}
 	entry.pendingJoins += 1
+	channel := entry.channel
 	cm.Unlock()
 
-	entry.channel.Join(client, key, isSajoin, rb)
+	channel.EnsureLoaded()
+	channel.Join(client, key, isSajoin, rb)
 
-	cm.maybeCleanup(entry.channel, true)
+	cm.maybeCleanup(channel, true)
 
 	return nil
 }
@@ -85,7 +91,8 @@ func (cm *ChannelManager) maybeCleanup(channel *Channel, afterJoin bool) {
 	cm.Lock()
 	defer cm.Unlock()
 
-	entry := cm.chans[channel.NameCasefolded()]
+	nameCasefolded := channel.NameCasefolded()
+	entry := cm.chans[nameCasefolded]
 	if entry == nil || entry.channel != channel {
 		return
 	}
@@ -93,23 +100,15 @@ func (cm *ChannelManager) maybeCleanup(channel *Channel, afterJoin bool) {
 	if afterJoin {
 		entry.pendingJoins -= 1
 	}
-	// TODO(slingamn) right now, registered channels cannot be cleaned up.
-	// this is because once ChannelManager becomes the source of truth about a channel,
-	// we can't move the source of truth back to the database unless we do an ACID
-	// store while holding the ChannelManager's Lock(). This is pending more decisions
-	// about where the database transaction lock fits into the overall lock model.
-	if !entry.channel.IsRegistered() && entry.channel.IsEmpty() && entry.pendingJoins == 0 {
-		// reread the name, handling the case where the channel was renamed
-		casefoldedName := entry.channel.NameCasefolded()
-		delete(cm.chans, casefoldedName)
-		// invalidate the entry (otherwise, a subsequent cleanup attempt could delete
-		// a valid, distinct entry under casefoldedName):
-		entry.channel = nil
+	if entry.pendingJoins == 0 && entry.channel.IsClean() {
+		delete(cm.chans, nameCasefolded)
 	}
 }
 
 // Part parts `client` from the channel named `name`, deleting it if it's empty.
 func (cm *ChannelManager) Part(client *Client, name string, message string, rb *ResponseBuffer) error {
+	var channel *Channel
+
 	casefoldedName, err := CasefoldChannel(name)
 	if err != nil {
 		return errNoSuchChannel
@@ -117,12 +116,15 @@ func (cm *ChannelManager) Part(client *Client, name string, message string, rb *
 
 	cm.RLock()
 	entry := cm.chans[casefoldedName]
+	if entry != nil {
+		channel = entry.channel
+	}
 	cm.RUnlock()
 
-	if entry == nil {
+	if channel == nil {
 		return errNoSuchChannel
 	}
-	entry.channel.Part(client, message, rb)
+	channel.Part(client, message, rb)
 	return nil
 }
 
@@ -130,8 +132,68 @@ func (cm *ChannelManager) Cleanup(channel *Channel) {
 	cm.maybeCleanup(channel, false)
 }
 
+func (cm *ChannelManager) SetRegistered(channelName string, account string) (err error) {
+	var channel *Channel
+	cfname, err := CasefoldChannel(channelName)
+	if err != nil {
+		return err
+	}
+
+	var entry *channelManagerEntry
+
+	defer func() {
+		if err == nil && channel != nil {
+			// registration was successful: make the database reflect it
+			err = channel.Store(IncludeAllChannelAttrs)
+		}
+	}()
+
+	cm.Lock()
+	defer cm.Unlock()
+	entry = cm.chans[cfname]
+	if entry == nil {
+		return errNoSuchChannel
+	}
+	channel = entry.channel
+	err = channel.SetRegistered(account)
+	if err != nil {
+		return err
+	}
+	cm.registeredChannels[cfname] = true
+	return nil
+}
+
+func (cm *ChannelManager) SetUnregistered(channelName string, account string) (err error) {
+	cfname, err := CasefoldChannel(channelName)
+	if err != nil {
+		return err
+	}
+
+	var info RegisteredChannel
+
+	defer func() {
+		if err == nil {
+			err = cm.server.channelRegistry.Delete(info)
+		}
+	}()
+
+	cm.Lock()
+	defer cm.Unlock()
+	entry := cm.chans[cfname]
+	if entry == nil {
+		return errNoSuchChannel
+	}
+	info = entry.channel.ExportRegistration(0)
+	if info.Founder != account {
+		return errChannelNotOwnedByAccount
+	}
+	entry.channel.SetUnregistered(account)
+	delete(cm.registeredChannels, cfname)
+	return nil
+}
+
 // Rename renames a channel (but does not notify the members)
-func (cm *ChannelManager) Rename(name string, newname string) error {
+func (cm *ChannelManager) Rename(name string, newname string) (err error) {
 	cfname, err := CasefoldChannel(name)
 	if err != nil {
 		return errNoSuchChannel
@@ -142,6 +204,17 @@ func (cm *ChannelManager) Rename(name string, newname string) error {
 		return errInvalidChannelName
 	}
 
+	var channel *Channel
+	var info RegisteredChannel
+	defer func() {
+		if channel != nil && info.Founder != "" {
+			channel.Store(IncludeAllChannelAttrs)
+			// we just flushed the channel under its new name, therefore this delete
+			// cannot be overwritten by a write to the old name:
+			cm.server.channelRegistry.Delete(info)
+		}
+	}()
+
 	cm.Lock()
 	defer cm.Unlock()
 
@@ -152,12 +225,12 @@ func (cm *ChannelManager) Rename(name string, newname string) error {
 	if entry == nil {
 		return errNoSuchChannel
 	}
+	channel = entry.channel
+	info = channel.ExportRegistration(IncludeInitial)
 	delete(cm.chans, cfname)
 	cm.chans[cfnewname] = entry
-	entry.channel.setName(newname)
-	entry.channel.setNameCasefolded(cfnewname)
+	entry.channel.Rename(newname, cfnewname)
 	return nil
-
 }
 
 // Len returns the number of channels
@@ -171,8 +244,11 @@ func (cm *ChannelManager) Len() int {
 func (cm *ChannelManager) Channels() (result []*Channel) {
 	cm.RLock()
 	defer cm.RUnlock()
+	result = make([]*Channel, 0, len(cm.chans))
 	for _, entry := range cm.chans {
-		result = append(result, entry.channel)
+		if entry.channel.IsLoaded() {
+			result = append(result, entry.channel)
+		}
 	}
 	return
 }

irc/channelreg.go

@@ -7,7 +7,6 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
-	"sync"
 	"time"
 
 	"encoding/json"
@@ -71,6 +70,8 @@ const (
 type RegisteredChannel struct {
 	// Name of the channel.
 	Name string
+	// Casefolded name of the channel.
+	NameCasefolded string
 	// RegisteredAt represents the time that the channel was registered.
 	RegisteredAt time.Time
 	// Founder indicates the founder of the channel.
@@ -97,58 +98,65 @@ type RegisteredChannel struct {
 
 // ChannelRegistry manages registered channels.
 type ChannelRegistry struct {
-	// This serializes operations of the form (read channel state, synchronously persist it);
-	// this is enough to guarantee eventual consistency of the database with the
-	// ChannelManager and Channel objects, which are the source of truth.
-	//
-	// We could use the buntdb RW transaction lock for this purpose but we share
-	// that with all the other modules, so let's not.
-	sync.Mutex // tier 2
-	server     *Server
+	server *Server
 }
 
 // NewChannelRegistry returns a new ChannelRegistry.
-func NewChannelRegistry(server *Server) *ChannelRegistry {
-	return &ChannelRegistry{
-		server: server,
-	}
+func (reg *ChannelRegistry) Initialize(server *Server) {
+	reg.server = server
+}
+
+func (reg *ChannelRegistry) AllChannels() (result map[string]bool) {
+	result = make(map[string]bool)
+
+	prefix := fmt.Sprintf(keyChannelExists, "")
+	reg.server.store.View(func(tx *buntdb.Tx) error {
+		return tx.AscendGreaterOrEqual("", prefix, func(key, value string) bool {
+			if !strings.HasPrefix(key, prefix) {
+				return false
+			}
+			channel := strings.TrimPrefix(key, prefix)
+			result[channel] = true
+			return true
+		})
+	})
+
+	return
 }
 
 // StoreChannel obtains a consistent view of a channel, then persists it to the store.
-func (reg *ChannelRegistry) StoreChannel(channel *Channel, includeFlags uint) {
+func (reg *ChannelRegistry) StoreChannel(info RegisteredChannel, includeFlags uint) (err error) {
 	if !reg.server.ChannelRegistrationEnabled() {
 		return
 	}
 
-	reg.Lock()
-	defer reg.Unlock()
-
-	key := channel.NameCasefolded()
-	info := channel.ExportRegistration(includeFlags)
 	if info.Founder == "" {
 		// sanity check, don't try to store an unregistered channel
 		return
 	}
 
 	reg.server.store.Update(func(tx *buntdb.Tx) error {
-		reg.saveChannel(tx, key, info, includeFlags)
+		reg.saveChannel(tx, info, includeFlags)
 		return nil
 	})
+
+	return nil
 }
 
 // LoadChannel loads a channel from the store.
-func (reg *ChannelRegistry) LoadChannel(nameCasefolded string) (info *RegisteredChannel) {
+func (reg *ChannelRegistry) LoadChannel(nameCasefolded string) (info RegisteredChannel, err error) {
 	if !reg.server.ChannelRegistrationEnabled() {
-		return nil
+		err = errFeatureDisabled
+		return
 	}
 
 	channelKey := nameCasefolded
 	// nice to have: do all JSON (de)serialization outside of the buntdb transaction
-	reg.server.store.View(func(tx *buntdb.Tx) error {
-		_, err := tx.Get(fmt.Sprintf(keyChannelExists, channelKey))
-		if err == buntdb.ErrNotFound {
+	err = reg.server.store.View(func(tx *buntdb.Tx) error {
+		_, dberr := tx.Get(fmt.Sprintf(keyChannelExists, channelKey))
+		if dberr == buntdb.ErrNotFound {
 			// chan does not already exist, return
-			return nil
+			return errNoSuchChannel
 		}
 
 		// channel exists, load it
@@ -181,7 +189,7 @@ func (reg *ChannelRegistry) LoadChannel(nameCasefolded string) (info *Registered
 		accountToUMode := make(map[string]modes.Mode)
 		_ = json.Unmarshal([]byte(accountToUModeString), &accountToUMode)
 
-		info = &RegisteredChannel{
+		info = RegisteredChannel{
 			Name:           name,
 			RegisteredAt:   time.Unix(regTimeInt, 0),
 			Founder:        founder,
@@ -198,46 +206,21 @@ func (reg *ChannelRegistry) LoadChannel(nameCasefolded string) (info *Registered
 		return nil
 	})
 
-	return info
-}
-
-func (reg *ChannelRegistry) Delete(casefoldedName string, info RegisteredChannel) {
-	if !reg.server.ChannelRegistrationEnabled() {
-		return
-	}
-
-	reg.Lock()
-	defer reg.Unlock()
-
-	reg.server.store.Update(func(tx *buntdb.Tx) error {
-		reg.deleteChannel(tx, casefoldedName, info)
-		return nil
-	})
+	return
 }
 
-// Rename handles the persistence part of a channel rename: the channel is
-// persisted under its new name, and the old name is cleaned up if necessary.
-func (reg *ChannelRegistry) Rename(channel *Channel, casefoldedOldName string) {
+// Delete deletes a channel corresponding to `info`. If no such channel
+// is present in the database, no error is returned.
+func (reg *ChannelRegistry) Delete(info RegisteredChannel) (err error) {
 	if !reg.server.ChannelRegistrationEnabled() {
 		return
 	}
 
-	reg.Lock()
-	defer reg.Unlock()
-
-	includeFlags := IncludeAllChannelAttrs
-	oldKey := casefoldedOldName
-	key := channel.NameCasefolded()
-	info := channel.ExportRegistration(includeFlags)
-	if info.Founder == "" {
-		return
-	}
-
 	reg.server.store.Update(func(tx *buntdb.Tx) error {
-		reg.deleteChannel(tx, oldKey, info)
-		reg.saveChannel(tx, key, info, includeFlags)
+		reg.deleteChannel(tx, info.NameCasefolded, info)
 		return nil
 	})
+	return nil
 }
 
 // delete a channel, unless it was overwritten by another registration of the same channel
@@ -274,7 +257,8 @@ func (reg *ChannelRegistry) deleteChannel(tx *buntdb.Tx, key string, info Regist
 }
 
 // saveChannel saves a channel to the store.
-func (reg *ChannelRegistry) saveChannel(tx *buntdb.Tx, channelKey string, channelInfo RegisteredChannel, includeFlags uint) {
+func (reg *ChannelRegistry) saveChannel(tx *buntdb.Tx, channelInfo RegisteredChannel, includeFlags uint) {
+	channelKey := channelInfo.NameCasefolded
 	// maintain the mapping of account -> registered channels
 	chanExistsKey := fmt.Sprintf(keyChannelExists, channelKey)
 	_, existsErr := tx.Get(chanExistsKey)

irc/chanserv.go

@@ -232,15 +232,12 @@ func csRegisterHandler(server *Server, client *Client, command string, params []
 	}
 
 	// this provides the synchronization that allows exactly one registration of the channel:
-	err = channelInfo.SetRegistered(account)
+	err = server.channels.SetRegistered(channelKey, account)
 	if err != nil {
 		csNotice(rb, err.Error())
 		return
 	}
 
-	// registration was successful: make the database reflect it
-	go server.channelRegistry.StoreChannel(channelInfo, IncludeAllChannelAttrs)
-
 	csNotice(rb, fmt.Sprintf(client.t("Channel %s successfully registered"), channelName))
 
 	server.logger.Info("services", fmt.Sprintf("Client %s registered channel %s", client.nick, channelName))
@@ -297,8 +294,7 @@ func csUnregisterHandler(server *Server, client *Client, command string, params
 		return
 	}
 
-	channel.SetUnregistered(founder)
-	server.channelRegistry.Delete(channelKey, info)
+	server.channels.SetUnregistered(channelKey, founder)
 	csNotice(rb, fmt.Sprintf(client.t("Channel %s is now unregistered"), channelKey))
 }
 

irc/client.go

@@ -50,7 +50,7 @@ type Client struct {
 	accountName        string // display name of the account: uncasefolded, '*' if not logged in
 	atime              time.Time
 	awayMessage        string
-	capabilities       *caps.Set
+	capabilities       caps.Set
 	capState           caps.State
 	capVersion         caps.Version
 	certfp             string
@@ -58,7 +58,7 @@ type Client struct {
 	ctime              time.Time
 	exitedSnomaskSent  bool
 	fakelag            Fakelag
-	flags              *modes.ModeSet
+	flags              modes.ModeSet
 	hasQuit            bool
 	hops               int
 	hostname           string
@@ -125,15 +125,13 @@ func RunNewClient(server *Server, conn clientConn) {
 	// give them 1k of grace over the limit:
 	socket := NewSocket(conn.Conn, fullLineLenLimit+1024, config.Server.MaxSendQBytes)
 	client := &Client{
-		atime:        now,
-		capabilities: caps.NewSet(),
-		capState:     caps.NoneState,
-		capVersion:   caps.Cap301,
-		channels:     make(ChannelSet),
-		ctime:        now,
-		flags:        modes.NewModeSet(),
-		isTor:        conn.IsTor,
-		languages:    server.Languages().Default(),
+		atime:      now,
+		capState:   caps.NoneState,
+		capVersion: caps.Cap301,
+		channels:   make(ChannelSet),
+		ctime:      now,
+		isTor:      conn.IsTor,
+		languages:  server.Languages().Default(),
 		loginThrottle: connection_limits.GenericThrottle{
 			Duration: config.Accounts.LoginThrottling.Duration,
 			Limit:    config.Accounts.LoginThrottling.MaxAttempts,
@@ -546,7 +544,6 @@ func (client *Client) replayPrivmsgHistory(rb *ResponseBuffer, items []history.I
 // copy applicable state from oldClient to client as part of a resume
 func (client *Client) copyResumeData(oldClient *Client) {
 	oldClient.stateMutex.RLock()
-	flags := oldClient.flags
 	history := oldClient.history
 	nick := oldClient.nick
 	nickCasefolded := oldClient.nickCasefolded
@@ -560,7 +557,7 @@ func (client *Client) copyResumeData(oldClient *Client) {
 	// resume over plaintext)
 	hasTLS := client.flags.HasMode(modes.TLS)
 	temp := modes.NewModeSet()
-	temp.Copy(flags)
+	temp.Copy(&oldClient.flags)
 	temp.SetMode(modes.TLS, hasTLS)
 	client.flags.Copy(temp)
 

irc/client_lookup_set.go

@@ -37,12 +37,10 @@ type ClientManager struct {
 	bySkeleton   map[string]*Client
 }
 
-// NewClientManager returns a new ClientManager.
-func NewClientManager() *ClientManager {
-	return &ClientManager{
-		byNick:     make(map[string]*Client),
-		bySkeleton: make(map[string]*Client),
-	}
+// Initialize initializes a ClientManager.
+func (clients *ClientManager) Initialize() {
+	clients.byNick = make(map[string]*Client)
+	clients.bySkeleton = make(map[string]*Client)
 }
 
 // Count returns how many clients are in the manager.

irc/errors.go

@@ -27,6 +27,8 @@ var (
 	errAccountMustHoldNick            = errors.New(`You must hold that nickname in order to register it`)
 	errCallbackFailed                 = errors.New("Account verification could not be sent")
 	errCertfpAlreadyExists            = errors.New(`An account already exists for your certificate fingerprint`)
+	errChannelNotOwnedByAccount       = errors.New("Channel not owned by the specified account")
+	errChannelDoesNotExist            = errors.New("Channel does not exist")
 	errChannelAlreadyRegistered       = errors.New("Channel is already registered")
 	errChannelNameInUse               = errors.New(`Channel name in use`)
 	errInvalidChannelName             = errors.New(`Invalid channel name`)

irc/getters.go

@@ -4,6 +4,8 @@
 package irc
 
 import (
+	"time"
+
 	"github.com/oragono/oragono/irc/isupport"
 	"github.com/oragono/oragono/irc/languages"
 	"github.com/oragono/oragono/irc/modes"
@@ -267,22 +269,20 @@ func (channel *Channel) Name() string {
 	return channel.name
 }
 
-func (channel *Channel) setName(name string) {
-	channel.stateMutex.Lock()
-	defer channel.stateMutex.Unlock()
-	channel.name = name
-}
-
 func (channel *Channel) NameCasefolded() string {
 	channel.stateMutex.RLock()
 	defer channel.stateMutex.RUnlock()
 	return channel.nameCasefolded
 }
 
-func (channel *Channel) setNameCasefolded(nameCasefolded string) {
+func (channel *Channel) Rename(name, nameCasefolded string) {
 	channel.stateMutex.Lock()
-	defer channel.stateMutex.Unlock()
+	channel.name = name
 	channel.nameCasefolded = nameCasefolded
+	if channel.registeredFounder != "" {
+		channel.registeredTime = time.Now()
+	}
+	channel.stateMutex.Unlock()
 }
 
 func (channel *Channel) Members() (result []*Client) {
@@ -314,3 +314,10 @@ func (channel *Channel) Founder() string {
 	defer channel.stateMutex.RUnlock()
 	return channel.registeredFounder
 }
+
+func (channel *Channel) DirtyBits() (dirtyBits uint) {
+	channel.stateMutex.Lock()
+	dirtyBits = channel.dirtyBits
+	channel.stateMutex.Unlock()
+	return
+}

irc/handlers.go

@@ -1607,8 +1607,8 @@ func cmodeHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Res
 		}
 	}
 
-	if channel.IsRegistered() && includeFlags != 0 {
-		go server.channelRegistry.StoreChannel(channel, includeFlags)
+	if includeFlags != 0 {
+		channel.MarkDirty(includeFlags)
 	}
 
 	// send out changes
@@ -2215,7 +2215,6 @@ func renameHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Re
 		rb.Add(nil, server.name, ERR_NOSUCHCHANNEL, client.Nick(), oldName, client.t("No such channel"))
 		return false
 	}
-	casefoldedOldName := channel.NameCasefolded()
 	if !(channel.ClientIsAtLeast(client, modes.Operator) || client.HasRoleCapabs("chanreg")) {
 		rb.Add(nil, server.name, ERR_CHANOPRIVSNEEDED, client.Nick(), oldName, client.t("You're not a channel operator"))
 		return false
@@ -2240,9 +2239,6 @@ func renameHandler(server *Server, client *Client, msg ircmsg.IrcMessage, rb *Re
 		return false
 	}
 
-	// rename succeeded, persist it
-	go server.channelRegistry.Rename(channel, casefoldedOldName)
-
 	// send RENAME messages
 	clientPrefix := client.NickMaskString()
 	for _, mcl := range channel.Members() {

irc/modes.go

@@ -290,14 +290,14 @@ func (channel *Channel) ProcessAccountToUmodeChange(client *Client, change modes
 	case modes.Add:
 		if targetModeNow != targetModeAfter {
 			channel.accountToUMode[change.Arg] = change.Mode
-			go client.server.channelRegistry.StoreChannel(channel, IncludeLists)
+			channel.MarkDirty(IncludeLists)
 			return []modes.ModeChange{change}, nil
 		}
 		return nil, nil
 	case modes.Remove:
 		if targetModeNow == change.Mode {
 			delete(channel.accountToUMode, change.Arg)
-			go client.server.channelRegistry.StoreChannel(channel, IncludeLists)
+			channel.MarkDirty(IncludeLists)
 			return []modes.ModeChange{change}, nil
 		}
 		return nil, nil

irc/modes/modes.go

@@ -335,7 +335,6 @@ const (
 // returns a pointer to a new ModeSet
 func NewModeSet() *ModeSet {
 	var set ModeSet
-	utils.BitsetInitialize(set[:])
 	return &set
 }
 

irc/semaphores.go

@@ -32,14 +32,13 @@ type ServerSemaphores struct {
 	ClientDestroy Semaphore
 }
 
-// NewServerSemaphores creates a new ServerSemaphores.
-func NewServerSemaphores() (result *ServerSemaphores) {
+// Initialize initializes a set of server semaphores.
+func (serversem *ServerSemaphores) Initialize() {
 	capacity := runtime.NumCPU()
 	if capacity > MaxServerSemaphoreCapacity {
 		capacity = MaxServerSemaphoreCapacity
 	}
-	result = new(ServerSemaphores)
-	result.ClientDestroy.Initialize(capacity)
+	serversem.ClientDestroy.Initialize(capacity)
 	return
 }
 

irc/server.go

@@ -61,10 +61,10 @@ type ListenerWrapper struct {
 
 // Server is the main Oragono server.
 type Server struct {
-	accounts               *AccountManager
-	channels               *ChannelManager
-	channelRegistry        *ChannelRegistry
-	clients                *ClientManager
+	accounts               AccountManager
+	channels               ChannelManager
+	channelRegistry        ChannelRegistry
+	clients                ClientManager
 	config                 *Config
 	configFilename         string
 	configurableStateMutex sync.RWMutex // tier 1; generic protection for server state modified by rehash()
@@ -89,9 +89,9 @@ type Server struct {
 	snomasks               *SnoManager
 	store                  *buntdb.DB
 	torLimiter             connection_limits.TorLimiter
-	whoWas                 *WhoWasList
-	stats                  *Stats
-	semaphores             *ServerSemaphores
+	whoWas                 WhoWasList
+	stats                  Stats
+	semaphores             ServerSemaphores
 }
 
 var (
@@ -113,8 +113,6 @@ type clientConn struct {
 func NewServer(config *Config, logger *logger.Manager) (*Server, error) {
 	// initialize data structures
 	server := &Server{
-		channels:            NewChannelManager(),
-		clients:             NewClientManager(),
 		connectionLimiter:   connection_limits.NewLimiter(),
 		connectionThrottler: connection_limits.NewThrottler(),
 		listeners:           make(map[string]*ListenerWrapper),
@@ -123,12 +121,12 @@ func NewServer(config *Config, logger *logger.Manager) (*Server, error) {
 		rehashSignal:        make(chan os.Signal, 1),
 		signals:             make(chan os.Signal, len(ServerExitSignals)),
 		snomasks:            NewSnoManager(),
-		whoWas:              NewWhoWasList(config.Limits.WhowasEntries),
-		stats:               NewStats(),
-		semaphores:          NewServerSemaphores(),
 	}
 
+	server.clients.Initialize()
+	server.semaphores.Initialize()
 	server.resumeManager.Initialize(server)
+	server.whoWas.Initialize(config.Limits.WhowasEntries)
 
 	if err := server.applyConfig(config, true); err != nil {
 		return nil, err
@@ -697,6 +695,12 @@ func (server *Server) applyConfig(config *Config, initial bool) (err error) {
 		server.accounts.initVHostRequestQueue()
 	}
 
+	chanRegPreviouslyDisabled := oldConfig != nil && !oldConfig.Channels.Registration.Enabled
+	chanRegNowEnabled := config.Channels.Registration.Enabled
+	if chanRegPreviouslyDisabled && chanRegNowEnabled {
+		server.channels.loadRegisteredChannels()
+	}
+
 	// MaxLine
 	if config.Limits.LineLen.Rest != 512 {
 		SupportedCapabilities.Enable(caps.MaxLine)
@@ -922,9 +926,9 @@ func (server *Server) loadDatastore(config *Config) error {
 	server.loadDLines()
 	server.loadKLines()
 
-	server.channelRegistry = NewChannelRegistry(server)
-
-	server.accounts = NewAccountManager(server)
+	server.channelRegistry.Initialize(server)
+	server.channels.Initialize(server)
+	server.accounts.Initialize(server)
 
 	return nil
 }

irc/stats.go

@@ -13,17 +13,6 @@ type Stats struct {
 	Operators int
 }
 
-// NewStats creates a new instance of Stats
-func NewStats() *Stats {
-	serverStats := &Stats{
-		Total:     0,
-		Invisible: 0,
-		Operators: 0,
-	}
-
-	return serverStats
-}
-
 // ChangeTotal increments the total user count on server
 func (s *Stats) ChangeTotal(i int) {
 	s.Lock()

irc/utils/bitset.go

@@ -9,17 +9,6 @@ import "sync/atomic"
 // For examples of use, see caps.Set and modes.ModeSet; the array has to be converted to a
 // slice to use these functions.
 
-// BitsetInitialize initializes a bitset.
-func BitsetInitialize(set []uint64) {
-	// XXX re-zero the bitset using atomic stores. it's unclear whether this is required,
-	// however, golang issue #5045 suggests that you shouldn't mix atomic operations
-	// with non-atomic operations (such as the runtime's automatic zero-initialization) on
-	// the same word
-	for i := 0; i < len(set); i++ {
-		atomic.StoreUint64(&set[i], 0)
-	}
-}
-
 // BitsetGet returns whether a given bit of the bitset is set.
 func BitsetGet(set []uint64, position uint) bool {
 	idx := position / 64

irc/utils/bitset_test.go

@@ -10,7 +10,6 @@ type testBitset [2]uint64
 func TestSets(t *testing.T) {
 	var t1 testBitset
 	t1s := t1[:]
-	BitsetInitialize(t1s)
 
 	if BitsetGet(t1s, 0) || BitsetGet(t1s, 63) || BitsetGet(t1s, 64) || BitsetGet(t1s, 127) {
 		t.Error("no bits should be set in a newly initialized bitset")
@@ -47,7 +46,6 @@ func TestSets(t *testing.T) {
 
 	var t2 testBitset
 	t2s := t2[:]
-	BitsetInitialize(t2s)
 
 	for i = 0; i < 128; i++ {
 		if i%2 == 1 {

irc/utils/sync.go

@@ -0,0 +1,35 @@
+// Copyright 2009 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package utils
+
+import (
+	"sync"
+	"sync/atomic"
+)
+
+// Once is a fork of sync.Once to expose a Done() method.
+type Once struct {
+	done uint32
+	m    sync.Mutex
+}
+
+func (o *Once) Do(f func()) {
+	if atomic.LoadUint32(&o.done) == 0 {
+		o.doSlow(f)
+	}
+}
+
+func (o *Once) doSlow(f func()) {
+	o.m.Lock()
+	defer o.m.Unlock()
+	if o.done == 0 {
+		defer atomic.StoreUint32(&o.done, 1)
+		f()
+	}
+}
+
+func (o *Once) Done() bool {
+	return atomic.LoadUint32(&o.done) == 1
+}

irc/whowas.go

@@ -23,12 +23,10 @@ type WhoWasList struct {
 }
 
 // NewWhoWasList returns a new WhoWasList
-func NewWhoWasList(size int) *WhoWasList {
-	return &WhoWasList{
-		buffer: make([]WhoWas, size),
-		start:  -1,
-		end:    -1,
-	}
+func (list *WhoWasList) Initialize(size int) {
+	list.buffer = make([]WhoWas, size)
+	list.start = -1
+	list.end = -1
 }
 
 // Append adds an entry to the WhoWasList.

irc/whowas_test.go

@@ -23,7 +23,8 @@ func makeTestWhowas(nick string) WhoWas {
 
 func TestWhoWas(t *testing.T) {
 	var results []WhoWas
-	wwl := NewWhoWasList(3)
+	var wwl WhoWasList
+	wwl.Initialize(3)
 	// test Find on empty list
 	results = wwl.Find("nobody", 10)
 	if len(results) != 0 {
@@ -88,7 +89,8 @@ func TestWhoWas(t *testing.T) {
 
 func TestEmptyWhoWas(t *testing.T) {
 	// stupid edge case; setting an empty whowas buffer should not panic
-	wwl := NewWhoWasList(0)
+	var wwl WhoWasList
+	wwl.Initialize(0)
 	results := wwl.Find("slingamn", 10)
 	if len(results) != 0 {
 		t.Fatalf("incorrect whowas results: %v", results)