// Returns a list of all the changes made on a channel.
// Does NOT handle the Wait option. Does NOT check authorization.
func (db *Database) changesFeed(channel string, options ChangesOptions) (<-chan *ChangeEntry, error) {
since := options.Since[channel]
channelLog, err := db.changesWriter.getChangeLog(channel, since)
if err != nil {
base.Warn("Error reading channel-log %q (using view instead): %v", channel, err)
channelLog = nil
}
rebuildLog := channelLog == nil && err == nil && (EnableStarChannelLog || channel != "*")
var log []*channels.LogEntry
if channelLog != nil {
log = channelLog.Entries
}
var viewFeed <-chan *ChangeEntry
if channelLog == nil || channelLog.Since > since {
var upToSeq uint64
if channelLog != nil {
upToSeq = channelLog.Since
}
// Channel log may not go back far enough, so also fetch view-based change feed:
viewFeed, err = db.changesFeedFromView(channel, options, upToSeq)
if err != nil {
return nil, err
}
}
feed := make(chan *ChangeEntry, 5)
go func() {
defer close(feed)
// First, if we need to backfill from the view, write its early entries to the channel:
if viewFeed != nil {
newLog := channels.ChangeLog{Since: since}
for change := range viewFeed {
if channelLog != nil && change.seqNo > channelLog.Since {
// TODO: Close the view-based feed somehow
break
}
select {
case <-options.Terminator:
base.LogTo("Changes+", "Aborting changesFeed (reading from view)")
return
case feed <- change:
}
if rebuildLog {
// If there wasn't any channel log, build up a new one from the view:
entry := channels.LogEntry{
Sequence: change.seqNo,
DocID: change.ID,
RevID: change.Changes[0]["rev"],
}
if change.Deleted {
entry.Flags |= channels.Deleted
}
if change.Removed != nil {
entry.Flags |= channels.Removed
}
newLog.Add(entry)
newLog.TruncateTo(MaxChangeLogLength)
}
}
if rebuildLog {
// Save the missing channel log we just rebuilt:
base.LogTo("Changes", "Saving rebuilt channel log %q with %d sequences",
channel, len(newLog.Entries))
db.changesWriter.addChangeLog(channel, &newLog)
}
}
// Now write each log entry to the 'feed' channel in turn:
for _, logEntry := range log {
if !options.Conflicts && (logEntry.Flags&channels.Hidden) != 0 {
//continue // FIX: had to comment this out.
// This entry is shadowed by a conflicting one. We would like to skip it.
// The problem is that if this is the newest revision of this doc, then the
// doc will appear under this sequence # in the changes view, which means
// we won't emit the doc at all because we already stopped emitting entries
// from the view before this point.
}
change := ChangeEntry{
seqNo: logEntry.Sequence,
ID: logEntry.DocID,
Deleted: (logEntry.Flags & channels.Deleted) != 0,
Changes: []ChangeRev{{"rev": logEntry.RevID}},
}
if logEntry.Flags&channels.Removed != 0 {
change.Removed = channels.SetOf(channel)
} else if options.IncludeDocs || options.Conflicts {
doc, _ := db.GetDoc(logEntry.DocID)
db.addDocToChangeEntry(doc, &change, options.IncludeDocs, false)
}
select {
case <-options.Terminator:
base.LogTo("Changes+", "Aborting changesFeed")
return
case feed <- &change:
}
if options.Limit > 0 {
options.Limit--
if options.Limit == 0 {
break
}
}
}
}()
return feed, nil
}
// Returns a list of all the changes made on a channel.
// Does NOT handle the Wait option. Does NOT check authorization.
func (db *Database) changesFeed(channel string, options ChangesOptions) (<-chan *ChangeEntry, error) {
since := options.Since[channel]
channelLog, err := db.GetChangeLog(channel, since)
if err != nil {
base.Warn("Error reading channel-log %q (using view instead) %v", channel, err)
channelLog = nil
}
rebuildLog := channelLog == nil && err == nil && (EnableStarChannelLog || channel != "*")
var log []*channels.LogEntry
if channelLog != nil {
log = channelLog.Entries
}
var viewFeed <-chan *ChangeEntry
if channelLog == nil || channelLog.Since > since {
// Channel log may not go back far enough, so also fetch view-based change feed:
viewFeed, err = db.changesFeedFromView(channel, options)
if err != nil {
return nil, err
}
}
feed := make(chan *ChangeEntry, 5)
go func() {
defer close(feed)
// First, if we need to backfill from the view, write its early entries to the channel:
if viewFeed != nil {
newLog := channels.ChangeLog{Since: since}
for change := range viewFeed {
if len(log) > 0 && change.seqNo >= log[0].Sequence {
// TODO: Close the view-based feed somehow
break
}
feed <- change
if rebuildLog {
// If there wasn't any channel log, build up a new one from the view:
entry := channels.LogEntry{
Sequence: change.seqNo,
DocID: change.ID,
RevID: change.Changes[0]["rev"],
}
if change.Deleted {
entry.Flags |= channels.Deleted
}
if change.Removed != nil {
entry.Flags |= channels.Removed
}
newLog.Add(entry)
newLog.TruncateTo(MaxChangeLogLength)
}
}
if rebuildLog {
// Save the missing channel log we just rebuilt:
base.LogTo("Changes", "Saving rebuilt channel log %q with %d sequences",
channel, len(newLog.Entries))
if _, err := db.AddChangeLog(channel, &newLog); err != nil {
base.Warn("ChangesFeed: AddChangeLog failed, %v", err)
}
}
}
// Now write each log entry to the 'feed' channel in turn:
for _, logEntry := range log {
hidden := (logEntry.Flags & channels.Hidden) != 0
if logEntry.RevID == "" || (hidden && !options.Conflicts) {
continue
}
change := ChangeEntry{
seqNo: logEntry.Sequence,
ID: logEntry.DocID,
Deleted: (logEntry.Flags & channels.Deleted) != 0,
Changes: []ChangeRev{{"rev": logEntry.RevID}},
}
if logEntry.Flags&channels.Removed != 0 {
change.Removed = channels.SetOf(channel)
} else if options.IncludeDocs || options.Conflicts {
doc, _ := db.getDoc(logEntry.DocID)
db.addDocToChangeEntry(doc, &change, options.IncludeDocs, false)
}
feed <- &change
if options.Limit > 0 {
options.Limit--
if options.Limit == 0 {
break
}
}
}
}()
return feed, nil
}
