/// <summary>
/// Subscribes this object to the given database's <c>Changed</c> event for
/// processing
/// </summary>
/// <param name="db">Db.</param>
public void SubscribeToDatabase(Database db, long since, ChangesOptions options)
{
if (db == null)
{
return;
}
Db = db;
IsAsync = true;
_since = since;
_options = options;
if (ChangesFeedMode == ChangesFeedMode.LongPoll)
{
var currentChanges = Db.ChangesSince(since, options, ChangesFilter, FilterParams);
IsAsync = !currentChanges.Any();
if (!IsAsync)
{
if (ChangesIncludeConflicts)
{
Response.JsonBody = new Body(DatabaseMethods.ResponseBodyForChanges(currentChanges, since, options.Limit, this));
}
else
{
Response.JsonBody = new Body(DatabaseMethods.ResponseBodyForChanges(currentChanges, since, this));
}
}
else
{
Db.Changed += DatabaseChanged;
}
}
}
// Processes a change in the subscribed database
private void DatabaseChanged(object sender, DatabaseChangeEventArgs args)
{
foreach (var change in args.Changes)
{
var rev = change.AddedRevision;
var winningRev = change.WinningRevision;
if (!ChangesIncludeConflicts)
{
if (winningRev == null)
{
continue; // this change doesn't affect the winning rev ID, no need to send it
}
if (rev.Equals(winningRev))
{
// This rev made a _different_ rev current, so substitute that one.
// We need to emit the current sequence # in the feed, so put it in the rev.
// This isn't correct internally (this is an old rev so it has an older sequence)
// but consumers of the _changes feed don't care about the internal state.
if (ChangesIncludeDocs)
{
_db.LoadRevisionBody(rev, DocumentContentOptions.None);
}
}
}
if (!_db.RunFilter(ChangesFilter, null, rev))
{
continue;
}
if (ChangesFeedMode == ChangesFeedMode.LongPoll)
{
_changes.Add(rev);
}
else
{
Log.D(TAG, "Sending continuous change chunk");
var written = Response.SendContinuousLine(DatabaseMethods.ChangesDictForRev(rev, this), ChangesFeedMode);
if (!written)
{
Terminate();
}
}
}
if (ChangesFeedMode == ChangesFeedMode.LongPoll && _changes.Count > 0)
{
var body = new Body(DatabaseMethods.ResponseBodyForChanges(_changes, 0, this));
Response.WriteData(body.AsJson(), true);
CouchbaseLiteRouter.ResponseFinished(this);
}
}
private void WriteChanges(RevisionList changes)
{
if (changes.Count > 0)
{
if (ChangesFeedMode == ChangesFeedMode.LongPoll)
{
var body = new Body(DatabaseMethods.ResponseBodyForChanges(changes, 0, this));
Response.WriteData(body.AsJson(), true);
Terminate();
}
else
{
foreach (var rev in changes)
{
var written = Response.SendContinuousLine(DatabaseMethods.ChangesDictForRev(rev, this), ChangesFeedMode);
if (!written)
{
Terminate();
break;
}
}
}
}
}