add distributor stub

internal/distributor/distributor.go

@@ -0,0 +1,96 @@
+/*
+   GoToSocial
+   Copyright (C) 2021 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package distributor
+
+import (
+	"github.com/go-fed/activity/pub"
+	"github.com/sirupsen/logrus"
+)
+
+// Distributor should be passed to api modules (see internal/module/...). It is used for
+// passing messages back and forth from the client API and the federating interface, via channels.
+// It also contains logic for filtering which messages should end up where.
+// It is designed to be used asynchronously: the client API and the federating API should just be able to
+// fire messages into the distributor and not wait for a reply before proceeding with other work. This allows
+// for clean distribution of messages without slowing down the client API and harming the user experience.
+type Distributor interface {
+	// ClientAPIIn returns a channel for accepting messages that come from the gts client API.
+	ClientAPIIn() chan interface{}
+	// ClientAPIOut returns a channel for putting in messages that need to go to the gts client API.
+	ClientAPIOut() chan interface{}
+	// Start starts the Distributor, reading from its channels and passing messages back and forth.
+	Start() error
+	// Stop stops the distributor cleanly, finishing handling any remaining messages before closing down.
+	Stop() error
+}
+
+// distributor just implements the Distributor interface
+type distributor struct {
+	federator    pub.FederatingActor
+	clientAPIIn  chan interface{}
+	clientAPIOut chan interface{}
+	stop         chan interface{}
+	log          *logrus.Logger
+}
+
+// New returns a new Distributor that uses the given federator and logger
+func New(federator pub.FederatingActor, log *logrus.Logger) Distributor {
+	return &distributor{
+		federator:    federator,
+		clientAPIIn:  make(chan interface{}, 100),
+		clientAPIOut: make(chan interface{}, 100),
+		stop:         make(chan interface{}),
+		log:          log,
+	}
+}
+
+// ClientAPIIn returns a channel for accepting messages that come from the gts client API.
+func (d *distributor) ClientAPIIn() chan interface{} {
+	return d.clientAPIIn
+}
+
+// ClientAPIOut returns a channel for putting in messages that need to go to the gts client API.
+func (d *distributor) ClientAPIOut() chan interface{} {
+	return d.clientAPIOut
+}
+
+// Start starts the Distributor, reading from its channels and passing messages back and forth.
+func (d *distributor) Start() error {
+	go func() {
+	DistLoop:
+		for {
+			select {
+			case clientMsgIn := <-d.clientAPIIn:
+				d.log.Infof("received clientMsgIn: %+v", clientMsgIn)
+			case clientMsgOut := <-d.clientAPIOut:
+				d.log.Infof("received clientMsgOut: %+v", clientMsgOut)
+			case <-d.stop:
+				break DistLoop
+			}
+		}
+	}()
+	return nil
+}
+
+// Stop stops the distributor cleanly, finishing handling any remaining messages before closing down.
+// TODO: empty message buffer properly before stopping otherwise we'll lose federating messages.
+func (d *distributor) Stop() error {
+	close(d.stop)
+	return nil
+}