snapshot of https://github.com/go-gitea/gitea.git (main, 2026-09-15; blobs > 131072B omitted)

services/pubsub/broker.go

@@ -0,0 +1,39 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+// Package pubsub fans real-time events out to local WebSocket subscribers.
+// Backend is chosen at boot: in-process map (single-instance) or Redis
+// (multi-process). DefaultBroker is wired by Init from setting.Websocket.
+package pubsub
+
+import "fmt"
+
+// subChanBuffer is how many messages a subscriber may fall behind before its
+// messages are dropped instead of stalling the publisher.
+const subChanBuffer = 8
+
+type Broker interface {
+	// Subscribe returns a buffered channel of messages for topic, and a cancel
+	// func that closes the channel and removes the subscription. cancel is
+	// idempotent.
+	Subscribe(topic string) (<-chan []byte, func())
+
+	// Publish delivers msg to every subscriber of topic. Non-blocking: a slow
+	// subscriber drops messages rather than stalling the publisher.
+	Publish(topic string, msg []byte)
+
+	// HasTopicSubscribers is an optimization hint for publishers that would
+	// otherwise do a DB lookup just to discover nobody is listening. Backends
+	// that cannot answer cheaply across processes return true to be safe.
+	HasTopicSubscribers(topic string) bool
+}
+
+// DefaultBroker is replaced by Init from setting.Websocket. It starts as an
+// empty memory broker so non-web entry points (e.g. CLI), which skip Init, can
+// publish without nil checks — with no subscribers every publish is a no-op.
+// Tests construct a broker explicitly (NewMemoryBroker) instead of relying on this.
+var DefaultBroker Broker = NewMemoryBroker()
+
+func UserTopic(userID int64) string {
+	return fmt.Sprintf("user-%d", userID)
+}