Accumulated changes for message queue (#6600)

* rename

* set agent address

* refactor

* add agent sub

* pub messages

* grpc new client

* can publish records via agent

* send init message with session id

* fmt

* check cancelled request while waiting

* use sessionId

* handle possible nil stream

* subscriber process messages

* separate debug port

* use atomic int64

* less logs

* minor

* skip io.EOF

* rename

* remove unused

* use saved offsets

* do not reuse session, since always session id is new after restart

remove last active ts from SessionEntry

* simplify printing

* purge unused

* just proxy the subscription, skipping the session step

* adjust offset types

* subscribe offset type and possible value

* start after the known tsns

* avoid wrongly set startPosition

* move

* remove

* refactor

* typo

* fix

* fix changed path

weed/mq/agent/agent_server.go

@@ -11,8 +11,7 @@ import (
 
 type SessionId int64
 type SessionEntry[T any] struct {
-	entry          T
-	lastActiveTsNs int64
+	entry T
 }
 
 type MessageQueueAgentOptions struct {
@@ -32,11 +31,15 @@ type MessageQueueAgent struct {
 
 func NewMessageQueueAgent(option *MessageQueueAgentOptions, grpcDialOption grpc.DialOption) *MessageQueueAgent {
 
-	// check masters to list all brokers
+	// initialize brokers which may change later
+	var brokers []pb.ServerAddress
+	for _, broker := range option.SeedBrokers {
+		brokers = append(brokers, broker)
+	}
 
 	return &MessageQueueAgent{
 		option:         option,
-		brokers:        []pb.ServerAddress{},
+		brokers:        brokers,
 		grpcDialOption: grpcDialOption,
 		publishers:     make(map[SessionId]*SessionEntry[*pub_client.TopicPublisher]),
 		subscribers:    make(map[SessionId]*SessionEntry[*sub_client.TopicSubscriber]),