[ntcore] Various NT4 fixes (#4474)

* TopicListener: Fix Add() return values
* Update PubSubOption poll storage documentation
* Update NetworkTableEntry::GetValue() doc
* Add documentation regarding asynchronous callbacks
* Unpublish entry: set publisher to nullptr
* Implement ValueListenerPoller default constructor
* Remove SetNetworkIdentity, make parameter to StartClient
* URI-escape client ID, improve error message
* Add connected message with client id; also improve disconnected message a bit
* Handle SetServers either before or after StartClient
* Fix client use-after-free; also delay reconnect after disconnect to rate limit
* Don't re-announce to already subscribed client; we especially don't want to send the last value again
* Always accept in-order sets, only use timestamp for tiebreak
* Fix LocalStorage::StartNetwork race
* Remove unused/unimplemented function

Also:
* [glass] Remove debug print
* [glass] Fix mpack string decoding
* [cameraserver] Fix up startclient

ntcore/src/main/native/cpp/net/ClientImpl.cpp

@@ -54,7 +54,6 @@ class CImpl : public ServerMessageHandler {
 
   void ProcessIncomingBinary(std::span<const uint8_t> data);
   void HandleLocal(std::vector<ClientMessage>&& msgs);
-  void SendOutgoing(std::span<const ClientMessage> msgs);
   bool SendControl(uint64_t curTimeMs);
   void SendValues(uint64_t curTimeMs);
   bool CheckNetworkReady();

ntcore/src/main/native/cpp/net/NetworkInterface.h

@@ -59,8 +59,8 @@ class NetworkInterface : public NetworkStartupInterface {
 
 class ILocalStorage : public LocalInterface {
  public:
-  virtual void StartNetwork(NetworkStartupInterface& startup) = 0;
-  virtual void SetNetwork(NetworkInterface* network) = 0;
+  virtual void StartNetwork(NetworkStartupInterface& startup,
+                            NetworkInterface* network) = 0;
   virtual void ClearNetwork() = 0;
 };
 

ntcore/src/main/native/cpp/net/ServerImpl.cpp

@@ -325,6 +325,7 @@ struct TopicData {
   std::string name;
   unsigned int id;
   Value lastValue;
+  ClientData* lastValueClient = nullptr;
   std::string typeStr;
   wpi::json properties = wpi::json::object();
   bool persistent{false};
@@ -627,6 +628,15 @@ void ClientData4Base::ClientSubscribe(int64_t subuid,
       removed = topic->subscribers.Remove(sub.get());
     }
 
+    // is client already subscribed?
+    bool wasSubscribed = false;
+    for (auto subscriber : topic->subscribers) {
+      if (subscriber->client == this) {
+        wasSubscribed = true;
+        break;
+      }
+    }
+
     bool added = false;
     if (sub->Matches(topic->name, topic->special)) {
       topic->subscribers.Add(sub.get());
@@ -645,7 +655,7 @@ void ClientData4Base::ClientSubscribe(int64_t subuid,
       }
     }
 
-    if (added && !removed) {
+    if (!wasSubscribed && added && !removed) {
       // announce topic to client
       DEBUG4("client {}: announce {}", m_id, topic->name);
       SendAnnounce(topic.get(), std::nullopt);
@@ -2086,11 +2096,13 @@ void SImpl::SetFlags(ClientData* client, TopicData* topic, unsigned int flags) {
 }
 
 void SImpl::SetValue(ClientData* client, TopicData* topic, const Value& value) {
-  // update retained value if timestamp newer
-  if (!topic->lastValue || value.time() > topic->lastValue.time()) {
+  // update retained value if from same client or timestamp newer
+  if (!topic->lastValue || topic->lastValueClient == client ||
+      value.time() >= topic->lastValue.time()) {
     DEBUG4("updating '{}' last value (time was {} is {})", topic->name,
            topic->lastValue.time(), value.time());
     topic->lastValue = value;
+    topic->lastValueClient = client;
 
     // if persistent, update flag
     if (topic->persistent) {

ntcore/src/main/native/cpp/net/WebSocketConnection.cpp

@@ -44,10 +44,12 @@ void WebSocketConnection::Flush() {
   }
 
   ++m_sendsActive;
-  m_ws.SendFrames(m_ws_frames, [this](auto bufs, auto) {
-    m_buf_pool.insert(m_buf_pool.end(), bufs.begin(), bufs.end());
-    if (m_sendsActive > 0) {
-      --m_sendsActive;
+  m_ws.SendFrames(m_ws_frames, [selfweak = weak_from_this()](auto bufs, auto) {
+    if (auto self = selfweak.lock()) {
+      self->m_buf_pool.insert(self->m_buf_pool.end(), bufs.begin(), bufs.end());
+      if (self->m_sendsActive > 0) {
+        --self->m_sendsActive;
+      }
     }
   });
   m_frames.clear();

ntcore/src/main/native/cpp/net/WebSocketConnection.h

@@ -4,6 +4,7 @@
 
 #pragma once
 
+#include <memory>
 #include <vector>
 
 #include <wpi/SmallVector.h>
@@ -15,7 +16,9 @@
 
 namespace nt::net {
 
-class WebSocketConnection final : public WireConnection {
+class WebSocketConnection final
+    : public WireConnection,
+      public std::enable_shared_from_this<WebSocketConnection> {
  public:
   explicit WebSocketConnection(wpi::WebSocket& ws);
   ~WebSocketConnection() override;