FEXServer: Use a pipe to register new log clients instead of signaling across threads

Source/Tools/FEXServer/Logger.cpp

@@ -12,12 +12,8 @@ void ClientMsgHandler(int FD, FEXServerClient::Logging::PacketMsg* const Msg, co
 }
 
 namespace Logger {
-std::vector<struct pollfd> PollFDs {};
-std::mutex IncomingPollFDsLock {};
-std::vector<struct pollfd> IncomingPollFDs {};
+int LogClientQueuePipe[2];
 std::thread LogThread;
-std::atomic<bool> ShouldShutdown {false};
-std::atomic<int32_t> LoggerThreadTID {};
 
 void HandleLogData(int Socket) {
   std::vector<uint8_t> Data(1500);
@@ -58,71 +54,75 @@ void HandleLogData(int Socket) {
 }
 
 void LogThreadFunc() {
-  LoggerThreadTID = FHU::Syscalls::gettid();
+  std::vector<pollfd> PollFDs;
+  PollFDs.push_back(pollfd {.fd = LogClientQueuePipe[0], .events = POLLIN | POLLHUP, .revents = 0});
 
-  while (!ShouldShutdown) {
-    struct timespec ts {};
-    ts.tv_sec = 5;
-
-    {
-      std::unique_lock lk {IncomingPollFDsLock};
-      PollFDs.insert(PollFDs.end(), std::make_move_iterator(IncomingPollFDs.begin()), std::make_move_iterator(IncomingPollFDs.end()));
-      IncomingPollFDs.clear();
+  while (true) {
+    int Result = ppoll(PollFDs.data(), PollFDs.size(), nullptr, nullptr);
+    if (Result <= 0) {
+      continue;
     }
-    if (PollFDs.size() == 0) {
-      pselect(0, nullptr, nullptr, nullptr, &ts, nullptr);
-    } else {
-      int Result = ppoll(&PollFDs.at(0), PollFDs.size(), &ts, nullptr);
-      if (Result > 0) {
-        // Walk the FDs and see if we got any results
-        for (auto it = PollFDs.begin(); it != PollFDs.end();) {
-          bool Erase {};
-          if (it->revents != 0) {
-            if (it->revents & POLLIN) {
-              // Data from the socket
-              HandleLogData(it->fd);
-            } else if (it->revents & (POLLHUP | POLLERR | POLLNVAL | POLLRDHUP)) {
-              // Error or hangup, close the socket and erase it from our list
-              Erase = true;
-              close(it->fd);
-            }
 
-            it->revents = 0;
-            --Result;
-          }
+    // Process events for client pipe
+    if (PollFDs[0].revents) {
+      --Result;
 
-          if (Erase) {
-            it = PollFDs.erase(it);
-          } else {
-            ++it;
-          }
+      auto [PipeFD, _, revents] = PollFDs[0];
+      PollFDs[0].revents = 0;
 
-          if (Result == 0) {
-            // Early break if we've consumed all the results
-            break;
-          }
-        }
+      if (revents & POLLIN) {
+        int ReceivedFD;
+        read(PipeFD, &ReceivedFD, sizeof(ReceivedFD));
+        PollFDs.push_back(pollfd {
+          .fd = ReceivedFD,
+          .events = POLLIN,
+          .revents = 0,
+        });
+      }
+
+      if (revents & POLLHUP) {
+        close(PipeFD);
+        return;
+      }
+    }
+
+    // Process events for log FDs
+    for (auto it = PollFDs.begin() + 1; Result && it != PollFDs.end();) {
+      if (it->revents == 0) {
+        ++it;
+        continue;
+      }
+      --Result;
+
+      bool Erase {};
+      if (it->revents & POLLIN) {
+        // Data from the socket
+        HandleLogData(it->fd);
+      } else if (it->revents & (POLLHUP | POLLERR | POLLNVAL | POLLRDHUP)) {
+        // Error or hangup, close the socket and erase it from our list
+        Erase = true;
+        close(it->fd);
+      }
+
+      it->revents = 0;
+
+      if (Erase) {
+        it = PollFDs.erase(it);
+      } else {
+        ++it;
       }
     }
   }
 }
 
 void StartLogThread() {
+  pipe2(LogClientQueuePipe, 0);
+
   LogThread = std::thread(LogThreadFunc);
 }
 
 void AppendLogFD(int FD) {
-  {
-    std::unique_lock lk {IncomingPollFDsLock};
-    IncomingPollFDs.emplace_back(pollfd {
-      .fd = FD,
-      .events = POLLIN,
-      .revents = 0,
-    });
-  }
-
-  // Wake up the thread immediately
-  FHU::Syscalls::tgkill(::getpid(), LoggerThreadTID, SIGUSR1);
+  write(LogClientQueuePipe[1], &FD, sizeof(FD));
 }
 
 bool LogThreadRunning() {
@@ -130,10 +130,7 @@ bool LogThreadRunning() {
 }
 
 void Shutdown() {
-  ShouldShutdown = true;
-
-  // Wake up the thread immediately
-  FHU::Syscalls::tgkill(::getpid(), LoggerThreadTID, SIGUSR1);
+  close(LogClientQueuePipe[1]);
 
   if (LogThread.joinable()) {
     LogThread.join();